Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
~ ntroduction Asbestos-associated diseases generally have been related to occupational exposures, such as those experienced by some miners, insulators, and factory workers (Doll, 1955; Gloyne, 1935, 1951; Merewether, 1930; Selikoff, 1979; Selikoff et al., 1964; Wagner et al., 1960) . Recent ly, however, there has been concern that exposure s to asbestos and related fibers may present a health hazard to the general public. Asbestos has been widely used in the United States for building materials and in other applications. Consequently, there is exposure to asbestos from many possible sources--in some schools and other public and private buildings, in ambient air, 1 and in drinking water (National Research Council, 1983; Sebastien et al., 1982; U.S. Environmental Protec Lion Agency, 1980~. Because asbestos and other asbestiform fibers2 appear to be ubiquitous, virtually everybody is exposed to some extent. During autopsy, asbestos fibers have been detected in the lungs of most urban residents studied (Churg and Warnock, 1977; Langer et al., 1971; Pooley et al., 1970; Wagner et al., 1982~. However, reported concentrations of asbestos in urban air are usually considerably below the current U.S. Occupational standard of 2 fibers/cm3. Exposure of the public is particularly worrisome because the populations involved are large and include unhealthy persons. Moreover, exposure may begin in childhood, leaving a longer time for development of adverse effects. Furthermore, asbestos may enhance the carcinogenic effects of other materials. There is little information about the health effects of most nonoccupational exposures to these fibers. Despite ninny epidemiological studies of workers and experimental studies on animals, questions remain about which properties of asbestos are responsible for the adverse health effects and which conditions of Ambient air is outside air to which the public is exposed (U.S. Environmen~cal Protec t ion Agency, 1982b) . 2These include asbestos and other fibers with some of the same physical propert ie s as asbe s tos . 16
17 exposure are most likely to lead to such effects. Certain other natural mineral fibers, as well as man-mate mineral fibers sometimes used as substitutes for asbestos and for other purposes, might have similar deleterious effects (Artvinli and Baris, 1983; Stanton, 1974; World Health Organization, 1983~. The term "asbestos" refers to the fibrous form of several specific silicate minerals that have been used commerc ial ly. Because of it s high tensile strength, flexibility, and resistance to heat and chemical at t ack , asbe s to s i s used in many produc ts, including asbestos-cement pipes, insulation, friction materials, and flooring and roofing tiles (Suta and Levine, 1979~. The consumption of asbestos in the United States has greatly increased during this century (Selikoff and Lee, 1978) . Annual U. S. consumption peaked at about 800, 000 metric tons in 1973 and 1974, but in 1982 it dropped to 250,000 metric tons, or about 6: of world production (U. S. Bureau of Mines, 1978, 1983) . Figure 1-1 shows U. S. asbestos consumption by year since 1890 and cumulative consumption since l90S. The millions of tons of asbestos already in place provide an ongoing potential hazard to workers and the public. The most serious health effects associated with exposure to asbestos are lung cancer, mesothelioma (an almost invariably fatal form of cancer), and asbestosis (a noncancerous but debilitating and sometimes fatal disease). In addition, other nonmalignant lung changes have been documented. Appendix A describes the chronology of the major observa- tions documenting the relationship between asbestos exposure and disease. Persons exposed to asbestos nonoccupationally can be at increased risk of contracting these asbestos-associated diseases. In one of the first studies linking asbestos exposure and mesothelioma, the disease was found among residents of a mining area in South Africa. These subjects had presumably inhaled the material in the surrounding air (Wagner et al., 1960~. In another study, persons living in households with asbestos factory workers in New Jersey were reported to be at increased risk of asbestos-associated disease (Anderson et al., 1919~. The diseases usually become evident clinically 20 to 40 years after initial exposure, and may occur even in the absence of continued exposure. Thus, many current cases of diseases assoc fated with asbestos exposure are primarily the result of occupational exposures that the individuals experienced many years ago. It has been est imated that up to several hundred thousand excess deaths could result over the next few decades from such exposures already experienced (Hogan and Hoel, 1981; Nicholson et al., 1982; Walker et al., 1983~. Results of current exposures would be manifested as disease in the future. Because of the long latent period, it is difficult to reconstruct exposure histories. Moreover, variations in particle size and in other
800,000 200,000 18 out 1 1 1 1 1 1 1 1 1890 ~1 J 1910 19 ~i950 1970 19 YEAR FIGURE 1-]A. Annual U. S. consumption of asbestos from 1890 to 1982. 4x107 o . _ C, E 3x107 o In o o 2x 1 of In lxlO' o / ~ _ 1~ 1 1 1900 1920 - 1 1 1 1 1 , ,1 t 940 1960 1 9B0 2000 YEAR FIGURE 1-lB. Cumulative U.S. consumption of asbestos from 1905 to 1982 Based on data from U.S. Bureau of Mines, 1973, 197B, 1983. J i l ? 1 l ·1
\ 19 properties of asbestiform fibers may lead to different degrees of health risk from apparently similar exposure. The effects of exposure to the fibers may also be modified by other factors, such as smoking. CONCURRENT NATIONAL RESEARCH COUNCIL AND GOVERNMENT ACTIVITIES - RELATED TO ASBESTOS While this committee carried out its task, numerous other efforts were under way to coordinate government activities and to summarize and interpret findings concerning the health effects of asbestos. The U.S. Environmental Protection Agency (1982a, 1983) issued reporting require- ments related to asbestos in schools and reaffirmed its interest in limiting the amount of asbestos used in certain applications. In 1983 the EPA, the Occupational Safety and Health Association (OS~A), and the Consumer Product Safety Commission (CPSC) formed an interagency task force on asbestos to coordinate information-gathering and regulatory efforts concerning asbestos among the three agencies. For example, OSHA has for several years considered revising the permissible exposure limit for asbestos in the workplace. In 1976 the standard became 2 fibers/cm3. An asbestos fiber for counting purposes means a particulate that has a physical dimension longer than 5 Am and a length- to-diameter ratio of 3:1 or greater (U.S. National Institute for Occupational Safety and Health, 1977, 1980~. In early November 1983, OSHA issued an emergency temporary standard lowering the permissible exposure limit to 0.5 fibers/cm3 (U.S. Occupational Safety and Health Administration, 1983), but a stay on the temporary standard was granted later in the month. Asbestos as a health hazard was considered by the Chronic Hazard Advisory Panel (CHAP) on Asbestos, which was formed in January 1983 by the CPSC (Consumer Product Safety Act, 1981; U.S. Consumer Product Safety Commission, 1982, 1983~. The panel was composed of persons nominated by the National Academy of Sciences. Its major purpose was to provide advice to CPSC on the risks of cancer associated with exposure to asbestos. The National Research Council (NRC) has also engaged in several activities related to asbestos. One was an analysis of data related to asbestos in drinking water, which was part of a study conducted by the NRC Safe Drinking Water Committee (National Research Council, 1983~. The Committee on Nonoccupational Health Risks of Asbestiform Fibers was able to draw upon the findings of the CHAP and NRC reports and on other draft documents. Another NRC activity is an ongoing study to identify and solve problems related to asbestos exposure in federal buildings. This report is being prepared by the Federal Construction Council Consulting Committee on Asbestos under~the NRC Advisory Board on the Built Environment (National Research Council, in press). :&
20 Tan COMMITTEE'S APPROACH To study the health effects of nonoccupational exposure to asbestiform fibers, this committee took as its overview a "chain of events" depicted in Figure 1-2. Thin figure shows that fibers may occur naturally or be synthesized and that exposure of humans may result from either commercial or environmental "flows." These human exposures may then lead to biological reactions and adverse health effects. While recognizing the difficulties involved in laterpreting data related to health effects of asbestiform fibers, the committee considered the following questions: 1. What are the major sources of nonoccupational exposure to asbestiform fibers, and how great are such exposures? 2. Which properties of the fibers seem to be most closely associated with adverse health outcomes? These properties may include length, diameter, chemistry, strength, durability, mans, and surface characterlatica. 3. Is it possible to distinguish different levels of carcinogenic and fibrogenic risks among the different types of asbestos fibers? The question is difficult to address by either epidemiological or laboratory studies, because virtually al1 samples of fibers contain a range of fiber sizes and other fiber characteristics may differ among the various studies. Thus, it in difficult to relate observed effects to Specific types of particles. 4. To what extent can the data on occupational exposures be used to develop risk estimates for the general public? In order to respond to its charge from EPA, the committee considered various routes of exposure, but placed emphasis on the inhalation route. To elucidate the relevant properties of the fibers responsible for the adverse health effects, it evaluated physical, epidemiological, and toxicological data related to asbestiform fibers. It also estimated the health risk for certain populations under various assumptions of exposure. Although many of the data reviewed in this study concern asbestos, the committee has drawn conclusions that encompass other fibrous materials as well. The committee has not carried out an exhaustive review of the literature, but has concentrated instead on those data that are most relevant to the charge. It found many excellent reviews and collections of articles related to asbestos and other fibrous materials that have appeared in recent years. Among the documents that were most useful during the course of this study were those prepared by Selikoff and Lee (1978), Wagner (1980), Craighead and Mosaman (1982), Walton (1982), and papers from a conference on biological effects of man-made mineral ! l
o E o i . ~' 21 C, - "C _ _ ._ ~ _ ~ o _ _ T , ~ o o . . ~ lU g E - ~ , _ o °m · ~ _ _ 2m 0 ._ C ~ _ ·n ~ C C~ ~ ~ C O g 0 ° &o · ~ T C o .C ~ ~ {,, - , o o ,: ~C ·O C ~o ~ ~ ~ . ~ c~ C ) o ~ o o ~ o . . - cO . . g . C~ C Ec o _ ._ C LU o D ~ . - ~ 0 E o · - ~ 3 cn 0 3 o - ,1 C) C) ~ o C) :^ C~ E - o s~ o o . - 3 0 o _ eS ~ ID . - S ~ CL oC ~ _ - o CI: l o - E ..g o ~ . - . - - s C 0 x 0 0 ~ . - ~ V C E o . - C h os ~ ~ 3 =,c o _ 1 v . . ..c 3 o 0 0 o' o CL X ~n ~ :' X o D o v -
22 fibers, which was held in Copenhagen in April 1982. The proceedings of that conference have been Prized by the World Health Organization (1983). The succession of chapters in this report reflects a logical sequence for pursuing this study. First, the committee defined the kinds of materials it was conaldering and described some of their properties. It then assessed exposure to these materials. Its next step was to consider the various ways of determining the amounts of fibers both in the workplace and in the ambient environment and to evaluate epidemiological and laboratory data. Finally, it integrated data from exposure, epidemiological and laboratory studies in order to make quantitative and comparative risk assessments. REFERENCES Anderson, H. A., R. Lilis, S. M. Da''m, and I. J. Selikoff . 1979. Asbestosis among household contacts of asbestos factory workers. Ann. N.Y. Acad. Sci. 330: 387-399. Artvinli, M., and Y. I. Barls. 1982. Environmental fiber-induced pleuro-pulmonary diseases in an Ar~atoliar~ village: An epidemiologic study. Arch. Environ. Health 37:177-181. Churg, A., arid M. L. Warnock. 1977. Correlation of quantitative asbestos body counts and occupation in urban patients. Arch. Pathol. Lab. Med . 101: 629-634. Consumer Product Safety Act. 1981. Section 1206 of the Omnibus Budget Reconciliation Act of 1981 (P.L. 97-35; 15 U.S.C. 2077, as amended). Craighead , J . E., and B . T . Monaman. 1982 . The pathogenesis of asbestos-associated diseases. N. EngI. J. Med. 306: ~ 446-1455. Doll, R. 1955. Mortality from lung cancer in asbestos workers. Br. J. Ind. Med. 12:81-86. Gloyne, S. R. 1935. Two cases of squamous carcinoma of the lung occurring in asbestosis. Tubercle 14:445-451. Glove, S. R. 1951. Paeumoconioala. A historical survey of necropay material in 1205 cases. Lancet l:~10-~14. Hogan, M. D., and D. G. Hoel. 1981. Estimated cancer risk associated with occupational asbestos exposure. Risk Analysis I: 67-79. Langer, A. M., V. Baden, E. C. Hammond, and I. J. Selikoff. 1971. Inorganic fibers including chrysotile in lunge at autopsy: Preliminary report. Pp. 683-694 in W. H. Walton, ed. Inhaled Particles III. The Gresham Press, Surrey. Levine, R. J., ed. 1978. Asbestos: An Information Resource. U.S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health. Merewether, E. R. A. 1930. The occurrence of pulmonary fibrosis and other pulmonary affections in asbestos workers. J. Ind. Byg. 12:198-222, 239-257.
23 National Research Council. 1983. Drinking Water and Health. Vol. 5. A report of the Safe Drinking Water Committee, Commission on Life Sciences. National Academy Press, Washington, D.C. National Research Council. In press. Identifying and solving asbestos problems in existing federal buildings. Draft report of the Federal Construction Council Consulting Committee on Asbestos. National Academy Pres a, Washington, D . C. Nicholson, W. J., G. Perkel, and ~ . J . Selikoff . 1982. Occupational exposure to asbestos: Population at risk and projected mortality-- 1980-2030. Am. J. Ind. teed. 3: 259-311. Pooley , F. D., P. D. Oldham, U. Chang-Hyun, and J. C. Wagner. 1970. The detection of asbestos in tissues. Pp. 108-116 in H. A. Shapiro, ed . Pneumoconiosi ~ . Proceedings of the International Conference in Johannesburg. Oxford University Press, Cape Town. Sebastien, P., J. BigDon, and M. Martin. 1982. Indoor airborne asbestos pollution: From the ceiling and the floor. Science 216: 1410-1413. Seilkoff, I. J. 1979. Mortality experience of insulation workers in the United Stances and Canada, 1943-1976. Ken. N.Y. Acad. Sci . 330: 91-116. Selikoff, I. J., and D. K. Lee. 1978. Asbestos and Disease. Academic Press, New York. 549 pp. Selikoff, I. J., J. Churg, and E. C. Hammond. 1964. Asbestos exposure and neoplasia. J. Am. Med . Assoc . 188: 22-26. Stanton, M. F. 1974. Fiber carcinogenesis : Is asbestos the only hazard? J. Natl. Cancer Inst . 52: 633034. Suta, B. E. , and R. J. Levine. 1979. Non-occupational asbestos emissions and exposures. Pp. 171-205 in L. Michaels and S. S. Chissick, eds. Asbestos. Properties, Applications, and Hazards. Vol. 1. John Wiley & Sons, New York. U.S. Bureau of Mines. 1973. Minerals Yearbook 1972. Bureau of Mines, Department of the interior, Washington, D.C. U.S. Bureau of Mines. 1978. Asbestos. Minerals Yearbook 1977. Bureau of Mines, Department of Interior, Washington, D.C. U.S. Bureau of Mines. 1983. Asbestos. Preprint from the 1982 Minerals Yearbook. Bureau of Mines, Department of the Interior, Washington, D.C. U.S. Consumer Product Safety Commission. 1982. Chronic hazard advisory panel on asbestos; invitation to submit suggestions for Scientists to serve as members. Fed. Regist. 47:17323-17324. U.S. Consumer Product Safety Commission. 1983. Report by the Chronic Hazard Advisory Panel on Asbestos. Consumer Product Safety Commission, Washington, D.C. U.S. Environmental Protection Agency. 1980. Asbestos-Containing Materials in Schools. Health Effects and Magnitude of Exposure. Support document for proposed ~ materials in School buildings. Office of Pesticides and Toxic Substances, Environmental Protection Agency, Washington, D.C. r'~1 A 6 On friable asbestos-containing
24 U.S. Environmental Protection Agency. 1982a. Asbestos; friable materials in schools; identification and asbestos-containing notification. Fed. Regist. 47:23360-23389. U.S. Environmental Protection Agency. 1982b. National primary and secondary ambient air quality standards. Definitions. Code of Federal Regulations, Title 21, Part 50.1. U.S. Environmental Protection Agency. 1983. Rules restricting the commercial and industrial use of asbestos fibers. Fed. Regist. 48:47880. U.S. National Institute for Occupational Safety and Health. 1977. Asbestos Fibers in Air. NIOSH Manual of Analytical Methods. Second Edition. Vol. 1. National Institute for Occupational Safety and Health, Cincinnati. U.S. National Institute for Occupational Safety and Health. 1980. Workplace Exposure to Asbestos. NIOSH-OSHA Asbestos Work Group. NIOSH Pub. No. 81-103. National Institute for Occupational Safety and Health, Cincinnati. U.S. Occupational Safety and Health Administration, 1983. Occupational exposure to asbestos: Emergency temporary standard. Fed. Regist. 48:51086-51140. Wagner, J. C., ed. 1980. Biological Effects of Mineral Fibres. Vola. 1 and 2. IARC Scientific Pub. No. 30. International Agency for Research on Cancer, Lyon. 1001 pp. Wagner, J. C., C. A. Sleggs, and P. Marchand. 1960. Diffuse pleural mesothelioma and asbestos exposure in the North Western Cape Province. Br. J. Ind. Med. 17:260-271. Wagner, J. C G. Berry, and F. D. Pooley. 1982. ' -' - -' Mesothelioma and asbestos type in asbestos textile workers: A study of lung contents. Br. Med. J. 285:603-606. Walke r, A. M., J. E . Laughlin, E. R . Priedlande r, K. J . Rothman, and N. A. Dreyer. 1983. Projectlons of asbestos-related disease 1980-2009. J. Occup. Med. 25:409-425. Walton, W. H. 1982. The nature, hazards and assessment of occupational exposure to airborne asbestos dust: A review. Area. Occup. Hyg. 25: Il7-247. World Health Organization. 1983. Biological Ef fects of Man-Made Mineral Fibers. Report on a WHO/lARC Meeting, Copenhagen, April 20-22, 1982. EURO Reports and Studies No. 81. World Health Organization, Copenhagen.
