You are here:
Empirical measurement of PFAS dosing within in vivo aquatic high throughput assays
Citation:
Blackwell, B., E. Stacy, K. Bush, K. Flynn, J. Hoang, M. Le, AND Dan Villeneuve. Empirical measurement of PFAS dosing within in vivo aquatic high throughput assays. SETAC North America, Pittsburgh, PA, November 13 - 17, 2022. https://doi.org/10.23645/epacomptox.21561225
Impact/Purpose:
Poster presented to the Society of Environmental Toxicology and Chemistry (SETAC) annual meeting November 2022. Per and polyfluorinated alkyl substances (PFAS) are a class of chemicals of high concern with respect to potential effects on human health and/or ecosystems. To improve the pace of testing PFAS for ecotoxicological effects, high throughput methods have been developed. Chemical measurements are needed to better understand the bioavailable chemical exposure in high throughput systems. Chemical concentration data for 22 tested PFAS were collected and will be summarized as it pertains to interpreting high throughput effects data and to the development of models for PFAS distribution within similar high throughput assays.
Description:
As part of the US EPA’s PFAS Strategic Roadmap, the agency is committed to increasing our understanding of the potential ecological effects of per- and polyfluoroalkyl substances (PFAS). To improve the pace of PFAS chemical assessments, new approach methods focused on ecologically relevant aquatic species have been developed, allowing a more rapid assessment of chemical toxicity by high throughput testing (HTT). Moving to HTT assays does create additional challenges for exposure characterization, and as a consequence, most HTT data are reported only for nominal exposure concentrations; however, unique chemical properties can lead to substantial deviations between reported nominal concentration and the free concentration in solution. While in vitro chemical distribution models exist, most are applicable only for neutral organics, whereas PFAS – most of which are ionogenic chemicals – fall outside of model domains of applicability due to their unique physicochemical properties. As such, empirical measurements of PFAS in HTT systems are currently needed to accurately determine exposure conditions within in vivo HTT assays. Here, we empirically measured the concentration of 22 PFAS in exposure media following 24 h exposure of individual PFAS to either Pimephales promelas larvae or juvenile Daphnia magna in a 96 deep well format. After exposure, aliquots of exposure media were removed and stabilized with an equal volume of acetonitrile. All analytes were subsequently measured by HPLC-MS/MS. Tested PFAS included multiple homologues of carboxylic and sulfonic acids, sulfonamides, and fluorotelomer sulfonates, among others. In general, homologues followed a predictable pattern of decreasing free concentration with increasing chain length (e.g., ranging approximately 70 – 1.0% of nominal for 5 – 14 chain carboxylic acids). A more volatile fluorotelomer alcohol showed less than 1% recovery likely indicating loss to headspace and/or method incompatibility, while a fluoroether compound was fully degraded prior to exposure likely due to initial stock solubilization in DMSO. The results highlight the need to fully consider the physicochemical properties of specific PFAS prior to HTT assay screening. Data will be presented and discussed as it pertains to interpreting HTT effects data and to the development of models for PFAS distribution within in vivo HTT assays. The contents of this abstract neither constitute nor necessarily reflect US EPA policy.
URLs/Downloads:
DOI: Empirical measurement of PFAS dosing within in vivo aquatic high throughput assays
BLACKWELL_SETAC22_HTTR PFAS_FINAL.PDF (PDF, NA pp, 302.657 KB, about PDF)