Mutagenicity testing of human milk from smokers and non-smokers in the Salmonella/microsome test

Human milk was tested in the Ames plate incorporation test using strain TA98. Pools from smokers and non-smokers respectively, as well as individual samples from 14 smokers and 15 controls were tested. No difference was found between milk from smokers and non-smokers in the concentrations and volumes used. Preliminary to this a cigarette smoke condensate (CSC) was tested. The CSC was then incubated with human milk which was fractionated, concentrated and the different fractions tested for mutagenic activity. 98% of the mutagenic effect added (measured as number of revertants caused by an equivalent volume of CSC) was recovered 52% of the revertant colonies were recovered from the fat fractions, 40% from the skimmed milk and 8% from a precipitate. Breast milk was also incubated with C14-benzo(a)pyrene and then fractionated by density gradient ultracentrifugation. 97% of the radioactivity was found in the lipid fraction.