A Case of Regulatory Failure - Popcorn Workers Lung


Occupational exposure to the vapors from artificial butter flavor can cause bronchiolitis obliterans, a debilitating and sometimes fatal lung disease. Dozens of workers at microwave popcorn factories or factories where these flavors are produced have become sick, and at least one worker has died. Others are awaiting lung transplants. Thousands more workers are exposed at factories that make or use flavorings throughout the country. This is a case study in failings of our public health protection system. For more than five years, government scientists have conducted studies that have identified ways to protect workers and prevent this illness. In the face of mounting scientific evidence of a serious hazard, and recommendations on ways to prevent the disease, the Occupational Safety and Health Administration (OSHA) has done virtually nothing.

Background (also see Background on Diacetyl document)

Diacetyl is a commonly used food flavoring and is the primary constituent of artificial butter flavoring. There is compelling scientific evidence linking occupational exposure to diacetyl to bronchiolitis obliterans, a debilitating and sometimes fatal lung disease.  In the general population, bronchiolitis obliterans is rare. In the last few years, however, numerous cases have been reported to or identified by the National Institute for Occupational Safety and Health (NIOSH) among workers employed in factories where flavorings containing diacetyl are produced or used.  (See: NIOSH Alert)  Dozens of workers employed at microwave popcorn packaging plants have developed occupational lung disease and at least one has died.  Several of these workers are on lung transplant lists.  (See: Baltimore Sun's: Disease is swift, response is slow)

The First Cases of Popcorn Workers' Lung: OSHA and NIOSH Respond

The sentinel case of the recent outbreak of bronchiolitis obliterans was a Missouri microwave popcorn plant worker diagnosed with the condition in 1999.  Dr. Allen Parmet, a Missouri physician who treated several of the workers, notified the Missouri Department of Health (MDOH), which immediately contacted OSHA and NIOSH.  The letter OSHA received from MDOH alerted the federal agency that ten workers from one microwave popcorn packaging facility had been diagnosed with bronchiolitis obliterans and three of these workers were awaiting lung transplants. The MDOH reported that it planned to conduct an epidemiologic investigation of the disease cluster, but notified OSHA that obtaining medical releases and physician reports would take some time. Consequently, the state officials asked OSHA to inspect the facility, noting that “[a]s a regulatory agency … [OSHA] can more promptly address this situation, and if there is an obvious hazard to workers, address it quickly.”

When an OSHA inspector visited the plant a few days later, he noted that four years earlier, the plant’s insurance carrier had conducted environmental sampling for total nuisance dust. Therefore, he conducted no additional dust sampling and offered his “professional opinion that it would be ludicrous to re-sample the area again.” He did collect samples of respirable oil mist, but the OSHA lab in Salt Lake City discarded them because the agency’s sampling method applies only to petroleum-based oils, not vegetable oils. Having failed to collect usable exposure samples, the inspector, according to his own notes: “determined the company to be in compliance and closed out the case file since there were no other OSHA sampling protocols at his disposal to test further at the plant.”

Sixteen months later, in September 2001, an attorney representing several of the sick workers filed a complaint with OSHA, and followed up with another complaint in December 2001.  In her letter, the attorney alleged that not enough had been done to improve ventilation in the plant, as evidenced by the fact that “one employee lost half of his lung capacity working in the plant after the remedial measures that NIOSH suggested were taken…” (emphasis in original)  This prompted OSHA to send another inspector to visit the plant.  This time, the inspector stayed 40 minutes and did not conduct an inspection. OSHA then sent a letter to the attorney who had filed the complaints, denying the need for further investigation at the plant. The letter explained: “[T]he hazard which you brought to our attention has been corrected and … Glister [sic] Mary Lee is complying with the recommendations of NIOSH... The hazard does not fall within OSHA’s jurisdiction because there is no Permissible Exposure Limits (sic) for the food blend chemicals of concern that are used at the factory.”

NIOSH's Response

In contrast to OSHA, identification of the cases of a rare lung disease among the microwave popcorn packaging plant workers led NIOSH, the federal occupational health and safety research agency, to conduct a series of important studies that have resulted in an improved understanding of the lung disease caused by exposure to chemicals used in flavors.  In August 2000, NIOSH began its investigation with comprehensive industrial hygiene sampling of one microwave popcorn packaging plant, finding diacetyl —a volatile organic compound predominant in the product’s butter flavoring —was present in concentrations up to 1000 times higher than the office and outdoor areas at the plant.  NIOSH also did health assessments of nearly 90% of the plant employees, discovering that their rates of chronic cough and shortness of breath were 2.6 times the national average, adjusting for both smoking and age.  Twice as many workers than expected reported being told by their physicians that they had asthma or chronic bronchitis, and lung function testing revealed that three times as many workers as expected had obstruction to airflow. These results were reported first in the CDC’s Morbidity and Mortality Weekly Report and then in the New England Journal of Medicine.

In December 2000, NIOSH issued interim recommendations suggesting that all workers wear respirators pending the implementation of engineering controls to eliminate exposure to the artificial butter flavoring.  Over the next year, while working with the company in planning and implementing control measures, NIOSH staff continued to monitor the health of employees.  In September 2001, NIOSH staff returned to the factory to inform workers about what they had learned, distributing materials that included the ominous warning: “There is a work-related cause of lung disease in this plant. We at NIOSH believe the problem is continuing even after the company made changes that we recommended.”  They also stated that plant workers with bronchiolitis obliterans “can’t breathe well. They do not get better.”

A Widespread Hazard

Recognizing that exposure to artificial butter flavor was not limited to the one Missouri popcorn plant, OSHA and NIOSH each took steps to address the problem.  The quality of their responses, despite the seriousness of the hazard, could not be more different.  NIOSH applied a traditional public health approach, collecting extensive information about the distribution and determinants of lung disease in other popcorn plants and conducting laboratory studies to better understand the chemical hazard itself.  In order to carry out their field investigations, NIOSH developed sampling and analytical methods for measuring exposure to flavoring-related chemicals.  The agency scientists measured exposure to butter flavoring vapors at 10 microwave popcorn facilities and assessed the prevalence of respiratory impairment among many of the workers.  Through the development of science-based approaches to reducing exposure, NIOSH attempted to prevent additional cases of occupational lung disease. (See: NIOSH Health Hazard Evaluations on Flavorings)    

NIOSH examined the effects of exposure through experiments on laboratory animals.  In the first of these studies, rats were exposed to airborne concentrations of butter flavoring for a single, six-hour period. The researchers were alarmed to discover significant lung damage among rats whose exposure was “not extraordinary when compared with levels measured in the workplace.”  According to the study’s lead investigator, Dr. Ann Hubbs, the findings were “the most dramatic cases of cell death ever seen.”    NIOSH scientists then conducted a study in which rats were exposed to pure diacetyl and found similar results.  A toxicological study of guinea pigs exposed to pure diacetyl found exposure to the chemical caused adverse effects to respiratory tissue and structure.  

At the initial Missouri plant, diacetyl was measured in concentrations ranging as high as 98 parts per million parts air by volume (ppm), with a mean exposure of 8.1 ppm.  In their evaluation of six microwave popcorn plants (five of which had workers with flavoring-associated lung disease), NIOSH scientists reported that the “lowest mean TWA [time weighted average] diacetyl air concentrations that we measured in mixing areas (0.02 ppm personal exposure and 0.2 ppm area air concentration) were at a plant with an affected mixer," meaning a sick worker.  On the basis of this finding, the NIOSH scientists concluded “it would seem prudent to maintain worker exposures to diacetyl below these levels.”  In December 2003, NIOSH issued an alert that was sent to 4,000 businesses that might use or make butter flavoring. The alert suggests safeguards such as limiting release of vapors in production lines. Employers were asked to caution workers about the potential for lung disease.

In contrast to the NIOSH scientists' efforts to identify the hazard and the prevalence of disease, OSHA's response has been trivial.  When faced with a hazard for which no standard has been set, OSHA has the authority to issue an emergency temporary standard or to invoke the “general duty clause” and require employers to reduce or eliminate clear hazards.  OSHA selected neither of these options.  Despite significant “bodies in the morgue” evidence, OSHA maintains that “a cause-effect relationship between diacetyl and bronchiolitis obliterans has not been established, as food-processing workers with this lung disease were also exposed to other flavoring agents.”

In September, 2002 OSHA's Regional Office in Kansas City (Region VII) entered “an agreement establishing an alliance” with The Popcorn Board, the trade association representing popcorn manufacturers.  This move was part of a larger effort by OSHA to form alliances with corporations, trade associations, and other organizations, to voluntarily develop and share information regarding worker health and safety. OSHA’s Assistant Secretary reported in February 2004 that the agency had forty-six national and 105 regional alliances. There are no specific requirements for forming an alliance with OSHA and by design, the agreements “do not include an enforcement component."

OSHA’s partnership agreement with The Popcorn Board indicated that the trade association would provide OSHA with a mailing list of member companies engaged in microwave popcorn packaging so that OSHA could send these firms "recent information on the potential adverse health effects of employees exposure to artificial butter flavoring compounds."  Another provision would allow The Popcorn Board to "review and provide comment and input on a draft OSHA 'Hazard Information Bulletin' to be developed by OSHA for internal distribution to it's compliance officers in the field."  The partnership agreement did not have any mechanism for participation by exposed workers, their representatives or the public health community. The "alliance" was concluded in March 2003, and to our knowledge the 'Hazard Information Bulletin" was never issued.

In July of 2006, the United Food and Commercial Workers Union (UFCW) and the International Brotherhood of Teamsters petitioned OSHA for an Emergency Temporary Standard to protect workers from diacetyl. SKAPP organized a letter to the Department of Labor, signed by 42 of the nation’s leading occupational health scientists and physicians, in support of the petition.

More Than Just Popcorn Factories

Since the initial reports focused on individuals employed in microwave popcorn factories, the disease is often called “popcorn workers' lung.”  Scientists now recognize a health risk to thousands of other food industry employees using diacetyl in manufacturing both artificial flavorings and associated products including candy, pastries, and frozen foods. The California Department of Health Services, for example, recently reported two cases of bronchiolitis obliterans among diacetyl-exposed workers employed at factories where flavorings are produced, one of whom was mixing flavors for dog food.  NIOSH is currently investigating 15 cases of respiratory disease, including some workers with bronchiolitis obliterans, among the employees at a single Cincinnati, Ohio flavor manufacturing plant. (See: Baltimore Sun's: Disease is swift, response is slow)

Some cases of pulmonary disease for which no cause was originally identified may also turn out to be linked to diacetyl. In 1985, for instance, NIOSH inspected International Bakers Services, an Indiana facility producing flavors for bakeries, because two young, previously healthy, nonsmoking employees were diagnosed with severe fixed obstructive lung disease (consistent with bronchiolitis obliterans) within one year of employment. Inspectors advised the facility to change equipment and practices to reduce employees’ exposure to dust in the flavor mixing room, but they did not identify a particular agent that caused the disease. Diacetyl is listed one of the 33 ingredients commonly used at the facility. (See: NIOSH’s HHE report on International Bakers Services)

The scientific evidence gathered to date indicates that the problem is not limited to diacetyl. It is likely other chemicals used in the production of flavorings can cause or exacerbate lung disease. OSHA has issued permissible exposure limits (PELs) and/or NIOSH has recommended exposure limits (RELs) for only 46 of the 1,037 flavoring ingredients considered by the flavorings industry to represent potential respiratory hazards.

Diacetyl currently appears on the Food and Drug Administration’s “Generally Recognized as Safe” (GRAS) list. In September of 2006, SKAPP petitioned the FDA to revoke diacetyl’s GRAS status.  As required by FDA regulations (21 CFR 10.30(e)), the agency is required to respond to a citizen petition within 180 days.  In a letter dated March 6, 2007, the Director of FDA's Office of Food Additive Safety wrote that FDA has not yet reached a decision about SKAPP's petition "because of the limited availability of resources and other agency priorities."

Regulation by Litigation

While OSHA has done little to compel employers to reduce exposures, the threat of law suits against the flavoring manufacturers has become a potentially important mechanism to prevent bronchiolitis obliterans. More than $100 million has been awarded through court cases and settlements to former popcorn plant workers whose lungs were destroyed by diacetyl. These suits are against the flavor manufacturers who knew or should have known that the flavorings were capable of causing lung disease. If they had warned employers and workers about the hazards associated with diacetyl, or if they had sold a less hazardous product, some or all of these cases might have been prevented.

Through this litigation, it was revealed that in 1993, years before NIOSH undertook its first animal study, a German chemical manufacturer had conducted a study in which laboratory animals were exposed to diacetyl vapors. That study, which was never reported to the government or published in scientific literature, found results very similar to those later reached by NIOSH: one four-hour period of exposure to diacetyl resulted in an “abundance of symptoms indicative of respiratory tract injury.”

Is there Risk from Exposure at Home? The EPA Isn’t Saying.

There is no published research on the exposure of consumers to the heated vapors of diacetyl and other chemicals released when microwave popcorn is popped. In the middle of 2003, the Environmental Protection Agency (EPA) announced that a study on the chemicals released in the popping and opening of packages of microwave popcorn was underway and was expected to be completed by the end of that year. The EPA has yet to disclose the results of that study.

In July 2006, in response to an inquiry from SKAPP about the status of the study, the Chief of the EPA’s Indoor Environment Management Branch provided the following response:

“The principle investigator on this project was transferred to homeland security duties, there the final report has been delayed. It is anticipated that the report will be sent as a manuscript for publication in a peer reviewed journal in October, once internal and industry reviews are completed. When it is published will be up to the journal.” 

On July 26, 2006, David Michaels, on behalf of the SKAPP Planning Committee, wrote to EPA Administrator Stephen L. Johnson, asking for expedited release of the study and objecting to the preferential treatment given to industry. The EPA responded that the paper summarizing their findings has undergone internal and external review and will be sent to industry “solely to ensure that no confidential business information is released”; the agency plans to submit the paper to a scientific journal this fall and anticipates publication by mid-2007.

About the Case Study

The authors of this case study, David Michaels, PhD, MPH, Chrissy Morgan and Celeste Monforton, MPH have no financial conflict of interest.  See also: Michaels D, Monforton C. Scientific evidence in the regulatory system: Manufacturing uncertainty and the demise of the formal regulatory system. J Law Policy 2005; 13(1): 17-41.

Related Documents (click here)

UPDATES: Several developments have occurred since this case study was first written:

August 2006: UFCW, Western States Council, and the California Labor Federation petitioned Cal/OSHA to adopt an emergency temporary standard for diacetyl in California. SKAPP Director David Michaels wrote a letter about the toxicity of diacetyl for inclusion in Cal/OSHA's record.

September 2006: SKAPP petitioned the Food and Drug Administration to revoke diacetyl's "generally regarded as safe" (GRAS) status. FDA responded that that the agency had not reached a decision on the petition "because of the limited availability of resources and other agency priorities."

February 2007California Assemblywoman Sally Lieber introduced a bill that would ban diacetyl in the workplace by 2010.

March 2007: Cal/OSHA drafted a standard on occupational exposure to food flavorings.

April 2007: Two Congressional hearings (one featuring testimony from David Michaels) and a front-page New York Times article focused attention on the Occupational Safety and Health Administration’s lack of action on several important workplace hazards.

May 2007: Congresswoman Rosa DeLauro wrote to FDA Commissioner Andrew von Eschenbach requesting a re-examination of diacetyl's GRAS status. Von Eschenbach responded that "the agency does not have evidence that would cause it to take immediate action with respect to diacetyl" and that "FDA continues to monitor the scientific literature for studies conducted to define and clarify the dangers associated with exposure to diacetyl vapors."

June 2007: Congresswoman Lynn Woolsey introduced legislation that would require OSHA to set an interim and final standard (within six months and two years, respectively) for occupational exposure to diacetyl.

August 2007: Manufacturer Pop Weaver announced that it has eliminated diacetyl from its microwave popcorn.

September 2007: David Michaels broke the news, on The Pump Handle blog, that Dr. Cecile Rose, chief occupational and environmental medicine physician at National Jewish Medical and Research Center, had diagnosed a case of bronchiolitis obliterans in a man who did not have occupational exposure to diacetyl but was a regular, heavy consumer of microwave popcorn. She had informed the FDA, EPA, CDC, and OSHA about the case in July but gotten very little response. Newspapers and TV shows across the country publicized the story, and ConAgra announced that it would remove diacetyl from its Orville Redenbacher and Act II microwave popcorn lines.

February 2008: The international union UNITE HERE requested NIOSH conduct a Health Hazard Evaluation at three large cafeterias in New York City where employees of Aramark are potentially exposed to articificial butter-flavoring agents.  The evaluation included an analysis of bulk samples of cooking oils, air sampling of cooking areas, a questionnaire administered to workers and lung function tests.  The preliminary findings from these HHEs were released in May 2008: JP Morgan Chase building (NIOSH HETA-2008-0125), Goldman Sachs (NIOSH HETA-2008-0126), and JP Morgan Chase Manhattan Plaza (NIOSH HETA-2008-0127).

December 2008: OSHA sent documents to OMB/OIRA for review and as first step in the SBREFA process (OIRA screenshot here)  (Regs.gov screenshot here

January 2009: OSHA published an Advance Notice of Proposed Rulemaking on diacetyl in the Federal Register.

April 2009: Documents related to SBREFA panel. (a) small entity reps and letter from Bob Burt; (b) schedule; (c) draft reg text options; (d) discussion issues; and (e) draft regulatory flexibility analysis.

July 2009: SBREFA report (259 pages); PopWeaver comments

November 2009: Senator Sherrod Brown (D-OH) letter to Labor Secretary Solis urging regulatory action on diacetyl

December 2009: SKAPP letter to FDA for update on diacetyl petition

January 2010: FDA response to SKAPP request for update on diacetyl petition