Studies in experimental animals exposed to trichloroacetic acid were limited by incomplete pathology examination, short durations of exposure, and small numbers of animals. Studies with such a design cannot show the full expression of carcinogenic response. For any study in which trichloroacetic acid is administered in the drinking-water, palatability is an issue; decreases in drinking-water consumption have been observed at high doses. Such decreased drinking-water consumption not only affects the dose administered but also may affect the health of the animals.

See Table 3.1

Studies of carcinogenicity in experimental animals given trichloroacetic acid by oral administration.

As part of an initiation–promotion study in male B6C3F1 mice (age, 4 weeks), trichloroacetic acid was administered in a buffered solution of drinking-water at a concentration of 5 g/L (Herren-Freund et al., 1987). Controls were given drinking-water containing sodium chloride at 2 g/L. The experiment was terminated at 61 weeks because of tumour induction. Histopathological examination was restricted to the liver. At termination of the experiment, mice treated with trichloroacetic acid were found to have an increased incidence of hepatocellular adenoma (2 out of 22 in controls versus 8 out of 22 in treated mice, [P