Chemical contamination of California drinking water

Our plain-English summary of Chemical contamination of California drinking water, by H.H. Russell, R.J. Jackson, D.P. Spath, et al (The Western Journal of Medicine, 1987).

The study

• Authors: H.H. Russell, R.J. Jackson, D.P. Spath, S.A. Book
• Journal: The Western Journal of Medicine
• Published: 1987;147(5):615-22
• Type of article: Review
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Free full text

Abstract

Drinking water contamination by toxic chemicals has become widely recognized as a public health concern since the discovery of 1,2-dibromo-3-chloropropane in California's Central Valley in 1979. Increased monitoring since then has shown that other pesticides and industrial chemicals are present in drinking water. Contaminants of drinking water also include naturally occurring substances such as asbestos and even the by-products of water chlorination. Public water systems, commercially bottled and vended water and mineral water are regulated, and California is also taking measures to prevent water pollution by chemicals through various new laws and programs.

In plain English

This 1987 article was a review meant to help physicians answer patients' questions about contaminated drinking water in California. It reported no new research. It covered how standards are set and summarized surveys and earlier studies of many contaminants, including asbestos. It said waterborne asbestos comes mainly from serpentine rock and mostly settles out in reservoirs or is removed in water treatment plants. It cited an EPA survey of urban water systems in 365 cities that found 41 with more than 10 million fibers per liter. Some San Francisco Bay Area water systems had more than 100 million fibers per liter. It stated that studies of cancer in animals ingesting asbestos, and epidemiologic studies of populations drinking water with high asbestos levels, had all been negative, but that the epidemiologic studies were flawed. On reanalysis, a National Research Council committee found those studies gave a relative risk similar to one calculated for gastrointestinal tract cancer from occupational asbestos exposure. That committee estimated a one-in-a-million added lifetime cancer risk at a little more than 1 million 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 article summarizing monitoring data, regulatory standards and earlier studies; no new study was carried out
• Who was studied: No study population; the review covered drinking water contamination in California, drawing on state and federal surveys and earlier studies, mostly from 1979 to the mid-1980s
• Exposure: Chemical contaminants of drinking water: pesticides (including DBCP), nitrate, industrial solvents, trihalomethanes from chlorination, lead, and naturally occurring substances (asbestos, selenium, fluoride, arsenic). Asbestos was described as coming mainly from serpentine rock.
• Main results:
  • Most asbestos in water settles out in reservoirs or is removed in water treatment plants
  • An EPA survey cited by the review found 41 of 365 cities' urban water systems with asbestos concentrations greater than 10 million fibers per liter
  • The review stated that studies of cancer in animals ingesting asbestos and epidemiologic studies of populations exposed to drinking water with high levels of asbestos had all been negative, but that the epidemiologic studies were flawed
  • A National Research Council committee, cited by the review, estimated that a one-in-a-million added lifetime cancer risk would come from a water concentration of a little more than 1 million fibers per liter
  • Some San Francisco Bay Area water systems had more than 100 million asbestos fibers per liter
  • About 2,500 California wells had been found contaminated with the pesticide DBCP
  • In sampling of large public water system wells under California's AB 1803 program, 18.3% of the wells had some contamination and 5.6% exceeded one or more state standards
  • State studies of birth defects near a solvent-contaminated well in Santa Clara County were described as inconclusive
• The authors' conclusion: The authors stated that trihalomethanes from water chlorination represent a higher cancer risk than most toxic pollutants at the levels measured in drinking water, and described new laws and programs to prevent contamination. The article gave no specific conclusion about asbestos.

Topics

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

Related studies

• Drinking water and cancer — K.P. Cantor (1997)
• Asbestiform amphibole minerals: detection and measurement of high concentrations in municipal water supplies — P.M. Cook, G.E. Glass, et al. (1974)
• Investigating possible effects of abestos in city water: surveillance of gastrointestinal cancer incidence in Duluth, Minnesota — B.S. Levy, E. Sigurdson, et al. (1976)
• Effect of population density on the results of the study of water supplies in five California counties — P.M. Conforti (1983)
• Is there a risk to health in using asbestos--cement pipes for the carriage of drinking water? — S.F. McCullagh (1980)
• Asbestos in drinking water and cancer incidence in the San Francisco Bay area — M.S. Kanarek, P.M. Conforti, et al. (1980)

Browse more research in The Western Journal of Medicine, or return to medical research.