Endocrine disruption and its varying connotations continue to be some of the most relevant and contentious topics in environmental science, reproductive and developmental toxicology, and endocrinology. Many of the xenobiotics (exogenous chemicals) involved are ubiquitous in the environment and/or have very important roles in agriculture, industry, and human health. Wildlife populations, particularly those living in aquatic environments, are usually the first animal species to exhibit adverse xenobiotic-associated effects on reproductive function. Chemical exposures have been associated with various neoplasias that can affect humans, including those of the breast, uterus, cervix, and prostate, as well as birth defects in children, declining sperm numbers in men, endometriosis in women, and increasing obesity within the general population. Some of the aforementioned effects might not only occur in the individuals directly exposed to these chemicals during pre- or postnatal development but transgenerational effects caused by appropriately timed, xenobiotic-induced genetic mutations or epigenetic modifications have been shown to also impact future generations of those exposed. Data have even suggested that some chemicals can have neurobehavioral effects, influencing sexual attractiveness and parenting skills. However, interpretations or, in some instances, overinterpretations of the experimental data continue to be subject to considerable debate and differences of opinion. Some experimental results might not be reproducible, and others appear to be dependent on the species, age, and strain of animal model being used, as well as the tissue and end point being evaluated. Yet, although some of these data might only apply to very well-defined conditions specified by experimental protocols, we, as a society, should also be prepared to not let excessive cynicism and the potential for financial inconvenience prevent us from at least considering the potential impact of such data when applied to a broader set of “real-life” circumstances. The number and volume of chemicals of concern and the critical importance of the environmental and health issues involved continue to require an ongoing and concerted effort by scientists and health professionals and the expenditure of hundreds of millions of dollars by government and industry to clarify these issues, especially as they apply to human health.
