REGULATING FOCUS
Regulating air toxics
Richard M. Dowd Last month in this column I discussed the problems associated with the lack of data on ambient concentrations of potentially toxic pollutants. The following is a summary of current federal and state activities to develop air toxics regulations. Federal regulations Section 112 of the Clean Air Act explicitly requires EPA to review evidence and provide a list of hazardous air pollutants to be regulated. Following the preparation of such a list, EPA is required to establish (within 180 days after listing) emission standards to provide an ample margin of safety to protect public health. Since the enactment of the 1970 amendments, the EPA has listed seven pollutants under Section 112. Emission standards were promulgated for four of the listed pollutants (asbestos, beryllium, mercury, and vinyl chloride) by 1976, but standards for the remaining three (benzene, inorganic arsenic, and radionuclides) have not been finalized, although some have been proposed. Many members of Congress have been extremely critical of the delay in listing and regulating toxic emissions. Rep. John 1). Dingcll (D-Mich.) and the House Energy and Commerce Committee requested a review of EPA's toxics listings and regulations by the General Accounting Office (GAO). The GAO report was highly critical of EPA's activities in terms of both the time being spent on the review of scientific studies and on EPA's de0013-936X/83/0916-0571A$01.50/0
cision-making process. Additionally, GAO criticized the agency's inclusion of economic and social welfare considerations in defining an ample margin of safety to protect the public from emissions of hazardous air pollutants. Selecting which chemicals might be listed has been an enormous task in and of itself. Of the 37 priority chemicals identified for further study in a Senate hearing several years ago, only 18 remain in the "top 37" following the application of a modified ranking system developed by Argonnc National Laboratory under contract to the EPA. Nearly 200 chemicals have been reviewed by Argonne and ranked under this system. At the Nov. 7, 1983, House Committee hearings on the Agency's Section 112 activities, EPA Administrator Ruckelshaus committed to complete action on 20 to 25 of the top 37 chemicals by the end of fiscal year 1985. During reauthorization of the Clean Air Act, Congress is likely to be more specific in its mandate to EPA on the number of chemicals to be regulated and the time frame in which toxic chemicals are selected and controlled. State and local regulation As a result of this hiatus in new federal activity on hazardous air pollutants, many state and local agencies have begun developing their own programs to control emissions of toxic air pollutants. Last month, I discussed the diversity of state and local ambient monitoring networks now in place. Similarly, regulatory programs being developed by various states differ in the number and type of chemicals being regulated, the way in which potential human health effects are assessed, and the implementation of the regulations themselves. Since the state programs are advancing more quickly than the federal programs, state or local programs may have more impact on industrial sources and resultant air quality than the federal program.
© 1983 American Chemical Society
As individual states wrestle with concerns about the effects of toxic air pollutants, they arc unable to benefit from EPA's experience or guidance because so few decisions on toxic pollutants have been made. Although many state programs use risk assessments to determine hazardousness, at least in theory, most of them use a fraction of threshold limit values (TLVs) in establishing acceptable ambient levels. Nevada, for instance, applies a factor of 1/2 whereas New Hampshire has indicated that 1/420 of a TLV is an acceptable ambient level. Roughly one-third or more of all states that presently have air toxic programs use TLVs, and at least seven states use risk assessments in some way. Some states directly regulate a broad range of compounds. New Jersey, for example, regulates I 1 compounds and the emissions of all sources of those 11 compounds. Other states have an open-ended regulation that depends on the relationship between modeled emission contributions and the state's acceptable ambient level. Unless EPA speeds up its decisionmaking process, identifying both those compounds that ought to be of concern and those that ought not to be, it is likely that individual states will continue developing their own unique programs. These will vary as to chemicals covered, methods used in assessing risks, and implementation strategies. Without a good national data base on ambient concentrations, the significance of background levels is very hard to determine. It seems clear that for a national program on toxic air pollutants to be developed, there must be adequate data on ambient concentrations and timely decisions on their associated risks. Richard M. Dowd, PhD. manages the Washington. DC.. office of Environmental Research & Technology. Inc. Environ. Sci. Technol.. Vol. 17. No. 12, 1983
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