Carcinogenicity of DDT (dichlorodiphenyl trichloroethane) in pure inbred Swiss mice.

Inbred Swiss mice were treated with technical DDT (1) orally with the diet or by intubation; (2) subcutaneously and (3) by skin painting. The total duration of the experiment was 80 weeks. There was no difference in body growth and mortality between the experimental and control groups. Toxic manifestations of DDT were observed in treated mice in the form of tremor, convulsions and corneal opacity usually after 40 weeks. Oral and subcutaneous DDT treatment resulted in a significant increase in the incidence of tumours mainly of lymphoid tissues, lung and liver. The highest tumour incidence was recorded in the group of mice receiving DDT by subcutaneous injections. Males and females were equally susceptible. No evidence of carcinogenicity was observed in the painted group.