article review

72 ProfessionalSafety JUNE 2012 www.asse.org

Exposures & Controls By Lori Schroth

D iacetyl (2,3-butanedione) is a chemical used to add flavor and aroma to food and other products. Diacetyl and its substitutes

are commonly manufactured in microwave popcorn and flavoring production plants, and they also are used in the making of beverages, snack foods, baked goods, prepared canned and frozen foods, and candy (OSHA, 2010a, b). Food and Drug Adminis- tration (FDA, 2011) classifies diacetyl and its substi- tutes as “generally recognized as safe (GRAS).”

While the substance may be safe to consume, that does not mean it is safe to work around. Through extensive research and case studies, NIOSH has found that diacetyl is a standard air contaminant in the popcorn and flavoring industry (OSHA, 2010a,

b). Numerous jobs may expose work- ers to diacetyl, including mixing, weighing, pouring, transferring or other handling activities, as well as during cleaning and maintenance op- erations, quality assurance and labo- ratory work (OSHA, 2010a, b).

In May 2000, numerous workers at a microwave popcorn processing facility displayed similar respiratory symptoms and, ultimately, devel- oped bronchiolitis obliterans (OSHA, 2011a, b, c). Since bronchiolitis oblit- erans is an uncommon lung disease, the local health department (Missouri Department of Health and Senior Services) launched an investigation and requested NIOSH’s assistance. NIOSH (2003a, b; 2006) linked the development of bronchiolitis oblit- erans to occupational exposure to diacetyl. Bronchiolitis obliterans be- came known as popcorn workers’ lung due to the correlation of the dis-

ease with the butter flavoring of microwave popcorn (Kanwal & Kullman, 2007; NIOSH, 2003a, b). Many

lawsuits from popcorn and flavoring plant workers, as well as regulatory concerns, soon followed.

NIOSH’s investigations sparked OSHA’s inter- est. The agency added microwave popcorn pro- cessing plants to its national emphasis program (NEP) in 2007 (OSHA, 2007a, b; 2011a, b, c). OSHA launched this program to address controls required to reduce and eliminate occupational exposure to diacetyl. In addition, OSHA (2007a, b) added the industry to the targeted inspection list and offered compliance assistance to processing plants.

Health Effects & Treatment OSHA Administrator David Michaels stated, “It

is alarming that workers continue to be at risk of dying from exposure to diacetyl and diacetyl sub- stitutes. Illnesses and death from these chemicals are preventable” (OSHA, 2011c). Inhalation of and physical contact with diacetyl can result in many health effects; contact can lead to eye, nose, throat and skin irritation (NIOSH, 2003a, b). NIOSH’s investigation at a flavoring plant revealed a high rate of reports correlated with diacetyl exposure– about 50% of all workers experienced nasal irrita- tion; nearly 50% of office and warehouse workers, as well as 80% of production and laboratory work- ers, had eye irritation; and 36% of production workers experienced skin problems (Kanwal & Kullman, 2007).

Inhaling diacetyl can result in fatigue, fever, night sweats and weight loss, as well as respiratory effects such as cough, difficulty breathing and occupational asthma (Kreiss, 2002; NIOSH, 2003a, b). In 2008, a study conducted by National Institute of Environ- mental Health Sciences determined that both acute and chronic exposures to diacetyl result in damage to the nose lining, throat irritation and airway in- flammation (OSHA, 2010a, b). These signs of illness usually do not improve when the worker is no lon- ger exposed to the diacetyl (OSHA, 2011a, b, c).

Symptoms appear slowly and steadily, but can quickly become more severe. Exposure to diacetyl also can cause permanent lung damage and lung disease, such as bronchiolitis obliterans (Kreiss, 2002). Severe lung damage and disease can ulti- mately lead to serious disability and even death.

Respiratory illnesses associated with diacetyl can easily be mistaken as other illnesses. To correctly di- agnose symptoms thought to be diacetyl-induced, a medical professional asks the patient a list of symp-

IN BRIEF Diacetyl is a chemical used

in microwave popcorn and flavoring production plants to enhance the flavors of the manufactured products. Diacetyl exposure has been

linked to the development of bronchiolitis obliterans, an ir- reversible lung disease. Regulatory guidance and

various research studies were analyzed to identify where government agencies stand on regulating diacetyl and what the future holds. This article explores the

background, health effects, regulatory guidance and control measures for diacetyl and diacetyl substitutes.

Lori Schroth, CSP, is a safety and occupational health professional at Concurrent Technologies Corp. in Johnstown, PA. She holds a B.S. in Safety Sciences and a B.S. in Natural Sciences from Indiana University of Pennsylvania. She is pursu- ing an M.S. in Occupational Safety, Health and Environmental Management at Columbia Southern University. Schroth is a member of ASSE’s Western Pennsyl- vania Chapter and a member of the Society’s Women in Safety Engineering and Young Professionals in SH&E common interest groups.

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tom-specific questions (e.g., symptoms displayed, where they first started, whether others show the same symptoms), occupational exposures and med- ical history (Kreiss, 2002; OSHA, 2002). Answers to these questions can provide valuable feedback and input, and lead to the correct diagnosis.

A medical professional also can conduct a pul- monary function test (PFT) or spirometry to assess a person’s lung function (NIOSH, 2003a, b). This test can help identify obstructed or restricted air- ways, which signify respiratory problems (NIOSH, 2003a, b). Patients with abnormal spirometry re- sults are often prescribed asthma medication to determine whether the airway obstruction is tem- porary or permanent (NIOSH, 2003a, b).

If the obstruction does not improve with the use of medication, then chest X-rays, CAT scans or lung biopsies can be performed to further identify problems in the respiratory tract (OSHA, 2002). Patients diagnosed with bronchiolitis obliterans are typically treated with steroids and informed about how to avoid aggravating their condition (OSHA, 2002). In extreme cases, lung transplants may be recommended (NIOSH, 2003a, b).

Historical exposure data and occupational air monitoring samples can be analyzed to identify links between occupational exposure to diacetyl and bronchiolitis obliterans. Frits and colleagues (Frits, Rooyackers, Prokop, et al., 2007; Frits, Smit, Houba, et al., 2008) investigated diacetyl exposure. They evaluated exposure data from numerous worksites and spirometry results from many workers. The documentation supported the investigation find- ings that diacetyl produced an occupational hazard to workers since many of them displayed signs and symptoms of bronchiolitis obliterans—mirroring NIOSH’s findings (Kanwal & Kullman, 2007).

Exposure Limits Agencies such as OSHA, NIOSH and American

Conference of Governmental Industrial Hygienists

(ACGIH) develop safety standards and guidelines to protect workers from hazards, including occupa- tional exposures. At the federal level, no agency has established a permissible exposure limit (PEL), rec- ommended exposure limit (REL) or threshold limit value (TLV) for diacetyl. California’s Occupational Safety and Health Program does, however, regulate diacetyl at the state level, which means facilities in the state of California that have exposure to diacetyl must follow this standard (OHS Online, 2010). The standard “requires employers covered by the stan- dard to create a regulated area for each process us- ing diacetyl, unless the process is enclosed.”

Although diacetyl exposure is not currently reg- ulated at the federal level, multiple agencies have taken several steps to ensure the safety of work- ers with exposures to diacetyl. In August 2011, NIOSH drafted a proposed REL of 5 parts per billion (ppb) as an 8-hour, time-weighted aver- age (TWA) during a 40-hour work week to protect workers against short-term exposures to diacetyl.

Industries & Jobs Using Diacetyl & Substitutes

or substitutes are used (e.g., snack foods, baked good, candy)

- vors containing diacetyl are mixed, weighed, poured, transferred and handled

Note. From Worker Alert: Diacetyl and Substitutes, by OSHA, 2010, Washington, DC: DOL, Author.

Inhaling diacetyl can result in fatigue, fe- ver, night sweats and weight loss, as well as respiratory effects such as cough, dif- ficulty breathing and occupational asthma.

74 ProfessionalSafety JUNE 2012 www.asse.org

In addition, OSHA (2011) added diacetyl and all diacetyl substitutes with the alpha-diketone struc- ture, including 2,3-pentanedione, to its NEP. The agency (2008) also established the targeted diacetyl concentration of 0.5 parts per million (ppm) (1.76 mg/m3) for a workplace where diacetyl is present.

Control Measures NIOSH (2007a, b) recommends several controls

to reduce hazardous exposures associated with di- acetyl. These include substitution, engineering and administrative controls, education, PPE, and expo- sure and worker health monitoring.

Substitution Substitution can effectively reduce or eliminate

an existing hazard. Numerous substitutes have been developed to replace diacetyl to reduce em- ployee exposure. These substitutes have not been extensively tested, so it is unknown whether they are safer than diacetyl (OSHA, 2010a, b). Before selecting a substitute, an employer should analyze and evaluate any substance’s hazards so the safest and healthiest substitution can be selected.

Engineering Controls Engineering controls are the preferred method

to minimize diacetyl exposure. Sites should evalu- ate work areas and select controls that are func- tional and mesh with site setup. OSHA (2011a, c) and NIOSH (2003a, b) suggest several engineering controls:

- duce the concentration of airborne diacetyl.

reduce the concentration of airborne diacetyl and remove diacetyl from the worker’s breathing zone. These systems should be located near operations that produce high diacetyl exposure levels. Sepa- rate ventilation systems can be utilized between areas where diacetyl exposure is high versus low. It is best to not rely on filtration systems since some will cause hazardous vapors to circulate back into the work area. Maintain negative air pressure in rooms with higher concentrations to prevent the air from moving into other noncontaminated areas (OSHA, 2007a, b). Ventilation should be appropri- ately maintained and inspected as well.

diacetyl, such as mixing rooms, spots near open tanks of oils or flavorings, and quality control ar- eas, can be isolated from the immediate production room. Use doors, walls and other barriers to isolate

the processes. Depending on exposure levels, per- sonnel entering these areas may need to wear PPE.

- ed, vapors are produced and disperse through the air, making the substance more volatile and eas- ier to inhale. Facilities should keep temperatures as low as possible while any flavorings are being heated. This limits the amount of vapors being pro- duced and minimizes occupational exposure.

Administrative Controls All stakeholders should partner to create admin-

istrative controls and form good work practices to prevent exposure to diacetyl. Recommended con- trols (NIOSH, 2003a, b; OSHA, 2010a, b) include the following:

1) Employ good housekeeping procedures. Promptly respond to spills. Avoid using compressed air to clean up powders that may contain diacetyl.

2) Use tight-sealing containers. A tight seal will prevent flavoring from being spilled or blown into the air.

3) Limit access. Limit the number of employees in areas where higher concentrations of diacetyl may be present. Train personnel how to minimize personal exposures.

Education Worker awareness and education are essential.

Workers should be educated about products that may produce diacetyl exposure and know how to protect themselves against those hazards. Employ- ees should be trained to recognize and understand hazard warnings, workplace postings, container labels, and the signs and symptoms of diacetyl- related illness (NIOSH, 2003a, b). They also should know where to obtain hazard information regard- ing each product, such as MSDS.

Personal Protective Equipment PPE can provide additional skin, eye and respi-

ratory tract protection to workers exposed to diace- tyl (NIOSH, 2003a, b). According to OSHA (2007a, b), PPE made of butyl rubber, Teflon or Tychem provides adequate protection against diacetyl. Chemical-resistant gloves, aprons and sleeves, and tight-fitting goggles can be used to protect against skin irritation and eye injuries resulting from skin contact, splashes and vapor exposures (OSHA, 2002).

The worksite should be evaluated to determine the need for respiratory protection equipment; this can be difficult in the absence of an OSHA PEL, NIOSH REL or ACGIH TLV. According to OSHA (2002), “respiratory protection in mixing rooms should be mandatory regardless of the amount of time employees spend in the room.”

OSHA (2002) and NIOSH (2003a, b) recommend that mixing-room workers be provided with a half- mask air-purifying respirator equipped with an or- ganic cartridge and particulate filters. Other options should be considered in warmer work areas where vapor exposures may be more prevalent. In these areas, a supplied air respirator or powered air-puri-

Does This Product Contain Diacetyl?

- tion on the MSDS.

diacetyl or CAS #431- 03-8.

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fying respirator with organic cartridges and particu- late filters can be used. If eye protection is required, then a full-face piece respirator should be consid- ered (OSHA, 2007a, b). OSHA 29 CFR 1910.134 must be followed when respirators are used.

Exposure Monitoring Exposure monitoring helps to identify hazards

and to determine whether controls are adequate. Such monitoring is critical in an industry where employees may be exposed to many different sub- stances in various forms. Exposure monitoring can detect the levels of harmful substances, such as di- acetyl, and pinpoint hazardous areas in the work- place. Before conducting exposure monitoring, an employer should assess current work practices and controls implemented at the worksite to determine whether current controls are working properly or whether additional controls are needed.

Industrial Hygiene Implementation Plan An industrial hygiene implementation plan

(IHIP) can be developed to prioritize and schedule monitoring for detectable amounts of diacetyl; the sampling should be conducted by qualified individ- uals. To obtain accurate results, the plan should ad- dress the rotation of conducting both personal and area samples. The plan should not only include air sampling strategies for diacetyl, but also sampling for any other flavoring chemical with an established PEL, REL or TLV (NIOSH, 2003a, b). Sampling for total dust and respirable dust also should be consid- ered because diacetyl can be present in a solid form.

Exposure monitoring should be conducted when diacetyl exposures are expected to be at their high- est. Monitoring provides valuable data on occupa- tional exposures and can help determine the extent of required controls. Sampling data gathered af- ter controls are implemented can help determine whether controls are reducing occupational ex- posures to diacetyl or other flavoring substances (OSHA, 2010a, b). High-hazard areas should be continually monitored to ensure worker safety.

Because established exposure limits are lacking, OSHA and NIOSH have developed sampling and analytical methodologies for evaluating diacetyl exposures. NIOSH sampling method 2557 utilizes sorbent tubes and a personal sampling pump cali- brated to a flow rate of between 0.01 and 0.2 L/min. The sample is collected by opening the sorbent tube, connecting it to a sample pump and pulling air through the sorbent tube with the pump. The tube is then sealed and analyzed at a laboratory using gas chromatography with a flame ioniza- tion detector (FID). Results are compared against NIOSH’s proposed REL of 5 ppb as an 8-hour TWA during a 40-hour work week. It should be noted that NIOSH (2003a, b) has reported that the relative humidity of the sampling area can lead to inaccurate and unreliable results.

OSHA sampling method 1013 utilizes silica gel sorbent tubes with a glass fiber filter and a person- al sampling pump calibrated to a recommended flow rate of 0.05 L/min for the TWA or 0.2 L/min

to evaluate a short-term exposure. Since diacetyl levels may be affected by sunlight, the sorbent tubes must be covered with foil or a tube cover to protect the sample from light. The sample is col- lected by opening the sorbent tube, connecting it to a sample pump and pulling air through the sorbent tube with the pump. The recommended sampling time is 180 minutes to assess the TWA and 15 min- utes to determine the short-term exposure. The tube is then sealed and its contents are analyzed at a laboratory using gas chromatography with a FID. Results are compared against the agency’s es- tablished targeted concentration of 0.5 ppm for a workplace where diacetyl is present (OSHA, 2008).

Worker Health Monitoring Workers should be continuously monitored

wherever diacetyl exposure is possible. A medical surveillance program should be in place to manage these exposures. This program should encompass prejob and annual spirometry testing to determine whether workers are experiencing health effects due to occupational exposure. Spirometry testing can be conducted as often as needed, especially if a worker is exhibiting signs and symptoms of respi- ratory illnesses that may be associated with diace- tyl exposure (OSHA, 2010). Information gathered from these tests can provide insight about work- er safety and health and also identify work areas where control measures are needed.

Keys to Prevention Both employers and employees should take the

initiative and extra steps necessary to prevent di- acetyl exposure.

Employer Prevention To promote safety and health, employers can: 1) Develop a training program to inform workers

on the dangers of diacetyl exposure. 2) Implement control measures where needed. 3) Establish and enforce good work practices. 4) Create and implement a continuous monitor-

ing plan. 5) Provide adequate PPE where required. 6) Stress the importance of the medical surveil-

lance program.

Diacetyl Exposure Limits

federal level, so there is no established OSHA PEL, NIOSH REL or ACGIH TLV.

a state level, addressing the need for a regu- lated area where diacetyl is handled.

8-hour TWA during a 40-hour work week. -

centration of 0.5 ppm for a workplace where diacetyl is present.

76 ProfessionalSafety JUNE 2012 www.asse.org

7) Track and trend reported signs of illness that may be associated with diacetyl exposure (NIOSH, 2003a, b; OSHA, 2010a, b).

Worker Prevention Workers can take steps to ensure their safety

when exposed to or potentially exposed to diacetyl: 1) Utilize information provided on MSDS. 2) Use in-place control measures, including PPE. 3) Tightly seal all containers when not in use. 4) Participate in the medical surveillance pro-

gram. Actively report any signs or symptoms that may

be associated with diacetyl exposure (NIOSH, 2003a, b; OSHA, 2010a, b). PS

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cross-sectional study of lung function and respiratory symptoms among chemical workers producing diacetyl for food flavorings. Occupational Environmental Medi- cine, 66, 105-110. doi:10.1136/oem.2008.039560

Frits, G.B., Rooyackers, J.M., Prokop, M., et al. (2007). Bronchiolitis obliterans syndrome in chemical workers producing diacetyl for food flavorings. American Journal of Respiratory and Critical Care Medicine, 176, 498-504. doi:10.1164/rccm.200611-1620OC

Kanwal, R. & Kullman, G. (2007). Report on severe fixed obstructive lung disease in workers at a flavoring manufacturing plant (NIOSH Health Hazard Evaluation Report No. 2006-030303043). Washington, DC: U.S. Department of Health and Human Services (DHHS), CDC, NIOSH. Retrieved from www.cdc.gov/niosh/ hhe/reports/pdfs/2006-0303-3043.pdf.

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