Hazardous Materials

CHAPTER 10 Chemistry of Some Toxic Substances

5'5< w 72 q: & <ZW C Q ;;;p:;m

Courtesy of The Fertilizer Institute, Washington, DC.

acid rain, p. 378 acute health effect, p. 354 antidote, p. 353 asbestosis, p. 405 asphyxiant, p. 352 beryllium sensitization, p. 356 beryllosis (chronic beryllium disease), p. 356 biological warfare agent (germ warfare agent), p. 410 Bioterrorism Acts, p. 412 cancer, p. 398 carboxyhemoglobin, p. 365 carcinogen, p. 398 ceiling limit (C), p. 360 chronic bronchitis, p. 355 chronic health effect, p. 354 cilia, p. 362 coronary heart disease, p. 354 countable elongate mineral Particle, p. 406 cyanosis, p. 372 diagnostic specimen, p. 414 dose, p. 355 emphysema, p. 355

epidemiology, p. 346 essential element, p. 401 friable, p. 405 gas poisonous-by-inhalation (poison gas), p. 347 hemoglobin, p. 365 hemotoxicant, p. 352 hepatotoxicant, p. 352 hyperbaric oxygen therapy, p. 370 hypergolic, p. 382 immediately-dangerous-to-life- and-health limit (IDLH), p. 360 infectious pathogen, p. 410 infectious substance, p. 413 ingestion, p. 349 inhalation, p. 349 initial isolation distance, p. 392 initial isolation zone, p. 392 initiation, p. 399 irritant, p. 353 lacrimator, p. 362 latent health effect, p. 354 lead-based paint, p. 402 lead poisoning, p. 402

lethal concentration, 50% kill (LCsol, p. 359 lethal dose, 50% kill (LD50), p. 359 Lethal London Smog Episode (Great Smog), p. 377 local effect, p. 352 lung cancer, p. 405 mesothelioma, p. 405 mesothelium, p. 405 metabolism, p. 350 metastasis, p. 399 methemoglobin, p. 385 methemoglobinemia, p. 385 nephrotoxicant, p. 352 neurotoxicant, p. 352 nurse tank, p. 387 olfactory fatigue, p. 380 oxyhemoglobin, p. 365 particulate matter, p . 361 permissible exposure limit (PEL), p. 360 pleural mesothelioma, p. 405 poisonous material, p. 347 progression, p. 399 promotion, p . 399

345

1/I I

protective--actlon distance-. p. 397 protective--action zone, p. 397 pulse CO-Oxlmeter, p . 366 RCRA toxicity characteristic. p. 347 recommended exposure limit (RELj, p. 360

risk group, p. 413 select agent. P- 412

sensitizer, p. 356 short-tenn exposure limit (STEL}, p. 360 short-tenn health effect. p. 354 skin absorption, P· 349

synergism, p. 400 systemic effect, p . 352 threshold limit value (TLV), p .

359 toxic metal, p. 401 toxicology, p. 346 toxic substance (toxlcant; Poison)

I

Ii

,I: I

I

toxin, p. 410 'P. 345 reproductive toxicant. p . 351 respiratory toxicant. p . 352

smoke, p. 361 soot p. 361

tumor, p. 399

toxi c su bsta nce (toxicant po ison) • Any subnance that neg a- tively im pacts an ind i- vidu al exposed to relat ive ly sma ll concen- trations, resulting in death, incapacitation. or the onset of d isease or other forms of harm

The study of toxic substances that adversely imp act the health of humans and other organ isms, as well as the ways the impact may be counteracted

epidem iolog y • The study of the adverse effects that tox ic sub- stances and d iseases pose to human populations

i +M,Mill Associa te rhe physical and health hazard~ of rhe tox.ic substances nored i_n this cha . rer with the informacion provided by rhe1~ hazard diamonds and GHS pictogram/ Idenrify rhe common means by which toxic substances may enter the body and adversd}' impact human health. . Describe generally the ways in which a toxic substance may adversely affect one's

health. · · I · f Identify the factors that affect the degree of rox1c1ty resu tmg rom chemical

;=:~:he mechanisms by which carbon monoxide and hydrogen cyanide interfere with the proper transfer of oxygen to the cell~ of the body. Identify how on-dury firefighters may determ1~e whether they have been overex- posed ro carbon monoxide and hydrogen cyamde. Identify the chemical features of commercial products that produce su lfur dioxide, hydrogen sulfide, and nitrogen oxides w_hen the products smolder or b~rn. Identify the primary industries rhat are likely rouse anhyd~ous ammonta. Identify the labels, markings, and placards that DOT requires on the packaging of roxic substances and the transpo rt vehicles used for their shipment. Identify the response actions to be executed w hen toxic substances are released from their packaging into the environment. Describe how emergency responders use DOT's Emergency Response Guidebook to establish the initial isolation and prorecti ve•action zones associated with large and sma ll spills of a toxic substance .

Certain substances cause death, illness, injury, or incapacitation when rhe body is exposed to them in relatively small quantities. They are called toxic substances, toxicants, or poisons. Throughout the remainder of this text, these terms are used intercbangeably.

The study of roxic substances is called toxicology. In particular, it investigates the manner in which how roxic substances adversely affect a living organism, the diseases they may cause, the concentrations at which the onset of the adverse effects is noted, and ways IO prevent or minimize them. The study of the adverse effects that toxic s ubstances and d iseases have on human populations is called epidemiology.

Toxic substances are routinely encountered by firefighters and other emergency responders. For example, carbon monoxide gas is produced by the assorted materials rhar burn, and asbestos and lead are encounrered in the dust that is generated as o ld buildings burn or are otherwise wracked by rhe forces associated with fires. It is for this reason th31

a need ~xists for emergency responders ro stud y the commonly encountered roxic sub· stances m some detai l.

346 Chapter 10 Chemistry of Some Toxic Substances

T 1 TOXIC SUBSTANCES AN 10, REGULATIONS D GOVERNMENT

hough ihe l:lypers~~ genera ll y understands the . t~~flo"'\edge the spcc1f1c :v?y the term is defined a:e:~:ng. of a poiso n, it is important to

. fl)' review how toxicity affects workpla . d m government regulations We bne,[3tions. ce, env ironm enta l, and transporta.tion rc&l

O 1.A WORKPLACE REGULATIONS INVOLVI 1 . g its responsibilities, OSHA requires em I NG TOXIC SUBSTANCES At1100

0 f employment free of conditions or acti;t?yer~ to provide their employees with a

pl 3~~ cJuse their death or serious physical harn 1

iesht at:re ~ecognized as hazardous and 'i~: ha za rds. Beyond this general duty ob li gat;~:, :~;/re 1~ a feasible method to abare t din rhe workplace, OSHA a lso requires empl toxic substances are stored or use xic substa nces is limited to no more t han certo~ers to .ensure that emp loyee exposure :::~

3 ged over the 8-h.our workday. am maximum allowable concentrations

OSHA also r~qu1res employers to tag, label, or otherwise .d .fy toxic substances m th.e workplace by the use of accident- rev I e_ntt the presence of signs. These ra~s ~nd signs_ warn employees that they should~xer:7t1on rags and wor~ed co reduce or e!tm1~ate _their exposure to toxic substances. Most b;e atequate precaution ·n 3ddition to the ,mpnnt of a skull and crossbones which h l art e word P?ISON :ionJlly acknowledged symbol for poison. ' as ong served as the mterna•

As we first_ noted in Section 1.9, O~HA also requires chemical manufacturers dis- tributors, an_d importers to mark co.ntamer labels with signa l words, GHS icto ;ams and app~opnate haza~d and preca_ut1onary statements. The health hazards afe ide~tified by markm? rhe. container labels w ith the skull-and-crossbones, health hazard, and excla• mation pomt p1ctograms.

10.1-B RCRA TOXICITY CHARACTERISTIC

RCRA toxic ity characteri stic• For purposes of RCRA regulations, the charac- teristic of a waste that contains one or more of listed constituents at concentrations equal to or greater than the threshold levels desig• nated at 40 C.F.R. §261 .24

gas poison ous-by- inhalation (poiso n gas) • For purposes of DOT regulations, a gas at 68"F (20"0 or less and

EP~ ~ses RC~ to regul~tc. the treatment, storage, and disposal of hazardous waste that exh1b.1ts certain charact~nsncs, one of which is toxicity. As noted at 40 C.F.R. §261.24, a che?1_1cal analyst d_et~rmmes wheth.er a representative sample of a waste exhibits the RCRA tox1c1ty characteristic by perform.mg a laboratory test designed to simulate the environ- me nt wit~in a landfill. In practice, the a nalyst conducts certain specified test procedures to determme whether one or more of the waste constituents listed at 40 C.F.R. S261.24 leaches from the sample at concentrations equa l to or greater than their relevant threshold levels. Some representative waste constituents and their threshold levels are listed in Table 10.1. Each listed substance adversely affects public health and the environment. When the analyst determines that at least one constituent leaches from the sample at a conce ntration equal to or exceeding the threshold le vel, the waste is said to exhibit the RCRA toxicity characteristic.

a pressure of 14.7 psi. (101.3 kPa) that is known to be so toxic to humans as to pose a health hazard during transportation; or in the absence of ade- quate data on human toxicity, is presumed to be toxic to humans because when tested on laboratory animals, it has an LC50 of less than 5000 mUm3

poisonous material For purposes of DOT

regulations, a material other than a gas that is known to be so toxic to humans as to afford a hazard to health during transportation, or that in the absence of ade- quate data on human toxicity, is presumed to be toxic to humans because of data

In ~hapter 6, we first noted that DOT regulates the transportation of severa l types of ;:~~~nde~r:t;e~:~l. roxi~ substances: gases poisonous-by-inhalation (poison gases), poisonous materials, and inhalation toxicity ~nd mfectious substances. These toxic substances are designated as hazardous materials tests performed on ani- m hazard classes 2.3, 6.1, and 6.2, respectively. All hazardous materials in hazard classes mals; or is an irritating 2 3 d 6 h I f h H d M · l material with proper-! an . I t at are designated by a 1, 2, 3, or 4 in co umn 7 o t e aza r ous l atena s tiessimilar to those of ab le pose a health threat by inhalation . . . tear gas that causes

\~hen toxic substances are transported, DOT requires shippers and earners t? com- extreme irritation, espe- p]y With applicable labeling, marking, and placarding requirements. \Vhen preparmg the dally in confined spaces

Chapter 10 Chemistry of Some Toxic Substances 347

10.1-C TRANSPORTING TOXIC SUBSTANCES

rn I

l 348

ifrii¥11 EPA HAZARD OUS WASTE NU MBER

0 004 0005 0018 0006 0019 000 7 0025 0028

0029 0 008

D009 0010 D0 11

0039 0040 1 40C.F.R. §261.14.

Id Co ncentra ti o ns of Some Representa tive Wa t Thresho ts Sub1ect to the RCRA Toxicity Character, st• Contam1nan s 1('1

HAZARDOUS WASTE CONTAMINANT

Arsenic

Ba rium

Ben zene I Cadm ium 1 Carbo n tetrachlor i de

Ch rom ium

p -Cresol l ,2-0 ichloroethane l , 1-Dich loroethyl ene

Lead M ercury

Selen ium Silver Tetrachloro e thylene

I Tr ich loroethylen e

I;:~c,HOLD LE\/El 5.0

100.0

0 .5

1.0 0.5

5 .0

200.0

0 .5

0 7

5 .0

0 .2

1.0

5 .0

0 .7

0 .5

..,,,

s hipping descrip tio n of a roxic substance, DOT req uires shippe r_s co includ ~ th e expres- sion " Poiso n _ Inhalation Hazard" a nd the releva nt haza rd zone m t he desc riptio n. DOT also requires shippers ro affix the app licable POISON GAS o r PO ISO N IN HALATION HAZARD la bels co the rele vant packaging.

DOT requires ca rriers to disp lay th e PO ISO N GAS o r PO ISON IN HAL ATIO N HAZARD placards shown in Figure 6. 13 as fo llows:

DOT requires ca rrie rs ro displa y the a pplica ble PO ISON GAS o r POI SO N L~- HALATION HAZARD placa rds o n both sides an d both en ds of the transport vehicl e, freight container, porta ble tank , uni t load device, or ra il ta nk ~a r use d fo r shipment of a haza rdous material ha ving the haz.a rd code 2.3 o r 6. 1, respecti ve ly.

DOT req ui res ca rriers to dis play POISON GAS placards w hen tra nsportin g any quantity of a substance that has bee n ass igned a haza rd cl ass numbe r 2 .3 .

DOT requires carrie rs to display POISO N IN H ALATION H AZARD placards when transporting any quant ity of a su bstance tha t has been ass igned a haza rd cl ass nwnber 6. 1 and a haza rd zo ne classifica tio n as Zo ne A o r Zone B.

A s noted in Section 6.6-D, when carrie rs tra nspo rt a haza rd o u s ma terial whose ha za rd class is 2.3 or 6. 1 by rail, DOT requ ires them to post PO ISON GAS or POI SO:-.l IN HA LATIO N HAZA RD placards on white squ a res w ith bl ac k borde rs w hen the haza rd zone fo r the haza rdo us ma teria l is Zone A.

When ca rri ers transport multiple toxic substan ces w hose haza rd cl a sses :u e dtsig· nated 2.3 and 6. l in no nbulk packages in the same tra nspo rt vehicle, DOT a ll ows them to pose POISO N GAS placa rds only o n the ve hicle.

When the subsidiary ha zard class o f a haza rd o us ma teria l is 6. 1, D OT requires carrie rs co display PO ISO N IN HALATIO N HAZ ARD placa rds on its packagi ng.

. When a ma ter ia l th a1 poses a hea lth haza rd by in ha la ti o n is ship pe d in bulk pack ~g· mg, DOT a lso requires th e shipper to mark the packagi ng on rwo o pposin g sides \\'lth

Cha pter 10 Chemistry of So me Toxic Substa nces

Shipping Descnpt1ons of Some Wastes Exhibiting the EPA li ~epresentat,ve Haza rdous

ox1c1ty Charactern,t,c

11DousWASTE tt,lZA ardous waste that exhibits the ;~~~~~;:~a racteristic fo r arsenic

. haz ardou s waste th at exhi bits the ~~

1 ~

1 tY ch aracte ristic for me rcury

SH IPP ING DESCRIPTION

~.'°;;ci~,~,(~l~~~~~~~aste, liqui d, n.o.s. (arsenic), o, ~.'°;,3ci~

1 ~,( ~~~:;dous waste, liquid, n.o.s. (arseni c),

NA3077, Haz ar dous waste, soli d, n.o.s. (mercury), 9, PG Il l (E PA to J1.icity) o,

~.A:i:1: ,(~~~;;dou s waste, so li d, n.o.s. (m ercury),

the words INH ALAT ION H AZ~ RD . E~en when a haza rdous materia l in di vision 6.1 does not pose a hea lt.h haza rd by mhalauo n, DOT may o bligate shippers and ca rri ers to d' close th at iri s po iso no us. T hey do so by entering " Poiso n" o r " Toxic"' in the ship- p:~g desc ription, a ffi xin g_ POIS?N la bels to the pac ka ging, ma rkin g POISO N orTOXl C 00 the pac kag ing, a nd d1 splay mg POISO N placa rds on the tr ansport ve hicle when the agg regate gross mass equ a ls or exceeds 1001 po unds (454 kg).

When ca rri ers tra nspo rt mo re tha n 1.06 q ua rt (1 L) per pac kage of a material th at poses a hea lth ha za rd b y inhalati o n a nd meets the crit eri a fo r Z one A, DOT a lso requires them to pr epa re a nd implement a secu rity p lan whose co mp o nents comp ly with the requirements o f 4 9 C .F.R. S 172. 802, Motor carr ie rs a re a lso requi red to obtai n a haza rd o us ma te ri a ls sa fety permit (Secti o n 6. 10 ) befo re tr a nspo rt ing an y o f the foll owing:

A materia l th a t poses an inhalatio n health hazard and meets the crit eri a fo r Zone A in an amount more th a n 1.08 po unds { 1 L) per pac kage A material that poses a n inha lat io n he alth haza rd and mee ts the c riteri a fo r Z o ne B in bulk packaging [ca paci ty grea ter than 11 9 gallons {4 60 L)l A materi a l tha t poses an inhalatio n health haza rd and meets the criteria for Zone C or Zo ne D in packagin g hav ing a ca pac ity equal to or greate r tha n 35 00 gallons 113,248 L)

Table 6.2 no tes th a t DOT requ ires sh ippers to identify a ny hazard o us w aste th a t exhibits the to xicity ch a rac terist ic in its shipping descriptio n b y using the term " EPA toxici ty" or the rel eva nt EPA hazardo us waste numbe r listed in Ta ble 10 .1. For ex am- pl e, when shippe rs offe r for do mes ti c tr a nspo rt a ti o n a haza rd o us wast e that ex hibits the tox icity charac te risti c ow ing to its a rsenic or mercury co nce ntratio n , DOT requires 1he was te ch aracte ri st ic to b e pa renthetically noted o n the acco mpa nying w aste mani- fest by use of eithe r "EPA t oxicity'' o r the EPA haza rdo us waste number o f the haza rd - ous co nsti tue nt. So me re prese ntat ive exa mples a re cited in Ta ble 10.2 .

in gestio n • The rece ipt of a substance through the mouth and into the digestive sy stem

skin absorption • The passage through the epidermis into the derm is or subcutaneous tissue

10.2 HOW TOXIC SUBSTANCES ENTER THE BODY : r::~a~:~;~t 1 :~ub -

A toxic substa nce ma y enter the bod y by vario us rout es including dir ect injectio n into the ::;c:a;ot~~~~ : i! t bloodst rea m, bur we a re concern ed here w ith the three mea ns o f most conce rn to e mer- or dust into the ge ncy responders: o ra l ingestion , skin a bsorption, a nd in hal ation . respir ato ry system

Chapte r 10 Chemistry of Some Toxic Substances 349

FIG URE 10 , 1 The ma,« com~tS of tht humand~~tm Asubstancttakt11 oro1!ty passes1hrou9h tht mouth,into!N!tSOoha- gus, and then 11to tht stomachPartialdtgrada- !IOn or comp'e1e chtn'l1cal a1t,n1nonofthesub- S"...an('!~ ll'ltnt mouth and nomach. Mol- ecuJes of the sut::s-.ance tht-nmaypas.sttv'ough thestomach walldiJ'Ktly inrothebloodstrNo'n Mcn~ly,~. ab:sorpncn intotheblood· st1Nmoccur;afterthe m~ of thesub- S"..J!'IC'!Ofitsdegradanon produopas:s ll"ltothe small ll"ltestu'le

metabolism • The sum totalofthe thE! m ita l pr0Cf!S!eS tha t occu r in th e body's ce lls to break down absorbed

S•li"'Y glaod

) Pharyn x

T .. lh ~ ?-: Tongue Epiglottis Esophagus

Salivary glands

Laryn ~ J. 4---

Stomach

Du ode num .--+-+- +--- Pancreas Large intestine

Small intestine

10.2-A ORAL INGESTION As shown in f igure IO.I , oral ingestion refers to the swallowing of a substance through the mo uth into the stomach and its subsequent movement throug h th e gastrointesti nal tract. Once it is inges ted, components of the substance may pass through the intestinal walls and into the circulatory system, where their molecules are further disseminated to the organs and ti ss ues of th e body. The substance may undergo chemica l changes in the cells of th ese organs and tissues. The combination of these chemical reactions is called metabolism. Although th e indi vidual organs of th e digestive system metabolize ma n)' substances, metabolic processes also occur within th e li ve r.

10.2-B SKIN ABSORPTION foods and ingested i ubrunces

The skin, a cross sed ion of which is illustrated in Figure 10.2, constitutes the largest si~e organ of the hwnan bod y. The skin of an average adult has an area of 21 square feet (2 m· ), weighs 9 pounds (4 kg), and contains more than 11 mil es ( 18 km ) of blood vessels. The skin he lps the body maintain a normal temperature. It also protec ts the internal o rgan s and pre- vents direct contad berween them and foreign substances.

350

Ah.hough the skin aCIS as an organ of defe nse, it also can act as a permeable membra ne. This is es pecia ll y tru e when rox ic substances directly contact the mu cous membran es and th e eyes. Some foreign substanc es also pene1ra1e the epidermi s, the outermo st skin la re~

Chapter 10 Chemistry of Some Toxic Substances

....,.

URE 10,2 Th e cro,ss sect ron of human skm showing some of its pllncipal comP011ents The outer layer of f!G tn is tt,e ,piderm1s, a thin surface membrane of dead cell s Before a substance may be absorbed into the ~ trean'I, it must first penetrate paSt the epidermis an.d t nter the derm is, a collection of ce lls that collectively ! as .i p0rous me dium From the derm1s, the substance is abso rbed Into th e bloodstream

and ent er the unde~l ying dermis or subcutaneous tissue, from which th ey may be funher al,sorbed into th e circu latory system and spread throughout th e bod y.

10_2-C IN HALATION Inhalation is the rout e respo~sible for th e movement of gases, vapors, and fumes through ihe compone~ts of the re spiratory sys~em. Eme rgency respond ers are most commonly injured by this route of exposure. As illustrated in Figure 10.3, th e respiratory system cons ists of the nasal pa ssageways, pharynx, larynx, trachea, bronchi, and lungs. When an inhaled substa nce enter~ the lungs, it is exposed to blood vessels that cover an average su rface area of approx imately 90 square yards (75 m2). Given this ma ssive area of

Diaphragm Alveol i

Pharynx

Laryn x Trachea

Bronchiole

Terminal bronchiole

FI GURE 10.3 The maJor components of the human respiratory system Inhaled gases, fumes, and vapors- 11'1Clud.ng air-first pass through e1ther the mouth or nose, throu gh the pharynx, and into the trach ea (com- rr.on~ called the w in dpipe) at the larynx. These inhaled substances then ent er either of two bronch i, each of ¼hich leads to a lung The ind 1Vl dual d1Vl sIons of each bronc hus are ca ll ed bronchioles.

Chapter 10 Chemistry of Some Toxic Substances 351

I

loaltffect • Arty.t il- me-ntocturrinqatth e site o r •~ thatat~c s.u bstanct in1t,a lly cnntacttd

systemlc etftct • Arty .tilme-nt occurTing omywh~ in the body, indud inq throughout the e ntire body.

hemotoJF:iant • Arty substance th at decreasesth,functron of the blood 's hemo- globm and deprives the tis.sl.Jes of oxygen

htpatotollicant • Arty su bstance that causes liver dama ge

n,phrotollic.Jn t • Art y su bstance that causes kid~ dama ge

neuroto)lk.ant • Any su bstanct tha t adve ~ ly affecuth, centtal nervous~em

respir.1110rytoJF:ican t • Any su bruinceca pa- blto f infl am ing the auw ays orotherwise decreas ing lung fu nct io n

rtproductivt taJF:iuint • Anysubsu nce that adv,rst lya ffectssuu al fun ctio n and fe rtJlity in adu lts, aswe ll asnor- ma l development in th eirothpr in g

orvapor thatd il utesor displacesa ira nd,wh t n inhaled,cau~uncon • sciousness or dea th

d , rJ pid lv into the bloo dstr e.1m .i nd th en exposure-, the subs r:ince is .1bsor~· /t~; bod )', . c1 rcul arrd to all che o cher org:lll5 .1nd nssue) o

OMMON WAYS TOXIC SUBSTANCES 10.3 !~~:R~ELY AFFECT HEALTH Once a wxic s ubs1.1ncr h:is be<"n abso rbed in to th e bo dy, it ac ts in t he following &e~ .

eral war s: . d"are dysfu ncci on, impairment , or death . It ma y C-J Ust' ,mme

1 1 ff ct the si te or area o f contact , s uch as th e onset of

h_ m~ y c: ;efin':~~ n: ineha l:;ion of hyd rogen fl uoride. . Pulrno . ~:i;a e.d:ffect the body as a whole , an d thereby, cause an ail ment that is not lacalii to on! s c or area. Thi s 15 3 systemic effect. H uman expos~re to ce rta in poisons, f~ e..'<a.mpl~ mpac ts th e ent ire nervous srstem and causes surv ivo rs to expe rienc e unre. stricted neuro be ha vio ral changes. ]' d d f It ma y r:i rget 3 specific orga n th at u~dergoes loca 1ze ys u~ct ion o r impai rment \Vhc n a wxic substa nce ra.rg~ts a spenfic orga n, the s ub sta nce 1s de no ted according!; as one or more of the fo llow ing: .

Hemotoxicant., a substa nce that decreases the funcu on of th e b loo d's hemoglobin and depri\•es rhe ti ssues of oxygen . Hepatotoxicant., a substance th:it causes h:e r da ma ge Nephrotoxicant, a subsc:ince that causes kidn ey damage Neurotoxicant., 3 substance th at adve rsel y affects th e ce ntr al ne rvo us system (the brain an d spina l co rd) Respiratory toxicant, a subs tance tha t adve rsely affecrs th e nasa l passages, phar- ynx, trachea, bronchi, and lungs Reproductive toxicant, a substance tha c a.dve rsdy a ff ec~s sexual fu nction and ferrilit}' in ::idulrs, as well as develo pment in th71r _o ffsprmg . .

Its met::ibolic by -prod ucts may ca use the host vic tim to ex pen ence 111 effects. For instance when an indivi du al ingests metha nol and eth ylen e glycol, neith er su bstance causes iii effects direc dy; nonetheless, cheir metabo lites a re toxic substa nces and ma)" cause che indi vid ual to expe rience ill effects, inclu d ing dea th.

1O.3-A ASPH YXIANTS One wa y that a gas or vapor adversely affects health is by indu cing unc o nsciousness when inha led. T he gas or vapo r ch:1 1 affects th e hum a n bod y in this ma nn er is ca ll ed an asphyxfant. Th e most common asphyxia nts a re carbon mo noxi de, ca rbon di ox ide, ni tro- gen, metha ne, and the noble gases. Asphyx.iants may be toxi c o r nontoxic.

The re are 1hree commo n mea ns by wh ic h an :isph yxiant ca us es u nco nsciousness in hum ans:

Simple asphyxiants. As first noted in Sec tion 2 .5- 8, a gas having a vapo r densit}' greater 1han l disp laces the air within the lowe r reg ions o f a n enclos ure. An example of such a gas is ca r bon dioxi de. A person who in ha les ca rbon dioxid e ca n lose con sc ious· ness, because the body is denied sufficient oxygen. Wh en prov id ed fresh ai r or oxygen in a timely fashion , conscious ness c:i n be rega ined, bu t if una ne nd ed , th e in di\·idu:il mu all1· d ies from as ph yxia tion or experi ences long- term neur o logica l d amage .

The reduced OX}'gen concentra tion, not the asp hyxi ant concent ratio n, is usua llJ' used t_o establish 1he nega til'e impact that is likely 10 res ult fr o m in h a ling an :isphpiJnf. T he _signs and sympcoms associate d wi1h brea thin g a reduce d -oxygen a tm o sphere \IW previousl y noted in Sect ion 7. l.

352 Chapter 10 Che mistry of Some Tox ic Substa nces

SOLVED EXERCISE 10.1 , 7 210 ,dent1fy theadve1sehealtheHect§mostt,~ely tobeex

~:~:~dn airr,osp here con tamin g 42 % methane and 9% oxygen by an emergency responder who

saw1ion~ 0 ~;e

1 : ; / ~~~

1 ;a~~.~;

1 :~~e 9:~0\:~ga;n ~~1~;1, ~t:,~:! on the mfo,mat,on 1n Table 7 2. any ind.

~ ss, an ashen face, fan tmg, andmenta lfa 11ure ytoeaper1tncenauseavom1.ng,uncon-

1 Action as a h~moto~ican_t. Asphy xiati on ca n a lso be c:i used by chemical ae1 io n 5u tis 1:i nces tha t chcrmca l_ly impa ir th e body'.s use o f oxygen ar e chemica l asph yxi ants. Fo; e,:a rnp le, ca rbo_n monoxi de_ ca use~ unco n_scmusness as a chemica l asphyx.ia nt by reacting

11 11 h thf blood s hemog lob m . T hi s chemica l actio n preve nt s th e no rma l tra nsmissio n o f

os) gen in rhe -~ 7 dSlr e~mil ;\ltho~g~ co_nsc iousness ca n be regai ned when fr es h ai r o r

0X}~:~c;: t~~~; 1

0 f ~on~ ;~:nis ;:~~~-n JO . IO that a sho rt-t erm exposu re 10 certai n

Jnabili~ to 11 ti!ize ~ellt1lar OX)•~en, -~ no th er way that an as ph yxia m causes un • ,onsc 1ousn~ss is by hmd erm g th ~ ce ll s :ibili ty to utili ze oxyge n. T his occ ur s w hen an indil' idua l inhales hydrog~n cya md e. In Section IO. I ! -A, we s hall lea rn tha t the inhal a- uon expasu~e rend ers a~ impo rtant enzy me inacti ve . Indi vidu als wh o have inha led hy - drogen cya nid e ma y ha\c ::in ad equ:i~e oxyg.e~ _lev~ I in thei r bl ood, but th e inacti vity of rhe enzy me prevent s.th em from effecnv_ely unlm ng It. Su bse qu ent ex pos ure 10 fres h air o r oxygen ma )' not re vive t_hem, a~d surn val may be possib le o nl y w hen t hey are pro mptl y crot td wit h a n appro prrn1 c antidote.

10,3-B IRRITANTS The in h:i lation of a ga s or va po r ma y al so affect th e bod y as an irritant by injurin g th e 115,;ues that it contacts . W hen a low co ncentra tion of an irritant is inhal ed, th e res ult is ofte n minor inflamn~a tion of the ti ss ues that line the respira1or y passa geways . T hi s hap pen s wh en a rela tivel y sm a ll a mount o f ammonia vap o r is inhal ed . How ever, inhal at io n o f an ele va1 ed con centra tion of th e same sub stance may cau se res piratory fa il ure . Wheth er a s u bstan ce cau ses res pi rator y irritat ion or fai lur e is ofte n associated wit h the degr ee to which it corr o des th e no se , pharyn x, la ryn x, trac hea , br o nc hi , and lungs .

Not all irrita nt s are gases o r va po rs. Skin ex pos ure to a solution o f a wea k aci d , for exam pl e, may cau se 1he deve lopment o f a ra sh or other skin diso rder at th e s i1 e of co nt ac t 1n susceptibl e indi viduals, especi ally after pro lo nged or re peated contact.

CPSC reg ulates ex pos ure co irritants in consu mer produ c1s. For it s purposes, a n ir ri - tJn t is defin ed as any no nco rr os ive s ubstance, which , on imm edi a te , prolon ge d , or repea ted co mac c wi1h li vin g ti ss ue, ind uces a local inflammator y react ion.

The CHS excl am ati o n-po int pie1 ogr;1m is affi xe d o n th e contain er labels of chemica l products holdin g skin a nd ey e irrita nt s un less the corrosio n o r hea lth hazard pictogram also is affi xe d.

10.4 TYPES OF TOXICOLOGICAL EFFECTS Th e ha rmful hea lth effec ls asso ci ated with ex pos ure to sub stan c<"S a re o ft en cl assi fied as ac ut r, c hroni c , shon-lerm , o r latent. Wh en th ese s ub s rnnc es are consti t uent s of commercial chemi ca l produ cts, th ese effects a re note d b y th e ma n u fac ture r o n la bels ~nd SDSs.

a ntldot, An agent t hat counteracts the ab llityofasubst ance t o act as a poison

capable of caus ing a reve rsible inf lammato ry effectatasiteupon immed iate, prolonged, or repeated co ntact with 11 vingt issue

Chapter 10 Chem istry of Some Tox ic Substa nces 353

r

I I

I I' ; I

.nitthNlth f'ffK1 • AAyd1$easeor 1mp1 1rmtnt whose oruet and progrwion occur rap idly after ,q,osureto•to:uc ffldtN>al atilSU bt, th al concentra tion

dlronlchNltheffKt • Arrycf!Setieor 1mpalf• ment whose onset and progt't'Ss.ionoccurslowly overant.n~~ peood(monthsto yN r\) afterexposureto ato.ocmatNVl ata ~l conttntrat1on

coroNryheartdisuse • Any di~ disorder, ordebilita tionassoci• at~withthenormal operation of the heart, such as a myocardia l infarct1 on (" heart .nack " J, congenita l heart disease, ilndcon- ge:sti-..! heartfa il ure

short -tenn hu lth

d iSNseofrelative ly short duration caused byexposure to a sub- staince and fromwh1 ch tKOVet)'OCCVl"S tap id ly

laten thu ftheffect

thatmariiffitliiUe tf on ly after considerable ti me has paned fo llow- ing one or more initi al uposurestoa su bnanc e

10 4-A A CUTE HEALTH EFFECT . • Hect is an lllJ UJ'}', diS('J.St'. or death tha t de \'elo ps rapid[ )' (in nun ui e-s

An acute hea~ ~I· mes to a cnsis fo ll o\\11ig exposure 10 a subs tance for less than 2

, hollI\ orda rs ) and qt'k? _co health effect is te-J ring of the eyes upo n exposu re to anini o/ ho~tt ~:n:~\~ju~ ~ers \linu:ill )' immtdJat d y from 3 short -term expos ure. ia 1allt\

10.4 -B CHRONIC HEALTH EFFECT A chronic health effect is an in1uf)': di sease, or deat h that de \·el: ps slowl y o1·er a da ·s week s., yea rs. or deca des fo Uowmg an exposure or repea_ted exp os ure to a substa ft-t., ,\l ~s~ types of coronary heart disease are cx:t mples of chrome heahh effects. Oct,

10.4-C SH ORT-TERM HEALTH EFFECT A short•term health effect 1s m:tnifested wh~n a~ injury or di sea se of rc-lati\'t[). sh dur.ic io n and from which reco\'er)' occurs rapidl y 1s ca~sed by exposure to a su bs t,1 flfl Fo r example, wben an indi vidual is _temporarily asph yx1at: d from car~n _dioxide extlct. sure but reco\lcrs when pro\lided with :imple oxygen or air, th e asphyxiation is call e~ short· termhealtheffect.

10.4-0 LATENT HEALTH EFFECT A latent health effect is man ifested_ wh~n an i~jury or disease caused by exposure to a substance occu rs only after an cxtcnsJ1'e time period ha.s passed. For example, the Onstt of certain cancerous and noncancerous di seases foll_owmg exposu re to asbestos fibers

15 rega rded as a latent health effect, because these dmases usually eme rge 20 co 40 )'ean aher an indi \lidual's initial expo sure to the fibe rs.

10.5 FACTORS AFFECTING THE DEGREE OF TOXICITY The human bod y is a \/Cry complex and delicately balanced system. Its cells .:1ssirnilau nutrients from foods, resi st biological .:1rtack, reproduce, and gen erate the substances tlut Ul e body needs for ics survi"al. Ccllubr reactions arc responsible for li fe itself; but wh m toxic substances .:1rc absorbed across cellula r membranes, _ they can upse_t 1_hese del icate!r controlled biochemical processes. When the cells malfunction, the hose v1cum exprricncrs impaired health, disea se, or death.

Fortunately, the body ha s natural mechanisms for protecting i1sdf aga ins1 the imp.ia of foreign substances. One such mechanism in\lo!ves the specific actio ns of its organs. for instance, che liver is particularly effective at conve rt ing many harmful substances into harmless on es or into substances that can be rapid ly excre ted . As a result of these meta• bolic changes, wxic substances may be modified in chemical structure, temporarilr stottd in specific organs, and/or dirmly eliminated from the bodr.

Aside from these natural protective mechanisms, the body is sometimes incapable of protecting itself from invasion br toxic substances. Whether exposure to a tox ic substa nct actuall y causes death, disease, or injury depend s on several factors, the most important of which arc th e foll owing: th e quant ity of substance, the duration of exposure; the rate~r which a substance is abso rbed into th e bloodstream; the age, sex, ethnicity, and heahhof the affl icted person; and indi \li dual sensiti \li ties. A parent's exposure to toxic substanctS ma y al so affect the hea hh of hi s or her children, including unborn children. We examir.r each fact or ind ependentl y.

10.S-A QUAN TITY OF SUBSTANCE Although all sub stances have the potential to be toxic, we are concerned with those sub- stances that cause an ad verse impact on an organism in relatively small amounts. Th

354 Chapter 10 Che m istry of Some Tox ic Substances

of the subs rnnce admin is1c red or ab so b d J~11.:, unt t,srnnces are so toxic tha t exposur t' to ;h e . ~ r bod y weight 1s ca ll ed the dose. 5onir d051r1d111m bo t11 /m 11m, th e ca usa tive a ge ne :~•~tt ~ose is le1_hal. For instance, the 10'

1 ~trriulll w patent that just I gram can cau se th e d~~i:;• JS a smgle cell that rel~a s~s

:1 t,J 1. fo rtu na tel y, th ere arc rclaci vd y ft'w s b of mort than 100,000 md 1• 11d~:/~f tox ic11y. . u stanc es ihat exhibit thi s pronounct>d Jc£ A sprcific subscance impacts 1he body as a funcii o f . d .

r ihe consumption o f alcoholic bcvuagcs affects t~: o~~s ose. For e~a~~l c, cons_1dcr hO' u h alco hol to ach ie"e a blood alcohol concentration of ~-

0 Whcn an mdmdual dnnk s

rno g subdued, relaxed, perhaps ei·en cl t>vated . . . mg.ldl , he or she may feel J1s~:l~ed IO ac hic"e _blood alcohol concemraci~~ ~1;1l~ b;c when sufficient _alcohol is ~::xicaced. (One deciliter (dl ) is 100 milliliters, or one- tenth ~1~1i'i~;.rrson JS patentl y

,o.S-8 DURATION OF EXPOSURE i\S ll genera l palicy, ~rcquenc expos~res to a toxic substance cause ind ividuals ro cxpe ri- rnce 1!1 effects. Consider ihe approximatel y 4000 substances that ha\lc been id entifi ed as eonsiituents of tobacco smoke, about 200 of which are wxic . Exposure co 1hem causes mon)' tob;icco smokers _to develop emphysema , chronic bronchitis, and/or cancers of th e lung>, mouth, la rynx, ki dney, or bladder; )'e c_, the exposu re appears to impact ocher smok- rrs a; if they were nonsmokers. If 200 toxic substances in tobacco smoke cause health probkins, why do son_1c smok.crs ~ppea r to be shielded from contracting these diseases?

The answe~ to this qucs_n_on ~s connected to che fact that che initiation, promotion, Jnd manifcscanon of a specific d1sc~sc occur stepwise. Alt hough manr random facto rs can accele rate or delay the_ progress ion ~f these steps, the possibi li ty cha, ill effects will r~ult from exposure to toxic substances increases when individuals are exposed mori:- and more frequentlr to them.

Alro, indi1·idua_ls do not respond in an identical fashion when exposed 10 a gi\len con- centration of a cox1c substance over tht' same lengt h of time. Some individuals arc more capable th an ot_hers of tolcraci~g_toxic substances in their environment. Some even appear 10 adapt to 1hc1r presence. lnd1v1dua ls respond co toxic subs1anccs 01·er a given length of time in rhe following ways:

1 Althoug h so me individuals experience ill effects from exposure to a toxic substa nce, others experience the same effcc1s only aftt> r they ha"c been repeatedlr exposed to the substance in the aggregate for a longer period of time.

I Alrhough some individ ual s ex perience adverse hea lth effects from exposure co a gi"en concentration of a substa nce, they may not experience chc same effects on subsequent exposure co the same concentration of the same substance.

1 Some individua ls who do not experience ill effects from a short-term exposure co one concentration of a substance may be unable to colcrati:- a long-term exposu re to a smaller co ncentration of the same substance. These individuals require chis longer prriod of exposu re to reac h th eir body burden, chat is, the concentration that causes them co expe rience ill effects.

10.5-C RATE AT WHICH A SU BSTANCE ABSORBS INTO THE BLOODSTR EAM

l.'(1hrn a toxic substance is inha led, the adverse effec1 cau sed by its presence m:i y not be ti id ent immediate!)'. Inhaling a lethal concent rat ion of chlorine or carbon monoxide, for mmple, causes dcJth within seconds or minut es, whereas inha ling a lethal concentration of hrdrogen chloride or nitrogen dioxid e may result in death hours or da1·s later. These observations demonstrat e ch at the manifestation of an effec t caused by exposure to :i toxic substance depends not only on the conccnu aci on to which an individual is exposed but on the race of ch c mechanism chat causes th e impairment or death.

a substance per body we1ghtadm inls-tered directly to and absorbed by an organism

inwhichthealveoll in thelungsbecome irre- versibtyd is-tended, decreasingtheeHi• dencyofrespiration and causing breathless• nessandwhee zy cough ing

d isease in which the bronch i ofthelungs become permanently inflamed.causing breathlessness and chronic cough ing

Chapter 10 Chemistry of Some Toxic Substances 355

I

_ /

runcetha t c.iu~a subsuntial proportion oftxpowd peop/e or anim.i lJtodevelopan all erg icrHctionafter repeatM uposures

bt,ylliumsensitiz.atlon

. m ested or ab sorbed through the sk111, suffici(nt tune !Tl Whc-n a toxic subsra~cc 15 /rt: absorbrd into the blood stream. When ingested Us1

thrn r]Jpse for rh r subst:1~:c:-fr~m ,he scom.1ch into 1he sma ll mtc- stme, when: ir 15 ;~ subsr-Jncr must usu~~ rC'am. When exposC'd to skin, 1he subs1ance muse first Nss inro ::abrorbN mro the ~I . bsorbtd t1110 ihe bl oodsiream. the dernus. where Lt 1s th C'n a d fo r thr absorption of :1 subs1.:ince into the bl

It 1s fort u_iwus that 11f~; :~ 1 :C';::~s to occur _provides a w~ndow _of opponunil)•: ·

sm·.1m. The ume- needed . nnd can .1dm1ms1er an antidote, in duce vomitin 1• ing which emergencr-mrd1ct lfipt;:d measures. g, o, implrmC"nl other appropru te irs

10.S-D AGE, SEX, ETHNICITY, AND THE GENERAL HEALTH OF INDIVIDUALS . . .

which toxic subst:1nces affect Ln d1 v1duals often depends o r~ thC' ir age, st~, ThC' d~rtt to al st.m of health. Young children and th e elderl y typJCall y are lllor, C'thmc1r:r, or ge ner 'ddk-a C'd indi ,·iduals to the effects of exposure _to t~xic substances. suscC'pnb!e th30 i:1"1

1 l g I erable because their average bod y weight rs rela1ively lo

_Ch1ldre~ ~re pa~~'t:r:~;~;e sull dtvcloping. A ~ ea~ immun e sym·m lea ves everyo= aocl th~1r =~e ro !onir:ict ing diseases and ~x~ nencmg othe r hea lrh-relatC'd compl 1C;1. ;:; : '~~wborn infu nrs :are at th e highes t nsk, becau_se ~h ey mu sr rel y heavil y on the imm~nC' factors acquired from cheir mothers before ,heir bm_h. _ . .

The sex and echniciry of 3 person also affrct the susc~pt1b1hty to comr~crmg crruin diseases For uamp!e, ei•rn th ough the physiology of th e c1rculat~ry system 1s the sa me in bO!h m~n and womrn, wome n are more prone co contract certain typrs o f hrart disrase tha t arr fundamrnrally different from the types contra.cted by men. Ano ther example is rvident whrn exa mining the diseasrs con rracrrd by whit e and bl ac k peop_le. E1·r n though thr composition of chr blood 1s the same i_n all races, bl~ck people of Af~1can descrm are mo rr prone to devrloping sickle-cr ll anemia than ~re ~vh1te ~eople. Wh y IS o ne sex or one ethnic group more prone to be stric ken_ with cert_ain diseases. ~ h ~~ugh the answer to tlus question has nor been identified, genetics most likely p_lays a significant. ro le.

Likrn'lse, tho~ persons already weaken ed from disease are more _li kely than healthy people to be susceptible to the effects resulting from _exposure to toxic subst~nces. This ~ nsitil'ity is pamcularly evident in indiv idual s suffering from hea rt a~d respi rator}' ail• ments. Indi viduals suffering from heart ailments , fo r example, ma y be incapable of roler• acing exposure to low concenuation s of ground-le1•el ozon e, but _healthy peop le ma) experience no srmp1oms at all when exposed to th e sa me concentration.

A well-acknowledged group of unhealt hy indi,,iduals are- tobacco smok ers. As a gen• eral rule, nonsmo kers can tolerat e an exposure 10 toxic substanc es better than smohrs because che immune srsrems of smokers ha l'e been compromised. Smoking inc reases the- potential that particulate matter will adhere to lung ti ss ue and delay th e rate of remo1eal of hai.ard ous sub stances. Th is may expla in why smoke rs are more like ly to suffer from asbestos - or radon-induced cancers than nonsmokers for the same expo sure.

::~~r?~~;=:~s;, 10.5-E INDIVIDUA L SEN SITIVITIES ~~!um duru and Sensitizers are a unique group of substan ces that cause on ly cer1ai11 expos<.'d indi viduals

10 experience an allergic reaction. An exposu re to a sensitizer can also influ ence the de,·d· beryllosis {thronic opmenr of a more se rious disease. For instance, exposure to 1he dust s and metal fum es of be,yllium disene) • Th, beryllium can promote th e allergic reaction ca lled beryllium sensitization, whose S)'mP- ::::!7z9~i;at:a,. toms !nclude coughing, short ness of breath , fatigue, fever, and night sweats. Con rracring ring of tht lung tissu, ~ rrll 1~m Rnsiri~ uon is the fi m m p towa rd s de\·eloping bery/losis, or chron ic beryl· following th, inhal•- li um disease, a painful sca rring of lung ti ssue for whic h there is no cure. t1on of t>,ryHi um dusts To explain why only cen::iin people adversely respo nd ro sensitizers is nm str.iighc for· and fumes ward. The explana tion may ha Ye som<.'th ing to do with one's inherired trait s; ih:11 is, our 356 Chapter 10 Chem istry of So me Tox ic Substances

niJ)' play a role 1_n. exp lain ing why some individuals tole rat e ex posu re 10 a gi1·en 6,nes n1r:1non of .1 scns1 11 zer where::is _ot her ind1v1duals experience ill effects from expo- conc:0 the s:unc or a lcs_ser concentration. ,,;rtlltrtc fr,J aa l agencies regul::itc exposure to sensi tize rs:

1 CPSC regulates exposure ro th e sensitizers li strd ac 16 C.F. R. §1500.13 when 1hey

tc0 nip0ncnts of consu mer products. . Jr I FDA regubr es expos ure to foods contaming peanuts, uee nuts, eggs, milk , shrll-

fi h wheat, and any food wh ose treatm ent produces a sulfite (S01 - ) concentration fis ~;1

1 ; 0 ~r greater than IO pamper mi~li_on,

3

eQ • OSHA regu late_s e~posure to se_nsmzers that are stored and used in , he workp lace. nufacturers, d1 s1r1burors, an d importers of res piratory and skin se nsitize rs are re -

T~;;ab}' oSH~ to affi~ hea lth haza rd and ex clamation point CHS pic1ograms on rh ei r ~pectivc contamer labcls.

10 _5.F ADVERSE HEALTH IMPACTS ON A DEVELOPING FETUS

When a pregnan t woman ha s been exposed _10 a toxic substance, her placenta ma y shiel d h dei·eloping fetus from exposure to a toxic substance. The placenta's primary func rion

:s : 0

provide the f~ tus with oxygen and ~utr~ents, but ii can also function as a b:'.lfrier by reienting the tox!c sub~tance from passmg into the mother's womb.

p Notwithsta nd mg this stateme nt , the placenta does not always block the passage of ·ic substances into the wo mb. Some substances appear to move unhindered through the

1 ~:cenca an d enter the fetu s's blood, after which they may cause harm by negativel y influ •

:ncing growth and development or contributing to an illness or disab iliry. The adverse hea lth effects face d by a develo ping fetus are Yividly ev ident when a preg-

n.ini woman is exposed to illega l drugs. A prrgnant woman who uses cocaine or heroin, for example, puts her unborn child ::i t ris k because the mother is likely to expe rience pre- rnarurc labor, miscarriage, and stillbirth. Babies who survive their mother's exposure a re nol on l)' born unde1·elope d, bu t they m::iy be addicted and requi re treatment for with• drawal from the drug . A woma n's use of ill ega l dru gs during her pregnancy may al so wl.'3kcn th e placenta and allow ot her toxic substance-s to cross mo re readily into her womb.

A developi ng fetus is also affe-cte d when a woman smokes tobacco products d uring h:r pregnancy, Inha ling t he toxic substa nces in tobacco smoke nearl y dou bles her risk of gi~ing birth to a n undevelo ped baby and increases he r risk of a prererm de li\'ery. Th e risk 10 ~ bab)"s hea lth is ex tended beyo nd the nine mo nt hs during whic h the fetus is carried in 1cs mother's womb. When a woman smokes du ring he r pregnancy, her newborn chi ld is likely 10 experie nce more illnesses and disa bilities compared 10 a child that is born to a nonsmo king mother. Beca use i1s lun gs are often unde1•e loped, the newborn chi ld may exwience difficulty in breathi ng. Later in life, the child is likely 10 experience disabilities such as mental re tardation and learning problems.

We shall not e lat er that a developing fetus may also be negati vely impacted when its mothe r kl rxposed during her pregnancy to ethanol (Section 13.2-E), Bisphe nol-A (Section 13.2-0), rthylene glrco l alkyl ethers (Section 13.3-E), and die rhylh exyl phthalare (Section 13.7-8).

10.6 MEASUR ING TOXICITY Toxico logi sts ha\'C dev ise d procedures for measuring the concentratio n of a su~stance 1h.i1 causes an o rganis m to experie nce inj ury, disease, or dea th. These procedures invol ve exposi ng groups of laborato ry anima ls 10 concentra tions of a substance, obse rving the dfec ti caused by 1he exposure, and extrapolating the resul1s to humans. Whe n ex po~rd to

unique concentration of a substa nce, a nimals and humans do not always respond in the SJme way. hen different anima ls res pond differently to an exposure. Consequently, these PJranmers ma y have o nl r limited releva nce.

Chapter 10 Chemistry of Some Toxic Substances 357

r In the wo rkpl:ice, OSHA and J'\ IOS H require emp loyers to reduce o r dinti nai ltkchhood thac employtts w,11 exper1~nce advc-rse hea lth effec ts fro_m ex posure to e tht subst:i.nces. To do so. c-mplo ye rs consider thr:e releva nt 7xposu~e hm1ts: t he short to~ ,c exposure lml\t, chc permi ss ible ex pos ure hm1t, a nd the 11nmed 1ate ly•d ~ngc rous-t~terrn and-hcahh level. f irefighters ma y also use these lumt s to evalua te the impac t Posc~i ft. mhalmg a known conccntr.rn on of an airborne wxic s ubs t:m cc. ~-

hstc~~ ~:l~~";o~~f}:;:~ea;~:1;;~v::!t!~:ev:~e:rss~mnc n1s noted in th is section ar,

MtlJlj(,iM Tox1c1ty Measurem~nts of Some Comm o n Gases a nd Va pors IMMED IATELY-

LC~ SHORT-TER M DAN GE ROU S- TO-LIFE- TOXIC SU8STANCE (PP M) EXPOSUR E UM1T EX POS URE LI MI T ' AN D-H EA LTH LIMIT (PPM)

Ammorua ,ooo 25 ppm (1 8 mg.lm 1) (NI OS H) SO ppm (35 mg /m 1) 300 (OSHA) JS ppm (27 mg.lm 1) (NI OSH )

Carbon mono,ude 3760 SO ppm (55 mg.lm 1J {OSHA) 1200 35ppm(40mg/m1) Ceil in g 200 ppm (229 mg/m 1) (N1 0S H)

0,1onne 293 Cedm g 1 pp m (3 mg/m 3) (OSHA) 10 Ceiling 0.S ppm(14Smg/ml), 15m in (Nl OSH)

Flu orme 185 01 ppmj0.2mgtm 3J 25 {05 HAJNIO SH J

Hydrogen chloride 2810 Ce 1hng Sppm(7mglm1J so {OSHAJNIOS H)

Hydrogen cyan.de lOppm (11 mgtm 1),sk in 4.7ppm(5 mgtml), so I absorption {O SHA} sk i n absor pt ,on

(NlOS H) ---- Hydrogen sulf ide 712 Ceilin g 20 ppm (2 8.4 mg/ml) 100 ! SO ppm/1 O•m in maximum peak

(OSHA) 10 ppm (15 mgtm 1), lO•min maumum peak (NIOSH )

N1uico:.;1de 115 2Sppm(30mgtm 3J I 100 I (OS HA/NI OSH) l Nitrogen d ioxide 115 Ceil in g 5ppm(9mgtm 3) 1 ppm(l .8 mgJm 3) 20

(OS HA) (N IOS H) Phosgene 0. 1 ppm {0.2 mgtm 3) (OS HA)

0.1 ppm (0.4 mglm 1) CeJh ng O 2 ppm (0 8 mgtml), lS·minexposure(N IOS H)

Phosph 1M 20 0.3 ppm(0.4mg/ml) 1 ppm(l mg!m 3J so Su lfurd~

(OSHA/N IOSH) (N IOS H) 2520 5 ppm (13 mgtm 3)( 0S HA) S pp m(13mglm1) 100

2 ppm {5 mgtml) (NI OS H) (NI OS H)

358 Chapt er 10 Ch e m i stry of Som e Toxic Subst an ces

,o.6·A LETHAL DOSE, 50% KILL Th letha l d ose, 50% kill , o r LD so , is the a moum f b f; bo rato r )' anima ls co whic h th r s ub sta nc . 0 J s~ _5(a ncr th a t kill s half of a group 0 nt:. The LD;o 1s ex presse d in milli grams o f a:~ :n~s t:~~lSCe~ed during a p reestabli shcd 11

1113 1111 kilogra ms (mg/kg ). When a substan ce aff su ~t.a nce per bo dy mass o f the

:a,ured b)' co nsidering th e ma ss o f th at organ . ects a spec ifi c o rgan , th e LD 50 ma y be The leth al do~e o f a su_bstance to humans is calcula ted usi n h l.D

obr.iuied fro m a nima l stud ies. Fo r a n ave rage perso n ha vin a g I

e 50 ~eas uremem kchal dose is th e prod uc t o f the LD so a nd the mass: g mass of w kil ograms, th e

leth al dose, SO o/. klll (LD sol • The doseof a su bn ancethat hletha l to SO¾ of a group of l abora tory ani mals tested dur in g a spe ci f iedt, me

Leth al dose :: LDso x w

SOLVED EXERCISE 10.2

: ::h~l~~~ •~1~:e~:7~~;sa 6ig,~;d~~~•~~~:~::1~ ~:~~l!m~ as a technical bas,s to estJmate

Solution : Thel etha\ doseofphenolfora200-poundpe f!.Onby !.k.,nton1aetiscalculatedasfolk:,•,•.-s

200),:i X 2 1

~ X 630 X~)( l ~ g~ = 57g

::n 1 :~~~-pound emergency res ponder absorbs 57 g 01 more of phenol through the ~n. the exposure is likely

10.6-8 LETHAL CONCENTRATION, 50% KILL The leth al co nce ntratio n , SO % kill , or LC so, is th e conc emrat io n of a substa nce tha t kills ha lf of a _gro up _of labo ra1orr anii:n::i.ls 10 w hich the s ub stanc e is admin istered during a precstabh shed tim e. A LCso IS t ypica ll y ex pressed in pa rt s per milli o n (ppm ) by vo lume . These measu rem e m s are use d in d iffe rem di sc ip lines for a va riety of purposes. DOT u ses LCso v:ilues to ch a racteri ze ma te rials in ha zard classes 2. 3 and 6. 1 10 esta b li sh th e ha z- ard zo ne fo r a s ubsta nce t ha t poses a hea lt h haza rd by inha la ti on. \Y/e rev iew this proce ss inS<:c tion 10.8.

The le thal co nc e nt ra ti o n o f a sub stance to human s is ca lc ulat ed using the LC50 mea- sureme nt obtained from anim al stud ies. For a n a,·erage perso n ha vin g a mass of w kil o- grams, the leth al con centrat ion is th e pro duct of th e LC50 and th e mass :

Le thal dose = LD so X w

10.6-C THRESHOLD LIMIT VALUE The t hres h o ld li m it va lu e , o r TLV, is the uppe r li mi t of a co ncentra tion co wh ic h an a vera ge healt hy person ca n be repea tedl y expose d on a n all-d ay, eve ryda y basis wit hout s uffe rin g adi·erse health effec ts. Th e TLV fo r a irborn e gaseous sub stances is us ua ll y expressed in pa rts prr millio n. The TLV fo r ai rborne fumes, mists , and particulates is e xpressed in m illi gr a ms prr cubic me1 c r (m g! m 3). The TLV is 1he level o f ex posure a t w hich th e pro bability of the occu rrence of adv e rse health effects is deemed negl igible. Th ese values ar e es ta bl ished by 1he America n Co nferen ce of Government al Jndusuial Hygie nists {AC GIH ), w hich rec ommends them to OSH A for it s con side ration of th e ad,•erse impact o n a worker's long- term hea lth.

1

l etha l co n cent rat ion, 50% kill (LCsol • The concentration ofa sub- stan ce t hatis let halto so •;. ofa groupoflab- oratoryani mal s t ested during a specif ied t ime

th~sho\d l imi t val ue

st an dard estab lished by ACG l H for exposure t o ana irbomeconce ntra • ti onof a substa nceto w hich an ave rage w orkerm ayb erepeat- ed \y e)(posed , dayaher day,without exp erienc- ingadver se h ealt h effects

1TI.V~ arc published by rhe American Conference oi Governmental lndumia l Hyg,enists in Donm>t",,t,mo" of lb, Tlnnhold Lmrrt \',;1/r1t$ 111,,/ B,ologi(,1 / £-.:posure Indu~s, C,ncmn,u i, Ohio (20 12).

Chapter 10 Chemi stry of Some Toxic Su bstances 359

11:

pem,iuiblev:pos urt limit(PE U• Forp ur- po5flof OSHA rt91.1 l.1t,on1.thtt,mt- wt,gh1i!d,1vtrage thmho ldhm itvalutof 1ubst.1nctstowhlch wor!o:.tnc1,n betxpo1td continuously during an 8-hourwor!o:.sh1ftw,th- outsufftrmg i!l tfftcts

ma•1mum perm iu,ble concentr,1tionofa subrulnct lnaworklng environment that shouldn-rbt ,xcffdi!dfor any dur,111on short-tfrmex posu,.

centru10nof asub- n,ll(f to which worke11 C.illnbfe:o:pos.-dcontinu• ous/yfor,15hortper10d oft1m,withoutsuffer- ing initat10n.chron1C. or irr-niblttiUUf dam,19e,ornarcosj1of sufficifntdt9rttto inat.1se the likelihood of,1ccid.-nt.1l injury, 1mp,1ir self-rtK1Jt,or n,,1teri,1llyri!duct work ,fficiel'ICY, and provided th.ithedailythrfihold !im1tvalue.nmt- we1ghtedavuageisnot v:cttdtd lmmtdiatt ly-d angu- ous-to-li f...and-h u lth

bomtconctntrationof a.nysubnancethat po5ean immediate thrf,1 tto l,ff,G1U lfiiln 1rrtvfflibltordflayi!d advernohea!thefftct.or ,nterler~wrthan !nd l• vidual"sabnitytoesc.ape during,13(}.m inute

"''""" r«o mfflfndtdDposurt limit(IIE U • ThtO<C\lpa• tlonalexposoreconctn- trationtoanairbome

10 6 -D PERMISSIBLE A ND CEI LING EXPOSU RE LIM ITS · . e lim it, or PEL 1s 1he rime-we1ght~d average level of c-xpos

The pe rm lss1ble expo,:~ ch workers can be exposc-d connnuously for either an to a cox1c sub stancc- tor workweek in conformance wit h relevant OSHA regu lations tu workday or_~ 40-~ou or C for some substances is al~o recommended by Nlo·s

The ceiling hmlt, · he maximum concentrauon co which workers ma 1--l to ~S~- :~s" ~~~~:;e:;;;:r~c:ng 111 effects. When ~orkers ~re c-xp_osed to a co:c:;;~Y tion o7: substance that exceeds its ceiling lima. their safe ty is considered to be 11111111111: nem danger.

10.6-E SH ORT-TERM EXPOSURE LIMIT . . The short-term exposure limit, or STEL. is the max~mum c~ncentrat10~ of a substanct 10 which workers may be exposc-d continuo~sly for a time pwod of 5 mm_u~es without suf. fering irritation, chronic or irre\·ersibl e msue damage, or _narcos1s suff1c1em ro incre,1~ the risk of accidental Jn]Uf}'. impair self-rescue, or mate~1ally reduce work-related tffi. ciency. The STEL should not be exceeded more than four nm~~ throughout a working~)' with at least 60 minutes bern·een ex posures. STELs for spec1f1c subs1ances are published when toxicological effects from relati\·ely elev,ued short-term ex~sures to ei ther huma ns or animals have been reponed. They are established by NIOSH.·

10.6-F IMMEDI ATELV-DANG EROUS-TO•LIFE-AND· HEALTH LIM IT The immediately-dangerous-to-life-and -health limit, or IDLH , 1s the airborne concem~- tion of any substance that poses an in_1mcdi~te ~h_reat t.o !if~•-causes irreversi~lc or delayed adverse health effects, or interferes with an md1 \'idual s ability to escape durmg a 15-rnm- ute period from a dangerou s atmosphere. These values arc estab lis hed by NIOSH.

10.6-G RECOMMENDED EXPOSURE LIMIT f\lOS H also recommends to OSHA the concentrations of certain subs1:1nccs that a focd - ity may use as guidelines for protecting its workers against an injurious outcome. Each concentration is called a recommended ex posure limit, or REL They account for th: safety of an employee during his or ha tenure at a facility when the y are used in combi- nation wi th recommended protecm·e equipment such as gogg les and masks, posted signs that warn of potenual dangers from e)(posurc, monitoring of exposure lc\'els, and ocher prudent safety measures.

NIOSH develops and publishes RELs that are based on a time-weighted average con- cent ration for a JO-hour workday.

10.7 CPSC CRITERIA OF A TOXIC SUBSTANCE At 16 C.F.R. S1500.3(c)(I) , CPSC defin es a consumer product as wx1c if it can product pe rsona l injury or illness 10 humans when it is inhaled, swall owed, or absorbed throuj;h the skin . Certain tests are conducted on anima ls 10 det ermin e wh ether a product can cause immediate injury. CPSC also regards a product as wxic if it ca n cause long-1enn chronic effects like cancer, birth defects, or neurotoxicity.

~:::n!/1~N~~~ 1STEL.s, PEW, Jnd IDLHs He pubh~hrd by rhr Nmona l lnsmu1r of O.:, upauon3J SJfrty and Hal!h in !\JOSH for adoption as a per- ~ itt 7wdt 10 a,,,,uc.i/ H~::.mls. U.S. DrpJrtn1rnt of HrJlrh and Hum.rn Serv1c ts Public 1-kJlth k n·'"' m1n1ble ex.posure li m,t d t7' or Disuw- Control Jnd Pm rrmon. \l:'Jshmg1on, DC 12010) PELI Hr c~mponrnr:s oi 1hr mr.J

:ro;h~:t';'/~;-~ '"';ry work er~ publ,;hrd JI 29 C.F.R. Sl91 0. IOOQ, Table Z-1: for conmuc11on mJ,1:n" · S 926.H, Ap~nd,x A: Jnd for mmumr wor h ri JI 29 C. F.R. §1915.10 00, Ta~lr Z

360 Chapter 10 Chem istry of Some Toxic Substances

,\t 16 C.f. R. S I S00}~\{2 )( i), CPS C defines a consumer product as highl y toxic 1f it '°~iplics with an}' of the ow mg co~d111ons:

It produces de~l h wi th111 14 da ys _111 half or more th an half of a group of 10 or more IJborator)' whne rals, each weighi_ng between 200 an d 300 gram s, at a single dose of -o mg/ks or less when orally adm1mstered; or

1 tt produces de:ith wi th1 n 14 d~ys _in half or more than half of a group of 10 or more \.lbor,itof}' white r~ts, eac h weighing between 200 and 300 grams, when inhal ed con•

111111 ously for a penod of 1 hour or less at an a1mos pheric concent ration of 100 parts

p(r millio~ by vo lume or less 0 ~ gas_ or_ vapor or 2 mg/L by volume or less of mlSI or dust, prO\'ided su~h conce ntration IS likely to be encountered by humans wh en th e ,ubsta nc e is used m _an~· reasonabl)' foreseeable manner; or

1 It produces death w1thm 14 da ys in half or more than half of a grou p of JO or more rabhitS rested m a_ dosage of 20~ mg/kg of body weight, when administered by con· t1nuous contact with the bare skm for 24 hours or less

10,8 TH E HAZARD ZONE In Chapter 6, it was n?te~ that DOT assigns one of four hazard zones to gases and one of t\\'O hJza rd zones lo liquids that pose a _health hazard by inhala tion of their vapors. DOT dmrniin es the ha zard zones fo r all tox ic gases and liqui ds by reference to their LC_'iQS as follo ws:

1 When the LCso is eq ual to or less than 200 parts per million, DOT assigns Zone A to th e gas or liquid.

1 When 1hc LC 50 is grea ter than 200 parts per million but equ:il to or less than 1000 parts per million, DOT assigns Zone B to the gas or liquid. When the LCso is greater tha n 1000 parts per milli on but equal to or less than 3000 pamper mi ll ion, DOT assigns Zone C to the gas. When th e LCso is greater than 3000 parts pe r million but equal to or less th an 5000 pJrts per million, DOT :issign s Zone D co the gas.

Emergency responders use the hazard zone designation to determine the dcg.rtt of tox.ic- 1l)' Of a gi\·en gas or liquid. Although exposure to a gas with a Zone A des ignation is likely ro lie immediately dangerou s to life, exposu re to a gas with a Zone D designation could be momentarily tolerable for some indi\· iduals. This disrincrio n notv:iths1anding, the warning to emergency responders at tr.:ansportarion mishaps involving the spill or leak of a gas or liquid to which any of the four haz.1rd zones has bttn assigned is to don fully-encapsulating protec- rnedothing and use se lf-contained breathing apparatus before executing a response action.

10.9 TOXICITY OF THE FIRE SCENE The fire scene is usually an extremely dangerous environment. Even if all its physica l hazards coul d be elim inated, 1hc atmosp here would s1ill be filled with smoke, dust, toxic gases, and other hazardous substances. The potential for illness and death at a fire scene most often results when individuals arc exposed to the smoke and mxic ga ses produced during 1he fi re.

smoke • Thfairdisper- donofpart iclesof carbon and other solids andl iquidsofincom- p!etecombust ion partku la! t matter • Sol idandl iquidpar- ticle1suspendedlnthe atmosphere

Puc simply, smoke is the gra y-to-blac k plume of matter consisting of an airborne dis· pmion of finely divided particulate matter co mposed of carbon par1ides whose diamc- 1m range from 0.0 I to 10 micrometers. During most fires, carbon is initially produced as a product of incomp lete combustion as microscopic par1icl es, which rapidly agglomerat e ::~t ;,r;:rt~~ii':t;era - mco blac k particulates coll ectively referred to as soot. When they are inhaled, 1he larger matter generated particula tes in smoke arc usually filtered in the nasal passageways, but the smaller o~es dur ing the incomplete can be drawn into the bronchi and lungs. When soot is produced during the combusuon combustion of carbona - of petroleum products, ii is primarily carbon black (Sectio n 7.6-F). ceous materials

Chapter 10 Chemistry of Some Tox ic Substances 361

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I I I I

sub- st.nctthatause, the eyes to involuntarily tur,ndclose

cili• • Fmehai rhkepro- JKtionssuchu tho5e alongtMe.rteriorof the resp iratory tract thatmove inunisonto htlppreventthepas- s.ageofftu id5andfine partirulate matter into thtlung5

l re m:mtr inro rwo classC'S, P~vl-2.5 and PM-JO. PM 2 5 EPA di\idrs partic~ner havmg paroclc diamrtcrs equal to or ltss than 2; · teb1

'° ultra~nC' parr;culatc . ·culate m:mcr ha\·ing parudc diamerc-rs ranging fro~ 2~crolll- ~heers/~1~r~1 paruclts pose rhc greater ri_sk co one's heal1h, brca~sc';h~O

, d~ I tn the lungs and arc not cleared by c~ug~mg. Trapped_ by ihe su rround<>q ~=~e of

1 t[ lungs, they obstruct their proper funcuon mg and conmbutc to the 0 ftsct1~

ulmonary ill n~~ and premature death. . p The long-rum inhalation of parcic~latC' rnan~ r h~s ~c~n lmked wn~ an increaSt I cardio\·ascubr and pulmonary diseases m susccpablc 1~d1v1duals. In particular, the in~o lation of p3rncul:ite marcer hastens the deaths of th e sick and eldc.rly b~ contributing~ the premature onset of heart attacks, strokes, and _emp hysema. le ts logical 10 infer l/ut soot parricul.ues can also comributc 10 the mcept!on of adverse healt h effects in t~ fi fi hrers who inhale soot regularl y while combati ng fi res. . ire lgure J0.4 demonstrates chac the produccion of smoke 1~ directly linked with th(

incompleie combusiion of matter. When produced at a fi_rc scene, the smoke and combus. rion products like ca rbon monoxide and hydrogen c~am?e often represe nt a greater Jui. ard to life and a more serio us hindrance co firefighting ef~orts 1han the fire it~lf individuals who are unable to escape from a fi re sce ne often di e from smo ke inhalario~ e\·cn beforethefire reaches th em.

Fires are not the sol e source of soot particles, al though th ey generally arc the indi source. Ocher sources include the flyash in stack emis~io_ns fro~ ~ossi l-fucl-fired po:: plants and industrial manufacturing plants an d 1he ra1lp1pc emiss ions from hea vy-duty \·ehiclesand m.achiner}'-

10.9-A TH E IMPACT OF SMOKE ON VISION When che eyes are exposed 10 che irritant compo?e~cs _of sm~ ke, they sting and in volun- tarily tear and close due to the presence of certain 1rntants m smoke ca lled la crlmators (Section 13.12). Their \'apors act on the sensi ti\·e nerve end ings of the muco us membranr of the eyes and cause an excessive, involuntary unleashing of :a flood of tears . Two exam- ples of lacrima1ors found in wood smo ke arc fo rmald ehyde and ac rol ci n. In the most severe instances, exposure to 1hcm causes u ro \'is ibiliry, especially when smo ke canllOI readily esca pe from a burning structure.

10.9·8 ILL EFFECTS CAUSED BY INHALING SMOKE The most immediate ill effect caused by inhaling smok e is hear dam age to the ti ssues of che respiratory tract. This damage is usually limited to [he tiss ues of 1he mouth and upptt ch roat, bur in the most egregious instances, it can cause pulmonary edema of the lungs {Section 7.3- B).

Another serious problem caused by smoke inhalation is deposition of carbon parrica- laces on the surfaces of the respiratory pass:agcs. The trac hea and bronchi arc lined with [iny hairl ike projections called cifla th at act in a wavelik e manner to force deposi ted p~r- ticlcs upward towards chc esophagus, where they generally are swa ll owed or deposited in phlegm. lnhal cd smo ke, however, greatly impai rs the abi lity of th e cil ia to cffccti\·dt· remove ca rbon particulates from the respiratory passages. Ci lia that ha ve been dam agtd br hear cause an indi vid ual co choke, gag, and experience labored brea th ing. Th en, OX)'• gen levels in the blood drop to serio usly low le\·el s, and fatalities arc more lik ely.

Breaching particulate matter also inc reases th e likelihood of contracti ng lung 0111cn, t~c form of cancer characterized by the emergence of ma lignant tumors on the lungs. lndi- \·1duals who regularly inhale particulate matter :arc 8% more likely to develop lung canctr r~an noncxposcd ind ividuals. The onset of lung cance r is typica ll y cx:accr bated by tht simultaneous exposu re to certain compounds 1hat arc adsorbed on smoke particulates. : .:c:~i:~;~~~:~ ;~~lt

2 ~c the ca ncer-causi ng polynuclear aromatic hyd roca rbons, which

362 Chap ter 10 Chem istry of Some Toxic Substances

Smoke

Heat

10.9-C THE ADSORPTION OF GASES ON TH E SURFACES OF CARBON PARTICULATES

Smo ke

The ca rbon paniculac cs in smoke act as adsorbents for gases. This implies that when we inha le smoke, i1 isn't just chc carbon paniculatcs that are drawn into our bronchi and lungs.

FIGU RE 10.4 Smoke, cafbonmono;,ude.and wattrvapora re typ,ull1 produ<eddunngthe 1ncom pletecombu5110n of fou,lfuel5 Depend,ngon thl'natureofthtfue l. 1he atmospherewrround,nga fore mayalsocon1a1n vaoorsoftheunbumed fuel,1tsd@'C omp051t1on p<oducts,andother ol.•dat,onp<odu<t5The 1n/ia!at10noftt,1scombl• nat,onofwb5tancesg en • erally 15more ,nJunous to the ht althoff.ref,ghter5 and f,re v1ct1msthanare tl'1tae<ompany,ngflame5 orhtat

Which gases adsorb to the particulates? To answer this ques tion, ii is nc_ccssa ry 1_0 rnisit two processes int roduced earlier: incom pl ete and complete combus tion. The ir natu re is schema tica ll y shown in Figure 10.5. When carbon-ric h materials igni te and

Chapter 1D Chemistry of Some Tox ic Substances 363

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_111

C..rbonmonoxidt

FIGURE 10.s The ,ncomp,ete comov1t,o-i of fOSSil fuels snowr on tN' ltit. proJucts ca rbon

:;:~!~~a~s ~~1-rrch e<ory,;ien-51arwd fre Thecori~te combvS1ot)n oflo11lfueh sho'...nonthe11gt,1,product1 car oonooxdea ndwater~a:,o, Th~srtua:,on <I typ<c.J1ofaluel1~a1wa1m ... edw1ha,ror oxygenbefort1t1 19n1>0<1

Smoke H;O

co co , H,O co t ! )co,I

""' burn, th e carbon unite s with oxygen co form car~n monoxide or carbon dioxide, both of wh ic h are colorless, odorless gases. Th ei r formauon occurs as follo ws:

Incomplete combust ion is tht burning_ ph enom enon occms when the supply of air or oxygen, or access to cithrr air or oxygen. ts lnmted; th at 1s, mcompletc- combumon m fuel-rich firi=-s . When fo ssil fuels bum, incomplete combusuon p~occsses produce C-Jrbon monoxide and soot. Jn ordin:i ry c1rcumitancts, the_ carbon m~n?x1de produced.dunng 111. complete combuscion ent ers the atmosphere, where 1t slowly ox1d1zes to carbon dioxi de.

By contrast, complete combus tion is the bu rn1~g process .that occurs when plenty of air or oxygen is a\'ailable. The compl ete combusnon of fossil fuels produces car bon diox ide. Complete combustio n occurs when the flow o f fuel and air can be regulated, .s m a normal heatmg sys1em.

Although carbon monoxide and carbon dioxide arc the pr inc ipal gases present at I'll'· rnally all fi re sce nes, se\'era l other gaswus co~b~stion _produc1s_ "'? also be present. They include hydrogen cyanide, ammonia, sulfu r.dmx1de, nitroge n d1ox1~e, hydrogen chlonde, and acrolein. Wheth('r one or more of them IS actually prese nt at a g1\'C' n fire sce ne deprnds on the chem ical n.:uure of the material that burns, smolde rs, or undergoes thrrmal d«om- pos ition. We sh,1 11 derermine how they are produced in lat er sections of thi s chapt er.

10.9-D ENVIRONMENTAL REGULATIONS INVOLVING PARTICULATE MATTER

Using t.he authority of th e Clean Air Act, EPA regu lates the conce ntra tion of particulate ITlJ t· cer (other than windblown dust or soils ) in th e ambient air as :1 criteria air pollutant (X'C· tion 1.3-A). For pamcles having a diameter of 2.5 micrometers or less (PM- 2.5 ), EPA set tlit primary and secondary daily sta nd ards at 35 µg.lm1 of air, averaged over 3 yea rs. It al soS(l t.he prinury and secondary national ambi ent air-quality annual sta ndard s at 15 µ!ifm 1 anJ 12 µg.lm 3 of air, each averaged ove r 3 yea rs, respect i\·e ly. For particles ha \'i ng a diJ~ltr ranging b<.-tween 2.5 and 10 micrometers (PM-IO ), EPA set the primary and seconda r)' national air-qua lity daily and annua l standards at 150 µg.!m 3 of ai r, averaged ove r J yea ri.

10.10 CARBON MONOXIDE Ca rbon monoxide is an odorl ess, colorle ss, taste less, and nonirritat ing gas at ordinl!'}' room conditions. It is also th e major poison most likely co be enco un te red by emergtng' responders. Some othrr importan t ph}•sica! properties are provi ded in Table I0.4. . As a commercial chemical product, ca rbon monox ide is l.irgely used by th e chemical mdu stry for th e production and manufacture o f other subst ances like methan ol (Ste· tion 13.2-~ ). Because it is a component of water gas {Section 7. 2-C), carbon monox:idt~ produced m large vo lumes b)' the chemical mdustry during the manufactu re of h>·drogen

364 Ch apte r 10 Chem istry of Some Toxic Substance~

jbl•ii¥1 Physical Properties of Carbon Monoxide - 341 . F{-20 7' O - -----3 14"FH 92 ' CJ - -------081 11 28 ' f {609' Q

125% by volume

742 % byvolume

In the "1l' tallurg1cal indu stry, carbon monoxide is used 10 reduce metallic oxides 10 iheir corrrsponding metals. F?r example, the fo llowing equation shows tha t metalli c cop- rer is produced by the redurnon of copper(II ) oxide:

CuO(s) - CO(_i:-J ---. Cu(J) - CO2(.~) Copp,.:r,ll \0,1 ,J,c C.11bonn1000\IJ., CoPf'(r Cirb,.,nd,o , ,J<

10.10·A PROD UCTION OF CARBON MONOXIDE The isolation of carbon monoxide from water gas serves as the primaf)' means by which mbon mono xi de is produced for commercial use.

10.1 0·B Ill EFFECTS CAUSEO BY INHALING CARBON MONOXIDE lnh.tla tion toxiciry is 1he primaf}' risk associated with expos ure to carbon monoxide. To undmtand why this gas is poisonous, we must first ex amin e the ch emistf}' that occurs du1ing respira1ion.

When ai r is inhal ed into the lungs , a supply of atmospheric oxygen is assimilated into the bloods tream. The oxygen is carried throughout the body by a complex component of 1he blood called hemoglob in. Each red blood ce ll comains about 300 million hemoglob in molecules, each of which contains iron in the fo rm of the ferrous ion (Fe!') , The molecu- br struct ure of each hemoglobin molecul e is ve ry complex; hence, we represent it her e by the srmbo l 1-lb.

When hemoglob in unites with oxygen, the compoun d called oxy hemoglo bin is pro- duced. Because its moleculrs are also co mplex, we rep resent them as O! l-l b. The impor- tance of its formation during respiration is represented as follows:

ll b(aq) + 0 1(11q) - 02 Hb(oq) O,)hrmog!ob,n

As oxy hemoglobin molecules move about the circulamry sys tem, th ey arri\'e at the mious tissues and orga ns of 1he body, where the oxygen is rel eased at 1hc cellular level and they again become hr moglobin molecules. The hemogl obin then returns th~ough the CJrculato ry sys tem to th e lungs, where they secure a new suppl y of oxygen. This process occur. O\' t r and over with every breath we take. . .

When ca rbon monoxide is inhaled into the lungs, it imerrupts normal respirati on by bonding to th e blood's hemoglobin molecules. This union produ ces the substance called ca rboxyhe mogl o bin, represent ed as CO Hb.

Hh(aqJ + CO(K) - CO Hb(aq) lfonoglobm C.uboo mono"M Carbo•)h.:nl('lglobm

ponentof red b lood cells that transports oxygentothetissuesof the body

compound that forms when oxygen comb in es with the blood 's hemoglob in

c;Hbo xy h, m oglob ln compound that

forms when carbon monoxide reacts with hemoglob in

Cha pter 10 Chem istry of Some Toxic Substances 365

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devi ce that maybe u1edtomeasurethe

iiH¥11 111 Effects AssociatMI with Varto~s Carboxyhemoglobrll Concentritttons in Human Bl ood ~~~;YHfMOGLOBIN INHALATION AN~PTOMS 0- l O Nosymptoms __ _

10-Z0 , Tighmessacron fo re ht>ad: po~ e huda~he ---- ZO-JO Headache, thr~ g in thetempl es; slow1ngofn! l le~

~ udache, wHkne11,d1 zz mess; dimv1s ion,na ~ vom1t1ng, collapse

40-50

50-60

60- 70

, .... 80-90

Same as immed iately abov~ wrth greater possi b ility of collapse ;;;-- fa mt,ng, 1ncrused res:..pir_" -'°-" -"'- '-' '-" ---- Fainting, incru~d resp1rat1on and pulse, coma wit h i nt er;;;;;;;;--

l convu ls1ons I Comaw,th interm1ttentco nvulsions; depressedresp iraUon~

funct 1on, poss1bteduth weak pulse and slowe d resp irat ion ; resp iratory fa ilure and duth

I Outh 90-100 Death •A(l.lpud In part from Liurtnct Brunton, Bruce o,, t,ne r, and Bjorn Kr,ollman. Goodm4n and G/lm,n) n,, F'NmYcologiCII B•liJ o f rt,r,, peu !KS, !1th eclnkln (Ntw Yori(, NY· McGr, w-H UI Bo o~ (omp1n y, 1001), p, l&8I ,

When hemoglobin is bound to carbon monoxide as CO Hb, it is u~~ble to perform its normal bodily funct ion. This is particularly gra~·e because. hemog!obm s chemical affinity for carbon monoxid e is roughl y 210 times greater Lhan its affimty for oxygen. Bet.iUSt COHb forms so readily when elevated conc('ntra1ions of carbon monoxide arc inhaled, th e situation may be immediate!)· deadly.

The ill effects caused by inhaling carbon monoxide a rc not solely associated with the production of CO Hb. Carbon monoxide inhaled into the lungs does 1101 always bond to th e blood's hemoglobin; instead, it assimila tes into the cells of the body's tissues, whm it may interfere with enzymatic processes. For this reason, long•tcrm exposure to a low con• ce mration of carbon monoxide may cause ill effects that are not otherwise experienced by a shorr-term exposure to the same concentration.

Individuals who inhale carbon monoxide expe rience the symptoms li stt"d in Tab le IOJ, but there arc multiple ways m acqui re lower-than-normal blood oxygen levels. Firefightm, for example, are rarely exposed at fire scenes to ca rbon mo noxide alone. h usually is pro- duced with otht>r combustion products like hydrogen cyanide and nitrogen oxides, Const· quemlr, when firefighters inhale these mixtures of noxious gases, they may t'Xpericnce 111 effects that are dissimilar from those listed in Table 10.5 for carbon monoxide alone.

When the srmptoms art' expericnct>d by individuals who have in haled ca rbon monox· idc, the y are link ed v.ith the conversion of hemoglobin into the biologically useless m· boxyhemoglobin. It is the presence of CO Hb in the bloodstream that hindt>rs the transpon of oxy.gcn and causes th e headaches, fainting, throbb ing in the temples, and other symp, roms listed in Table 10.5.

o1tyhemoglob in, car• 10. 10·C CARBON MONOXIDE AT FIRE SCENES AND OTHER LOCATIONS ~::::mJ~~~~n, arici Carbon mon?xi~e becomes a component of the atmosphe re at virtually every fire scent. To concen1rationi in a assure that firefigh1crs do no t inhal e a letha l concent ration of carbon monoxidt , cxJ)frtl per1on's blood r«:omm end their use of a pulse CO-oximeter. This device has been constructed to t'stimate 366 Chapter 10 Chem istry of Some Toxic Substances

J lb co nce nt rn tion m th e blood of th e use JC tti< CO ·it ion of CO i lh, but also chcconcentraci o~s f urre nt models measu re no t onl y th e c,Jfl(<'n cr.10. 14-B). These me:1sumnents are ('SS<'nual oty~cmoglobm and m('th emoglobm 1Sr-1'1on Monitonng fo r poisoni ng by p I CO or ac1 natmg the on-seen(' f ('COV('ry of fi r<'figh1;~\ ,;, NFPr\ 4 fo r Mall )' fi refight er e~i:sed ,; ximmy or mher avai labl e m~thod s is ~1JodJt use;1 shortn ess of brea th or g . .carbo n monox ide or pr<'Se nt mg w11h hrlJ~;:;~ ,;a ixrs~ n·s CO Hb concentr~u ona;~;;:~; 1~ ~ S)'~lptom s. M JI<' ITl<'dica l actenti~n for the md.1vidual. fae n when th; •s~i,!'! ~c~: ~: ;;; :c:;:t1s

1 ::: ~;:

I, however, survivors may mil ex pen <' ncc lo ng- term ca rdia c, neuroco •n11 ive and :~ropsych1acnc ~amage (s uch as r~e onset of demenua ). g •

ExPo5~tc~~~;;~~~ :,T1~0 ~~~: .1~~~=: ~<' ~ith th e ma jor it}'. of th e illnes ses and death s chJ r art ><' . • carbon mon oxide 1s not associated so lel y 111th ch<' burnm g of buildings and ot he r str uctures. As ill ustrat ed in Figure 10.6, the

--.0-Chimoov fl,e FIGURE 10.6 The comb1m1on productspro-ducedw,th nanoperaton9!,re~actmayenter thenono ewhen ach,mney flu ebecofl'es b'ocked Underth,scircumstance, tilefire~ace serve1asapo1en11alsource olcarbonmonox- 1depo,son,ng Topreventthedevelopmen1ola poisonousatmosphere,nthetiome,occup,;JnU \h0ul(la!waysconf,rmtha! ch ,mneyfluesare unblocl::ed , so1henox1ouscom~t,onproducts prope•ly vent up tilellueand 1ntotheouu,de atmo1phere

1A.i J!\J.logo us &vice ,~ the bl ood-oxygen-s~ rurat io n meter calle d in o:C)gtt1 p11/u o.tm1eter. h meJ;um blood• Oiyg(n saru, at, on, i.e. , the r:i tio of 1hr mtal o.xyhr moglobin conctntrm oo ro th e wu l hrmoglobin rnnctntrJ• IJO:l l!l the blood. Normal read ings u nge fro m 95% to !00% at SCJ le·, d. Va luC"S brio ~ 90 % u e com1dcr~ ~. £xperc\ recommend th at pilon u\.C i n o~-ygr n pulse oximctet when flyi ng unprt"S1unl~ planC'S :i t 1h1~des t.::ween 8000 fe.: t 1243 8 m) ~rid 12,000 fn:t t3658 m) m determine whether they rcq u1rr supplemcnul 0~1gcn

:~;~~ ~~ :: 0;,:-,::::;d0 :~;~;· Rrh.1bJ/ itarion rroasJ fo r Me,rrbt rs D11rmg Emergt11C)' Optral/Om a11d TrJ mmg

&r1c,st1 (Quincy, MHsJchuset1s: Nmonal Fire Prorcc non Agency, 2008 ). Chapter 10 Chemistry of Some To.x ic Substances 367

d dunns the use o.f fau lty furnaces, sto\'es, sp~ct inh;ifauou of c:irbon nio~ox1d; N::;~:t;onsidered rh e !(;1ding causi:- of acc1di:- ntal P01SOrJ.

hcJWS, b]oeked ch1~1; ~:.· an . lly wary of exposuri:- to carbon monoxide 1ng 111 the Ame~ic:in pregnant must bi:- espra ral barrier 3 nd dissolving in the blOOd J

\\;'omen w 0s ~:pable of crossing th e Pi3''::\.)'gen it is subj«-te d to an increased n.l: becauS<' rhe f;d1 Jkc"Juse rhe fe tus recewes esshe moth~rs have inh.aled sufficient c.1rbo ihe. un~~~' ~irth defects, parocularl~ : ·:::sst. . . . c ~o~:~idc t~ cause chem to ]oSc ':;;;;d with exposure IO carbon mon.ox1de lS mhalatio~

Airhough th ~ primary/:~~ ;:ss 3150

pose th e nsk of fi re and explos ion. When ignuro,

wx1c1ty, bulk qu;inun; s o to carbon dioxide. c:irbon monoxide ox1 izes JC(Xg) ... O~(g ) __. !CO;(g)

(a,t,.,nd1owk'

SOLVED EXERCISE 10.3 Thr ~rwn ~de c011Crn:rat on n 1ne ;iha~\1:;;!:,~;;;:~u~a ~~:~Y;~'e ':;r:rt~~~ ~;P~°:i'~:,~: by volume whtn t/'le c.tr s di /I~. b<Jt is re uce concenrra: Ol'!S sod SSIT' 1.,,, 7 r inned as ,ns,de a car's comb us! on cnambers, incomplete com!M'.o, Solution: When tt>e supp'y of~~~,: wt,en rts fuel bums A compara1,1·ely sma l'er volu me of a,r Is dr.wm ,rco occurs and carbotl moMl!de 11 Pd n ,di,ng than when the car 1s mo~mg Th, s ca 1Jses a cor rt'Spond ng', iar:jfl' :o~:s;~,t~:i=~ ,:'pr!IJCed wt,en the car 1s 1dl: ng comoared 10 when ,t 1s movmg

SOLVED EXERCISE 10.4 usmg a pu~ (C)-0.Qrreter, a paramed< establ,shes mat the b'ood of an on-duty f1ref19h 1er cont a ns carbe')flt- rnog'OOln a1 a concentrabon ol 62'Ml by volum e lsth,sconc entraboncons,deredhle-threatenmg ? Solution: T;ib'e 105 ,nd.ca:estha1acarbol)'hernog'ob1nconcen trat1on 1n1he rangeof60% to70%cou'dt:t fa-.al BaSld on tt\js mform~bOl'I, 11 ,s prudent to conclude that a u rboryhemog!obm concentrat1on of 62~ 5 ife-tllfeaten,ng

10.10-D WORKPLACE REGULATIONS INVOLVING CARBON MONOXIDE Wh en t~c ~se of carbon monoxide is necessary In the workplace, OS HA requires emplo)'· ers ro hmn employee exposure to 3 maximum concentration of 50 pans per million (55 mglm \ averaged ove r an 8-hou r workday.

10 .10-E ENVIRONMENTAL RE GULATIONS INVOLVING CARBON MONOXIDE

~;l~~~·~it~ow c~nc~ntrat~ns of carbon monoxide are natura l compo nents of pol!utd 1~;tion in th; :~tbi:~~t~i; a: ae ,;iir:ar~a Act, EPA regulat.es the c;1r.bon mon~xlde conctn· a1r-qualit)' s1and3rd for c3 rbon mon ·lollutant by settm? ,.he p ri ma ry nat1011:tl ambirm aver3gc and J5 pans per million (

4 0oxi e jt 9 pamper million (10 mg/m

3 ) as :in 8-hour

368 Chapter 10 Chemistry of Some Toxic Substances mg/m ) as :t I-hour a1·er;1ge.

A DANGER Us in g II generator Indoors. CAN KI LL YOU IN MINUTES, Ge nerator e)( haust contains carbon mono)(•d e. Th is Is a po ison you cannot see or sme ll .

NEVER use Inside a home On ly use OUTSIDE and or garage, EVEN IF doors far awav from win dows , and windows are open . doors,andven1s.

Avo idothergeneratorhuards. REA D MANUA L BE FORE USE .

10 7 To m1n .m,ze or ehm1na 1e exoosure to carbon monoJUde from the use of portable 9enera101s. ~~~:q .i r;s ai 16 c FR 1407 3 to affix this label to portab1e generators and the,r pa<:k.a9 1ng

=---- 10. 10-F CONSUMER PRODUCT REG ULATIONS INVOLVING

CARBON MONOXID E The death toll from i.nh.aling c:trbon monoxide In the home is considi:-rable. T h is fact has caused th e CPSC to mform the public that exposu re to the gas is potenti:i ll y letha l. The CPSC uses lab eling to warn peop le abou t two relatively common ways of generating car- bon monoxide: the burning of cha rcoa l in doors in gr ill s, hibac h is, and similar items; and che operation indoo rs of portable gene rators. The production of ca r bon monoxide in bo1h inst:tnces m.ay kill a home's occupants in minu tes.

As note:d e:t rlier i n Section 7.6-G, CPSC req u ires cha rcoal manufacturers to affix the label shown In Figure 7. 17 on charco;1I packaging. CPSC a nd FEMA also requi re pomblc generator ma n ufacturers to affix the label shown in Figure 10.7 on po rtable generators to warn the unsuspecting pub lic that using these device s indoors co ul d lead

1ofa1alitic s,

10.1 0-G TRANSPORTIN G CARBON MONOXIDE Ca rbon monoxide is comme rcia ll y av:tilable as a nonliquefied compressed gas and cryo- genic liquid. When shippe rs offe r ei the r commodity fo r transportation, DOT requires chem 10 provide the re levant shipping descriptio n shown in Table 10.6 o n the accompany• mg shi pping paper. DOT a lso requires shippers and carriers to comply wi th a ll app licab le IJbdmg, marking, and placa rding requirements.

iilhll·IM CAR BON MONO XIDE

C.ubonmonoxide, compressed gas Carbon monoxide cryogenicliqu id '

Sh1ppmg Descriptions of Carbo n Monoxide

SHIPPING DE SCRIPTION UN1016, Carbon monox ide, compressed, 2.3, (2 .1). (Poison - Inhalation Hazard, Zone DJ NA9202, Carbon monoxide, refr igerated liq uid, 2.3, (2 .1), (Polson - Inhalation Hazard, Zone D )

Chapter 10 Chemistry of Some Toxic Substances 369

r hypetb•rit oxygt n thtr• py • The1nhala- uonofoxygenunder incru~pres~re w1th1nar.ea!Mstttl ch amber

G TO INCIDENTS ASSOCIATED W ITH EXPosu~ 10.1 0-H RESPONDIN ONOXIDE E

TO CA RBO N M ness from inhaling carbon monox1d,.., thq• sh Wh en md1\ 1du;1.l s lose '

1 ~:s:~:u:·here 3 mrans of amfic1al rc:sp irauon an d fre~h :ul~ bi:

mo1ed swiftl y to ;rn opt rfun IOO¾ oxygen fo r on~ hou_r _reduces the conct>ntrai( &eti c;i n be :idmmist ned. ~;e~loolro approximately half its 1m11al con ce ntration. on or carbon monoxide mt de s hav<' b('en excessively exposed to carbon rn o

When rm ergency respon f:c1li1 where arr noxidc, th(}' :ire o.ften mmspo~;r~ to aunde r : physic1a hyperbanc oxygen thi ,h!~rhan -normal-oxygen ~unos~hue 1~s1de a pr subiecong them

5 ~::.n Figure IO.S. The intermittent mhala.tl on o~ 10 0 oxygen at

ber of the type h (202 6 kra ) for ½ to I hour can be hfe-savmg bt'caust' 1l i pressure of 2 a~:;:~o~r:f ca rboxyhemoglobm to oxyhemoglobm co mpared wnh /h~~t1 ~nf ;hoeo~::: ~oen at I atmos ph ere (10 1.J kPa ) for the same period . . \'<' hen hypcrbaric OX)~ gen ther.ip/i~ ust"d to trea t indi viduals exposed to ca rbon monoxide, the ox}gen acts ~

an 3~~~:t:~ of a hyperbaric cham ber was fi rst introduced ~uring the nineteenth cent llrj•

tO aid divers suffering from wo rk -relat ed disorders. When divers movl' dl'l'per and d~Ptt

FIGU RE 10.B Hyl)frt:anc oxygen therapy ,nvolves adm,n ,ste ring 100% O)()'gen at a pre\1ure up to three t rrt! the normal atmo1ohenc pressu re for 30 to 60 minutes to patents wh,le they l, e ,ns,de enc losed ct,arr bers TN u1eolhyperba11c oryg enth erapyat2atmmpheres (2026k Pa)acceleratesthe removalof carbonmonoxid! from the blocdstrearn fo r this reason. 11 can potent,ally save the lives of emerge ncy responder; who ha·ie t:,et, o~ere;po1ed to carbon mono)(Jde (Co,,rresyo/Perrys,,romro,c.i1coroor,1 r,on, R,wy,1Be-ac.n. noroa)

370 Chapte r 10 Chem istry of Some Toxic Substances

Jcrii :itt'f, th<' 1'.1'~~ 3 s~d pre ss ure/{ ihc surroundings cau st's more rntrogt' n and oxygen ;; Jis sohe 111

th ~

1 ;0 1: ;~ ~mounr dissolYt'd a11he water's surface. When

,hr d11'rrs retu~st ream and tissues. Tfus )' th e-e gases form bubbl es th Jt relea se rapidl y ntO their bloo 1 . omprt'sses nen·es and obstructs arteries, vem s,

~nJ l)n1phaw: v~::1~'. ~:~;~n~ t~:c~~ti~ng pam,. esprc1all y m the joint s. This pa inful ndit1on is com ) 5• To avo id it, divers must return 10 tht' surface ~r} slowl y or rakr advanta g~ of th t' use of a hypt'rbanc chamber. The hypt" rbanc cham- ~ r 3u0 ws the di~·ers 10 ~~pmence th e same pressure that they experienced at undtrwater ~rrihs. Undt'r 1h1 s cond1oon, the gases t'SCapt" naturall y.

Hyperb.:mc chambers ha ve ?et'~ ~St'd not only 10 tn.""at divers and mdi\'iduals exposed ro ,.,rbon monox ide, but also individuals subj ected wit h certam o1her ailments. Ph ysi- o~ns h:1. 1·c successfull y treated d1ab_t"t1c foot ukt'rs, bone infecti ons, ,humal burn s, and rJdiauon bur~s 10 _ bone and soft tissue: The success of hyperhanc o xygen th erapy fo r crtJllllS th ese m1unes occu rs fo r two ma,or reaso ns:

1 The use of a h)•perbari c chamber incrt'ases the amou nt of oxygen that the blood Jr~irrs ro a patient's organs and tissues.

1 Bre:11hi ng oxy~en undt' r inc~eased pressure allows th e blood to carry oxygen drtP"r m!O the body s org:ins ~nd m sue s. ~ nd er th is increased pressure, th e capillarit's diffuse the blood f_:irtht'r, allowmg oxygen-rich blood to be carried to areas that may oth- trwisc be maccess1ble.

Although the use of hyperba ric OX}'gen therap y ha s bttn successfu l for 1rt'at ing indi- iiduals exposed to c:1rbon mono xide, the same degree of success has not been achieved ~·hen i1 is use d for the trea tm en t of indi vi duals exposed to other poi so nou s gases like hid rogen cyanide (Section 10. 1 l l and hydrogen sulfide (Section 10. 13).

10.11 HYDROGEN CYANIDE At te mpera tures above 79°F (26°C), hyd rogen cya nide is a colo rless, toxic gas. Some of its ph)'>ical properti es are prov ided in Table 10.7. ln the chemical industry, it is used prima r- J), to produce methac rylates (Section 14.6-E ). In the pa st, hydrogen cyanide w:is used as i fum igant to kill rodents and in sect s, especially onboard ships, but given 1he accompan y• ing huma n dange r, thi s practice is no longer popular.

Hyd rogen cya nide g:is possesses the di stinccivt' odor of bitter almond s, which nor- mJlly is pt'rceived at a concent ration of 0.2-5.0 parts per million. Due to a unique geneuc pred1spos1 tion, how eve r, some peop le cannot perceive th e odor of bitter almonds.

iilhil·il Physical Properties of Hydrogen Cyamde "1elt1ngpoint 1•F(-14•Q Boiling point 79"F(26•CJ Spe< 1fic gravi tyat68°F (20 ' C) 0.69 ~ ens ity{air : I) 0.938

---------t-':.c'':::(-::";;''';J:;;;;;:;------- Auto ign ition point - 1ooo•F(-538' Cl Lower flammab le limit 6% by volume lipper flam ma ble limit 41 % by volume

Hydrogen cy1n ld1

Chapter 10 Chem istry of Some Toxic Substances 371

r

cyi nosi s • ni,comb1- n11.Jonofphysical iymptomsis~itl!d with.ir ed uced o.:ygen concentrat10n jnth@ blood

As shoirn m the follo win g dlusira 11on, there :irr l\10 thcorrf1cal Lt'.'wi~ StrlJ for .i subscJncr whose molecules contJin onlr one ca rhon , hydrogt'.'n, and n11::t~

II N ~ C

Th 1

unds repreS( [l[ed by rhese di stinctly differc-nt ~trucrur(."s are inse p,ir,1b l , econ po h b;fJnce called hydrogrn cyanide is rrpresemcd hy the h e. f0r

h1s10nc rea sons, t e su ' c ern1Cill fo rmu!J HC , .

10. 11-A PRODUCTIO N OF HY DROGEN CYANID E Hrdr ogen cyanide 15 produced as :1 commw:ial chrm1cal product by the ca ral nic reaqlOn bemeen :i.mmonia and air w11h na rur:il gas.

:!NH1(~l -+- 30:(ef - 2CH_ifgl - :2 HCN(g) ._ 6H10(g)

0 ,.~ .. n \k1lunc HJ<l<O¥•fl ,).ui,Je \\~i~r

The hydrogen cy:im de molrcults produced by the reaction !~nd to ~eac1 at an explos ii·e r:He wnh other hydrogen qanide molecuks. To preveor thi s reac11on, the cornrn grades of h)drogen cya nid e arc srab1lizc-d wirh wartr and 0.05% phosphoric acid . trciil

1 0 .11-B ILL EFFECTS CAUSED BY I NHA LI NG HYD ROGEN CYANIDE Exposure to hyd rogen cyanide occurs primarily when th e gas is inhalrd, as a resu l which rhc bod y ex periences 1hc ill effects hst~d in '.able 10.8. Th e initial sy mpt;~; include dizziness, headache, diarrhc.1, and anemia, w~1ch arc also characte ri stic of expo. sure to most poisons. Exposure to hydrogen cyanide can a lso occur by absorpt ion throu gh rhe skm. . . .

Expos ure to hydrogen cya nide generally 1s associated with _the onset of cyanos l bluish colorauon m the finge rnail btds, lips, ca r lobes, conjuncuvc, mucous membra

5 '

and tongu e. CyJnosis 1s caused when th e la ck ~f oxygen m 1he blood (hypo:i:,a ) is ~v:: The general public 1s most famili:ir wnh cyanos1s as th~ ca use of the bfo e- baby S)'ndromt. C)·anosis is not so!cl r symptomanc of h)•drogcn cyanide exposure. It also results v. hrn ccrta m ot herharmfulgasesarcmhaled.

Mflhilil:M Ill EffKts Caused by lnhahng Hydrogen Cyanide .. HYDROGEN CYANIDE (PPM)

02-50

10

SIGNS AND SYMPTO MS

Odor thresho ld

Thruholdl imitvalue

10-36 ______ ~::..D"=' ;:::°'c::"•c:h•:::•d:::•:::<h•::_•'=;':::":::h•:::•• .::'°:::' .::'°:,:'m_::":_:':::":::" .'.'." .'.'." '..:" l'.'.'.ho:::"':'....' 1()..6()

120-150

'" JOO

Toleratedfor20mintolhourw ithoutd ifl iculty

~ fatalafter30·m lnexposure

____ L_ike-'ly-"-tobefatalafter 10-minexposure

372 Chapter 10 Chem istry of Some Toxic Substances

The rncch :rn1s m by 11h1ch h)drogen C)anidc kills m 1 b1olog1cal acnvity of C)tochromc dnidual s is lmkcd v.1th 11 s ab1l11 y

energy produ cnon Cya d c oxidase, an en:i;)me csscm 1 1] fo r ' ce lls

0 ~\:e expos,u re renders th e enzyme m3 c

r cell bod) St1 ssues mJ y be plcn ufu l, th e v.h csnt~h~sc rhe ox)gen effcctnel)

roccss forms cytotoxic byp rod uct s v.ho bod) is mcapJble of using OX)ge n :~~t 5

ro c1Jrnde to x1c1 ty ' sc accumulation m th e bloodstream con

10.11-C USE OF HYDROG EN CYA NID E FOR LEGAL EXECUTIONS Jrogcn cyanide formerly was used as a means f

~~!Jrcd by certain judicial coum. Toda y, only six :~a::;:mg Olli lh c death penalties \Jnd, ~!ississi ~p1, i\'11 ssoun, and Wyoming-srill authorize ttnzona, California, .\ilary - crf!Jl tl cOJ1d111ons for c?nductmg 1udicially mandJt ed cxccut~o~: ~ ~hac!c~h~ r!a:::~:r

Jc is thr lerhal ga s, It IS gene~atcd by dropping mmll .d I Y g ) · :; .1cid wirhin an rnclosrd, ai mght gas chamber. ic cyam c pc lets mto a container

N:iCN (1l -f- HCl(aq) --. N:1C haq) + HCN!gl So,hum,);m l..k, ll )dro..hlol'l(C a.: 1J ',o,,humchlonJ.c lt )Jrogcns)llH,k

In contcmporar)' mnes, most stat es have condemned the use of 3 lethal gas for con - ducting death sentences. In bet, there exists toda y a nationwid e inclination towards abol- 1slung the d_cath sentrncr altogether-by any mean s. In states where capi tal punishment is sull authonzc<l

1 , the us~ of 3 lethal gas has been rtplaced by lethal inJcction as the pre -

frired mea ns o execution.

10.11-D HYDROGEN CYAN I DE AS A CHEM ICAL WARFARE A GENT During the HolocauSr in Wo~ld War II, Nazi Germany used hydrogen cyanide as a chcmi- cil wa~fare agent for th e ~akmg of h'.1man lifo. Th e Germans had dc\·t loped a method for adso rbing hydrogen C)'_a~ 1de on calcium sulfate pcllm, and sca ling chem in steel cans for po1rn1ial use as~ pc:t 1c1dc callc~ Zyklon B, wh ere th e "BR refers to the German word Blau;ii11re, meaning hydrocyarnc. Hyd rogen cyanid e was gene rated wh en the pellets were exposed to the atmosphere.

Zyklon B was us ed b)' the Nazis_ as a weapon of ma ss destruction to systematical\ )' mermmatc European Jews, non -Jewish Pol es, political opponents, gypsits, homosexuals, dtSJbl ed, _and other people d~emcd to be "undesirablc.R At the Nazi death camp s, pellets of the poison were _dropped mto the _\'ents of locked rooms that served as ga s chambers. The hydrogen cyanide tha t evolved kill ed the occupants within 20 minute s.

The most infamous Nazi death camp was loca ted in Auschwitz, Poland. Hmonans mimatt that exposure to hydrogen cyanide at this single camp alone caused the deaths of I 10 2 million people. lbcir murders sc n·e as one of the wo~t instances of genocide in the t'olentie1h century. In all, it has bee n estimated that 6 million people died in the death camp s.

In modern times, therr have been allegations that domestic terrorists attempted to use h)"drogcn cyanide as a weapon of ma ss de struction. In 2003, the U.S. Dcpar1m ent of Home!Jnd Security issued a warning to la w enforcement personnel tha t al-Qaida opera- mes planned to use hydrogen cyanide within the confines of the New York City subway $)Stem. Although this incident was never confirmed, it highlights the fact that cya nid e could be used as a chemical weapon against Americans.5

Given rhe unorthodox ways by which tt rrorim may potentially use hazardous mat e- rials to kill massive numbers of people, law enforcement agencies should be pro1·idtd wi1h

3R.on Su1\c.,nd, T/J, 011, Prruut Doctrmt (New Yo rk, NY: S,mon Schu~m, l 007), pp. 194- 196. Chapter 10 Chem istry of Some Tox ic Substances 373

I I

I ! 374

.:a JU nsd1cuonJ I accou nnng of the cya nide produc ts that tt' rro nscs ma y obt ain for clJn d<'\,

une purposrs.

10 11 -E HYDROGEN CYANIDE AT FIRE SCENES • d t fi rt' scc-nes by fht' th c- rmJl dt"CO mpos111011 of c

Hydrogr n cya nidr 15 gdc-~; 0 ::~amc compounds wh osr mol.c-culc-s have one or 11~0~:u~

products m,a~fa ==t~rt Thc-sr produc ts includc- fabri cs, carpeu ng. a~d m:Htrt'ssc-s ma nu(~· mdc- group~ ( C-, J I nd pol )•urt' th:inc. Hydrogc-n cya mdc- 1s rc-lc-a sc-d i a,. turc-d fro.m pol y:icr;m:~11t~//produc[ of thrir dt'Co~posit.ion.. nto the su rr~;h::::~v-~;~gen cy:i mde ma r forni dur ing a fire, sc1e1_1t1 ~1s. generally bc- lic-\'t' th,u does not ultim: rel y sun·1\'C' bc-ca use HS lower flammabl t' lin1tt LS onl y ~% hr \'Olulll(~ Hydrogen cya nide readil y ignit es by mcomplet c- and complc-tc- combustion, as dernon: srr.u ed by tht' fo l!owmg equatwns:

... 502(.g) - 4CO(g) + ... (a.,t,.,ii ,uono"clc ,,mco<1dc

th dro ~nc)Jn,dc

--1/I CN(g) + 90 211.') --IC0 2(g) _.. --I N0:(1.'J + C:ffl'Ond1<J \ 1Jc , uro!ll"n.l10\ 1dc \ \~tl'T

The c-as e of combustion implies rhal hydrogen cyanidt" is lik~ly to be ~resent at its hightti concentration durmg the early srage s of 3 fire, whrn sufficient ht-at 15 prt-scm to initiatr rhtrma l decomposition bur before the ga ~ ox,d1 zes. . . .

Nonvithsrnndmg its ease of combumo n, .h)'drogrn cyamdr 1113~ survive m the atm01· ph ere of a fire scene when cext iles smolder m confined·Sp3Ct' env1ronme n_ts having low levds of ox rgen. On-scene firefighters must be wary because th t"y may mhale the ~ 1 before it oxidizes. Because of thi s possibility, they a r~ often trratt"d 3S a precautioruiy me:isure even when 1t is unclear whether they actu3Jly mhaled th t" gas.

Firefighte rs who hav e survived acute exposurt' to hydrogen cyanid e are treated by admini stration of an 3ntidote. Tod3y, manr physicians choost' 10 3dminister hrdroxoco- balamine.6 Whc-n injected intra 11enously, prefernbly by paramedics a t the fire scene, this substance binds the cyan ide to form cyanocobalamin e, whic h subsequently is excrmd from th e body in urin e.

10.11 -F WORKPLACE REGULATIONS INVOLVING HYDROGEN CYANIDE

=~:i:h::;~o~-~:: ~~:~:~;~:n~d:oi~c~~:~~~~ ~t 1\~o;:~tlsa;:r~~i~~t~e(jL;ir~:J:Yil:::: 3ged O\'er an 8-hour workday.

10.11 -G TRANSPORTING HYDROGEN CYANIDE When shippers offer hydrogen cyanidr for transportation, DOT requires thrm to pro1·idt th e relevant shipping description shown in T3ble 10.9 on the accompan ying sh ipp ing pa per. DOT also requi res shippers and ca rriers to comply wi th all applicable l3bth ng, ma rking, 3nd placarding requirements. As noted in Sectio n 6.6-D, when h>·drogc-n C)'J · nide is transported by rail in bulk pacbging, DOT requires th e car ri ers 10 displa )' tht PO ISO N INHALATION HAZARD plac3 rds on whi te squa res with b[3ck borders.

6 Stephm W. Borron, f ridfoc J. 8Ju d, Bru no Mi-g.i rbJ nr ~nd ChJnt~I Bismuth ·HydroxocobJ!Jmin lo1 i!" C/1'

acute cyanide po1sonmg by IMge)flon or ,nh~l mon, • A m;r, j. Emng. ,\!rd., vol. l S (l 007), PP· 55 1- 558 . Chap ter 10 Chem istry of Some Toxic Subnances

Shipping D@Scr,pttons of Hydrog@ n Cy,m,de

t1¥D~OGEN CYANID_E___ , -+ SHIPPING DE SCRI PTION ;;;drogen ?'a nide, sta bili zed (c onta ins len than UN1051 Hydrog en cya nide nab ih zed 6 1(3) J'!o wattd :~~a(~.a~;~::;•utant) (Polson lnhal,1t1on

~ cyan ide, stablhled(conta lnsltssthan UN1614.Hydrogencyan ,de,sub ilized, 61 . water; abrorbed into a porous Inert PG 1 (M,r ine Pollutant)

1r:a1er i1 1l' :::~:: :~:.;~n~r~ : :: ~t~~i'1,

1 : 1~0':f~°'.1o~f ,:~~bltar>Ce to hydrogen cya nide 10 lnh,bit its aut opolyrntr•

l0,11 -H HYDROCYANIC ACID H ·drogen cyanide dissolves .in W3te.r to . form a colo rl ess solution known as hydroC)'anic a/id, or p~uss1c acid_. '.he 3Ctd solution ~s so weak it is in_capable of tur~ing litmus paper

d. Soluuons containing more than 20 ¼ hydrogen cyamdc are so vo]311 le that they have :en used 35 fumigants 3nd rodenticid es in ships, warehouses, and green houses.

10,11· 1 TRANSPORTI NG HYDRDCYANIC A CI D Thret" hydroqanic acid solutions are avai lable in commerce. When shippt- rs intend to transport a hydr ocyanic acid solution in bulk, DOT requires 1hem to identify the appro- priate sol uc_ion 35 shown i~ Table 10.10 o~ 3n accom~anying shi_pping p3 ~r. DOT also requires sh ippers and ca rriers to comply with 3]\ applicable labdmg, markmg, and plac• ~rdmg requi reme nt s.

10.11 -J M ETALLIC CYANIDES ,\ let:il!ic cya nides 3re ionic compounds composed of me1allic and cyanide ions. Sodium cyanide3n d p01assium cyanidt" arc 3vailable commercially as so lids and 3queou5 so luti ons, whmas copper(ll) cyanide and zinc cya nide are 3vaibblt' sold y as solids. The 3queous sol utions of the se la ue r two substances are used to elect rop late copper 3nd zi nc, rrs pcctively.

One of the m3jor commercia l uses of sodium cyanide is connee1ed with the leaching of precious mt'tals from th eir ores. As the price of gold a nd si lver began to inc rease throughou t the 2000s, mining for precious mern ls became profitable. Accordingly, th e commc-rci3 1 demand fo r sodium cyanide has grown.

illi!ll·ll·I Shipping Descr1pt1ons of Hydrocyamc Acid FORM OF HYDROCYANIC ACID

Hydrocyanicacid,aqueousso\utions contain ing not mo re than 20% hydrogen cyanide Hyd1ocyanicacid, aqueo us solut ions conta ininglessthanS '"- hydrogen cyan ide Hydrogen cyanide, solution in alcohol conta ining notmore than45% hydrogen cya ni de

SHIPPING DESCRIPTION

UN1613, Hydrocyan ic add aqueous solutions, 6.1,PGl(MarinePollutant)(Poison - lnhalation Hazard,ZoneB) NA1613, Hydrocyanlc ac id aqueous solutions, 6.1, P'G II UN3294, Hydrogen cyan ide solution in alcohol, 6.1, (3), PG l(Mar ineP'ollutant)(Po lsonlnhalation Hazard,ZoneB)

Sodium cy1nld1

Chapter 10 Chem istry of Some Toxic Substances

I

375

I

Sulfur diox ide

li+iiiHll&iiM ptro n s of Some R@presentativ ., METALLIC CYANIDE

Potass ium cy•n ide, sol,d

Sod,um cy;m ide, solld

Zone cyan ide

SHI PPING D ESCRIPTIO N

UN1680, Potamum cyanide , SO ii d, 6 1 PG 1 (M • --- (Poison) _ ' arine Po llut~

Sod ,um cyan ide, solid, 6 1, PG l (Mar,ne

- UN1713 , Z1nc~a~ 1. PGi(Mar ~ ePof~

CPSC b3nned rhe sale of products co ntaining warcr-so/uhle me rallk cy .d stuuent s of consumer produc ts intended for use in the Urured Stares. This r:n~i"s as con. is published at 16 C.F. R. 5 1500. 17. g 3 toryb~ n

1 0.1 1 - K TRANSPORTI NG METALLIC CYANIDES When sh ippt" rs trnnspon a me1altic cyanide in bu lk , DOT requires them to id . approp riate su bsrnnce on an acco mpanying ship ping paper. Table J 0. 11 prov·~ntify tlk represemari ve examples. DOT a lso requires sh ip pers and carriers to comp! 1 ts. s:~ applicable labeling, marking , and p lacards rcquiremcnrs. y wu all

When th e name of a metallic cya nide or its so lut io n is not lis ted in th e H d Materials Ta bl e at 49 C. F.R. § 172. 101 , DOT requires s hi ppers to provid e rh/;3( 0ui shipping .de script ion gene rically a nd ro prov ide the name of th e speci fi c com~:::~ paremhct1cally.

10. 12 SULFUR DIOXIDE Sulfu r d ioxide is a co lo rl ess, nonflammable, toxic gas havi ng th e s h arp, pungent odor associated wit h burning matches or ti res. Some ot her p h ysical propert ies of th is gas are note d in Table 10.12 . These d a ta indicate ch a t su lfur dioxide m a y a lso be encountered comme rcia ll y as a liquefied gas. W hen used as a comme rci al c hem ica l product, sulfur dioxide is primarily produced by burning sulfur.

Toda>•, s ulfur dioxide is used mainly as a bleaching agent by the pu lp and paperindu s• try. It is a lso use d by the agri cu ltura l indu stry to w hit en refi ned sugar a nd 10 lengthen the shelf li fe of dried fruits. When g rapes arc dri ed a nd processed in a n annosphere of sulfur di oxid e, raisins wit h a go lden color are p ro duced. When th ey are nor exposed to sulfur dioxide, rh e ra isins arc dark brown. Foods th at have been lreated w ith sulfur dioxide do not ferment or support rh e growth of fungus a nd mold .

Sul fur d ioxide is also used to fum iga te sto rage co mpartm en ts o nb oard ships, wheren functio ns as an in secticid e a nd rodenricide. In rh e chemica l industr}', it is use d prima ril)· for the production and manufacture of sulfuric acid (Sectio n 8.7) a nd metallic su!fit~

Ai+l!IIIIN Phys tcal Properties of Sulf ur 01ox1de Meltin g po int

Boiling point

Specific grav ity at 68 • F (2o• q

-10S "F(-76 °C)

14"F(-10 "C)

Vapor density (a ir= l) 1.436

2 .22

376 Chapter 10 Chemistry of Some Tox ic Substances

su lfU l'I DIOXIDE (PPM ) SIGNS A.No S'f'MPTOMs

d)l

;,O 1 ~ oco~~ ct lon in se'.1_111,ve. e1tercis,ng a1;;;;:.a1,c, ~allydetcc1ab le ~1ane and1m;i1 -

!_::. lung~ ct 1onchange1lnh~ lth -- ,S ___ Rtpeated ~

1 e Ynona ~ at ,cln d ,,..,d ual\

20-50

20 minute exposur e produce ;erman ent pulmonary impairment --- ~ ddeningofthethroatandm,!d

eyes an~ de,..ctopment of chroni~ of breath, and connr,ct,on of ~h: 0:,~•;i· (hen pa,n1, 1honne11

S0-100 Ma1timumtolerab!eexpo1urehm ,tfor)()..(;Om in - ;,100 lmmed1a te lydangeroustoh, ft;,---------

::~\:~;~:ym1~1~:'.e \Ource1 Incl uding CHEM/NfO. s.,11~, Oiox ldt, Ci n..dlin Ctnt,t for Occupitloni l Hulth

10.12-A ILL EFFECTS CAUSED BY INHALING SULFUR DIOXIDE Inhalation toxicity is the pr imary hazard associa ted wi th exposure 10 su lfu r dioxide. As $hown in Table 10. 13, coug hing, ches1 pa ins, shortness of brea1h, and co nstr iction of the ai rways sy mptoms a ssoc iated wit h an exposu re 10 thi s gas. These toxic effec1s are derived .... holly from rh e abilitr o f sulfu r dioxide 10 directly irritate the mois1 mucou s membranes o( the uppe r res piratory tra ct an d rh e lun gs. Although many indiv idu als are ab le 10 tol er- ate \'Cr}' low concentrations of sul fur dioxide-such as those routi nely fou nd in po llut ed ai r-for sho rt periods of time, an ex posure to a concenrrat ion of 100 part s per million in air is usually fatal. The specific cause of respira1ory fai lure from exposure to su lfur di ox- ide 1s mos , likel y assoc iat ed with rap id lowering of 1he blood's pH.

Ast hmati cs ar e especia ll y susce pt ible 10 ex perienci ng ill effec1s from inha ling sulfur dioxide. Typically, whe n exe rci si ng, they a re unable to tole rate a short ex posure to a co n- centra tion as low as 0. 1 part per mill ion wit ho ut exper iencing constriction of the bronchi- olr tubes.

10.12-8 ENVIRONMENTAL EV ENTS ASSOCIATED WITH THE GENERATION OF SULFUR DIDXIDE

ln December 1952, coa l was virt uall y. th e so le. fuel use~ in \ond;~~~r ~:~:~.:t::s1~;.1i:~ dwellings and operating local factoncs. Durmg th~•~::d~' !n~ articulate ma iler were lo~don~rs burned coa l for thes.e pu~poses, sul fu~ n~ became d:adl)', The situation was emitted mto th e at mosph ere unol .ihe ir conce~:~:~ the llut ants from di ssipa ring, forc- ~xacc rbated by the absence of a wmd th at p~c\oo Lond:ers died during the initia l da ys mg Londoners to inhal e th em. Subsequ cntl), d , ti c event is recalled as thr Lethal and ano thrr 8000 died in the next rwo mo~ :~. a~te~~;ioi~

10 the fact that our well -being London Smog Episode, or Great Smog. It re

rlepen ds on the q ual ity o f th e ai r we breathe.

Leth al Londo n Smog Eplsod t (G,.at Smog)

occurred when London re~ idents inhaled sulfur d ioxide that could not d in iP3te due 10 mete• orolog icalcond1t 1on1

Chapter 10 Chemistry of Some Toxic Substances 377

r

I I

acid r,1 in • PrK1 prt at1on having an approximate pHofS.6orlessand caused by disso lved nitrogen oxides and sul fur diOlllde

umes sulfur dioxide 1s sull a ma jor air compo nen t. Almost In contemporary _cl .' h air 15 gent'r:Hed by the c~a l-fi red powe r plants th

1~'0- thi rds of the sulfu r dioxide mt ; PA regulations that req111re If s curbing in stac k e a~ 0.Ptr- ate in cheUnitedSrntes, espne n11 ss1oni,

by the use of' scri~~~/:~:d ~~hJ~i~~~\•ays other than th ~_bu ro ing of coal . It is duceSdu~~;u~~f1; dunng thterupoon of vok:rnoes. In Haw311, fo~ e~ample, the kil:;:· volcano has contin uo usl y spewed massive amounts of sulfur d1ox1?e a_nd panicuta,: mamr into the a~morhere since at least January 3, 1983, when SC1Cnt1 s 1s first ~ n st

udt~fu~t~~i:~ 1 t r:i eased into th e ai r slowly ~xidi_zes to sulfur trioxide, wh ich in turn

reacts with atmosph('ric moisrnre to form sulfuric acid.

250 1(g) + O~(g ) - 2S0j(g) Sul for(!iO., Jc 0,)gcn Su\fo, 1n o\1 d~

S~lfurmo\l.k Sulfu ncac,d

The presence of sulfu ric acid in the atmosphere produces a type of acid rain, that is, prt• cipitation having a pH of 5.6 or Im. Aci? rain has severely_ dam aged building maitria ls made of co ncrete marble mortar, and limeston e. A startlmg example of the ntgai ii·t im pact that acid :ain ha s had on stone structures is evident fro _m ~bserving Cleopatr;i's Need.le an obelisk that was moved from Egypt to Ne w York City m the late nin eteenth cent~. Its surface has dereriorated more in 100 years from exposure to acid rain than it did during the 3000 years it stood in Egypt. .

The relea~ of su lfur dioxide to the atmosphere produces the environmental probltm referred to as atmospheric cooling. Wh en sulfur dioxide is_ ejee1ed into the atmosphere by an erupting volcano, it oxid izes to sulfuric acid, which m turn seeds aerosol part icles. These particles reflec t th e incoming sun's rays away from our planet bac k into spm, thereb y reducing 1he amount of radiation that reach es Earth's surface. This ph enomenon can cause a seve re drop in temperature that pers ists for eons. For exa mple, scientists ha1t proposed that th e sulfuric acid aeroso ls produced during volcanic eruptions in lndontSia caused the Lud e Ice Age, the approxima1e period from 1550 to 1850 du ring which ba· terly cold winters were experienced in many parts of th e world.

10.12-C SULFUR DIOXIDE AT FIRE SCENES Sulfur-containing co mpounds are consriruen ts of many producrs including th e followin g:

Coal, natural gas, and crude oil Complex protei ns present in woo l, hair, and animal hides (S mion 14.5-B) Se\·eral natural and sy nthetic polymers, including vulcanized rubber (Section 14.1 I-Ci When th ese products bum, the sulfur is converted into sulfur dioxide. Firefighters

encounte r it wh en the y respond to fi res invol ving their combustion or the bur ning of other products ro which sulfur was added.

10.12-D WORKPLACE REGU LATI ONS INV OLVING SULFUR DIOXID E '.Vh_en the us e of sulfur dioxidt is ~eeded in the workplace, OS HA req uires employers j0 limn empl oyee ex posure to a maximum concentration of 5 parts per mi ll ion ( 13 mglm I, averaged ol'e r an 8-hour workday.

~:it !~~~::~;,'·•1;~;~:•;;~~n.1 fo r nupri ve pr oces1e.1 as ind ,cJt ed by sulfur d10.~ idc em1.11 1om irom K,butJ 378

' ' J. Volcano/, Grorl,rrm. Rn ,Vo l. 108 12001) pp. 283-302. Chapter 10 Chem istry of Some Toxic Substances

12.E ENVIRON MENTAL REGU LATIONS INVOLVING 10, SULFUR DIOXIDE

Osing 1he ;i uth o r_ir r of th~ Cl_ean _Air Act, EPA regulates rhe sul fur dioxide concentration ht' arnb1ent air as a cmcria air pollutant. EPA set th e daily and annual primary Slan-

~l ;d for su lfur dio~ide at O. t 4 pans per milli on (365 µi;,'m 3) and 0.03 parts pe r million SO µg./111 3), respccovely. EPA3 also set the secondary sta ndard for sulfur dioxide at 0.50 ~ ris per mill ion ( 1300 µg/m ) as a 3-hour average.

10_12.F TRANSPORTING SULFUR DIOXIDE 1f r dioxide is available commercially as a liquefied comp ressed gas, When shippers

~~n~pOrt sulfur dioxide, DOT requires 1hem to identify it on an accompanying shipping paper as follows:

UN 1079, Sul fu r dioxide, 2.3, (8), (Poison - Inhalation Hazard, Zone C)

oOT also requires shippe rs and carriers to comply with all applicabl e labeling, mark- ing, and placarding requirements.

When fi rst-on -t he scene emergency re sponders are called to a transpor1arion mishap 101-olving the release of a bulk shi~ment of sulfur dioxide, they must acknowledge 1ha1 ihe 53 fcry of the team, transportation personnel, and the general public is at ri sk. The Emergency Response Guidebook recommends isolation and evacuation distances when la rge spills of s~ lfur dio~ide occur from ~ultiplc small cylinders, single ton cylinders, multiple ton c~l~nder:, rail tankcars, and highway tank trucks and trailers under prev ail - ing wind condmons.

10.13 HYDROGEN SULFIDE Hi·drogt n sulfide is a colorless, flammable, and toxic gas having the physical properties nottd in Table 10.14. Perhaps its mos! immediately apparent featu re is the disagree able siench of rott en eggs. Humans detect this smell at just 2 pam pe r billion. The stench is truly offensive at co ncentrations as low as 3 to 5 parts per million. Sometimes individu- als describe the odor of a material by saying that it smells lik e sulfur. Because elemental sulfur is an odorless so lid, what they actuall y mean to say is that the mat erial smells like hydroge n sulfide.

ihhiiMI Physical Properties of Hydrogen Sulfide Me lti ngpo in l i -11 rF(-86 ' Q

-Boiling ~ ----------l..- ~ cgravltyat68•F(20"Q

~ ordensity(a!r::1) Fl ashpo in t

Autoign il ionpo int

Lower flammabl e limit

Upperflammable hm,t

1.54

1.18 -116' F(-82'O

500"F(260' C)

4.3¾ byvolume

46¾byvolume

'r~blc 3, Emtrgmcy Rl'spot1u Gwdebook (W~ihington, DC : U.S. Deprnmrnt of Tr msportati on, 2012 ), p. 35 5.

Chapter 10 Chemistry of Some To xic Substances 379

r oH.ct oryfa-ligu e • The temporary in.tb ilityto 1dentifythe odorofan a1rbomesubstance after prol011ged expoiure

Althou h h droge n sul fide is avJtlable as 3 liqu efii:-d com,r r~sse~ g.1s , ll is 1101 a 1..ir comme~c1a/ product. For its hmm:d use m commerce, ~t rs primarily dcrivedPoP\I.

etro kum rdineries and n:uural g;1s wdls. In th~ ch emical mdus~r y. hydrog m roduce de mcntal sulfur :md sulfuric :acid, to pr~ ess mmeral ores,

metallic ~ul fid~ such as nickd sulfide and molrbd enunt sulfid e, and co

pho~ u~ed in tcl~~i~io_~ ~~~s~ced n:iturally by the decay of organi sm s m swamps under \;~;~"s:~r~ ~;,uns, and oth er an.ae robic (~o_noxrnen ) envir~nments fro~s:11·er1, the ga~ seeps mm the armospht're. The dccom posJUon_ of sewage gives rise 10 th e t~:ch sewer gas, 3 term usrd by sanitary enginerrs who wo rk m sewers a nd at se wage treat Ill fu cili ues. Th e odor of hyd rogen sulfide is also c-nco untered at petroleum refineries, "'~! ihe gas is reco\·ered by the desulfu rizatton of sour crude (Section 12 . 13 -F), and as 3 ~, sntuent of mammalian flatulence. The bod y generates trlce amounts that it uses to r:::

late ~::li~;d~:~~~ sulfide ha s a highly repulsi l'e odor, mo st people become aw irs presc-nce immediatel y upon expo.sure. Noneth eles~, when the.y ,experience long~;:r~ exposure to low concentratmns, their sens.e of smell 1s temporanh deadened. This pht. nomenon is called olfactory fatigue . Connnued exposu re causes them ro become ob! ous ro th e pre se nce of hrdrogen su.lfide, increasi ng the possib iliry that th ey unknowingl y inhale a lethal concenrrauon.

10.13-A ILL EFFECTS CAUSED BY INHALING HYDROGEN SULFIDE Table 10. 15 indicaies that inhalation toxicity is ih e primary hazard associa ted with expo. sure to h}'drogen sulfide. Exposure initially givrs rise to di zzi ness and the on se t of a h~aJ . achr, but unconsciousness and respiratory paral ysis can follow immrdiately. Inhalation of air having a hydrogen sulfide concentration ~f 1000 plrts per mi!lion is rega rded as fac al.

The mech:inism by which hydrogen sulfide causes adverse ailments is similar to diai previously noted for hydrogen cyanide poisoning: Hydrogen sulfide reacts with cyro- chrome c oxidase, th ereby prrventing cellular respi rati on. The treatment of indi\·iduali exposed to d evated concemrations of hydrogen sulfidr with hyperb:i ric oxygen has bttn only minimally successful. There is no known antidote.

id=l!il•lti HYDROGEN SULFIDE (PPM)

0.011

2.8 5.0

7or14 5-29

28

>140

>560

.- 100

Ill Effects Cause d by lnhahng Hydro gen Sulfide'

SIGNS ANO SYMPTOMS

Odorthrl!shold Bronchialconstriction inasthmaticindividuals ___ _ Increased eye compla ints Decreasedoxygl!nuptake Eye irritat ion

F~t1~ue, loss of appetite, headache, irritability, poor memory, d1uiness Olfactory paralys is

I Respfrato~d ;,tce,, Death

~~:::1 ;1~::~~~;~::tt;;(~ Chou, "H~d,ogtn sulfide : Hum an he alth aspem • c~ n tnt~,;i. Sw,tlerland, World Health Organ izat ion, 2003), p. 14.

380 Chapter 10 Chem istry of So me Toxic Substances

10 _13.e HY_DR_OGEN SULFIDE AT FIRE SCENES

Ji)d rose n sulfid e is a fbmmahle gas. Wh en ignitt'd in air, it readil y bu ms as foll ows:

21-1!5(.11) + 30 2(g) --. 2H ~Otg J .., ~O,(~) ll )dro~c n ,ullijc O, )ftn \l, JICI Sulfu, d~u\lJC

At fi re scen es, the presence of hy~rogen sulfide-although possible-is gen eral] ' im rob - ~bl,, Althou ~h small con ce mran ons m~y evolve dur ing the th ermal decomp~si ti~n o f certJlll niarenals n~anuf~ctured from animal products (i nclud ing leather items and wool cirptung), 1he gas 1s easily co nsumt"d by combust ion.

10.13 -C :~::i~~Es~i~i~':TIONS INVO LVING

When .the use of hydrogen sulfide is n~e ded in th e workplace, OSHA requi res employers 10 ]tm it emplo~ ee expos~re to a maximum concemr:mon of 50 pans per million in a 10-min~ce maximum permd. :vhen an area may contain an atmosph ere of hyd rogen sul- fi de, 3 sign such as the followmg should be posted:

HYDROGEN SULFIDE GAS

MAY BE PRESENT

10.13-D TRANSPORTING HYDROG EN SULFIDE H)·drogen sulfide is transpo rted in steel cy linde rs an d bulk tran sport vehicles. When ship- pm offe r hydrogen sulfide fo r transportation, DOT r('quires th(' m to provide its shipping descri ption on an accompanying shipping paper as follow s:

UN IO H, Hydrogen sulfide, 2.3, (2 .1 ), (Poison- lnhala1ion Haurd, Zone A)

DOT also requires shippers and carriers to comply with all applicable labeli ng, mark - ing, and placa rd ing requirements. When hydrogen sulfide is transported by rail, DOT requires carriers to post th e POISON GAS placards on white sq uares with black borde rs on the bulk packaging used for shipment.

10.13-E RESPONDING TO INCIDENTS INVOLVI NG A RELEASE OF HYDROGEN SULFIDE

,\lost fata lit ies associated wit h hydrogen sulfide exposure have occur red wh en employ- m ignored safety practices at petroleum refin eries and chemical manufacturing facili- ti es, in sewer sys tems, and at other locations where hydrogen sulfi de was stored or generact'd.

Special attention must be given to enclosures in which hydrogen sulfide may be gen• n,ned unknowi ngly. For example, chambers are used for storing se wage onboard mod- ern sh ips, umil i1 can be treat ed on shore. Hydrogen sulfide can accumu late in th ese chambers at a lethal concentration. When it is necessary to repair fractures in the wa ll s or their connecting pipes, worke rs mus t avoid exposure to this deadl y gas by wraring

Chaptl!r 10 Chemistry of Some Toxic Substances 381

Nitricollid•

totheab1 htyof asub- stanceto ignitesponta- neouslyoncontactwith anothers1.1bstance

• breathmg air from self-contained sources. Work sh fully-enca psula1ed sui ts ari<l •here hydrogen sulfid e can potrnr1,1\1y ace Ou]d ne\·er be conducted in any area \ ;won . urnulati w11hou1 firs r mon11onng its conccnt

10.14 NITROGEN OXIDES known but we are concerned here \~ith only two n ~:i

1 ~~ (:~s:1ti~~:;

0

3 :~ nitrog;n monoxide ) and nitr~g~n dioxide. T~eir ~h:~;

formulas are '.'\O and :-;o 1

, respecti\'ely. Tht molecules of mtnc oxide an d n1trogcn diox.

idearcst:ible frer radicals.

Ikea use th ey often are produced m combination, ni u ic ~xid e and ni~rog:n dioxide com- monly are repr esr nt ed jointly as NO.r and ar~ called c~e _nnr_ogen oxides. Nitric oxi& IS

3 colorless gas with an irritaung odor, and nitrogen d1ox1de 1s a dark red-brown gas hai·-

ing a pungent, acrid odor. They arc ~oisonous, nonflammable, an~ corrosive substancrs_ Thei r phy si ca l propert ies are listed in Table 10. 16. Both are avai lable comme rcially as HazardClass 2.3gases. . . . . _

Desp ite its poisonous nature, mmc ox_1d_e often is_ enco untered m modern hospi- tals and clinics, where low doses are administered with oxygen to treat emp h}·uma and other pulmonary diseases. Nitric oxide caus~s the blo~d vessels to dilate; conse- quently, respiratory pati en ts experience reduced mflammauon and lower blood pres• sure. Nitric oxide has sa1•ed the lives of premature babies, because i1 red uces the mk of fatalitie s from such diseases as bronchopulmonary dys plasil. It has also helptd firefighters avoi d labored breathing, especially whe n their lungs were coa ted with soot while combating fires .

Kirrogen dioxide is used by the aerospace industry to oxidize rocket fuels. Fo r mm- pie, the Apollo astronauts used it with unsymmetrical dimerhylhydrazine to leave the moon's surface.

CH , H \ I N- N I \

CH3 H w1151m- D1 11l(th} lh~d1:11mc

A mix ture of ni~rogen dioxide and unsym- dimeth ylh ydr.izine is se lf- reactive, or ~ypergolic; that 1_s, the substances react immediatd}· on contact. The ni 1rogen diox- ide an~ uns)'m-dim ethylhydrazine act as an oxidizi ng age nt a nd a reducing agem, resp ect 11·e!y.

illlill1iti Physical Properties of N1tnc Oxide and Nitrogen D10,nde Melti ng po int

Bo iling po int

Spec ificgravitya t6B ' F(20' Q

Vapordensity(air:: 1)

I NITRIC OXIOE - 263 ' F(-164"C)

- 243'F(-153 ' C)

1.34

1.04

NITROGEN DIOXIDE

12°F(-11 "C)

6B ' F(20'C)

1.49

1.59

382 Chapter 10 Chemistry of Some Toxic Substances

SOLVED EXERCISE 10.5

i•:i 00

r1,0 n,irogen d ox de molecu 'es comb, ne to proa uce a s,ng e mo'ecue of d 11,u-ogen tetrox,de1

~1~tio\!:s\e~~~~;~::sn'.i~~~~ ~'.~~~:~/=rt~;ga~"f: 11:: are ·'- · and O, respe<1Ntly Us1rig them, the 1o; ,,,.,pg

-~:N:: O: or 0-\,_Q

. ,ieth, 5wucturehasanunpairede lectron,1tae1ua' ly 1epresentsafree-rad,calmo'ecule (Stct,onSl1) To it<~e·t the unf,l'ed octet and ach eve e'ectron c stability, two n,trogt:ri d ox.de molerules comb,ne to produce a

d• n trogen 1e11ox de mo'oo.J'e

10.14·A PRODUCTION OF NO,

0-N=O I

0-N=O

l\itric oxide rand ni1roge n dioxide are produced for comme rcial use by the catalytic oxida• 110n of ammonia as fo ll ows:

-INl-\i(g) + 501 (8) --o -INO(g) + 6H~O(g) ,\'itncoudt

2NO(g) + Ozlg) -,. 2NO~(gl N1tnC O\ldt N11rogcnd1oudc

When confi ned in a cylinder at room temperature, 1he nitrogen dioxide com bines with 11sd f, mole fo r mole, ro become dini1rogen tet roxide.

2N0 1lg) -, N104(/) /l.'nrogcnd10x11k D,n11rogtnteuo"Je

Although di ni troge n letroxide exists at room conditions, iris commo nl y sti ll refe rred to as nuroge n dioxide.

10.14-B ENVIRONMENTAL ISSUES ASSOCIATED WITH THE NITROGEN OXIDES

!n the lower atmosphe re, nitrogen and oxyge n combine ve ry slowly to produce nit ric oxide and nitrogen dioxide at ambie nt 1emperatures. However, the combination occurs rapidly at elevated temperatures.

N2(g) + 02(&) 2NO(g) Nitrogen

2NO(g) + Oig) --, 2NO~(g) N1tnc u~1dc N11rogcndn>l1dc

Ai fo~sil-fue l-fi red powe r plan ts and in the combustion cha mbers of motor vehicles, nitro· gen dioxide is produced at (he concentrations shown in Fi gure 10.9. For this reason, the

is regarded as a ma jor air pollu tant. It is the principal culprit responsib le for t he rown atmosphe ric haz e 1hac hangs O\'er many ci1ies.

Nitrogen dioxide

Chapter 10 Ch e mistry of Some Toxic Substances 383

r R GURE 10.9 NN!fy.ill W"-'O,ll'lthe,lJTll;rtflt.:l,r e~~ dunngtrans• ocr.attonandfuel- ccrnounionactrYltlts 1Ca.n!'5Yol t.nrfd5~res

~~'Wlg('Cl'I.DC)

Nonchem 1cal industria l

Ch emicel lndustri•I processes

1%

Fuel combusti on

46%

The presence of ~ Ox in the lower. atm?spher_e is dircc.tly .lin~ed wi~h _the prod ut- tio n of ground-level ozone. Sunlight d1ssoc1ates ~mog_cn d1ox1de mt_o mtnc oxide and oxygen atoms. The oxygen atoms rapidl y combine wnh atmospheric oxygen to form

N0 1{g) - NO(g) + ·Q ·(g) \ iirogen d1oud,: , nn, 0~1dc o~> scn 01001

01(g) • -ii•(gl - OJ(g) 0\)gt"n O~}S~n:11001 OtQ nt:

Nitrog en dioxide is also re sponsible for th e formation in the lowe r atmosphmof a group of unstable compounds called peroxyacyl nitrates, or PANs. These compounds have the following gene ral ch emical formu la, where R is an alkyl or aryl group (XC - tions 12.2-C and 12.11, respecti\•ely ).

0 //

R- C \ O - O -N0 2

Pr ru~);ic)! nllmlt (PAN )

These constituents of polluted air are especially powe rful respira tory and eye irritants. The presence of ozone and PA Ns is characteristic of photochemica l smog.

Concerned about the advers e impact on public hea lth posed by NO.n es peciallJ· in urban atmospheres, EPA required automobile ma nufac turers to bui ld cars that reduced the a~ount of_ NOx emincd in vehicular ex haus t. In response, cata lyt ic convrners were installed m new automobiles. One chemical reac tio n that occurs on the surface of th e convener is the reduction of nit ric oxide into environmenta ll y friendly nitrogen and ox ygen. The use of conveners during the ope ration of modern-day moto r veh icles has red uced th e amount of N Ox t hat otherwise wo ul d be ejec ted into the atmosphere.

384

. Alt~ough t~e nitrogen oxides can migrate to the ozone laye r, t hei r presence dOt"s I\Of impact us quality. In th e ozone layer, the nitrogen oxides react with ozone 10 produce

Chapt er 10 Chem istry of Some Toxic Substances

1, 0 gen dioxide a ll d. ~orni~! ~X);en. The nitrogen dio xi de th en reacts w11h oxy ge n atom s

: rcfon n n11rous ox1 e, w ic t en proceeds agai n to rea ct wi th ozo ne.

NO(g) + 01(g) -.. N02(g) -t- 02(gl t-..,1rou,o,.,.k Olooc- ,\urog~n d10\1Je

N02(~l + ·9 ·(1:) - NO($) J\ 1!rofc nd1o"dl' O,) gcnaiom J\itl'O\l\o,iJ.o

10_14.C ILL EFFECTS CAUSED BY INHALING NO, tn hJl ltion toxi~ity_ is th e _p~ imary hazard associated wirh ex posure to both nitric oxide ,1 nd nitrogen dioxide. lmtial exposure produces irritation of the mucous membran es of th e e)'CS, ~hroat, "?sc '. a nd lun~s._ ~s Tab le 10.1 7 shows, when an individual 1s ,~posed 10 mt rogen d1ox1de, t~esc 1m11al sy mpt oms arc followed by coug hin g, chok- ing, he:idac ~e, ~a_usca, and fattgue. Wh ~n _the exposure is grea ter than 200 parts per millio n, th e individual suffer s from lung tnJur y, bronchopneumonia, :ind possible fatal

lmon ary edema. pu Both nitric oxide and nitrogen dioxide arc readil y absorbed into the bloodstream, i\here the y com bine _wir_h h~~oglobin to fo rm met hemogl obin !( NO z)HbJ. For exam- ple, when nitrogen dmx1de 1s inha led, methemoglobin is produced as follows:

Hb(aq) + NO~(g) --. (N02)Hb(llq) lk nioglobm NUro£C11d10Auk Mc1hen10globin

Mcthemoglobin is an oxidized form of hemoglobin. The iron in its molecul es occurs as the ferric ion (Fe3*), not the fe rrous io n (Fe2*). Li ke carboxyhemoglobin. methemoglo- bin cannot effectivel y transport oxygen to the body's tissues, so the host suffers from the :ul ment called methemoglobinemia . Individuals who inhale nitric oxide or nitrogen dioxide ex hibit the in itial sy mptoms of poisoning (dizzine ss, headac he, diarrhea , and anc· mia ), but thei r blood also becomes chocolate brow n in color. It is this color that initially sign als the severity of i\"O., poisoning.

Hyper baric oxygen therapy is ineffective whe n used to treat individuals afflicted with mtt hemoglobinemia. In stea d, blood exchange transfus ions are usuall y needed to dec rease the methemoglobin concentration in the bloodstream. Latent effects ma y also be experi- enced, and dea th can occ ur da ys afte r the initial exposure.

iili!IWI Ill Effects Caused by lnhahng Nitrogen D1ox1dei) NITRO GE N DIO XIDE (PPM) SIGN S AND SYMPTOMS

10-20

25-<0

S-0

80

>200

25-0

Thresholdl imitfor detectio nbysme ll

Mild irr ita tion to the eyes, nose, and upper respiratory tract

No adverse effects to workers exposed over a period of ye ars

Distinct irritationtotheeyes, nose,andupperresp!ratorytract

Tightnessinthechestafter3-to 5-minexposure

Lung injury; bronchopneumon ia:threattolifeafter20-to60-min exposure from pulmonary edema Immediate danger of death follow in g short-term exposure

'Ad.ipt,d from mu ltiple sources lnclud,ng Center5 for D15e;i~ Control arocl Prevent ion, 1988 Permissible hposuie llmltiPro)ectOocumentatlon,CDC24/7.

met hemoglo bln hemoglob!n,

produced whennitro• gen dioxide reacts with the blood's hemoglobin

methemogl obin emla health ailment

resultingfromanindi· vidual'sexposureto nitrogen dioxi de, metallicnitrites,m etal • lic nitrates,andsimil ar substances

Cha pt er 10 Chemistry of Some Toxic Substances 385

. d s exacerba1ed by the ability of th e gas to The toX !Clt)' of nitrogen d~rl l !;IC acid IS produced as follows: reaq .... ,th

\\ -;Her. A nuxture of mtrous ac, an m ,~0,("') ... l-i!Ol'-'l __. I-INO~(aqJ + lli\O, (lltl) - · • • "11 rou , .1<.1J '\ 11n~ .11.1J

\ itr0~nd10\1.li: •

0 en dioxide reacts with atmospheric moi ~tu re to Prod

W.hen 1t 1s inhale~, n~tr e:tl within the respirator~ sys~em. Because nnric acid is a 5 Ucc i

mixture of chese acids ir [ h I s and conneco,•e msues, and even at low c tr0rig acid. it damages the hmng o tul~ ~~!rr edema, oncentr1. 11 0 ns, its presencecanc;1use P

10 14-D NITROGEN OXIDES AT FIRE SCENES . · d' 'de art' the produm of tht' inco mplete an d co mpl et

l'\iinc oxide and miror~ IOXln--containing mamials. Examples of nit rogenous Ille COQl. bustti~~~~::~; ::~~;:~mxide 1~c l~de the polyur~thane pro ducts use~ in b::~~:~ ~ha :ddin and furniture cush1om ng. ~though its r~d-brown color is essentii msullno n, b ~• "ble 10 decect the color ma predommantly black, smoky pl Y ~i~:h ti;r~::a/d

1 ;:~:~e wheiher they have bee n overl y exposed to NO x by use u~

puls~~r?a-i~~:::~rcial explosives also p~o.duce nitr ogen di~ xide when they detona it. Exa mples of these explos ives include mmtrotol_uene (Sectron 15.9), cyclonite (Sec. tion 15.10), terry! (Section 15. 11),and H.t\i!X (Section 15.13 ).

10.1 4-E WORKPLACE REGULATIONS INVOLVING THE NITROGEN OXIDES

When the use of ni tr ic oxide and nitrogen dioxide is ~eede d in the w~rkplace, OSHA requi res em ployers to limit emp loyee ex~osure to maximum conce ntrations of 25 p;lrri per millio n (30 mglm 3) and 5 pans per million {9 mg/m 3), res pecti\'ely.

10.14-F ENVIRONM ENTAL REGULATIONS INVOLVING THE NITROGEN OXIDES

EPA regula tes the concent ration of NOx in the ambient air.as a cri teria air pollutant. EPA has se1 both the primary and secon

3 da rr national am?ient a~r-qua li ry stand ard s for N0, 31

0.053 pa ns per million (100 µg/m ) as an annu al amhmeuc mean.

10.14-G TRANSPORTING TH E NITROG EN OXIDES When shippe rs transpo rt nitrogen dioxi de (dinitrogen tetroxide ) or nitr ic oxide, DOT requires them to provide the shipping description of the gas as shown in Table l0.18 o~ an accompanying shi pp ing paper. DOT also requires shippers and ca rri ers to compl y with all applicabl e labeling, mark ing, and placarding requirements.

iilhll·if:i NITROGEN OXID E

Dinitrogentetrolide

Nitricol ide

Sh1ppmg Oescr1pt1ons of the NO.-- Components

SHIPPING DESCRIPTION

UN1067, Dinitr ogentetrolide,2 .3, (5 .1), (8), (Poison Inhalation Haza rd, Zo neA) UN1660. N1tr icoxide,comp re1sed, 2.3. (5 .1). (8), (Po i~on - In ha lation Hazard. Zone A)

386 Chapter 10 Chem istry of Som e To~ ic Substances

Physica l Properti es of Amm onia

i,4tlt•fl!lpoint -10~ o ____ _ ,11119Po1nl _ .....,28' F(-33' C) :~ ty (li quid) at 68 ' F (20"() o 77

1 ;ific!lr~ 8' F{ 20 ' Cl __ _

~ d~ ---__,1,.:'c:"::'_ :;,:.---t52' F'11 "C)

- • I _A11to•gn1t ionP01nt --+- 1204' F(651 ' 0 ~

--+ 16%by volume ~ m•t 2S %byvo lum e

Wh~n these nitroi:;en oxides, are transported by rai l in bulk packaging, DOT requires the earners to post th e POISON GAS placa rd s on whi te squares wi th bl ac k borders.

1o.15 AMMON IA Animonia is a colorless gas_ that is easilr det ected and recognized by its familiar pungent odor. It ha s been kn own smce the dars of alchemy, when it wa s produced by hea ting either coal or an imal hoofs and horn s. Some of its impo rtant ph ysica l prope rties are noted 1nTable 10. 19 . . .

Om 80 % of th e ammoma produced m the United Stales is applied to farm lands as a ferti lizer, Because the nitrogen coment of ammonia is 82% by mass, it is an idt"a l agricul- tutJ I fer tilize r. Wh en form ers apply i1 10 farmland, they di spense the gas di rectly to the soil or into irri gatio n waters throug h a di str ibution pod fr om a rra ctor sadd le tank or nurse tank like th at shown in Figure 10.10. A nurse tank is a spec ific type of portable !Jnk with :i capacity of 3000 gallons (1 1 m3) or less, is pa inted white or aluminum, and is nem filled completely. It is mounted behind the tillage too!.

Lm than 2 % of th e ammon ia produced in the United States is used as a refrigerant in [Jrge refrige rat io n srstems. It is th e most economical coola nt of choice for meatpacking p!Jnrs, da iries, an d similar faci lities.

When ammonia is used as a refrigerant or fe rtilizer, it is enco unte red as th e liquefied com pr essed gas called a11hydro11s ammonia. This product is transported by hi ghwa y, rail - war, and watercraft and transferred by pipeline. In Alaska, anhydro us ammonia is rhe mos t prev alent hazardous sub sta nce throughout the sta te, where it is used as a refrigerant 31 sea food-p rocess ing plants and in radiators associated wit h th e Trans-Alaska Pipeline System. In th e latter, th e ammo nia disperses the hea t th at evolves from the hot crude oil as it travels through elevated pans of the 799-mile (1242-km) pipeline. The heat must be dispmed to preve nt th e melting of the underly ing permafrost, the permanently froz en rnbsoil in which th e sup ports for the elevated portions of 1he pipeline are embedded.

Anhydrous ammonia is also used in shuttl ec raft, wh ere it se rves as the coolant in the 3ir-conditioning syste m. Ir is al so being used to cool the Internationa l Space Starion.

10.1 S-A PRODUCTI ON OF AMMONIA For commercial use, ammonia is produced from atmospheric nitrogen and hydrogen at clm1ed tempe r:nure and pressu re. The production reaction is represented as follows:

2NH3(g)

Anhydrou s 1mmonl1

nu rse Forp ur- posesofDOTregu la- tions,acargotank having a capac ity of 3000gallons(11 m1) or less, pa inted wh ite or a!uminum,neverfil le d to capacity. and used solely forthetrarispor- tat ionof anhydrous ammon ia

Chapter 10 Chemist ry of Some Toxic Substances 387

388

FIGU RE 10. 10 DOT requ.res a nur;e tanl: used for the appl1 c.1 t1on of anhyd rous ammoni a to agncult ur;ij ~ h to be mark ed AN HYDROUS AM MONIA on all four sides and INHAtATION HAZA RD on two op~ rng si d~ Th@ DO T 1dEm,fication numbe< 1005 must also be displayed aaoss the center of green 1'.QN.f tA MMABLE GAS p/acardspos:1ed onallfour1,desoftlieta nh 1Counesyo/Thefert//!lf' /rnr,ru1e,Wash,ngton, DC J

~hemica/ manufacturers generally produce ammonia at a pressure and tempe rature rang• rng from 3000 pounds per square inch (20,300 kPa) ro 8900 pounds per square inch /10,800 kPa ) and 842°F (450°C) to 1 I l2°F (600°C), respectively.

10.15-B AMMONIA AT FIRE SCENES ~;;i~uitd~~:mmable ~s .wi_chin the_ range o~ 16% to 25% by vo lu~e. W~en !t

. . ,_ammonia dissipates with the wind, and a flammable m1xrure m air1s nor ordrn,m/y arramed. ~nder th ese circumstances, an ammonia fire cannot occur. . None rhe_less, ammo~ia concentrations within the flammable range are a1tained due· mf amdenr ~e naraos like rhe indoor release of ammonia into a confined area from ~:ei~s ~ig~J~~~::~:i'3~~t escape. I~ this circumstance, the occurrence of an ammoni.i 122 5 kJ/g) and de. _en ammonia burns in air, the combustion evol\'es 9650 Brullb · pro uces nitrogen and water vapor.

4NHJ(g) + 30 2(8) -- 2N2(g) + 6H, 0 ( ) Ammonia O\y~n Nurosr n \\;:Ue rg

This heat of combusrion is low com d . subsrances. fr is for rhis reason rhat ~:e w.irh _rhe \'alucs listed in Table 5.2 for och er exposed roan addiriona/ hea t sou rce. mama fires are noc susta inable unless rh ey are

Chapter 10 Chemistry of Some Toxic Substances

•. ,, .• Af,!r.40NIA(PPM) _1 SIGNS~ -

:::;;---- .... Detectable hm it by ~ or .::!- - '

Ill Effects Cause d by lnho1hng Ammonia•

5tl -,. Odor detected, but no chronic effects

150-200 J Verys-trongodor;.genera l discomfortand irr itationofnose throat.--;-;;-- ----f exposedmo1stsk,n, eye-tear,ng ' 400-700 ~rd inari ly, no ser ious results following short exposures; pronounced 1rr.1tation, d1Komfort to the ears, nose, throat. bronch i lungs and mo ist

::::s~vr~se eye irr itation that may lea d to (oss of ;1ght f~llow ing ---20IJ0-300o Barely tol~rable for more than a few moments, convulsive coughing I

accompanied by severe ~e Irritat ion and blistering of the skin· danger ~i:~':::~eedema, asphyxia, and death by suffocation even· after a

s000-10,000 Resp iratoryspasms;rap!dasphyxia; deathbysuffocationwith inm lnutes •,l,d, pttll In p~rt from OSHA Regu lat ions Applltiblf' to Ammonia (2007)

Ammonia ma y be generated at a fire scene in at leas1 two ways:

, ,\\ac eria ls manufactured from anima l produc1s- like leather items and wool GJ.rpeting-thermall y decompose when they are exposed ro intense heat. When chese ni;1terials a_re present al ~re sce nes, the odor of ammonia often is perceptible, but the concentration generally 1s coo low to cause harm.

• Frrtilizers containing ammonium compounds decompose on exposu re to heat. For rxamplc, when ammonium s_ulfate fertilizer is heated t0 high temperatures, it th er- mal!)' decomposes to ammonia, sulfu r dioxide, ni1rogen, and water as foUows:

Ammo niurn,ul fa tc Ainn10ma Nmub'tn Su lfu1d10,;1dc Wa1cr

10.1 5-C ILL EFFECTS CAUSED BY INHALING AMMONIA When individuals are exposed to ammonia vapor, they expe rience the ill effects listed in Table 10.20. The eyes, skin, mouth, trachea, bronchi, and lungs are particularly suscepti- blr ro se\·ere irritation from the exposure. The inha lation of ammonia at concentrations exceeding approximacelr 2000 pans per million causes death by suffocation.

10.15-0 WORKPLACE REGULATIONS INVOLVING ANH YDROUS AMMONIA

'X'hen t~e _use of anhydrous ammonia is needed in the wor kplace, OSH~ ~eq uires emp\of ers ro limit employee exposure to a concentration of 50 parts per m1 lhon (35 mg/m ), ave raged over an 8-hour workdar. OSHA also regu lates how anhydrous ammonia is Sro red and hand led in all workplaces other than ammonia manufactu ring facilitie s and refrige ration plants using anhydrous ammonia solely as a refrigerant.

10.15-E TRANSPORTING ANHYDROUS AMMONIA Wh en shippers offer anh yd rous ammonia for uansponation, DOT requires them ro pro- vide the relevant shipping description shown in Table I 0.21 on a shipping paper. DOT

Chapter 10 Chemirtry of Some Toxic Substances 389

m nnW-iif.l:54¥iMl::l::1·1:li iflt:er~- ----... SHIPPING DESCRIPTION

Ol EMJCAL COMMOOJTY ,I UN1005, Arnmon ia anrlydrous, 2.2 (l nhal atio ~

Anhydrous Am moru il UNlOOS, Ammo~ia, anhydrous, 2 J, {8) (Pois~ Anhydrous Ammon ,a H.1nrd. zone DJ

'Oomestkrr• tt$pOl'U!IOll. "111ttm.111oNI 11,nsportat,on.

also requ ire-s shiprxrs a nd carriers ro compl y wi1h all applicabl e labeling, marking, i~ pbc:Jrding requirements.

10. 15-f RESPONDING TO INCIDENTS INVOLVING A RELEAS E Of ANHYDROUS AMMONIA

Ammonia injures rhe human organism rhrough two differenr mechanisms:

As 3

cold liquid ar _28"F (-JJ°C), anhydrous ammonia freezes skin and orh e, tlss ties

at th e ~inrsl o/ccodat:~~,viduals who brearhe :immonia experience the adverse hea /.1 As previous y no e , 111 effecrs nored in T:ib/e 10.20. Gi,·en rhe nature of the iJ1 effects resufring from exposure to ammonia, ,_he use of stlf.

ronr.1ined breaching appararus is essenti:tl when_ emergency re~po_nde rs arrrve at _a SCCII(' im,o/ ving a release of ammon ia. When rel eased dire':"rly from a /1.qu_1d storage tank mtothc atmosphe re, ammonia gc-ncra J/y is visible as a white fog co~s•~ rm ~ ~f-~ro~lcts of con. densed atmospheric moisrure. Alrho~gh its presence severely l1m1 ts v1S1b 1l1ty m the irnmt- &are em•ironmenr, the initial fo rmation of rhe fog hel~s workers loca te rhe spot at which rhe ammonia is /caking from ifs sror:ige ran~ or c?nr~me_r. . . .

The v:ipor den siry /isred in Table JO. l ~ 1s :in md1~ar10~ that ~mmom~ 1s l1ghrer 1hJn air. When it is rele:ised outdoors into dry :ur, ammoma qu1 cklf d~spe rses m~o ~he armos. here especially under windy conditions. When anhydrou s l1qwd ammonia 1s releasrd fnw dioist :iir, however, sm:i/1 liquid droplets of :immonia in _ water are produced. Un~,

such conditions, these droplets behave as a dense gas, traveling along th e surfa ce of 1he ground instead of rising into the air and dispersing.

Warer absorbs 3 very large volume of am monia: Ar room condi tions, one volume of wa ter absorbs l l i6 volumes of ammonia gas. This physical property is used to advanr3gc when responding ro incidents involving a release of ammonia. The recommended prncrice is to est.1blish a warer currain downwind from rhe poinr 3t which the ammonia is being relm n!. The wa ter &sso/ves rhe ammonia 3nd reduces rhe concentra tion rhar ca n rravel farther.

"" e~posure to ammonia bums !he eyes and na~I PIS\.39fWays ilnd the mhalatl()(l of elevated ,mm e-d ate asohy.i<1flon, tht lmp!ementat.Ol'I of any em'ergfncy response act,on ,nvoh,,ng

1tsflammo1ble nl, ~eiy ,f the ammor-1,1 sub~equen tly 1gr11tes Rtscue workers m~ be unable to successfully

1 hdve ,nhaled ammonia The treatmMt may be l;m,ttd to itdm,n.stering oxygen unt,1 thty can :movtd to a med,ca lfac1l11y

When first-o n-the scene eme~gency responders are called to a 1ran spor1ation mi shap ni·olrins the release of 3 bulk sh1pme~u of anhydrous .1mmonia, the )' mu st acknow ledge

1 hr 53 fery of 1he tea m, transportation personnel, and th e gene ral public is ar risk. The : ~;gene)' Response Guidebook. recommends isola_ri on and ev3~uacio n ~isr:mces wh_en

spills of an hrdrous ammoma occur from multiple sma ll cylinders, single ton cyhn- multiple ton cy_li.nder;, r.1il tankcars, and highw.1y rank trucks .1nd 1railers under

, iling wind condmon s. P~';he largest rran spo rrat io n spill of ammoni.1 in the United Stat es occur red in 2002, when J I rail t~n kcars ~era.il_ed near Minot, No rth D.1kora, ~uring the wreck of_a Can a- d Pacific Radway mun. Five of th e 3 1 tank c3 rs catastrophica ll y ruptured and instantly 1 ::sed 146,700 ga ll ons (555 m3) of 3mmonia into the atmosp here. Exposure to rhe

;~~oni::a resulted i~ the d~ath ?fa lo~%! residenr. More th an 1400 others expe rienced some degree of respir:1.tory 1mpa1rmenr.

10,15· G AMMONIA SOLUTIONS Almost everro ne has encou ntered ammoni.1 as the gas that esopes from the commerci~ I deaning product ca ll ed household ammo11ia. This is ~n aqueous soluri?n of ammonia rim.1 ril y used for deaning glass, marble, and porcel:iin su rfa ces. Chen11 srs refer to an_y

:queous solution of ammon ia as ammonium l,ydroxide, aqtfeous ammo,_,ia, or ammo11'.a solution. Its chemical formula is NH3(aq ), or NH. OH. The concentrauon of ammonia dissoh·ed in household ammonia ranges from 2% to 5% by vo lum e. The vapo r is percep- uble at concentrati ons as low as approximately 5 parts per mi llion. Most individuals do not find this concentration irritating. .

Commercia l ammon ia solution s co ntain disso lved ammonia that ranges in concenc~a- rio n fro m 10% to more rhan 50 %. These aqueous solu ti ons are hazardous primanl y owing w the ammonia that rapidly escapes from them .

10.15· H TRANSPORTING AMMONIA SOLUTIONS

SOLVED EXERCISE 10.6

DOT reg ulates the tra nspo rtat ion o( am monia soluti~ns acc~rding to their am n~on ia co n• cemrarions. When shippe rs offer an aqueo us .1 mmoma soluuon for .rran sportauon, DOT rrquires rh em to provide the relevant shi pping ~escription _shown m ~a bl e I0.2_2. DOT also requi res shippers 3nd ca rri ers ro comply wuh all apphcable label ing, markmg, and plm rd ing requirement s.

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To p,otte1 public health, safety, and the envrronment what imm ediate action sh ould be tak en by f,rst-on•:1-l- .scene responders when they encounter a s-trong odor of ammonia 1n an enclosed room ar an ice -cre.im piano Solution: Ammonia cannot ignite 1t1 air unless a concentration within ,ts fl am mable range 1s exposed to an 19 "' tion source The flammable range of ammon,a is 16% to 25% by vofume A concemrat1on within this r.ai,qt~ read1fy ach,eved when ammonia eS(..3pes from large refngeratJon units into an enclosed room When emer9erq responders frn detect an espec1a1fy strong odor of ammonia, th eir pnmary concern should be aimed at eJ.m not· Ing the nsk of its ign,tJon. They can do th,s by o~nrng doors and windows to ven t the ammonia from the encJi>- sure while s,muhaneovsly taking precautJons to avoid generatJng a spark

Chapter 10 Chem istry of Some Toxic Substances

1 7Jb/e I, Eme~t•tcy Rt spo115e Guid_rbook (WJshingt.on, DC; U.~a~t.::rcr;r:~1 :ti;::i;a9~~:iz:n~o ~: ~~::~; R,11/roJd Acci dent Re-port, ·oerarlmen ~ of Ca nJdian Pacific ;

8 ., ~.,. NTSRIRAR -04/0 1 PB2 004 -

Rdme of Anhydrous AmmoniJ Near Minor, North DJkOtl, January , - -, ' 91610 1 (Wn hingron, DC: Nation;1I TrJnspormion Safery BoJrd, 2004).

chapter 10 Chemist ry of Some Toxic Substances 391