Development, Validation and Application of an Accelerated Weathering Protocol for Assessing Bisphenol A Release from Polycarbonate Materials into the environment

Abstract

Bisphenol A (BPA) is under continuous regulatory scrutiny and listed as substance of very high concern (SVHC). Particular concern is related to its frequent detection in surface waters, despite being readily biodegradable. Several studies have been conducted to investigate sources and pathways of BPA in the environment, concluding that its main use as monomer in polycarbonate (PC) contributes only marginally to environmental BPA releases over its life cycle. To better understand the actual releases of BPA from PC under environmental conditions, a newly developed methodology (Federal Institute for Materials Research and Testing, BAM) was applied, which comprises a novel accelerated weathering protocol for polycarbonate (PC) materials, combined with an advanced analytical setup allowing for improved detection of BPA at trace level concentrations. The weathering protocol achieves a 13.6-fold acceleration compared to Central European outdoor conditions and simulates environmental stressors (global radiation, rain, temperature variations) in a laboratory weathering chamber, with simultaneous BPA release measurements using an organic isotope dilution calibration LC-MS/MS approach. Validation was performed in parallel outdoor exposure tests, by using haze and yellowness index measurements as reference parameters. PC sample types representative of major polycarbonate applications were examined: Samples with different levels of UV-protection as used in transparent sheets used outdoor in construction or housings in Electro- and Electronic applications as well as samples with a protective coating as used in automotive applications (headlamps, glazing and construction). Results demonstrated consistently low total BPA releases of around 0.3 mg m⁻² for samples with exposed PC surfaces, while releases from coated samples were significantly reduced by around two orders of magnitude. In all cases examined, the BPA release ceased to zero after a period of four to six weeks, equivalent to approximately 1 to 1.5 years of outdoor exposure. This suggests that potential BPA releases diminish to virtually zero after that timespan. While the newly developed test method is not suitable for routine laboratory implementation, it provides crucial quantitative data on BPA release from PC materials during accelerated environmental weathering