Endocrine Abstracts

Several lines of evidence fuel concerns about endocrine disruptors and human health: First, there are increasing trends of endocrine-related disorders such as endocrine cancers, neurodevelopmental disorders, diabetes, thyroidal diseases, and congenital malformations. Second, several widely used chemicals have been linked to such disorders in epidemiological studies and experiments with laboratory animals. Although human exposures involve many endocrine disruptors simultaneously, these efforts have largely focused on single chemicals. Using the example of declines in male reproductive health, this presentation summarises the state of the art of experimental mixture studies with chemicals known to disrupt male sexual development. These studies show that risk assessments should consider combined exposures to bisphenols, polychlorinated dioxins, polybrominated diphenyl ethers, analgesics, parabens, phthalates, triclosan and azole pesticides together. The first mixture risk assessment with focus on declines in semen quality which considers all these chemicals together is presented. It shows that current exposures of the general population are several-fold higher than levels judged to be tolerable. Bisphenols, dioxins and analgesics make the largest contribution to combined risks to semen quality. This analysis calls for substantial reductions in exposures to several chemicals to protect the developing foetus and childhood, life stages vulnerable to impacts on semen quality. It helps prioritise those chemicals that should be targeted to achieve the greatest impact on risk mitigations. The findings provide explanations for reports of substantial declines in semen quality in Western countries.