The effect of transplacental administration of ddt on organ cultures of foetal mouse lung tissue

Recent data pointing to a possible oncogenic action of DDT‐one of the most widely used pesticides‐have led the World Health Organization to undertake, through the International Agency for Research on Cancer in Lyons, a collective international study on this compound. Organ cultures of foetal lung tissue from strain A mice exposed to DDT through the transplacental route showed intensive growth as compared to controls, a total of 1,076 DDT‐exposed explants and 712 controls being examined. A dose of 50 ppm (parts per million) DDT induced a diffuse hyperplasia and focal proliferations, i.e. pre‐adenomatous lesions, in the first generation. A progressively higher incidence of these lesions was observed at a dose level of 10 ppm, rising from 8.9% in the F1 generation to 39.9% in the Fa generation; however the incidence dropped in the F4 and F5 generations (30.1% and 20.1% respectively). These observations may be suggest that DDT an oncogenic agent but with only a relatively weak activity.