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Toxicological information

Carcinogenicity

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Weight of evidence: Experimental results with trichloroacetic acid and read-across from sodium trichloroacetate. 
Drinking water studies of the carcinogenicity of trichloroacetic acid in male and female mice and in male rats. A number of studies have been reported which indicate that trichloroacetic acid is a hepatocarcinogen in the mouse strain B6CBF1. The male is more sensitive than the female. In a single study conducted in the rat, trichloroacetic acid was observed to be hepatotoxic but not hepatocarcinogenic.
Read-across:
In a two-year feeding study with the substance sodium trichloroacetate in rats, there was no evidence of substance-specific neoplastic alterations in any of the groups.

Key value for chemical safety assessment

Additional information

Weight of evidence: Experimental results with trichloroacetic acid and read-across from sodium trichloroacetate.

Drinking water studies of the carcinogenicity of trichloroacetic acid in male and female mice and in male rats. A number of studies have been reported which indicate that trichloroacetic acid is a hepatocarcinogen in the mouse strain B6C3F1. The male is more sensitive than the female. It is also well known the high sensitivity of the B6C3F1 mouse liver to the consequences of disruption (by both genotoxic and supposedly non-genotoxic carcinogens) of cellular growth regulation.

In a single study conducted in the rat, trichloroacetic acid was observed to be hepatotoxic but not hepatocarcinogenic.

Read-across:

In a two-year feeding study with the substance sodium trichloroacetate in rats, there was no evidence of substance-specific neoplastic alterations in any of the groups. Because trichloroacetic acid causes liver tumours only in the male B6C3F1 mouse after administration of very high concentrations and the peroxisome proliferation detected represents an extensively rodent-specific processs, which has a subordinate meaning in humans, a tumour-initiating action is unlikely for the substance trichloroacetic acid. It is also well known the high sensitivity of the B6C3F1 mouse liver to the consequences of disruption (by both genotoxic and supposedly non-genotoxic carcinogens) of cellular growth regulation. In the male B6C3F1 mouse the background rate of appearance of liver tumours is notably high, whereas the female mouse liver shows a considerably lower background incidence both in the trichloroacetic acid studies and in other studies. Therefore, based on these results, there is no evidence that humans are at significant risk for hepatocellular toxicity.

Justification for classification or non-classification

Based on the reported results, there is no evidence that humans are at significant risk for hepatocellular toxicity and therefore, the substance is not classified for carcinogenicity.