Leaching of bisphenol A and F from new and old epoxy coatings: laboratory and field studies
Laboratory tests were carried out with three types of new epoxy resins to assess the release of bisphenol A and F (BPA and BPF) and potential halogenated phenolic by-products. Tests were carried out over a duration of 6 months in the presence and absence of disinfectants (chlorine and chlorine dioxide) at realistic doses and contact times. None of the three systems exhibited Fickian-type diffusion for BPA. Leaching was quite low for two epoxies while the third showed a trend of increasing leaching during the first 5 months of immersion. BPA was only observed in the absence of disinfectant while no BPF was observed under any condition. 2,4,6-trichlorophenol (TCP), a BPA chlorination by-product was sporadically observed in the chlorinated water during the first months of contact. Following discontinuation of the disinfectants, its release was significantly enhanced in the water having been exposed to chlorinated water. Laboratory leaching tests also indicated rapid oxidation of epoxies by chlorine and chlorine dioxide. Analysis of 27 epoxy-coated drinking water storage tanks did not reveal any BPA, BPF or TCP. On the other hand, a large-scale examination of about 200 pipe sections rehabilitated with epoxies during the 1990s led to a high frequency of BPA and BPF detection, sometimes with maximum values around 1 μg/L.