Chronic effects of dietary exposure to amosite and chrysotile asbestos in Syrian golden hamsters

Our plain-English summary of Chronic effects of dietary exposure to amosite and chrysotile asbestos in Syrian golden hamsters, by E.E. McConnell, A.M. Shefner, J.H. Rust, et al (Environmental Health Perspectives, 1983).

The study

• Authors: E.E. McConnell, A.M. Shefner, J.H. Rust, J.A. Moore
• Journal: Environmental Health Perspectives
• Published: 1983;53:11-25
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Bioassays of amosite, short-range (SR), intermediate-range (IR) or intermediate-range chrysotile asbestos in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted with male and female Syrian golden hamsters. Amosite and both forms of chrysotile asbestos were administered at a concentration of 1% in pelleted diet for the entire lifetime of the hamsters starting with mothers of the test animals. Group sizes varied from 125-254. There was no adverse effect on body weight gain or survival by either type of asbestos or by IR chrysotile asbestos in combination with DMH. A significant increase (p less than 0.05) in adrenal cortical tumors was observed in male hamsters exposed to SR and IR chrysotile asbestos and in females treated with IR chrysotile asbestos when compared to the pooled control groups. However, statistical significance (p less than 0.05) was lost when these dosed groups were compared with temporal control groups. Neither of the male or female amosite asbestos groups showed increased neoplasia in any tissue or organ compared to the control groups. The cocarcinogen studies using IR chrysotile asbestos and 1,2-dimethylhydrazine dihydrochloride were considered inadequate because there was no increase in intestinal neoplasia in the DMH group.

In plain English

This was a lifetime feeding experiment in Syrian golden hamsters. Mated female hamsters, and then their offspring of both sexes for life, were fed pellets containing 1% by weight of amosite asbestos, short-range chrysotile or intermediate-range chrysotile. Group sizes varied from 125 to 254. One set of groups also received 1,2-dimethylhydrazine (DMH), a chemical known to cause intestinal tumors, to test whether chrysotile added to its effect. Asbestos did not harm weight gain or survival. Adrenal cortex tumors called cortical adenomas were significantly more common in males fed either type of chrysotile, and in females fed intermediate-range chrysotile, when compared with all control groups pooled. They were not significantly more common when compared with the control groups run at the same time. The authors reported no increased tumor rate in any organ in the amosite groups. They also reported none in the digestive tract in any treated group, although some groups had slightly higher counts than controls. DMH alone did not produce a significant increase in intestinal tumors, so the combination test was considered inadequate. The authors concluded that, under the conditions of this study, the three asbestos types were not carcinogenic when eaten by these hamsters.

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: Animal experiment: lifetime dietary carcinogenicity bioassay, with exposure starting with the mothers of the test animals, plus a cocarcinogen study combining intermediate-range chrysotile with DMH
• Who was studied: Male and female outbred Syrian golden hamsters born to mated females obtained in 1977 from Charles River Lakeview Laboratories, New Jersey. Group sizes ranged from 125 to 254, and each exposure study had its own temporal control groups.
• Exposure: 1% by weight in pelleted diet of: amosite (sample S-33, from Penge, Transvaal, South Africa); short-range chrysotile (COF-25, from the New Idria serpentine mass, California); or intermediate-range chrysotile (Plastobest-20, from the Jeffrey Mine, Asbestos, Quebec). In the cocarcinogen study, intermediate-range chrysotile was combined with oral DMH at 4 mg/kg every other week for 5 doses, starting at 6 weeks of age.
• Main results:
  • Body weight gain was not adversely affected in any dose group. Survival was not adversely affected by any test diet, with the possible exception of DMH-treated females.
  • In males, adrenal cortical adenomas were significantly increased compared with pooled controls (25/466, 5%) in the short-range chrysotile group (26/229, 11%) and the intermediate-range chrysotile group (24/244, 10%). There was no significant increase in the DMH plus chrysotile group or the amosite group.
  • In females fed intermediate-range chrysotile, adrenal cortical adenomas (18/234, 8%) were also increased compared with pooled controls (15/468, 3%).
  • These adrenal increases were not statistically significant when the dosed groups were compared with their temporal control groups. For example, the temporal controls for intermediate-range chrysotile had 7/115 (6%) in males and 6/118 (5%) in females.
  • Neither the male nor the female amosite group showed increased tumors in any tissue or organ. The only statistically significant difference in the amosite study was a decrease in islet-cell adenomas in females: 2/222 (1%) versus 15/456 (3%) in pooled controls.
  • Male intermediate-range chrysotile hamsters were the only group with a significant increase in overall primary tumors: 78/245 (32%), versus 95/472 (20%) in pooled controls and 26/116 (22%) in temporal controls. The authors attributed this mainly to adrenal tumors.
  • The authors reported that no treated group showed an increased rate of tumors in the gastrointestinal tract, which had been chosen in advance as the target organ.
  • Some treated groups had slightly higher raw proportions of gastrointestinal tumors than controls. For example, amosite-treated males had 6/248 (2%), compared with 6/472 (1%) in pooled controls and 1/122 (1%) in amosite temporal controls.
  • Males given DMH had a significantly increased incidence of leukemia or malignant lymphoma (7/127, 6%) compared with pooled controls (8/472, 2%). Significance was lost when compared with the temporal control group.
  • Males and females given DMH did not show a statistically significant increase in intestinal tumors, so the cocarcinogen study with intermediate-range chrysotile was considered inadequate.
• The authors' conclusion: The authors concluded that, under the conditions of this bioassay, amosite, short-range chrysotile and intermediate-range chrysotile were not carcinogenic when ingested by male and female Syrian golden hamsters. They considered the biological importance of the adrenal tumors questionable, given the absence of tumors in the target organ.
• Limitations the authors state:
  • DMH did not produce enough intestinal tumors to test whether chrysotile adds to its cancer-causing effect, so the authors considered the cocarcinogenic potential of oral asbestos untested.
  • Food consumption was not measured, because hamsters hide their feed in the bedding.
  • Longer survival in the chrysotile groups contributed to their higher incidence of primary tumors compared with controls.
  • The study was not designed to evaluate non-cancer disease.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Jeffrey mine, Asbestos, Quebec
• Penge mine, Transvaal

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Amosite, Chrysotile.

Medical terms in this study, explained in our Lexicon: Amosite, Chrysotile, Statistical Significance.

Related studies

• Chronic effects of dietary exposure to amosite asbestos and tremolite in F344 rats — E.E. McConnell, H.A. Rutter, et al. (1983)
• Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the Syrian golden hamster. Part II. Results of chronic exposure — E.E. McConnell, C. Axten, et al. (1999)
• Studies on the inhalation toxicology of two fiberglasses and amosite asbestos in the syrian golden hamster. Part I. Results of a subchronic study and dose selection for a chronic study — T.W. Hesterberg, C. Axten, et al. (1999)
• Investigations on the effects of chronic cigarette-smoke inhalation in Syrian golden hamsters — W. Dontenwill, H.J. Chevalier, et al. (1973)
• Chronic inhalation study of fiber glass and amosite asbestos in hamsters: twelve-month preliminary results — T.W. Hesterberg, C. Axten, et al. (1997)
• Inhalation studies with Syrian golden hamsters — A.P. Wehner, B.O. Stuart, et al. (1979)

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