Bisphenol A: an endocrine and metabolic disruptor

Bisphenol A (BPA), initially designed, like diethylstilbestrol, as a synthetic estrogen, has been rapidly and widely used for its cross-linking properties in the manufacture of polycarbonate plastics and epoxy resins. Because of incomplete polymerization and degradation of the polymers by exposure to higher than usual temperatures, BPA leaches out from food and beverage containers, as well as from dental sealants. In humans, free active unconjugated BPA is metabolized by rapid glucurono- or sulfo-conjugation and eliminated via renal clearance. However, exposure to environmental nanomolar concentrations of BPA is ubiquitous and continuous via different routes: oral, air, skin. In rodents, fetal and perinatal exposure to such environmentally relevant doses of BPA has been shown to affect the brain, liver, gut, adipose tissue, endocrine pancreas, mammary gland and reproductive tract and function. Similar concentrations are also able in vitro to impact human malignant breast, prostate, male germ or adipocyte cell lines (with a promoting effect and by interfering with chemotherapy drugs), or to stimulate pancreatic β cell insulin secretion. High levels of BPA have recently been correlated with obesity, diabetes, cardiovascular diseases, polycystic ovarian disease or low sperm count. However, before the real impact of BPA on human health can be clearly assessed, prospective longitudinal epidemiological studies are needed as well as characterization of selective biomarkers to verify long-term exposure and selective imprinting.