study guide need by tomorrow afternoon

1

 Dose-response relationship

 Threshold dose, NOAEL, NEL

 No threshold in carcinogens

 Indicators of relative toxicity

 LD50, LC50

 ED50, EC50

 Types of toxic effects

 Acute

 Subacute

 Chronic

 Toxicity depends on

 Substance

 Route of administration

 Species tested

 Safety factor

 Epidemiological studies

 Descriptive

 Prospective cohort

 Retrospective cohort

 Disposition of a toxin

 Absorption

 Distribution

 Metabolism

 Excretion

 Routes of exposure

 Inhalation

 Ingestion

 Skin absorption

 Injection

 Toxin distribution

 Filtration

 Diffusion

 Active transport

 Phagocytosis

 Biotransformation

 Toxin excretion

 Liver

 Kidney

 Lungs

EHST 3700/3701:

Industrial Hygiene

 To explain the dose-response relationship and

the concept of threshold dose

 To discuss how toxins enter the body and are

transported to different organs and tissues

 To describe the types of toxic effects

resulting from substance exposure

 To describe how toxins are altered,

detoxified, and eliminated from the body

 To enumerate different classes of toxins

 Definition of Toxicology

 Dose-Response Relationship

 Indicators of Relative Toxicity

 Routes of Exposure

 Distribution of Toxins

 Biotransformation of Toxins

 Excretion of Toxins

 Classes of Toxins

2

 Irritants

 Sensitizers

 Systemic toxins

 Neurotoxins

 Reproductive toxins

 Carcinogens

 Irritation

 Physical damage to tissues that is localized

(i.e. site of contact)

 Corrosion – most severe response

 Ulceration and tissue damage

Chemical burn by acid

 Marginal irritants

 Cause irritation

resulting from

repeated exposure

 Sensitization: adverse reaction that occurs

following more than one exposure event to a

substance

 Sensitizers: substances that stimulate a

response from the immune system

+

Toxin

(hapten)

Protein

Hapten-protein

complex

Antibodies

 Materials that affect target organs or

organ systems

Systemic Toxin Systemic Effect

Vinyl chloride Liver damage

Liver cancer

Cadmium Kidney damage

Benzene Blood marrow damage

Leukemia

 Compounds that have a

negative effect on the

nervous system

 Can impact thinking

ability, motor control,

and regulation of

breathing and

heartbeat

Nervous System: Central and Peripheral

Substances Associated with

Central Nervous System

Effects

Substances Associated with

Peripheral Nervous System

Effects

Organic solvents

Lead and lead components

Asphyxiant gases

Carbon monoxide

Cyanide compounds

Arsenic

Organic mercury

Organochloride compounds

Organophosphate

compounds

Manganese

Arsenic

Organic mercury

Methanol

Ethylene glycol

Lead

n-Hexane

Organophosphate compounds

Organochloride compounds

3

 Interfering with the transmittal of nerve

impulses

 Increase or decrease a neuron’s sensitivity to

nerve impulses

 Neuropathy: progressive decline and death of

nerves

 Increase in nerve stimulation by reducing

production of or inhibiting the enzyme

acetylcholinesterase

 Decrease oxygen supplied in the bloodstream

 Substances that affect the reproductive

process

 Germ cell (gamete) production

 Fertilization

 Implantation of the developing embryo

 Gestation

 Males

 Causes decreased number of sperm

 Causes defective sperm

 Pregnant females

 Causes deformities in the developing fetus

 Class of toxins that cause cancer

 Able to cause neoplasm

 General classes

 Genotoxic: reacts with the DNA

 Epigenetic: do not interact with the DNA

One-hit theory:

A single exposure

could be enough

to trigger cancer.

 Initiation

 Exposure to initiators make the cell susceptible

to the development of cancer

 Promotion

 Exposure of damaged tissue to promoters

activates the development of cancer

Chemical

 Toxins may be classified as irritants,

sensitizers, systemic toxins, neurotoxins,

reproductive toxins and carcinogens.

 The difference between irritants and

sensitizers is the involvement of the immune

system.

 Systemic toxins affect target organs.

 Neurotoxins affects the central and

peripheral nervous system through different

mechanisms.

 Theory of cancer causation involves initiation

and promotion.

4

Explain the toxicity cases in terms of the

following:

 Toxin involved?

 Workers exposed to the toxin?

 Specific effects of toxin?

 Type of toxic effects: acute or chronic?

 Route(s) of entry?

 Target organ?

 Method of excretion?

 Toxin classification?