The National Institute for Occupational Safety and Health (NIOSH) has announced its intent to review its approach to classifying carcinogens and establishing recommended exposure limits (RELs) for occupational exposures to hazards associated with cancer. In its August 23 Federal Register notice, NIOSH requested information from stakeholders and the public on issues associated with revision of the Carcinogen and REL Policies.
A review of the Carcinogen Policy was prompted in 2010, after NIOSH and stakeholders alike expressed concerns about its limitations. One major limitation is the use of the term “Potential Occupational Carcinogen” which dates to the 1980 OSHA hazard classification for carcinogens outlined in 29 CFR 1990.103 and is defined as “ any substance, or combination or mixture of substances, which causes an increased incidence of benign and/or malignant neoplasms, or a substantial decrease in the latency period between exposure and onset of neoplasms in humans or in one or more experimental mammalian species as the result of any oral, respiratory or dermal exposure, or any other exposure which results in the induction of tumors at a site other than the site of administration. This definition also includes any substance which is metabolized into one or more potential occupational carcinogens by mammals.”
A major limitation of the definition is that it allows for only one cancer category--“potential occupational carcinogen,” which conveys uncertainty that is not warranted with many carcinogens such as asbestos or benzene. It does not provide for classification on the basis of the magnitude and sufficiency of the scientific evidence.
In contrast, other organizations, such as the International Agency for Research on Cancer (IARC) and the National Toxicology Program (NTP) allow for a more differential classification. The revision of the NIOSH Carcinogen Policy also coincides with the international realization that there is a need for a more efficient means to classify chemicals. Qualitative and semi-quantitative approaches such as hazard banding are being investigated increasingly as a means of addressing the vast numbers of unregulated chemicals. NIOSH has been in collaboration with various organizations to consider the use of hazard banding approaches to control chemical exposures.
The Agency's Request for Information notice stated that it will place special emphasis on considering the technical and scientific issues related to the current Carcingen and REL Policies that require further examination. As part of this effort, NIOSH has requested initial input on the following questions:
1. Should there be an explicit carcinogen policy, as opposed to a broader policy on toxicant identification and classification (e.g. carcinogens, reproductive hazards, neurotoxic agents)?
2. What evidence should form the basis for determining that substances are carcinogens? How should these criteria correspond to nomenclature and categorizations (e.g., known, reasonably anticipated, etc.)?
3. Should a 1 in 1,000 working lifetime risk (for persons occupationally exposed) be the target level for a recommended exposure limit (REL) for carcinogens, or should lower targets be considered?
4. In establishing NIOSH RELs, how should the phrase ‘‘to the extent feasible’’ (defined in the 1995 NIOSH Recommended Exposure Limit Policy) be interpreted and applied?
5. In the absence of data, what uncertainties or assumptions are appropriate for use in the development of RELs? What is the utility of a standard ’’action level’’ (i.e., an exposure limit set below the REL typically used to trigger risk management actions) and how should it be set? How should NIOSH address worker exposure to complex mixtures?
Responses to these questions will be taken under consideration and used to inform NIOSH efforts to assess and document its carcinogen policy and REL policy regarding occupational hazards associated with cancer. Comments must be received by September 22, 2011.
