The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.est.8b00770. Moderately PFBS- and PFHxS-contaminated drinking water is an important indirect exposure source. Prenatal PFAA exposure and postnatal PFAA exposure significantly contribute to infant PFAA serum concentrations, depending on PFAA carbon chain length. Infants living in an area receiving PFAA-contaminated drinking water had 3-fold higher mean perfluorobutanesulfonate (PFBS) and PFHxS concentrations and higher mean %br PFHxS. PFOA, PFNA, and PFHxS levels increased 8–11% per week of exclusive breast-feeding.
Bottle-fed infants had mean concentrations of PFAAs 2 times lower than and a mean percentage of branched (%br) PFOS isomers 1.3 times higher than those of exclusively breast-fed infants. Infant PFOA, perfluorononanoic acid (PFNA), and PFOS levels increased 0.7–1.2% per day of gestational age. Median infant/maternal ratios decreased with increasing PFAA carbon chain length from 2.8 for perfluoroheptanoic acid and perfluorooctanoic acid (PFOA) to 0.53 for PFUnDA and from 1.2 to 0.69 for PFHxS and perfluorooctanesulfonate (PFOS). In exclusively breast-fed infants, maternal serum PFAA concentrations 3 weeks after delivery explained 13% (perfluoroundecanoic acid, PFUnDA) to 73% (perfluorohexanesulfonate, PFHxS) of infant PFAA concentration variation. Associations between serum PFAA concentrations in 2–4-month-old infants ( n = 101) and determinants were investigated by multiple linear regression and general linear model analysis.
Little is known about factors influencing infant perfluorinated alkyl acid (PFAA) concentrations.
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