No matter what you read—or what anyone else tells you—some environmental risk factors do seem to exist. In fact, so-called endocrine-disrupting chemicals and carcinogens (which may increase breast cancer risk) are present in many working environments. For example, one study found that women who worked in certain jobs, such as plastics manufacturing and food canning, had more than twice the risk of developing premenopausal breast cancer compared to women who did not work in these environments.
6. Exposure to carcinogens