Document vV05Y37gjpNqJ24k8JKvOn5L9

ASBESTOS IN DRINKING WATER - A STATUS REPORT BY Joseph A. Cotruvo, Director Criteria & Standards Division Office of Drinking Water Environmental Protection Agency Send galley proofs and reprints to J.A. Cotruvo . Telephone 202-382-7575 CAP CO JEN 0011980 I have been asked to make some observations about the direc tion of activities in the United States and the Environmental Protection Agency in dealing with asbestos contamination of drinking water. I also will comment on what I think 1 heard in the discussion of the last two days as it relates to those activities. But first, I wish to express my congratulations and appreciation to Jim Millette and the other members of HERL who have assembled this program. It is an excellent mechanism for gathering and evaluating the latest information that people like myself must use to arrive at some regulatory decision. The program has been effective and timely since EPA is now in the midst of the decision process to deal with asbestos in drinking water. My discussion will be confined to "where do we go from here" in the context of the Safe Drinking Water Act which controls decision-making on regulatory activities affecting drinking water contaminants. The debate on asbestos and the human risk from ingestion of asbestos fibers has been going on since at least 1971 (1,2,3). One of the earliest questions to be asked was, in the light of the clear carcinogenesis of inhaled asbestos, what is EPA's regulatory posture related to ingested asbestos from drinking water? Our response, at that time, was that CAP CO JEN 0011981 -2we did not feel that there were sufficient data on which to make a judgement on the risk. Me recommended, however, thatwhere asbestos fibers were found in drinking water, some of the many'available means for minimizing fiber concentrations should be utilized to avoid unnecessary exposure. The issue has ripened considerably since then. Virtually all of the data, including the results of research on epidemiology and animal feeding studies, transport phenomena and jLn vitro studies, have been summarized in this program. Very few other issues have had the volume and intensity of study and resultant information that has been presented here, and there is no question that the importance of the issue warranted that much attention. Based on all of the information, and in the context of the Safe Drinking Water Act, we have to answer a few questions. First, is there a risk associated with the ingestion of asbestos fibers in drinking water? Second, if so, what is the magnitude of that risk? Finally, if it turns out that the risk, if any, is of sufficient magnitude, what kind of judgement should EPA make in a regulatory context? 'My understanding of the animal and human epidemiology data, based on the discussions of this meeting is that there is a substantial question as to whether there is a risk at all CAP CO JEN 0011982 -3from small amounts of asbestos fibers in drinking water. On the other hand, if there is a risk, the magnitude of that risk must be quite small at fiber levels typically found in drinking water or perhaps even at atypical levels, such as the 100-million-plus fiber per liter concentrations. There have been several analyses which have attempted to estimate the upper limit of that risk and one of these was performed in 1980(4). Extrapolations were made from the occupational inhalation data to project gastrointestinal intake and several fairly tenuous conservative assumptions were included in that analysis. One of the estimates indicated an approximate upper excess risk of one in 100,000 per life time for gastrointestinal cancer at 300,000 fibers per liter for 2 liters of water ingested per day for 70 years. The available data indicate that substantial populations are exposed to this concentration of fibers in drinking water in the U.S. and Canada; approximately 5 to 10% of the population in this country may be consuming asbestos-containing water at that level. The fundamental question is, though, does this constitute a significant risk? If it is a real risk, then what is the evidence which indicates the existence of that risk and what is the best quantitative estimate of the risk? CAPCO JEN 0011983 -4- Under the provisions of the Safe Drinking Water Act, the choices EPA has are: ................ (a) to regulate by providing some sort of legal limit; (b) not to regulate, but to provide guidance (which often is well received and followed); (c) or to conclude that there are not sufficient data on which to base regulations or provide guidance. If EPA were to regulate, the options would be to establish a numerical limit, called a'maximum contaminant level (MCL) expressed in terms of a fiber count, or mass, or to require the application of one or more specific treatment processes known to be capable of reducing the fiber concentration. Either of these approaches would establish a ceiling on the amount of asbestos that could be present in drinking water in a given situation. The decision on alternative approaches, by law, must be based on the availability and feasibility of analytical methodology. The previous discussions have indicated that the analytical technology, although existing in certain sophisticated laboratory settings, is probably not widely available to public water systems, so perhaps there are other approaches to be taken if a limit is necessary. To summarize the data that I have heard these last two days, the results of animal feeding studies, including the National Toxicology Program study, indicate essentially that no toxicity was demonstrated in whole animal lifetime exposure (5,6). CAPCO JEN 0011984 <? -5In tho epidemiology studies, it appeared that in the one ecological study where there was some apparent correlation between asbestos fiber concentration and cancer risk, there . were some confounding factors that had not been, or could not be considered in that particular case, thus rendering the correlations questionable (7,8). Reanalysis of the data (9) seemed to produce anomalous results when San Francisco (city) populations were differentiated from others. A case control study (10), using a smaller sample population, in the Pacific Northwest, apparently did not detect the existence of a measurable risk due to exposure to a level of asbestos fibers much higher than that found in the ecological study in the Bay area of California. It can be said then that the epi demiologic evidence of risk from ingestion of water con taining asbestos fiber is not convincing, and that, in view of the lack of confirmation by animal studies, the existence of a risk has not been satisfactorily demonstrated. There remains, however, the vexing question of the gastrointestional 2&AAOA risk reported from occupational exposure studies (11). There apparently is some migration of asbestos fibers "vivo. There also apparently are chemical transformations that occur in the gastrointestinal tract - transformations which probably do not occur in the respiratory area. This might explain apparent differences in the toxicology of asbestos depending on the route of exposure. The in vitro CAP CO JEN 0011985 6- mutagenicity studies appear to be for the most part negative", but there does appear to be some element of co-carcinogenicity of asbestos with some polycyclic aromatic hydrocarbons. This situation is one which might call for additional study. In order to make a decision on the regulation of asbestos in drinking water, EPA must consider all of the available information, not only the credibility of and magnitude of the risk, but also the analytical science, the treatment technology and the cost of control. Within the context of the Safe Drinking Water Act, themechanism for making the decision is operating right now. Within approximately six months, an Advance Notice of Proposed Rulemaking (ANPRM) will appear in the Federal Register. This ANPRM relates to EPA's total revision of the existing National Primary Drinking Water Regulations and the possible inclusion of additional contaminants in Revised Primary Regulations; asbestos is one of several candidates to be mentioned in the ANPRM. There will then be several workshops, a public meeting, and other opportunities to debate the issue. The ultimate decision goes beyond science and calculations - it becomes a function of a social judgement in the context of the Safe Drinking Water Act in terms of the appropriate decision based upon a weighing of all of the available information. CAPCO JEN 0011986 8- that are commonly available, and to do so economically. Well-known methods are available to minimize the presence of asbestos fibers in finished drinking water. In the case of natural fiber in raw water, standard or augmented filtration practices are extremely effective. There are many good reasons why surface water should be filtered, and the presence of asbestos is just one more of them. If the source of asbestos fiber is asbestos-cement pipe which is being attacked by corrosive water, there is then more than sufficient economic reason to correct the excessive corrosive action of the water on the pipe. Additional extensive research is not likely to shed much more light on the question of the risks of asbestos in drinking water. It is EPA's responsibility to make a decision using the data that we now have; it is the water industry's responsi bility to provide drinking water for their customers that is as safe and wholesome and as free from adulterants as can be economically achieved using filtration or corrosion control techniques which are readily available. CAPCO JEN 0011988 REFERENCES 1. Cunningham, H.M. and Pontefract, R.D. Asbestos Fibers in Beverages and Drinking Water. Nature 232:332-333 (1971) 2. Cook, P.M., Glass, G.E. and Tucker, J.H. Asbestiform amphibole minerals: Detection and measurement of high concentrations in municipal water supplies. Science 185:853-855 (1974). 3. Nicholson, W.J. Analysis of Amphibole Asbestiform Fibers in Municipal Water Supplies. Environ. Health Perspect. 9:165-172 (1974) 4. Ambient Water Quality Criteria for Asbestos. EPA 440/580-022. U.S. Environmental Protection Agency, Washington, D.C. 20460 (1980) 5. Carcinogenesis Bioassay of Amosite Asbestos in Syrian Golden Hamsters. Draft Report. National Toxicology Program, Research Triangle Park, NC (1981) 6. Carcinogenesis Bioassay of Chrysotile Asbestos in Syrian Golden Hamsters. Draft Report. National Toxicology Program, Research Triangle Park, NC (1981) 7. Kanarek, M.S., Conforti, P.M., Jackson, L-.A. Cooper, R.C. and Murchio, J.C. Asbestos in Drinking Water and Cancer Incidence in the San Francisco Bay Area. Am. J. Epidemiology 112(1):54-72. (1980) CAP CO JEN 0011989 -10 8. Conforti, P.M., Kanarek, M.S., Jackson, L.A., Cooper, R.C. and Murchio, J.C. Asbestos in Drinking Water and Cancer in the San Francisco Bay Area. J. Chron. Dis. 34:211-24 (1981) 9. Tarter, M.E., Cooper, R.C., Freeman, W.R. A graphical analysis of the interrelationships between waterborne asbestos, digestive systems, cancer and population density. Proceedings of a Summary Workshop on Ingested Asbestos, U.S. EPA, Cincinnati, Ohio (1982) Environ. Health Perspect. (1983) 10. Polissar, L., Severson, R.K., and Boatman, E.S. Cancer from asbestos in drinking water: A case-control study in western Washington. Proceedings of a Summary Workshop on Ingested Asbestos, U.S. EPA, Cincinnati, Ohio (1982) Environ. Health Perspect. (1983) 11. Hammond, E.C., Selikoff, I.J., and Churg, J. Neoplasia Among Insulation Workers in the United States With Special Reference to Intra-abdominal Neoplasia. Ann. N.Y. Acad. Sci. 132:519-525, (1965). 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