No Substitute for Safety

Following the diacetyl hazard scare, many food manufacturers turned to flavor alternatives -- only to find out their problems had followed them.

It has been more than a decade since the National Institute for Occupational Safety and Health first made public the hazardous inhalation properties of diacetyl, a popular flavoring chemical used by many food manufacturers. Since that time, the path to regulation of diacetyl exposure has been a winding one.

In 2006, the United Food and Commercial Workers International Union (UFCW) and the International Brotherhood of Teamsters (IBT) petitioned the Department of Labor for an Emergency Temporary Standard for all employees exposed to diacetyl. Although it denied the petition, OSHA did initiate a rulemaking based on NIOSH evidence associating diacetyl exposure with the development of bronchiolitis obliterans, a debilitating and often fatal disease of the small airways of the lungs. On Jan. 21, 2009, OSHA published an Advance Notice of Proposed Rulemaking but quickly withdrew the notice less than two months later and initiated a review of the draft standard in accordance with the Small Business Regulatory Enforcement Act.

Meanwhile, Cal/OSHA moved forward and on Dec. 2, 2010, became the first state to release a diacetyl standard. The new standard, section 5197 of the California Code of Regulations, requires employers covered by the standard to create a regulated area for each process using diacetyl, unless the process is enclosed. Employers also must provide safeguards for employees who work with diacetyl at certain concentrations. These safety measures include creating a written diacetyl control program, periodic monitoring of exposure levels, and providing personal protective equipment, respirators, training, and medical surveillance at no cost to employees.

One Breath at a Time
Jackie Nowell, director of the Occupational Health and Safety office at UFCW, said the California standard has shortcomings but is an important step forward for protecting workers. "It's going to cover flavoring manufacturing, but the one percent bar is really too high," Nowell said. "But again, the process of getting worker standards on health and safety is that it's a collaborative process, a public process where both sides weigh in, both industry and the advocacy side, and a compromise is developed. And that's what's going to happen on the federal level, too."

The food flavoring industry has not sat idle during the past decade. From the day concerns about diacetyl's health hazards began to be made public, many manufacturers have taken the initiative and turned to the use of flavor alternatives. "Whatever substitution has gone on, it's been done fairly recently in the last few years and we just don't have any data on that yet," said John Hallagan, general counsel for the Flavor and Extract Manufacturers Association. "I think it's fair to say there's been a decrease in diacetyl use, but I don't know to what degree these substitutes have taken over."

While substituting for diacetyl by food manufacturers may have been well intentioned, a Dec. 7, 2010, OSHA Safety and Health Information Bulletin is cause for concern. The bulletin said recent NIOSH findings, conducted in conjunction with the association, suggests more than 150 of these substitute flavorings are just as detrimental to a worker's health as diacetyl.

In April, NIOSH plans to release for peer review a guidance document whose purpose is to evaluate and analyze the scientific literature concerning potential health effects, toxicology, engineering controls, work practices, PPE, and recommendations pertaining to diacetyl, its substitutes 2,3-pentanedione (CAS 600-14-6, also known as pentane-2, 3-dione; acetyl propionyl), and other alpha-diketones. The Department of Health and Human Services published a request for information on behalf of NIOSH for these substances in the Jan. 10, 2011, Federal Register. Early indications are that OSHA shares these same concerns as the agency revised its National Emphasis Program on Jan. 24 to focus on protecting workers from exposure to diacetyl and diacetyl substitutes, including 2,3-pentanedione and other related diacetyl substitutes.

Dr. Lauralynn Taylor McKernan, ScD, CIH, acting senior team lead for the Document Development Branch within the Education and Information Division at NIOSH, is leading this effort. She said the draft diacetyl/2,3-pentanedione criteria document will contain NIOSH Recommended Exposure Limits (RELs). A public meeting will be held 30 days after the Federal Register notice is published.

Exposure Controls
One of the largest roadblocks in researching these chemicals is that not enough is known about their use because many of these flavorings' ingredients are proprietary information. Also, the industry is often driven by market demand.

"Industry's a moving target with this stuff," Nowell said. "The food industry is all about flavor, and they've been using flavorings forever. And they are going to find a substitute for butter flavor because they thoroughly believe that people want it. Now, which came first, the chicken or the egg? They introduced us to all of theses flavorings and now we want them, but that doesn't mean that they couldn't do something different. But they choose not to because this is how they make their money. 'My popcorn tastes more buttery than yours.' So, we're stuck with an industry that will continue to make chemicals and flavors that sell products. That's the reality."

McKernan said manufacturers should err on the side of caution by assuming these formulations have toxic properties and should preventively employ the use of respirators and other PPE. "Published reports on the toxicity of 2,3-pentanedione are currently only in abstract form but suggest that in rats, 2,3-pentanedione causes airway epithelial damage similar to that produced by diacetyl," she said. "Preliminary data also suggest that, under certain conditions, both diacetyl and 2,3-pentanedione can cause changes in the central nervous system. Diacetyl and 2,3-pentanedione are both in a class of chemicals called alpha-diketones. Additional alpha-diketones that have been used in food manufacturing and are thus of interest include, but are not limited to, 2,3-hexanedione and 2,3-heptanedione."

If diacetyl or its many substitute flavorings must be used, OSHA's Safety and Health Information Bulletin recommends many engineering controls as the first line of defense for protecting workers. Manufacturers should isolate flavoring production and handling areas with structurally sound walls, doors, or other appropriate barriers. A separate ventilation system is also recommended and should maintain negative air pressure (0.04" w.g. ± 0.02" w.g. relative to the rest of the plant) in the production room with respect to adjoining or adjacent rooms or areas. This will prevent the migration of contaminated air from the production room to other areas of the plant.

There should be a local exhaust ventilation (LEV) system wherever powder or liquid flavorings are manually blended, weighed, mixed, poured, transferred, packed, or handled (e.g., ingredient batching tanks, tank or blender filling operations, powder dumping operations, drum pouring operations, quality control operations, and compounding operations). At a minimum, LEV should achieve a capture velocity of 100 feet per minute (fpm) for liquids and a minimum of 200 fpm for powders between the emission source and hood opening.

OSHA warns against relying on recirculation filtration systems to control flavor vapors. These systems capture dusts and protect flavor and food integrity but do not protect workers from vapors. In addition, these systems can spread vapors to other parts of the facility. Also, the use of closed processes such as pumps and direct piping to transfer ingredients to blenders or tanks eliminates the need to open them to add ingredients.

Flavoring substances should be added at room temperature, but, if preheating is necessary, the warmed substances should be transferred to the mixing tank via a pumping system rather than manually. These actions will minimize the release of flavoring vapors into the workroom air but are not a substitute for LEV. Small openings should be installed in tank lids for adding flavoring substances through funnels, and hoppers should be maintained under negative air pressure at all times while flavorings are added. For disposal, using commercially available bag-dumping stations equipped with LEV (e.g., a three-sided canopy hood) will reduce dust exposure.

Other Controls
Beyond engineering controls and PPE, work practice controls play an equally important role in safety. Access to areas where flavorings are mixed, stored, or openly handled should be restricted to authorized personnel. Compounding and dispensing of flavorings should be scheduled when fewer workers are in the vicinity. The exposure hazards from flavor weighing and measuring steps can be eliminated completely by obtaining flavoring substances in sealed, pre-measured containers suitably sized for routine production batches. If an ideal pre-measured container cannot be found, consider adjusting the facility's batch size accordingly.

If manual production of flavorings is necessary, they should be produced under controlled conditions using the following steps:

  • Seal containers tightly when storing or transferring flavorings. Replace lids on empty or partially used containers immediately after adding flavorings in a batch process.
  • Pour flavoring substances slowly and use funnels to reduce exposures, splashes, and spillage.
  • Minimize manual transfer of flavoring substances. Do not use a shovel to transfer powdered flavoring substances.
  • Establish standard procedures to minimize each worker's exposure to flavoring substances when cleaning work areas, tanks, containers, and spills. This includes promptly cleaning up spills, such as from overflowing tanks or from leaks in seals and fittings, and performing operations requiring workers to enter tanks or containers in compliance with OSHA's Permit-Required Confined Spaces standard (29 CFR 1910.146).
  • Do not use compressed air or dry sweeping to clean surfaces and remove powdered flavoring substances because they may become airborne.
  • Use room temperature or cold water to pre-rinse mixing containers and tanks before cleaning with hot water or sanitizing. Steam or hot water may release volatile flavoring substances during cleaning.
  • Change work clothes and wash skin immediately if flavoring substances are spilled or splashed on them.

Medical Surveillance
In addition to these protective measures, manufacturers should employ a medical surveillance program that includes spirometry to identify health effects from exposure and should monitor exposure. When done in accordance with the American Thoracic Society's guidelines, spirometry will measure the breathing capacity of workers' lungs and provide early detection of decreasing or abnormal lung function. A medical evaluation will establish a health baseline for all workers from the start and should include a health questionnaire focused on respiratory symptoms and a history of preexisting lung disease. These exams also provide an opportunity to educate workers about potential workplace hazards and the signs and symptoms of occupational lung disease, such as cough, wheezing, and shortness of breath.

OSHA recommends that, when monitoring, employers collect personal, full-shift samples in order to accurately measure workplace air concentrations, in addition to short-term personal sampling for operations involving open handling of flavoring substances, such as pouring, blending, transferring, and packing operations. OSHA has two fully-validated air sampling methods: Method 1012 and Method 1013. Both methods allow samples to be collected from 15 minutes to three hours and are posted on OSHA's website.

As research moves forward, the safest approach for manufacturers is to proceed as though these chemical flavorings are toxic. Engineering controls, safe work practices, and appropriate PPE should be used regardless of whether the flavoring in use is diacetyl or one of its many substitutes.

"A conscientious industry would control all of these chemicals as if they were hazardous," Nowell said. "Treat it as if it is hazardous, don't wait for the research. It's not fair to the workers to do that."

WORKER ALERT: Diacetyl and Substitutes
Diacetyl is a chemical used to add flavor and aroma to food and other products. Workers who breathe diacetyl on the job have become disabled or have died from severe lung disease. Some diacetyl substitutes may also cause harm; diacetyl substitutes that have not been proven to be safe include diacetyl trimer, 2,3 hexanedione, 2,3 heptanedione, and 2,3 pentanedione.

Examples of Flavors that May Contain Diacetyl and Substitutes

Dairy flavors (e.g., butter, cheese, yogurt flavors).

  • "Brown" flavors (e.g., caramel, butterscotch, brown sugar).
  • Other flavors (e.g., butter pecan, some fruit flavors).

Industries and Jobs using Diacetyl and Substitutes

  • Flavor manufacturing plants
  • Plants where flavors containing diacetyl or substitutes are used, such as some makers of snack foods, baked goods, and candy
  • Jobs at or near mixing, weighing, pouring, transferring, or other handling of diacetyl, or flavorings containing diacetyl, especially if heated
  • Cleaning and maintenance operations
  • Quality assurance and laboratory jobs

Worker Protection

If you work with flavorings containing diacetyl or substitutes for diacetyl, your employer should:

  • Measure air in your workplace for flavorings exposure, including air in your breathing zone (personal air monitoring).
  • Use engineering/work practice controls such as local exhaust ventilation, isolating processes, and restricting access to areas where diacetyl or its substitutes are used.
  • Provide personal protective equipment (PPE) such as respirators, goggles, and gloves.
  • Provide medical clearance for respirator use and provide instructions and training in protective equipment care and use.
  • Refer workers for medical evaluation for symptoms of coughing, breathing difficulty, or eye irritation.
  • Provide training on how workers can protect their health.

Health Effects and Symptoms

  • Breathing diacetyl can result in permanent lung damage, including a disabling and potentially fatal lung disease called bronchiolitis obliterans.
  • Symptoms of flavoring-related lung disease include ongoing cough and shortness of breath. If you have either of these, ask your employer to send you to a doctor for evaluation.
  • Flavorings containing diacetyl may also burn the eyes, cause soreness in the nose and throat, and irritate the skin.

Source: OSHA

This article originally appeared in the March 2011 issue of Occupational Health & Safety.

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