Asbestos in water supplies of the United States

Our plain-English summary of Asbestos in water supplies of the United States, by J.R. Millette, P.J. Clark, J. Stober, et al (Environmental Health Perspectives, 1983).

The study

• Authors: J.R. Millette, P.J. Clark, J. Stober, M. Rosenthal
• Journal: Environmental Health Perspectives
• Published: 1983;53:45-8
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The review of available data on the concentrations of asbestos in U.S. water supplies suggests that the majority of water consumers are not exposed to asbestos concentrations over 1 million fibers/Liter. A few populations, however, may be exposed to concentrations over 1 billion fibers/L. Of the 538 water supplies for which waterborne asbestos data are available, 8% have concentrations of fibers over 10 million fibers/L. The vast majority of asbestos fibers found in U.S. water supplies are under 5 micron in length.

In plain English

This article reviewed available data on asbestos in U.S. drinking water. It also reported a survey of tap water from 100 water utilities, chosen by stratified random sampling to represent system size and geographic region. The article did not study health effects. In the 100-utility survey, the highest asbestos level was below detectable limits in 61 utilities, under 1 million fibers per liter in 27, 1 to 10 million in 7, and over 10 million in 5. Among all 538 cities with data available in 1982, 46 (8.6%) had levels over 10 million fibers per liter. The authors noted that the larger data set may over-represent places already thought to have asbestos problems. Fiber-size data from two other studies, in the San Francisco Bay Area and the Puget Sound area, showed that most fibers were under 5 micrometers long. The authors cautioned that the two studies used different sizing methods. The authors concluded that most U.S. water consumers are not exposed to constant concentrations over 1 million fibers per liter, but that in some areas people are exposed to over 1 billion fibers per liter.

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 available data on asbestos in U.S. water supplies, plus a survey of 100 water utilities selected by stratified random sampling
• Who was studied: U.S. drinking water supplies: compiled data for 538 cities available in 1982, and tap water samples from 100 utilities drawn from the Community Water Systems Survey Database, stratified by EPA region and population served
• Exposure: Asbestos fibers in drinking water, measured as fibers per liter. The survey tables do not break counts down by fiber type.
• Main results:
  • In the 100-utility survey, the highest asbestos concentration was below detectable limits in 61 utilities, under 1 million fibers/L in 27, 1 to 10 million fibers/L in 7, and over 10 million fibers/L in 5.
  • Among all 538 cities with asbestos data, the highest concentration was below detectable limits in 187 (34.8%), under 1 million fibers/L in 264 (49.1%), 1 to 10 million fibers/L in 41 (7.6%), and over 10 million fibers/L in 46 (8.6%).
  • Compared with the 538-city data, the representative 100-utility sample showed a slightly lower percentage of supplies over 10 million fibers/L.
  • The authors estimated that the percentage of the U.S. population receiving water over 10 million fibers/L was similar to, but somewhat less than, the 5% figure reported for Canada.
  • The vast majority of asbestos fibers found in water supplies were less than 5 micrometers long.
  • In fiber-size data from two other studies, the share of fibers 5 micrometers or longer was 2.3% for California (Bay Area) water (7,375 fibers sized) and 0.2% for Washington (Puget Sound area) water (6,977 fibers sized).
  • In the 100-utility survey, turbidity of tap water ranged from 0.1 to 19 NTU, with a mean of 1.9 NTU.
• The authors' conclusion: The authors concluded that the majority of U.S. water consumers are not exposed to constant asbestos concentrations over 1 million fibers/L, but that in some areas people are exposed to concentrations over 1 billion fibers/L.
• Limitations the authors state:
  • The overall 538-city data may over-represent areas thought to have asbestos problems, because more samples were collected there.
  • Because of time, cost and effort, the representative survey sampled only 100 water supplies.
  • The fiber-size comparison should be read with caution, because the Puget Sound study used more refined methods that were perhaps more sensitive to small fibers.

Related studies

• Concentration and size of asbestos in water supplies — J.R. Millette, P.J. Clark, et al. (1980)
• Analysis of amphibole asbestiform fibers in municipal water supplies — W.J. Nicholson (1974)
• Asbestiform amphibole minerals: detection and measurement of high concentrations in municipal water supplies — P.M. Cook, G.E. Glass, et al. (1974)
• Effect of population density on the results of the study of water supplies in five California counties — P.M. Conforti (1983)
• Asbestos in public water supplies: discussion of future problems — J.P. Hills (1979)
• Engineering and operating approaches for controlling asbestos fibers in drinking water — G.S. Logsdon (1983)

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