In vivo formation of a carcinogenic substance from diethyl pyrocarbonate in the presence of ammonia

Mice of different strains have been treated repeatedly with diethyl pyrocarbonate (DEPC) and/or ammonia by gastric tube. In adult mice treated with DEPC plus ammonia, pulmonary tumours developed. However, DEPC or ammonia alone proved not to have any carcinogenic effect. When DEPC administration was followed by ammonia treatment more pulmonary tumours developed than in the case of ammonia-DEPC sequence. The shorter the time interval between DEPC and ammonia administrations the higher the number of lung tumours observed. Pulmonary tumours could not be observed in the offspring of pregnant mice treated with DEPC and ammonia or in suckling mice whose mother was treated with DEPC and ammonia. In gastric juice a new substance is formed from DEPC in the presence of ammonia. This new substance was very similar or identical to urethane according to the thin layer chromatographic investigation.