Asbestos fibres in drinking water: are they carcinogenic or not?

Our plain-English summary of Asbestos fibres in drinking water: are they carcinogenic or not?, by C. Varga (Medical Hypotheses, 2000).

The study

• Author: C. Varga
• Journal: Medical Hypotheses
• Published: 2000;55(3):225-6
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The paper discusses the possibility of a carcinogenic effect of consuming drinking water contaminated by asbestos fibres.

In plain English

This short paper offered an explanation for why studies of people drinking asbestos-contaminated water have given mixed results. The author proposed that waterborne fibres might act together with organic pollutants found in chlorinated drinking water. The paper summarized laboratory experiments reported in earlier publications. In those experiments, F-344 rats were given amphibole asbestos (crocidolite and anthophyllite) by mouth, with or without benzo[a]pyrene (BaP) attached. The fibres took up BaP from dilute water solutions. The fibres significantly increased sister chromatid exchange, a marker of chromosome damage, in bone marrow cells, and the effect depended on BaP concentration. Without BaP, the fibres did not cause this damage. A test for DNA breaks found high levels in cells from the omentum and intestine. Adsorbed BaP significantly increased the damage in the omentum. Parietal peritoneum and macrophages showed none of the early DNA damage studied at 24 hours. The author suggested they may not yet have been exposed or may not have been sensitive. The paper gave no numerical results for these experiments. The author concluded that these findings could explain the mixed human results mechanistically, but that the hypothesis still needs confirmation in studies of people.

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: Hypothesis paper summarizing earlier laboratory and animal (rat) experiments
• Who was studied: F-344 rats (number not given); cells from bone marrow, peritoneal washing fluid, parietal peritoneum, omentum and intestine
• Exposure: Amphibole asbestos fibres (crocidolite and anthophyllite), with or without adsorbed benzo[a]pyrene (BaP), given orally (oral gavage)
• Main results:
  • In laboratory tests, the fibres adsorbed BaP from low-concentration water solutions
  • In rats, the fibres significantly increased sister chromatid exchange in bone marrow cells 24 hours after oral treatment. The effect depended on BaP concentration, and the fibres without BaP were not genotoxic in this test
  • Urine and serum from treated rats were negative in the Ames bacterial test. The author interpreted this as supporting transport of BaP on the fibre surface in the blood
  • The comet assay found high levels of single and double strand DNA breaks in cells from the omentum and intestine
  • Adsorbed BaP significantly increased DNA damage in the omentum
  • The parietal peritoneum and macrophages were not involved in the early genotoxic changes studied at 24 hours. The author suggested they may not have been exposed to fibres by then, or may not have been sensitive
• The authors' conclusion: The author concluded that the experimental findings can explain the mixed epidemiological results at a mechanistic level, but that the hypothesis requires epidemiological confirmation
• Limitations the authors state:
  • The hypothesis has not been confirmed in human (epidemiological) studies
  • Bone marrow, used in the sister chromatid exchange test, is not a real target tissue of asbestos or BaP

Topics

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

Related studies

• Drinking water and cancer — K.P. Cantor (1997)
• Drinking water and cancer — R.D. Morris (1995)
• Asbestos in drinking water and cancer incidence in the San Francisco Bay area — M.S. Kanarek, P.M. Conforti, et al. (1980)
• Cancer of the gastrointestinal tract and exposure to asbestos in drinking water among lighthouse keepers (Norway) — K. Kjaerheim, B. Ulvestad, et al. (2005)
• 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)

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