Bisphenol A (BPA) is a synthetic chemical with endocrine-disrupting properties that is present in many consumer items: the linings of aluminum cans, heat-activated or pressure-printed cash register receipts, dental sealants and polycarbonate plastic products such as food and drink containers. Because of its prevalence, many people are exposed to BPA on a recurring basis. Data from the US Centers for Disease Control and Prevention suggest that BPA is present in the bodies of more than 90% of American adults.

Concerns regarding the risks of this widespread exposure have grown during the past 15 years, as hundreds of studies have reported adverse effects of low-dose exposure to BPA in animal models. In rodents, fetal and neonatal exposure has been shown to affect reproductive development in both males and females. But the relevance of results from rodent studies to human health has been questioned, in part because metabolism of BPA differs between rodents and humans, even though the pharmacokinetics of BPA within the body were recently reported to be quite similar in rodents, nonhuman primates and humans. To address these concerns, researchers led by Patricia A. Hunt (Washington State University, Pullman) evaluated the effects of BPA in animals more closely related to humans: rhesus macaques. The results provide evidence that exposure to BPA can alter chromosomes and affect reproductive viability in primates.

Hunt studied BPA exposure in pregnant macaques and their unborn female offspring and found that it caused damage during two stages of oogenesis. First, during early meiosis, Hunt's team observed disturbances in prophase events that affect chromosome segregation and could cause eggs to divide improperly, potentially resulting in birth defects (Proc. Natl. Acad. Sci. USA published online 24 September 2012; doi:10.1073/pnas.1207854109). Second, during follicle formation later in oogenesis, the group noted defects in oocyte packaging, which could limit the number of viable eggs in female offspring, impairing their fertility.

The results indicate that BPA exposure can affect multiple generations simultaneously: a pregnant female, her fetus and that fetus' future offspring, if the fetus is female. “It's a three-for-one hit,” Hunt said (USA Today, 26 September 2012; http://usatoday30.usatoday.com/news/nation/story/2012/09/26/bpa-damages-chromosomes-in-monkeys/57838050/1). The implication is that the effects of BPA exposure may not be fully manifested for one generation, which could complicate efforts to establish direct links between exposure and adverse outcomes.

Hunt's findings in rhesus macaques confirm results of earlier studies in rodents and suggest that fetal exposure to BPA may adversely affect reproductive potential in humans.