Asbestos in drinking water: a Canadian view

Our plain-English summary of Asbestos in drinking water: a Canadian view, by P. Toft, M.E. Meek (Environmental Health Perspectives, 1983).

The study

• Authors: P. Toft, M.E. Meek
• Journal: Environmental Health Perspectives
• Published: 1983;53:177-80
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000649).

Abstract

For several years now, public health professionals have been faced with evaluating the potential hazards associated with the ingestion of asbestos in food and drinking water. In Canada, this is a subject of particular concern, because of the widespread occurrence of chrysotile asbestos in drinking water supplies. The results of available Canadian monitoring and epidemiologic studies of asbestos in drinking water are reviewed and discussed in light of other published work. It is concluded that the risk to health associated with the ingestion of asbestos, at the levels found in municipal drinking water supplies, is so small that it cannot be detected by currently available epidemiologic techniques.

In plain English

This paper was a review by two Health and Welfare Canada scientists of Canadian monitoring and epidemiologic studies of asbestos in drinking water, discussed alongside other published work. A 1977 national survey of 71 locations found chrysotile was the main asbestos type. Only 7% of 336 samples had detectable amphibole fibers. About 5% of the population received water with more than 10 million fibers/L, and about 0.6% more than 100 million fibers/L. The highest tapwater result was 1,800 million fibers/L, at Baie Verte, Newfoundland. In a 1977 study of 22 Quebec municipalities, men in the mining towns of Asbestos and Thetford Mines had excess lung cancer deaths (78 observed, 46.8 expected), which that study's authors linked to mining and milling work. A later comparison found a higher stomach cancer death rate among Thetford Mines men (38.7 versus 16.8), also judged probably occupational. Sherbrooke had 153 million fibers/L and no nearby mining, yet had lower death rates from all gastrointestinal cancers combined than seven comparison cities. The authors judged that animal feeding studies gave no conclusive evidence of cancer. They concluded that the risk from ingesting asbestos at drinking-water levels is probably extremely small.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review of Canadian monitoring and epidemiologic studies of asbestos in drinking water, discussed alongside other published work, including animal (toxicologic) studies
• Who was studied: Studies of Canadian municipalities: a 1977 mortality study of 22 Quebec municipalities (1964-73); a 1977 national water survey of 71 locations; a mortality comparison (1966 to 1976) of two high-asbestos cities (Sherbrooke and Thetford Mines) with 52 low-asbestos cities; and a comparison of Sherbrooke with seven matched municipalities
• Exposure: Asbestos fibers in municipal drinking water, mainly chrysotile; amphibole fibers were rarely detected
• Main results:
  • In the 1977 national survey, only 7% of 336 water samples had detectable amphibole fibers, and these were generally associated with high chrysotile levels
  • In the national survey, about 5% of the population received water with more than 10 million fibers/L and about 0.6% with more than 100 million fibers/L; the highest tapwater result was 1,800 million fibers/L, at Baie Verte, Newfoundland
  • In the 1977 Quebec mortality study, men in Asbestos and Thetford Mines had excess lung cancer mortality (observed = 78, expected = 46.8). Mortality from all cancers was not elevated for women (observed = 127, expected = 138.2). That study's authors related the excess in men to occupational exposure, not drinking water
  • In the high-versus-low comparison, the age-standardized stomach cancer mortality rate for males in Thetford Mines was 38.7, more than double the 16.8 rate in the comparison group. That study's authors considered it probably caused by occupational exposure
  • In Sherbrooke (153 million fibers/L in distributed water, no asbestos mining nearby), mortality rates for all gastrointestinal cancers combined were lower than in seven matched comparison cities for both men and women. Differences for specific sites were minor and not statistically significant
  • In the animal studies reviewed, the authors found no conclusive evidence that ingested asbestos causes cancer: gastrointestinal tumors in asbestos-fed animals were not significantly more frequent than in controls
• The authors' conclusion: The authors concluded that the risk of disease from ingesting asbestos at the levels found in drinking water supplies is probably extremely small
• Limitations the authors state:
  • The authors noted that several factors complicate the interpretation of ecologic epidemiologic studies generally
  • The authors noted that data on whether asbestos fibers penetrate the gastrointestinal tract are contradictory and are complicated by insensitive analytical techniques and possible contamination

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Chrysotile.

Related studies

• Cancer incidence in relation to asbestos in drinking water in the Puget Sound region — L. Polissar, R.K. Severson, et al. (1982)
• A case-control study of asbestos in drinking water and cancer risk — L. Polissar, R.K. Severson, et al. (1984)
• Epidemiology study of the use of asbestos-cement pipe for the distribution of drinking water in Escambia County, Florida — J.R. Millette, G.F. Craun, et al. (1983)
• Cancer risk from asbestos in drinking water: summary of a case-control study in western Washington — L. Polissar, R.K. Severson, et al. (1983)
• Assessment of studies on cancer risks from asbestos in Connecticut drinking water — J.W. Meigs (1983)
• Additional notes on the case-control study in western Washington on the cancer risk from asbestos in drinking water — L. Polissar, R.K. Severson, et al. (1983)

Browse more research in Environmental Health Perspectives, or return to medical research.