Regulatory Decisions Concerning Chrysotile and Mesothelioma
Regulatory agencies look to research data to formulate rules, procedures, and regulations to support policy decisions. It is not always the case, however, that decisions by various organizations reflect the best or the latest assessment of the data or are based on the scientific method. The regulation of toxic and other substances is customarily divided into two discrete aspects: risk assessment and risk management. Risk assessment is a scientific activity, whereas risk management is always a sociopolitical one, and they are not necessarily separate. The process of risk assessment has been accepted as a necessary base on which to build rational policy decision making, and at the same time it provides an opportunity for improved dialogue for scientists to have an important role in shaping public policy that is scientifically defensible (Hughes and Weill, 1986; Mossman et al., 1990; Camus, 200la; Savitz, 2003; U.S. EPA, 2004). In a special treatise for the Geological Society of America, calling for asbestos regulations based more on science, the authors state:
The scientific and medical information available does not justify the claim that exposure to any amount of any fiber presents an unacceptable health risk. (Ross and Nolan, 2003)
In any regulatory context, the integration of administrative policies with risk assessment is a key concept used now by decision makers for the purpose of protecting health. Modern standard setting serves to minimize the exposure of workers, but also addresses technical and societal choices and decisions (Corn, 1992). The U.S. Occupational Safety and Health Administration (OSHA) must make a determination if a "significant" health risk exists and that a new standard will reduce or eliminate that risk (Fed. Reg. 51:22646, June 20, 1986). For its latest standard setting, OSHA made no distinction for "asbestos" among the asbestos types and defined a "fiber" as one that possesses an aspect ratio of equal to or greater than 3:1. The basis for the OSHA permissible exposure limit (PEL) included epidemiological studies involving mixed-type asbestos exposures. Future uses of asbestos were thought likely to be mixed, so there was no practical need at that time to distinquish fiber types. OSHA requires fiber counts to be made using a phase-contrast microscope. Although the method is quick, easy, inexpensive, and detects low concentrations, it does not enable identification of fiber type. According to OSHA, assigning a higher PEL to chrysotile would present OSHA and employers with analytical difficulties in separately monitoring exposures to different fiber types (OSHA, 1994). Thus the presumption that all exposures would be to mixed fiber types and the use of phase-contrast microscopy to detect exposures prevented important distinctions to be made in the assessment of potential risk of different fiber types.
Referring to the U.S. Supreme Court's ruling in Industrial Union Department, AFL-CIO v. American Petroleum Institute, the following explanation of precautionary health regulations was provided in the OSHA asbestos standard. The U.S. Supreme Court indicated that a significant risk determination for federal health regulations is "not a mathematical straitjacket," and that "OSHA is not required to support its finding that a significant risk exists with anything approaching scientific certainty." The Court ruled that "a reviewing court [is] to give OSHA some leeway where its findings must be made on the frontiers of scientific knowledge [and that]... the Agency is free to use conservative assumptions in interpreting the data with respect to carcinogens, risking error on the side of over protection rather than under protection." The Court also stated that "while the Agency must support its finding that a certain level of risk exists with substantial evidence, we recognize that its determination that a particular level of risk is 'significant' will be based largely on policy considerations" (Fed. Reg. 51:22615, June 20, 1986).
Precaution provides a means of guiding decisions under conditions of uncertainty: "The precautionary principle encourages policy makers and public health officials to consider, in their approach to public health, how to account for growing complex icity and uncertainty" (WHO, 2004). Called conservatism in a recent staff paper of the U.S. EPA Office of the Science Advisor, the agency "seeks to adequately protect public and environmental health by ensuring that risk is not likely to be underestimated" [italics as in document] (U.S. EPA, 2004). The effect of the approach on the science of asbestos risk assessment is illustrated by an example from the U.S. EPA in 1986 when the risk assessors' choices tended to overestimate the final exposure risk gradient (Camus, 200Ib). Precautionary-based measures should be maintained "as long as scientific data are inadequate, or inclusive, and as long as the risk is considered too high to be imposed on society" (Jordan and O'Riordan, 2004). According to Siemiatycki et al. (2004), lists of identified carcinogens have been limited by "unclear criteria" and "by inconsistent and incomplete information" and provide no basis for strength of the effect. Determination of carcinogenic status can change as new data emerge. This review suggests that the application of the precautionary principle is no longer supported by the cohort epidemiological data for chrysotile absent amphiboles and mesothelioma (see Tables 3 and 4).