Mutagenic activity in nipple aspirates of human breast fluid.

The Ames Salmonella mutagenesis test was applied to nipple aspirates of breast fluid from 456 women attending breast-screening clinics. Positive tests for presumptive mutagenic substances were found in 6.7% of the women tested. These findings support our hypothesis that mutagenic substances reach the breast epithelia and may have etiologic implications in the pathogenesis of benign disease and breast cancer.