The effect of long‐term exposure to DDT on CF‐1 mice

Abstract

Abstract CF‐1 minimal inbred mice were given technical DDT mixed into the diet at the dose levels of 2, 10, 50 and 250 parts per million (ppm) for the entire life span for two consecutive generations. Exposure to all four levels of DDT resulted in a significant increase of liver tumours in males, this being most evident at the highest level used. In females, the incidence of liver tumours was slightly increased following the exposure to 10 and 50 ppm, while a marked increase was observed following exposure to 250 ppm. In DDT‐treated animals the liver tumours were observed at an earlier age than in untreated controls. The age at death with liver tumours and the incidence of liver tumours appeared to be directly related to the dose of DDT to which the mice were exposed. Four liver tumours, all occurring in DDT‐treated mice, gave metastases. Histologically, liver tumours were either well‐differentiated nodular growths, pressing but not infiltrating the surrounding parenchyma, or nodular growths in which the architecture of the liver was obliterated showing glandular or trabecular patterns.