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Asbestos exposure Biogarphy

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Late in 1985, asbestos contamination was discovered in the public water supply of the Town of Woodstock, Ulster County, New York. Contamination resulted from asbestos-cement (AC) pipes installed in the town water system in the mid to late 1950s and the corrosiveness of the local water. The New York State (NYS) Department of Health established the Woodstock Asbestos Exposure Registry (WAER) in 1986 to monitor rates of cancer among individuals who lived on the water supply between 1960 and 1985. Demographic, health, and residential information were collected on 2,936 registrants. The follow-up period for observation of cancer was 1980-1998, consistent with the expected lag of 20-30+ years for development of asbestos-related cancers. The NYS Cancer Registry was used to confirm cancer diagnoses and to identify unreported cancers. Standardized incidence ratios (SIRs) for gastrointestinal, respiratory, and total cancers were all approximately 1.00 or less and all 95% confidence intervals (CIs) included 1.00. For individual types of the gastrointestinal cancers, only the SIR for pancreatic cancer was marginally statistically significant at 2.19 (95% CI=1.00-4.16), based on a total of nine observed cases. The excess in pancreatic cancer occurred primarily among men (SIR=3.08; 95% CI=1.13-6.70), and was only slightly elevated among women (SIR=1.39; 95% CI=0.29-4.06). This association may be related to factors other than asbestos exposure such as cigarette smoking, or to chance. No cases of mesothelioma were observed among WAER participants. There was no increase in incidence by latency or duration of residence on the water supply, but the ability to detect these trends is limited by small numbers and unknown dates of initial exposure. The general pattern of results did not demonstrate a likely link between exposure to asbestos in drinking water and cancer occurrence among participants in the WAER. This is the final report for this study; follow-up of the Woodstock Asbestos Exposure Registry has ended.
Background
In November 1985, residents of the Town of Woodstock, Ulster County, NY, reported a decrease in water pressure following a temporary interruption in water service. Town and New York State (NYS) Department of Health (DOH) staff determined that strainers on faucets and showerheads were clogged with asbestos fibers. The source of the asbestos fibers was asbestos-cement (AC) pipes installed in the town water system in the mid to late 1950s. Examination of the pipe showed significant deterioration of its interior, probably due to the high corrosivity of the local water. All water delivered by the public water supply traveled through AC pipes located near the pumping stations. The time frame during which asbestos fibers started leaching into the water is unknown but the entire town water supply system may have contained some level of asbestos fibers since around 1960. A 10-year-old sample of water drawn in 1976 (tested in 1986) contained asbestos, confirming that leaching of asbestos into the water supply began as early as 1976.
A 1982 survey of 47 NYS public water supply systems performed by the United States Environmental Protection Agency (USEPA), which did not include the Woodstock water supply, found only one water system with an asbestos level greater than 10 million fibers per liter (MFL). Ulster County officials collected five water samples from different locations on the Woodstock water supply in November 1985, following flushing of the water mains. Four of the samples had asbestos levels greater than 10 MFL, with the maximum equaling 304.5 MFL.
To address the asbestos contamination problem, a variety of actions were taken. In December 1985, a water advisory was issued, cautioning people against use of the town water supply for drinking, cooking, food preparation, or mist-type humidifiers. Emergency procedures also included distribution of uncontaminated water and replacement of the AC pipes with ductile iron pipes. The majority of the AC pipe replacement was completed in early March 1986, with a few remaining sections replaced in early June. Extensive flushing of the water supply system, cleaning or replacement of water service meters, and repeated testing for asbestos were conducted before lifting the water use advisory in July of 1987.
Carcinogenicity of Asbestos
Asbestos has been classified as a human carcinogen by the USEPA and the International Agency for Research on Cancer (IARC) (USEPA, 1993), (IARC Working Group on the Evaluation of Carcinogenic Risks to Humans, 1987). Numerous studies have linked occupational exposure to airborne asbestos with excess risk of lung cancer and mesotheliomas of the pleura and the peritoneum (Selikoff, 1965), (Peto et al., 1985), (Enterline et al., 1987). A weak association between occupational exposure to airborne asbestos exposure and gastrointestinal cancer was first noted by Selikoff et al., (1964), and was supported by a meta-analysis of 31 occupational cohorts using a lung cancer standardized mortality ratio of 2.0 or greater as a proxy for asbestos exposure (Frumkin and Berlin, 1988). Investigators proposed that the increase in gastrointestinal cancers was the result of ingestion of airborne asbestos fibers that occurred following clearance from the airways. A more recent meta-analysis of 69 occupational cohorts does not support a causal relation (Goodman et al., 1999). Some investigators have speculated that the elevated rate of gastrointestinal cancer attributed to occupational asbestos exposure reflects misdiagnosis of mesothelioma and lung cancer (Peto, 1989), (Gamble, 1994). Peto (1989) noted that relative risks for cancers other than lung and gastrointestinal are correlated with relative risks for lung cancer in cohorts of male asbestos workers. An increase in risk for all other sites of cancer similar to that observed for gastrointestinal cancer supports the misdiagnosis theory.
Both huma and animal studies have examined the relationship between ingestion of asbestos fibers and cancer. Animal studies of ingested asbestos carcinogenicity have generally produced negative results (Chouroulinkov, 1989). However, based on the results of genotoxicity studies, Varga et al., (1999) suggest that combined exposure to asbestos fibers and waterborne asbestos may have a carcinogenic effect. Cancer incidence or mortality has been studied in eight populations exposed to asbestos in drinking water in the United States, Canada, and Norway (see Table 1). In several instances, the same study population was the subject of two or three investigations. A later study extended the scope or study period of the original investigation. The results of the most recent study of each population are summarized in Table 1.
Erosion of rock containing asbestos was the source of asbestos in several study locations: the Bay Area of California; Quebec, Canada; and the Puget Sound region of the state of Washington. Dumping of mine tailing wastes into Lake Superior resulted in asbestos in the water supply in Duluth, Minnesota. AC pipes were the source of asbestos in selected water supplies in Connecticut and Escambia County, Florida. Weathering of AC roof tiles by rainwater runoff used for drinking water was the source of asbestos exposure among lighthouse keepers in Norway. In some cases, asbestos levels were relatively low. Concentrations were less than 0.1 MFL in town water supplies in Connecticut (Meigs et al., 1980); in Escambia County, Florida, seven census tracts with detectable levels measured 0.11-0.7 MFL (Millette et al., 1983). Much higher concentrations were measured in lighthouse keepers' cisterns (range=1,760-71,350 MFL) (Andersen et al., 1993), in water supplies in two cities in Quebec, Canada (> 100 MFL) (Toft et al., 1981), and in the Puget Sound area of Washington (200 MFL) (Polissar et al., 1984). Intermediate levels were reported in water supplies in the Bay Area of California (up to 36 MFL) (Conforti et al., 1981) and Duluth, Minnesota (range=2-64 MFL) (Sigurdson, 1983).
As shown in Table 1, an excess of stomach cancer among males was observed in five study populations (Conforti et al., 1981), (Toft et al., 1981), (Sigurdson, 1983), (Polissar et al., 1984), (Andersen et al., 1993), and pancreatic cancer was associated with exposure among males in one population (Meigs et al., 1980) and among females in another (Conforti et al., 1981). A positive association was not reported for more than one study population for any other cancer site. Despite indications of increased risk in early investigations, the epidemiologic studies conducted to date generally do not provide strong evidence of an association between exposure to asbestos in drinking water and gastrointestinal or respiratory cancers. However, a number of study limitations prevent firm conclusions. Six of the eight studies employed an ecologic design. The most serious weakness of ecologic studies is the potential for bias in attempting to draw conclusions about individual-level risk based on group-level observations. The assignment of exposure status to all individuals in a region undoubtedly results in exposure misclassification. Geographic boundaries used to identify cases and controls often do not correspond perfectly with water system boundaries. In addition, migration can contribute to misclassification since residents who have recently moved into an "exposed" region would not be at risk of exposure-related cancer. Other considerations include inadequate latency (Meigs et al., 1980), (Sigurdson, 1983), (Howe et al., 1989) and small sample size.
The case-control study by Polissar et al. (1984) was able to avoid many of these limitations. Detailed information on residential and occupational history was used to estimate asbestos exposure, data were collected on personal risk factors for cancer, and latency was taken into account. Statistically elevated risk of cancers of the stomach and pharynx were reported among men. In view of the large number of statistical comparisons (84) in conjunction with nonsignificant protective effects observed among women for cancers of the stomach and pharynx, the authors suggested that positive findings were due to chance. The study had power to detect relative risks as low as 1.4-1.6 for cancers of the colon, lung, gastrointestinal system, and respiratory system.
A preliminary study of cancer incidence for the years 1973-1983 among Woodstock residents living in the census blocks that include the water district, conducted by the NYS DOH, is included among the studies summarized in Table 1 (Howe et al., 1989). No evidence of elevated gastrointestinal or respiratory cancer incidence was observed when rates of cancer for census blocks including the water district were compared to rates for NYS excluding New York City (NYC). Insufficient latency and the inclusion in the exposed population of individuals who did not live on the public water supply were limitations of the study.
Most of the community studies conducted to date did not have individual-level information on source of water and duration of residence. The exposure assessment for the present study improves on these studies. Only people who lived on the water supply were included and information on duration of residence was examined.Study Subjects and Methods
Construction of Cohort
In 1986, the NYS DOH began a prospective cohort study to monitor cancer incidence among individuals who lived in homes serviced by the Woodstock water supply. Specifically, NYS DOH established the Woodstock Asbestos Exposure Registry (WAER) to collect exposure and health status information on individuals who, between 1960 and 1985, had resided for six months or more in a home serviced by the Town of Woodstock water supply. Information on demographics, smoking history, drinking habits, occupation, family history of cancer, and residential history was obtained through questionnaires and interviews. The registrants were followed through 1998. Address and health information was updated every two years. The objectives of the WAER were:
To identify individuals who lived for six months or more in a residence served by the town water between January 1, 1960, and December 31, 1985.
To notify these individuals of their exposure.
To obtain demographic and medical history data on registered individuals and to periodically update this information.
To calculate cancer incidence rates among the WAER population for total cancers, mesothelioma, respiratory cancers and gastrointestinal cancers and compare these to cancer rates for NYS excluding NYC.
An in-person registration week was held in the Woodstock Town offices in June 1986. The following month, introductory letters and questionnaires were mailed out to an additional 565 households currently serviced by the public water supply. A variety of sources were used to identify and trace former property owners and tenants: tax assessor's records, voter records, city directories, post office change-of-address records, neighbor referrals, and Department of Motor Vehicle files. Extensive efforts were made to contact and recruit current and former residents. If possible, individuals who did not respond to mailed questionnaires were contacted by telephone and offered a telephone interview or remailing of the questionnaire. Those with non-published telephone numbers or otherwise not reachable by telephone were mailed registered letters.
The person-years of observation contributed by each person in the study cohort began at the start date of the follow-up period (January 1, 1980), or on the date of first residence on the water supply if residence began after 1980 (exceptions are noted below for the analyses accounting for latency and exposure beginning in 1976). Follow-up ended at the date of cancer diagnosis, date of death, last date before loss-to-follow-up or the end of the study period (December 31, 1998), whichever came first. An individual diagnosed with cancer no longer contributed person-years after his or her date of diagnosis. Similarly, accrual of person-years stopped as of date of death or loss-to-follow-up. Registrants for whom information was missing on duration of residence or date of birth were excluded from the study cohort. Since individuals who had a cancer diagnosis prior to 1980 would not be at risk of a first diagnosis of a primary cancer during the study follow-up period, persons with a confirmed diagnosis of cancer prior to 1980 were excluded from the study population.

Asbestos exposure Wallpaper Photos Pictures Pics Images 2013