Airborne carcinogens: EPA’s proposals
Environmental Protection Agency administrator Costle recently signed a proposed policy for regulation of airborne carcinogens under the Clean Air Act. Its Federal Register publication was delayed pending release on September 28, 1979 of a government-wide carcinogen policy prepared by the Regulatory Council. The EPA draft, entitled “Policy and Procedures for Identifying, Assessing and Regulating Airborne Substances Posing a Risk of Cancer”, reveals that the Agency is finally coming to grips with one of the most significant long-term, and unquestionably controversial, areas of its jurisdiction under the Clean Air Act.
The problem EPA projects that “one American in four is expected to contract some form of cancer in his or her lifetime, and one in five is expected to die from the disease.” “Environmental factors” are increasingly thought to be a major cause of cancer, and while they are defined to include smoking, occupational exposures, diet, and solar radiation, the problem posed by airborne carcinogens is “significant”. Further, in industrialized areas in particular, “composite national figures may mask significantly higher air pollution cancer risks”, and in the vicinity of sources emitting carcinogens, the risks to individuals can reach “very high levels”. Several important factors dramatically compound the regulatory problem. First, there is disagreement within the scientific community on how carcinogenicity can be accurately determined since the evaluation of risk to humans requires extrapolation from
tests on animals. Secondly, the suspected sources of carcinogenic emissions are widespread, involving much of American industry, including: mining, smelting, refining, manufacturing and end use of minerals, combustion processes, petroleum refining, and the synthetic organic chemical industry. Thirdly, scientists are also divided on whether a threshold or “safe” level of exposure may exist or whether carcinogens pose risk of cancer at any exposure level. This controversy creates for the regulator the dilemma of whether carcinogenic emissions must be reduced to zero or whether there is room for the installation of less comprehensive and thus less costly controls. The statute does not resolve the above problems. Section 1 12 of the Act defines a “hazardous air pollutant” as one which “causes, or contributes to, air pollution which may reasonably be anticipated to result in an increase in mortality or an increase in serious irreversible or incapacitating reversible, illness.” The administrator must ‘‘list’’ such substances and then establish standards which provide “an ample margin of safety to protect the public health”. The primary standard-setting consideration under Section 1 12 is the protection of public health, giving rise to the argument that a balancing of the risks against the cost of control and the benefit of the regulated activity is not permitted.
EPA’s regulatory response Although EPA and several other government agencies, including the Occupational Safety and Health Administration, the Consumer Product Safety Commission, and the Food & Drug Administration, have been grappling with the carcinogen problem for several years, it was not until the Environmental Defense Fund (EDF) petitioned EPA in November 1977, calling for a “generic approach” to classification and regulation, that the government’s response assumed new emphasis and focus. EPA’s proposal predictably seeks to justify a middle ground which the Agency feels is administrably feasible.
0013-936X/79/0913-1343$01.00/0 @ 1979 American Chemical Society
While seeming to accept the argument that carcinogens pose some risk of cancer at any level above zero, EPA asserts that to attempt to totally eliminate those risks would result in the closure of some of the nation’s basic industries. Therefore, it adopts a policy in which not only the risks but also the costs to and benefits from the activity to be regulated are evaluated. Potential airborne carcinogens (“candidate substances”) w il I be identified and then screened for the “greatest potential for public exposure”. A preliminary evaluation will then be made, categorizing substances with “high, moderate, or low” probability of human carcinogenicity. Those substances with a high probability or which have evidence of “significant public exposure” will then be “listed” under Section 112. Where possible, generic standards will be concurrently developed and applied. Sources of carcinogens will also be categorized and given a “high, moderate, or low” probability rating. Categories presenting “significant risks” to public health would be required, as a minimum, to install “best available control technology” (BAT) which considers economic, energy, and environmental impacts. Additional controls could be required to eliminate any remaining “unreasonable residual risks”. Consistent with other sections of the Act, more stringent regulations will be imposed on new sources. Particular emphasis is given to siting considerations on the premise that new sources have the option to locate in less densely populated areas which have reduced exposure rates. The scientific and legal uncertainties associated with EPA’s proposed cancer policy virtually guarantee continued controversy on issues ranging from the “no-threshold” approach, to risk-assessment methodologies, to industrial technology control requirements. These uncertainties, when coupled with the unquestioned longterm significance of this policy, underscore the importance of informed participation in the rulemaking process now underway. Volume 13, Number 11, November 1979
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