Transmigration of ingested asbestos

Our plain-English summary of Transmigration of ingested asbestos, by M.E. Meek (Environmental Health Perspectives, 1983).

The study

• Author: M.E. Meek
• Journal: Environmental Health Perspectives
• Published: 1983;53:149-52
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

There has been speculation that the ingestion of asbestos in food and drinking water may play some role in the etiology of cancer of the gastrointestinal (GI) tract. An important question in the evaluation of the possible human cancer risk associated with asbestos ingestion is whether fibers can penetrate into and through the GI tract in sufficient numbers to cause adverse systemic or local effects. Factors that complicate interpretation of the available data on the transmigration of ingested asbestos are discussed, and the preliminary results of our ongoing investigation of the penetration of amosite fibers into the normal and abnormal intestinal mucosa of the Wistar rat are reported.

In plain English

This short paper discussed factors that make earlier studies hard to interpret on whether swallowed asbestos fibers pass through the wall of the gut. It also reported preliminary results of the author's own experiments in Wistar rats using UICC amosite. When amosite was injected directly into the wall of the duodenum (the first part of the small intestine) of two rats, granulomas made of dense masses of macrophages were present 4 days later, with crystals resembling amosite visible inside cells. Saline injected into two control rats caused a smaller reaction. Rats given 100 mg of amosite by stomach tube daily for 5 days showed no macrophage response or other changes in the small intestine under the light microscope. In six female rats given amosite plus a drug to cause ulcers in the gut, no fibers were seen inside cells in ulcerated areas. The author concluded that the rat gut wall may be an effective barrier to asbestos even where the lining is lost. The author noted that the dosing period may have been too short, and that fibers too small for the light microscope could have been missed.

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: Discussion of earlier studies combined with preliminary animal experiments in rats, using light microscopy
• Who was studied: Wistar rats. Two rats received amosite injected into the duodenal wall, with two saline-injected controls. Rats (number not stated) were fed amosite by gavage for 5 days. Six female rats received amosite plus indomethacin to induce ulcers, with six corn-oil controls.
• Exposure: UICC amosite, given in three ways. First, 0.1 mL suspensions injected into the duodenal wall. Second, 100 mg by gavage daily for 5 days. Third, 100 mg by gavage daily for 2 days, then 10 mg/kg indomethacin to induce ulcers, followed by 25 mg amosite daily until the rats were killed at about 24 to 120 hours.
• Main results:
  • In the two rats injected with amosite into the duodenal wall, granulomas of dense macrophage masses formed at the injection sites, with intracellular crystals having the polarizing characteristics of amosite.
  • In the two control rats, a smaller and more localized tissue reaction occurred at the saline injection sites.
  • In rats given 100 mg amosite by gavage daily for 5 days, there was no macrophage response or other pathological change in the small intestine 5 days later, on light microscopy.
  • In the amosite-fed rats given indomethacin to induce ulcers, no intracellular fibers were seen in ulcerated areas on polarizing light microscopy.
• The authors' conclusion: The author concluded that these preliminary results indicate the rat gut wall may be an effective barrier to asbestos penetration, even when the epithelium is lost.
• Limitations the authors state:
  • The administration period may not have been long enough.
  • Fibers smaller than the resolution limit of the light microscope could have been missed. Electron microscopy might reveal them.
  • The method does not entirely rule out limited penetration by small fibers.
  • Injection into the gut wall is not a natural route and does not simulate human ingestion. That experiment was done only to characterize the tissue response.

Topics

Medical terms in this study, explained in our Lexicon: Etiology, Amosite.

Related studies

• Review of published studies on gut penetration by ingested asbestos fibers — P.M. Cook (1983)
• Accumulation of ingested asbestos fibers in rat tissues over time — K. Patel-Mandlik, J. Millette (1983)
• An investigation of the penetration of ingested asbestos into the normal and abnormal intestinal mucosa of the rat — M.E. Meek, P. Grasso (1983)
• Ingested mineral fibers: elimination in human urine — P.M. Cook, G.F. Olson (1979)
• Quantitative assessment of chrysotile fibrils in the bloodstream of rats which have ingested the mineral under different dietary conditions — M. Weinzweig, R.J. Richards (1983)
• Distribution of 6-6(n)-3[H]sucrose and its radiolabeled degradation products from isolated, perfused rat small intestine loops following prolonged ingestion of chrysotile asbestos — R. Jacobs, R.J. Richards (1980)

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