Transmaternal variation of the Berenblum experiment with NMRI-mice: tumour initiation with DMBA via mothers milk followed by promotion with the phorbol ester TPA.

DMBA which is applied transmaternally via the mothers milk can initiate tumour cells in the F-1 generation. Subsequent application of the tumour promoter TPA to the back skin of the young animals induced the formation of skin papillomas and carcinomas. Animals treated according to this scheme also developed malignant neoplasms in the other organs. Control animals treated with DMBA only, rarely developed tumours, whereas treatment with TPA alone had no effect. This variation of the Berenblum-experiment suggests that the transfer of carcinogens in human milk should be considered in addition to transplacental carcinogen transfer as a potential hazard to the developing human infant.