Endocrine Abstracts

Human-made chemicals have become an inevitable part of life. There are approximately 100 000 chemicals on the European market and 70% of them have not been assessed for human health risks. As a consequence, every citizen faces exposure to mixtures of poorly characterized chemicals that include, for instance, flame retardants, plasticizers, additives in personal care products, and persistent organic pollutants. The exposures correlate with multiple adverse health outcomes including infertility. My research has centred on women living in Sweden. Complex mixtures of persistent organic pollutants were found in every woman of reproductive age participating in our studies, and the levels correlated with lower ovarian reserve, longer time-to-pregnancy, and smaller chances to succeed in infertility treatments. The chemicals were present in follicular fluid at similar levels to serum, indicating direct exposure of the maturing oocytes. Several associations were found between exposure and markers of ovarian function and fertility. For example, the concentration of the perfluoroalkyl substance PFOS in follicular fluid associated with higher basal antral follicle count but lower embryo quality in women undergoing IVF tretments. In controlled exposure experiments, PFOS disrupted gene expression and DNA methylation in bovine blastocysts at human relevant levels. Further, our in vitro studies with human endometrial cells showed that PFOS might also disrupt decidualization. Finally, persistent organic pollutants including PFOS were found to cross the placenta and deposit to vital organs in human foetuses. In summary, exposure to human-made chemicals is life-long and starts before birth. Epidemiological research together with experimental studies suggest multiple associations between chemicals and adverse fertility outcomes including altered oocyte maturation and embryo development. It is essential that chemical hazards towards fertility in women are better studied. Immediate actions should include development of assays that can be applied to study the safety of chemicals already in commerce, and new ones to come before they enter the market.