Susan G. Komen for the Cure asked the Institute of Medicine (IOM) to perform a comprehensive review of environmental causes and risk factors for breast cancer. Interestingly, none of the consumer products (ie, bisphenol A, phthalates), industrial chemicals (ie, benzene, ethylene oxide), or pesticides (ie, DDT/DDE) considered could be conclusively linked to an increased risk of breast cancer, although the IOM acknowledged that the available evidence was insufficient to draw firm conclusions for many of these exposures, calling for more research in these areas. The IOM found sufficient evidence to conclude that the 2 environmental factors most strongly associated with breast cancer were exposure to ionizing radiation and to combined postmenopausal hormone therapy. The IOM's conclusion of a causal relation between radiation exposure and cancer is consistent with a large and varied literature showing that exposure to radiation in the same range as used for computed tomography will increase the risk of cancer. It is the responsibility of individual health care providers who order medical imaging to understand and weigh the risk of any medical procedures against the expected benefit.