Genotoxicity of human milk extracts and detection of DNA damage in exfoliated cells recovered from breast milk

Genotoxic agents of environmental or dietary origin may play a role in brea st cancer initiation. The ability of extracts of human milk to cause mutati ons in S. typhimurium TA1538 and YG1019 and to induce micronuclei and DNA s trand breaks in MCL-5 cells was investigated. Twenty samples from different donors were analysed and of these, 6 were adjudged to produce a positive m utagenic response in one or both bacterial strains. The same samples also i nduced significant micronucleus formation in MCL-5 cells. In the comet assa y, 13/20 samples caused DNA strand breaks in MCL-5 cells. Viable exfoliated breast cells were recovered from fresh milk samples and the ability of mil k extracts to cause DNA damage in these cells was demonstrated. The results show that human milk can contain components capable of causing genotoxic d amage in test systems and in human breast cells, events that may be signifi cant in the initiation of breast cancer, (C) 1999 Academic Press.