Matrix selection in the biomonitoring of per- and polyfluoroalkyl substances (PFAS)

Abstract

Human exposure to per- and polyfluoroalkyl substances (PFAS) is of public health interest. PFAS are environmentally persistent man-made chemicals. Some epidemiologic studies suggest that PFAS may affect immunity and reproduction and may increase the risk for certain cancers, hypercholesteremia, and thyroid function. In the United States, exposure to PFAS is widespread with universal detection in the general population. Long-alkyl chain “legacy”, short alkyl-chain, and alternative PFAS have been detected in drinking water around the world. The elimination half-life of PFAS varies from days to years in the human body. The selection of the appropriate human matrix to quantify PFAS is important to properly report concentrations of PFAS in the population. The CDC developed isotope dilution liquid chromatography-tandem mass spectrometry methods to accurately quantify PFAS in human serum (or plasma) and urine. CDC has reported population-based concentrations of PFAS in serum since NHANES 1999-2000. In 2013-2014, NHANES paired serum-urine samples were analyzed for legacy, short-alkyl chain, and alternative PFAS. The majority of the U.S. population did not have detectable urinary concentrations of PFAS, with 67.5% with no detectable PFAS in urine. By contrast, almost 100% of the same population had detectable concentrations of PFAS in serum. In addition, when PFAS were detected in urine and serum, serum concentrations were markedly higher. For example, the geometric mean (GM) serum concentration of perfluorooctane sulfate was 3.45 μg/L while GM urine concentration was < 0.1 μg/L. Similar findings were presented in MMWR (July 2019), with targeted biomonitoring in 30 persons with contaminated drinking water from Cape Fear River, NC in 2017. In this study, only one sample showed detectable concentrations of PFAS in urine versus all 30 samples with detectable concentrations in serum. The findings support the use of serum in biomonitoring of PFAS in the general population.