Bisphenol A (BPA) is a chemical first synthesized more than 100 years ago; it is frequently used for the production of polycarbonate plastics and epoxy resins.1, 2 BPA can bind to estrogen receptors with weaker affinity than estradiol, and even so may affect estrogen-responsive tissue and cells.2, 3 Studies suggest numerous health disorders associated with high BPA levels, typically associated with industrial exposure.4, 5
There is still scarce evidence on the effects of long-term, low-dose exposure to BPA in human health.5 Sources of low-dose BPA include canned food, meat products, plastic bottles, thermal papers (receipts), personal care products and dental restorative composites.6-8 Diet is the main source of BPA exposure in most countries.9
Acceptable exposure limits are specified by national or regional regulatory agencies, such as the U.S. Environmental Protection Agency (EPA) and European Food Safety Authority. In the U.S., a consortium was created to address research gaps and interpret relevant data, the Bisphenol A Toxicity (CLARITY-BPA) core study, which is a research program between the National Institute of Environmental Health Sciences (NIEHS) and the National Center for Toxicological Research (NCTR) of the U.S. Food and Drug Administration (FDA). Initial results in rats suggested that differences between BPA treatment groups (below 25,000 μg per kg body weight per day) and the control group were not dose responsive and did not demonstrate a clear pattern of consistent responses, suggesting that potential adverse effects of low-dose BPA exposure are uncertain.10
Specifically relevant to dentistry, significant increase in urinary BPA levels has been observed in pediatric patients two days after treatment, which declined to baseline levels after 4 weeks.11 Three trials have compared potential outcomes of BPA exposure between children with amalgam restorations to children with resin composite restorations. The first was a randomized, controlled trial that examined behavioral parameters and did not find differences between the two groups.12 A second trial found no statistically significant differences in body mass index, percentage body fat, or height.13 The third trial monitored psychological problems, and found no relationship with the type of dental restorations children had, except for an association between psychological problems and having more than 13 surfaces of resin restorations.14