Biological effects of ingested asbestos: report and commentary

Our plain-English summary of Biological effects of ingested asbestos: report and commentary, by D.H. Lee (Environmental Health Perspectives, 1974).

The study

• Author: D.H. Lee
• Journal: Environmental Health Perspectives
• Published: 1974;9:113-22
• Type of article: Review
• Cited by: 10 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. 001276).

In plain English

This article is not an original study. It is the author's report and commentary on a conference on ingested asbestos, organized by the National Institute of Environmental Health Sciences and the Environmental Protection Agency in Durham, North Carolina, in November 1973. The conference followed the discovery of mine-residue asbestos in Lake Superior near Duluth's water intake. The author stated that the interpretations were the reporter's own. The overview was restricted to conference information, plus only such additional material as needed for continuity and perspective. The report summarized other researchers' work on fiber measurement, fibers in water, food and drugs, gut-wall passage, and tissue reactions. For example, Nicholson reported 20 to 70 million amphibole fibers per liter in Duluth's drinking water. The author judged there was little doubt that fibers can pass through the gut wall. However, no substantial evidence was presented linking ingested asbestos to the rise in gastrointestinal cancer. The author also stated that negative animal feeding results could not be taken as indications of safety for humans. The author concluded that the conference raised more questions than it answered, and listed research needs.

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: Conference report and commentary (overview of papers and discussion at a scientific conference); not an original study
• Who was studied: Contributions and discussions at a joint NIEHS-EPA conference held in Durham, North Carolina, November 18-20, 1973. Attendees included geologists, crystallographers, chemists and biomedical scientists. The conference was prompted by asbestos pollution of Lake Superior near Duluth, Minnesota, which was recognized in early 1973.
• Exposure: Ingested asbestos in drinking water, food, beverages and drugs. This included chrysotile and amphiboles, with the cummingtonite-grunerite series mainly seen at Duluth. It also included tremolite contamination of talc.
• Main results:
  • The author's overall judgment from the presentations and discussion was that there seemed to be little doubt asbestos fibers can penetrate into and pass through the gastrointestinal wall. The open question was whether they do so under normal conditions in the human gut, in quantities sufficient to be a serious cancer threat.
  • According to the report, no substantial evidence was provided at the conference for an association between the increase in gastrointestinal cancer and ingestion of asbestos.
  • Very little was said at the conference about the production of mesothelioma, beyond its appearance in certain experimental animals after intraperitoneal injection.
  • Nicholson, a conference participant, reported 20 to as high as 70 million amphibole fibers per liter in Duluth's drinking water system. Nicholson did not find detectable amphibole asbestos in the drinking water of New York City or Grand Marais, Minnesota.
  • Speil, a conference participant, reported chrysotile content in the water supplies of ten cities ranging between 0.005 and 6.0 micrograms per gallon.
  • Webster's paper reported that baboons fed asbestos-contaminated food and water for 5 years did not develop peritoneal or gastrointestinal tumors. The author noted that 5 years is too short for tumors to develop if baboons react like humans.
  • The author stated that failure of experimental animals to develop bowel cancer or mesothelioma after oral feeding of asbestos cannot be taken as indications of safety for humans.
• The authors' conclusion: The author concluded that the conference raised more questions than it answered. The author wrote that how great the risk from ingested asbestos is "only time will tell" but that until then it cannot be ignored. The author listed urgent research needs, including better fiber detection methods and epidemiological surveys.
• Limitations the authors state:
  • The overview does not attempt to summarize all available knowledge. It is restricted to information presented at the conference, with only such additional material as is necessary for continuity and perspective.
  • Not all contributions on measurement techniques were turned into formal presentations.
  • Detection methods were at the limits of their sensitivity. A tenfold variation can be expected in replicate analyses.

Related studies

• Recovery of ingested asbestos fibers from the gastrointestinal lymph in rats — P. Sebastien, R. Masse, et al. (1980)
• Effects of ingested chrysotile on DNA synthesis in the gastrointestinal tract and liver of the rat — D.E. Amacher, A. Alarif, et al. (1974)
• The dose-dependent effects of ingested chrysotile on DNA synthesis in the gastrointestinal tract, liver, and pancreas of the rat — D.E. Amacher, A. Alarif, et al. (1975)
• Ingested asbestos in filtered beer, in addition to occupational exposure, as a causative factor in oesophageal adenocarcinoma — R.C. Fitzgerald, J.M. Rhodes (2019)
• Multiple factors in carcinogenesis — S.S. Epstein (1974)
• Ingested mineral fibers. Do they penetrate tissue or cause cancer? — P. Gross, R.A. Harley, et al. (1974)

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