The volume emphasizes that there are many challenges to studying breast cancer risk, including the possibility that some exposures that may influence risk occur early in a woman’s life, even in utero. The book recommends examining exposures at all stages of life, not just during adulthood, as well as taking a multidisciplinary approach to studies of breast cancer risk. It also emphasizes developing new methods for epidemiologic research, for accurately assessing exposure to potential risk factors, and for testing the cancer risk of chemicals and other substances.
Because data from human studies are often unavailable or inconclusive, the committee did not find strong evidence linking many suspected chemicals to breast cancer risk; only exposures to benzene, 1,3-butadiene, and ethylene oxide had “possible association[s]” with increased breast cancer risk. Several other chemicals, including BPA, had “biological plausibility as a hazard,” but no human studies have confirmed an association with cancer risk.

