A Lancet Oncology report summarises the conclusions from IARC’s October 2012 meeting on the carcinogenicity of several chlorinated solvents and some of their metabolites. The full report will be published as volume 106 of IARC’s series of Monographs on the Evaluation of Carcinogenic Risks to Humans.

Studies associating trichloroethylene (TCE) exposure with an increased risk of kidney cancer have provided “sufficient” evidence for carcinogenicity in humans. Animal evidence was also judged to be “sufficient” on the basis of several studies exhibiting increased incidences of tumours at multiple sites in rats and mice following oral or inhalation exposure. As a result, the working group classified TCE as “carcinogenic to humans” (Group 1).

Human data on the carcinogenicity of tetrachloroethylene was judged to be “limited”. However, findings from studies in rats and mice provided “sufficient” evidence for its carcinogenicity in animals, and mouse studies identified several potential genotoxic and non-genotoxic mechanisms of liver carcinogenesis of relevance to humans. It was classified as “probably carcinogenic to humans” (Group 2A).

Although the evidence for the carcinogenicity of chloral hydrate in humans was inadequate, it was upgraded to group 2A (“probably carcinogenic to humans”) on the basis of its genotoxicity in most experimental systems and in humans, and “sufficient” evidence of carcinogenicity from several mouse studies showing increased incidences of liver tumours (hepatocellular adenomas and carcinomas).

Dichloroacetic acid, trichloroacetic acid, 1,1,1,2-tetrachloroethane and 1,1,2,2-tetrachloroethane increased the incidence of liver (hepatocellular) tumours in several chronic bioassays in mice, and hence were classified as “possibly carcinogenic to humans” (Group 2B) on the basis of “sufficient” evidence for carcinogenicity in animals.

Guha N et al. (2012). Carcinogenicity of trichloroethylene, tetrachloroethylene, some other chlorinated solvents and their metabolites. Lancet Oncology. Early online publication.

http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045(12)70485-0/fulltext?_eventId=login#tbl1

 

The above item was taken from the December 2012 issue of Toxicology and Regulatory News which is sent automatically to members of bibra (click here for more details).

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