Environmental chemicals and breast cancer risk--a structural chemistry perspective

In modern industrialized societies, people are exposed to thousands of naturally occurring and synthetic chemicals throughout their lifetime. Although certain occupational chemicals are known to be carcinogenic in humans, it has been difficult to definitively determine the adverse health effects of many environmental pollutants due to their tremendous chemical diversity and absence of a consistent structural motif. Many environmental chemicals are metabolized in the body to reactive intermediates that readily react with DNA to form modified bases known as adducts, while other compounds mimic the biological function of estrogen. Because environmental chemicals tend to accumulate in human tissues and have carcinogenic and/or estrogenic properties, there is heightened interest in determining whether environmental chemicals increase risk for endocrine-related cancers, including breast cancer. Breast cancer is the most common cancer in women worldwide, but established risk factors account for a relatively small proportion of cases and causative factors remain ambiguous and poorly defined. In this review, we outline the structural chemistry of environmental contaminants, describe mechanisms of carcinogenesis and molecular pathways through which these chemicals may exert detrimental health effects, review current knowledge of relationships between chemicals and breast cancer risk, and highlight future directions for research on environmental contributions to breast cancer. Improved understanding of the relationship between environmental chemicals and breast cancer will help to educate the general public about real and perceived dangers of these pollutants in our environment and has the potential to reduce individual risk by changing corporate practices and improving public health policies.