Government
Ho surprises at OSHA cancer policy hearings Except for suggestions for improvement, OSHA-invited witnesses spoke in favor of the proposal to categorize chemicals by carcinogenicity There was a much-needed break last week in the Occupational Safety & Health Administration's hearing on its precedent-setting proposal for regulating workplace carcinogens. The first month of the hearing has been taken up by testimony from the more than 45 witnesses the agency specifically requested to comment on the cancer policy. As might be expected, most of the testimony, so far, has been supportive of the OSHA proposal. However, a number of witnesses had suggestions for changes to correct what they saw as weaknesses and deficiencies in the policy. In its broad rule-making proposal, OSHA says it hopes to establish: new procedures and a regulatory framework for regulating exposure to potential occupational carcinogens; OSHA's scientifically based policies concerning the identification and classification of potential occupational carcinogens; and three model standards for use in specific rule making involving such substances. Under the proposal, toxic substances would be placed in one of four categories based on their potential carcinogenicity. In general, Category I toxic substances are those whose carcinogenicity has been determined in humans, or in two or more mammalian species of test animals, or in one study, if the results of that study have been replicated, or if positive results in one mammalian species are supported by positive results of short-term tests. Category II toxic substances are those whose carcinogenicity has been reported but the evidence for some reason is only suggestive, such as positive results of short-term tests or a test in only one mammalian species. Category III toxic substances are those for which the evidence is inadequate to raise any concern regarding carcinogenicity. Category IV toxic substances are those that might be classified in any one of the above three categories but are not found in U.S. workplaces. In deciding which category a substance belongs in, OSHA says, it will place as much weight on experiments in which only benign tumors are observed as upon experiments in which both malignant and benign tumors are introduced. In addi-
Jellinek: urges risk estimation
tion, it will interpret the results of experiments showing an increased incidence of tumors in treated animals as positive evidence of carcinogenicity regardless of spontaneous tumor incidence, provided the increase is statistically significant. The agency says it will not at this time place sole reliance upon short-term tests and place no reliance on structural similarity to a known carcinogen. The scientific validity of OSHA's approach—using animal studies to predict human carcinogens—generally was not questioned by any of the invited witnesses. As Dr. Richard A. Griesemer, acting director of the National Cancer Institute's bioassay program, said, "The most logical and scientifically sound approach to identifying chemical carcinogens is through animal experiments." However, he believes that the proposed OSHA classification system is "too conservative" because it requires replication of animal studies even in cases where a very high incidence of cancers is found or the latency period is very short. Griesemer points to NCI bioassays, such as one on ethylene dibromide, which caused tumors in 100% of the animals as early as 12 weeks, and one on direct black 38 dye in which liver cancer developed in rats in only 90 days, as examples of studies that should not need to be replicated before a substance is placed in Category I. Dr. Samuel Epstein, professor of occupational and environmental medicine, School of Public Health, University of Illinois, Chicago, was one of the most outspoken critics of the OSHA proposal, mainly because he believes it does not go far enough. According to Epstein, there is
no justification for OSHA's "undue leniency" in requiring the replication of a positive animal bioassay before placing a substance in Category I. On the other hand, he says, "the investment of regulatory status and force to the results of short-term carcinogenicity tests appears ill advised and invites legal as well as other challenges, particularly on the grounds of lack of appropriateness." Epstein also objected to what he terms a "serious deficiency" in the OSHA proposal—discretionary provisions allowing the Secretary of Labor to rebut a Category I classification on the basis that carcinogenicity data "are not scientifically relevant to man." "To give the Secretary such broad discretion," he says, "invites ambiguities, constraints, and political pressures and a possible return to individual rule-making procedures." Also, Epstein would like to see the Delaney zero tolerance concept applied to the regulation of occupational carcinogens. Consideration, he says, must be directed to the possible banning of the manufacture and use of the carcinogen or the restriction of its use to closed systems that are continuously monitored with instrumentation of maximal sensitivity and with automated and visible readouts. Epstein admits that "a wide range of criticism has been and still is leveled against the Delaney zero tolerance concept." But, he says, "all such criticisms have emerged from industrial groups, trade associations, and from groups that are clearly identified with protection of industrial interest. Another factor generally characterizing criticism of the Delaney amendment by such 'captive' spokesmen is their lack of expertise and national recognition in the field of chemical carcinogenesis." The Environmental Protection Agency also is "seriously concerned with the fact that the proposed regulations provide that animal test results generally cannot be relied upon as a sufficient test for stringent regulatory action unless replicated or supported by short-term studies," says EPA assistant administrator for toxic substances Steven Jellinek. He points out that it is EPA's policy that an unreplicated test "can be a perfectly adequate basis for concluding that a chemical must be regulated as a carcinogenic risk," warning that the delay caused by waiting for replication of a test often can be quite substantial. And Jellinek predicts that OSHA's tying a finding of carcinogenicity to a specific regulatory response "will pose problems for the agency." He urges OSHA to include risk estimation in its regulatory June 19, 1978 C&EN
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process, with the estimation being used, in some instances, to determine whether to regulate. "If a substance is believed to be a carcinogen but is a weak carcinogen to which few people are exposed, the best regulatory course might be to defer any regulation in favor of concentrating limited resources on higher toxicity, higher exposure substances," he explains. And he faults the OSHA proposal for not appearing "to permit the agency to adopt this course." OSHA's proposed foreclosure of consideration of structural similarities drew criticism from Dr. Lawrence Fishbein, assistant director of environmental surveillance of the National Center for Toxicological Research. He says that it would be "irrational" to foreclose any consideration of the growing body of structural and metabolic information given the fact that other government agencies such as EPA have stated their intent to use structural similarity to at least set priorities for regulating chemicals. Fishbein believes the combination of positive results in one well-conducted animal study and structural similarity to a known carcinogen or group of carcinogens would be sufficient to place a chemical in Category I. And evidence for Category II could be satisified with multiple short-term tests and structural similarity. In another area, Dr. Robert N. Hoover, head of environmental studies at NCI, believes that there should be a mechanism in the proposal to review decisions based on new scientific information. He says that "if the mechanism of carcinogenic risk in laboratory animals can be shown not to apply to man because of differing metabolism of the substance, then this information should be used in deciding whether or not to revise a decision." Since understanding the precise mechanism of carcinogenesis usually takes a very long time, and has in fact only rarely been accomplished, preventive action should hot be delayed until this understanding is obtained, he adds. And finally, Dr. David G. Kaufman, associate professor of pathology and biochemistry and nutrition at the University of North Carolina school of medicine, Chapel Hill, in his testimony urged OSHA to formulate separate guidelines or regulations for small research laboratories. He points out that, as currently proposed, the regulations would require monitoring and record keeping for each carcinogen present in a lab and they do not provide for distinctions between the widely varying hazards such as the kilogram quantities of a carcinogen used in lifetime animal feeding studies and the microgram quantities employed in radioactive tracer studies. Such requirements, he says, could force smaller laboratories to devote a significant portion of their resources to monitoring, reducing the resources available for cancer research. The hearings will pick up again tomorrow, with three days of testimony from the American Industrial Health Council, the first of a long line of industry witnesses scheduled to appear. •
Federal Alert— new regulations This list covers noteworthy regulations appearing in the Federal Register from May 10 to June 9. Page numbers refer to those issues. PROPOSED Consumer Product Safety Commission— Proposes to ban benzene from consumer products; comments by June 30 (May 19, pages 21838, 21839, 21852, 21853). Issues general order to manufacturers to submit data on use of nitrobenzenes in consumer products by Sept. 5 (June 5, page 24325). Council on Environmental Quality—Proposes uniform procedures for federal agencies in implementing National Environmental Policy Act; comments by Sept. 11 (June 9, page 25230). Department of Transportation—Proposes amendments to hazardous materials transportation regulations to include hazardous waste materials (May 25, page 22626). Environmental Protection Agency—Proposes rules to implement Clean Water Act of 1977; comments by July 14 (May 12, page 20821). Proposes ban on manufacture, distribution, and use of PCB's; comments by Aug. 7; hearing in Washington, D.C., on Aug. 21 (June 7, page 24802). Nuclear Regulatory Commission—Proposes safeguard requirements for special nuclear material of moderate and low strategic importance; comments by June 23 (May 24, page 22216). FINAL Food & Drug Administration—Revokes rule specifying procedures for analyzing for carcinogens in meat, pending reproposal of new rules; effective June 23 (May 26, page 22675). NOTICES Environmental Protection Agency—Publishes drafts of reports on health effects of cadmium and polycyclic organic compounds in ambient air (May 31, page 23648). Publishes guidelines for obtaining waivers for alcohol/gasoline blend fuels (June 2, page 24131). Publishes preliminary export guidelines for PCB's and fully halogenated chlorofluoroalkanes (June 7, page 24818). Food & Drug Administration—Adds 71 flavoring compounds to the agency's review of substances generally recognized as safe (GRAS list); extends compliance date for bulk flavor labeling to July 1, 1978 (May 26, page 22784). Nuclear Regulatory Commission—Publishes report on safeguarding mixed oxide nuclear fuel from hypothetical terrorist threat (May 31, page 23665). National Cancer Institute—issues carcinogenicity report on 2,4-dinitrotoluene and 3-nitropropionic acid (May 19, page 21737).
