Our knowledge of which environmental chemicals can cause breast cancer (and how) is not complete. Research continues to be conducted on a number of substances to increase our understanding.
There are, however, some substances that people are encouraged to minimize exposure to. One such chemical is bisphenol A (BPA), which is found in polycarbonate plastic and in the lining of tin cans. Some research suggests that BPA may be an endocrine disruptor. This means that it may mimic or disrupt hormones (in this case, estrogen) and can lead to an increased risk of breast cancer. New evidence indicates that it may be especially important for pregnant women to limit their exposure to BPA to protect their offspring from future breast cancer risk. However, scientists disagree about the results of these studies and more research continues to be done.
Parabens, which are preservatives used in many pharmaceutical and cosmetic products, are also being researched as a potential risk for breast cancer. Parabens are absorbed through the skin, and they have been found in biopsy samples from breast tumours. Some researchers have suggested that parabens increase the risk of breast cancer by mimicking the effects of estrogen, however, more research is needed to establish this link.