ABSTRACT
Environmental factors may play an important role in the etiology of female breast cancer. This paper reviews existing evidence to compare and analyze environmental agents in relation to breast cancer. The authors have reviewed multiple studies focusing on xenoestrogens, organochlorines, polychlorinated biphenyls, and other environmental agents, and the results are cited. Current use of oral contraceptives and prolonged use of hormone replacement therapy moderately increase risk. Evidence regarding organochlorine exposure and breast cancer risk is mixed. Atrazine is not associated with breast cancer risk, but dieldrin and lindane are. The effects of polychlorinated biphenyls vary according to specific congeners. An observational study has linked benzene to breast cancer, but another case control study has refuted the association. Risk of breast cancer with smoking is strong in families with a history of breast cancer, ovarian cancer, or both. Studies have shown a positive association of breast cancer with heterocyclic amines in women who eat well-done meat. Thus, many environmental factors have been significantly associated with breast cancer. Differing distribution of socio-demographic factors, including race/ethnicity, parity, and, possibly, nutritional status, may explain some of the inconsistencies across studies. Further research is needed to verify associations.