Biomonitoring Six Per- and Polyfluoroalkyl Substances Included in the U.S. EPA Third Unregulated Contaminant Monitoring Rule

摘要

Per- and polyfluoroalkyl substances (PFAS) are an assortment of substances used in a variety of industries and consumer products. As a result of their use, these persistent chemicals are found in the environment including drinking water. The U.S. EPA tests drinking water for six PFAS contaminants under the Third Unregulated Contaminant Monitoring Rule (UCMR3), which includes perfluorobutanesulfonic acid (PFBS), perfluoroheptanoic acid (PFHpA), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorooctanoic acid (PFOA), and perfluorooctancsulfonic acid (PFOS). A quantitative assay for the linear components of these substances has been developed to test serum specimens by using HPLC separation with negative-ion electrospray tandem mass spectrometry (LC-MS/MS). Samples are prepared for analysis by adding analyte specific ~(13)Carbon isotopes as internal standards with subsequent protein precipitation. The analytical measurement range (AMR) is 0.05 to 10 ng/mL for PFBS, PFHpA, PFHxS, and PFNA; and 0.5 to 100 ng/mL for PFOA and PFOS. The within and between day precision of 5 replicates measured for each of 3 days (n=15) are less than 10% CV for these analytes at three respective levels 0.05, 0.25 and 6.0 ng/mL for PFBS, PFHpA, PFHxS, and PFNA; and 0.50, 2.5, and 60 ng/mL for PFOA and PFOS, except for the within day precision values for PFHpA at 0.05 ng/mL (14.2%CV) and PFNA at 6.0 ng/mL (10.8%CV). A population of individuals (n=151) with unknown exposures to these substances showed the following respective median and 97.5th percentile as measured for PFBS (<0.05, 0.06 ng/mL); PFHpA (<0.05, 0.47 ng/mL); PFHxS (0.99, 5.75 ng/mL); PFNA (0.42, 1.44 ng/mL); PFOA (1.12, 4.13 ng/mL); and PFOS (1.77, 11.5 ng/mL). These values are comparable to other studies measuring these substances in the general population. This assay in serum can be used for biomonitoring those PFASs tested in drinking water under EPA UCMR3.