• Public Affairs

  • ACOEM Provides Comments to OSHA Regarding Occupational Exposure to Diacetyl

    OSHA Docket Office
    Room N–2625
    U.S. Department of Labor
    200 Constitution Avenue, NW
    Washington, DC 20210

    Docket No. OSHA–2008–0046

    To Whom It May Concern:

    The American College of Occupational and Environmental Medicine (ACOEM) is pleased to provide the following comments to the Advance Notice of Proposed Rulemaking (ANPRM) -- Occupational Exposure to Diacetyl and Food Flavorings Containing Diacetyl. Although OSHA has withdrawn the ANPRM in order to promptly convene a Small Business Advocacy Review Panel, we ask that our comments be included in the public rulemaking docket.

    ACOEM represents more than 5,000 physicians and other health care professionals specializing in the field of occupational and environmental medicine. ACOEM is the pre-eminent organization of physicians who champion the health and safety of workers, workplaces, and environments.

    Thank you for your consideration of these comments.


    Robert Orford, MD




     Occupational Exposure to Diacetyl and Food Flavorings Containing DiacetylDocket No. OSHA–2008–0046] 

    The American College of Occupational and Environmental Medicine has previously expressed our disappointment1 over the lack of regulatory action with respect to occupational exposure to diacetyl, such as promulgation of an Interim Final Standard by OSHA in connection with occupational and other possible exposures to diacetyl as well as other food flavorings.2,3,4,5 

    These exposures are of major concern for several reasons. Of paramount importance is the insidious nature of the serious lung disease caused by diacetyl and possibly other related substances, which we shall abbreviate in the rest of this comment as DAPORS. Thus, although these agents can cause severe and even lethal lung disease, some workers have been exposed to them in amounts sufficient to cause a subclinical form of the condition known as bronchiolitis obliterans. That is, early in the course of this condition, exposed workers may have neither symptoms nor abnormal physical examination findings,2 nor changes that are manifested via the usual radiographic technique (i.e., plain films, as distinguished from images obtained by thin section expiratory high-resolution computed tomography6,7). The spectrum of radiographic patterns of abnormality and lung pathology in symptomatic workers is sufficiently characterized to define the disorder as a form of bronchiolitis obliterans. We do not however believe that histologic confirmation of this diagnosis is required in most cases. A second reason for our concern is the lack of effective treatment for bronchiolitis obliterans, other than cessation of all further exposure. While this disorder has been shown to result in obstruction to air flow in the lungs, as well as air trapping in them, the obstruction does not improve when a bronchodilating aerosol is administered2,7,8 as it does in most patients with asthma, and in many others who have a bronchospastic form of chronic obstructive pulmonary disease (COPD). A third concern is the severity of the impairment in function in some persons who have developed bronchiolitis obliterans after exposure to DAPORS, leading to premature disability requiring lung transplantation,7 and even death. While some published evidence suggests some form of dose-response relationship between air concentrations of DAPORS and the development of respiratory disease in humans2 and experimental animals, such evidence is not extensive. It is not clear what threshold might exist, below which disease would be unlikely. ACOEM acknowledges this uncertainty regarding the specific exposure-response relationships with respect to DAPORS.

    It is the position of the College that health monitoring is an essential component of occupational health practice, when a potentially hazardous condition is recognized and the level of risk to individuals in workplaces using the materials is not sufficiently characterized. ACOEM asserts that health monitoring for workers with potential exposure to respiratory hazards, using standardized respiratory questionnaires and periodic spirometry testing, is a well accepted and widely available occupational health practice. Health surveillance for DAPORS using these methods is both practical and feasible, and provides an essential tool for the recognition and secondary prevention of bronchiolitis obliterans among individuals in workplaces that manufacture, handle, or use DAPORS. We believe that the medical surveillance outline published by the Occupational Health Branch, California Department of Public Health9 is an excellent resource document.

    ACOEM asserts that there is sufficient documentation in the available literature to determine that inhalation exposure to diacetyl and possibly other volatile flavoring components (DAPORS) can result in a severe, disabling, and potentially lethal lung disorder. The progression of the disorder often takes place over a period of months to years, and frequently results in progressive respiratory tract symptoms and irreversible losses in ventilatory lung function. There is sufficient current scientific knowledge to determine that measures to control occupational exposures to DAPORS are feasible. 10,11 Product substitution is one attractive control measure because the evidence base on the serious toxicity of diacetyl itself is quite strong. The absence of a toxicology database on other putative toxic agents – often used as a basis for inaction – is not a compelling reason to continue using diacetyl. For those applications where its use is seen as critical for business reasons, failure to use best industrial hygiene practices to minimize exposures to DAPORS is no longer ethically acceptable. Pending the establishment of definitive criteria for safe exposure, engineering methods to reduce these exposures to the greatest extent feasible is mandatory.10,11 

     ACOEM itself does not possess data on current exposure levels or other categories of information listed in the ANPRM. We are, however, aware of the numerous published investigations on this topic, which we believe comprise a critical mass of knowledge sufficient for proceeding to establish at least a preliminary standard, using diacetyl as a surrogate for other possible analytes which may contribute to the development of bronchiolitis obliterans. We strongly believe that intervention and continued medical and environmental surveillance are needed now, and also believe that close collaboration between OSHA and NIOSH is useful for industrial hygiene input, improved medical surveillance, and establishment of criteria for the diagnosis of lung disease. ACOEM suggests that the subject rulemaking presents an opportunity, albeit belated, for OSHA to demonstrate international leadership, since DAPORS have been associated with bronchiolitis obliterans in other countries including those from which diacetyl is manufactured, rather than being synthesized in the United States.

    ACOEM notes OSHA’s previous reticence to establish an Emergency Temporary Standard (ETS) for diacetyl, citing the rigor of the evidentiary requirements for such action. Perhaps it is time to re-examine the need for such rigor, while workers are continuing to be exposed to DAPORS in the absence of an ETS.


    1. Letter of May 31, 2007, Robert K. McLellan, MD, MPH, FACOEM to Hon. Lynn Woolsey and Hon. George Miller, U.S. House of Representatives.
    2. Kreiss K, Gomaa A, Kullman G, Fedan K. Bronchiolitis obliterans in workers at a microwave-popcorn plant. New Engl J Med. 2002;347:330-8.
    3. Lockey J, McKay R, Barth E, Dahlsten J, Baughman R. Bronchiolitis obliterans in the food flavoring manufacturing industry. Am J Respir Crit Care Med. 2002;165 (Suppl):A461 (Abstract).
    4. Alleman T, Darcey DJ. Case report: bronchiolitis obliterans organizing pneumonia in a spice process technician. J Occup Environ Med. 2002;44:215-6.
    5. Parmet AJ, Von Essen S. Rapidly progressive, fixed airway obstructive disease in popcorn workers: a new occupational pulmonary disease? J Occup Environ Med. 2002;44:216-8.
    6. Arakawa H, Webb WR. Air trapping on expiratory high-resolution CT scans in the absence of inspiratory scan abnormalities: correlation with pulmonary function tests and differential diagnosis. AJR Am J Roentgenol. 1998;170:1349-53.
    7. Akpinar-Elci M, Travis WD, Lynch DA, Kreiss K. Bronchiolitis obliterans syndrome in popcorn production plant workers. Eur J Respir J. 2004;24:298-302.
    8. van Rooy F, Rooyackers JM, Prokop M, Houba R, Smit L, Heederik D. Bronchiolitis obliterans syndrome in chemical workers producing diacetyl for food flavorings. Am J Respir Crit Care. 2007;176:498-504.
    9. Cal/OSHA. Medical surveillance for flavorings-related lung disease among flavor manufacturing workers in California. Occupational Health Branch, California Department of Public Health. August, 2007.
    10. van Rooy F, Smit L, Houba R, Zaat V, Rooyackers JM, Heederik D. A cross-sectional study of lung function and respiratory symptoms among chemical workers producing diacetyl for food flavorings. Occup Environ Med. 2009;66:105-10.
    11. Sahakian N, Kreiss K. Adv Food Nutr Res. 2009;55:163-92.