Risk Assessment of Per- and Polyfluoroalkyl Substances (PFASs) Mixtures: A Relative Potency Factor Approach

By Wieneke Bil, Marco Zeilmaker, Styliani Fragki, Johannes Lijzen, Eric Verbruggen, and Bas Bokkers
Environ. Toxicol. Chem.
August 4, 2020
DOI: 10.1002/etc.4835

PFASs often occur together as contamination in exposure media such as drinking water or foods. The Relative Potency Factor (RPF) methodology facilitates the risk assessment of mixture exposure. A database of liver end-points was established for 16 PFASs, using data with the same species (rat), sex (male), exposure route (oral), and comparable exposure duration (42-90 days). Dose-response analysis was applied to derive the relative potencies of three perfluoroalkyl sulfonic acids (PFBS, PFHxS, PFOS), eight perfluoroalkyl carboxylic acids (PFBA, PFHxA, PFNA, PFUA, PFDoDA, PFTeDA, PFHxDA, PFODA), two perfluoroalkyl ether carboxylic acids (HFPO-DA, ADONA), and two fluorotelomer alcohols (6:2 FTOH, 8:2 FTOH) compared to PFOA, based on liver effects. In addition, the RPFs of 7 other perfluoroalkyl acids were estimated based on read-across. This resulted in the relative potencies of 22 PFASs compared to the potency of index compound PFOA. The obtained RPFs can be applied to measured PFAS quantities resulting in the sum of PFOA equivalents in a mixture. This sum can be compared with an established PFOA concentration limit (e.g. in drinking water or food) or external health based guidance value (e.g. a TDI, ADI or RfD) to estimate the risk resulting from direct oral exposure to mixtures. Assessing mixture exposure is particularly relevant for PFASs, with omnipresent exposure in our daily lives. This article is protected by copyright. All rights reserved.

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