Comments on "Estrogenicity of Resin-Based Composites and Sealants Used in Dentistry"

Considerable concerns about bisphenol A (BPA) as a potential endocrine disruptor remain controversial among dentists and patients due to the study of Olea et al. (1). Their study has frequently been mentioned in scientific papers as well as in the mass media, popular journals, and books. When I read the paper, I was shocked to find unscientific data related to high performance liquid chromatography (HPLC) analysis. I am concerned about continued reference to this study. Ashby (2) commented on the study in a letter in EHP titled "Bisphenol-A Dental Sealants: The Inappropriateness of Continued Reference to a Single Female Patient," but I feel his comments are insufficient. Olea et al. (1) reported that 90-931 pg of BPA was identified in saliva collected from 18 subjects treated with 50 mg of a bisphenol A diglycidyl methacrylate (bisGMA)-based sealant on molars during a 1hr period after treatment. However, based on data presented in their Table 1, this is unlikely. According to Table 1 (1), 50 mg of the sealant should contain 3.7 pg ofBPA or 78.7 pg of a mixture of bis-GMA, bisphenol A diglycidyl ether (BADGE), bisphenol A dimethacrylate (BPDMA), and BPA. This mixture (78.7 pg) is equivalent to 48.2 pg of BPA. Assuming that all the components of the mixture leached into the saliva uncured and were degraded completely to BPA within 1 hr, the amount of BPA collected from the saliva should be 48.2 pg. However, their Table 2 (1) showed 1.9-19.3-fold higher values than expected (89.9-931.0 pg). In the "Results," Olea et al. (1) reported that