Comparison of per- and polyfluoroalkyl substance exposure levels in neonatal cord blood between an e-waste recycling area and a general exposure area

Background Per- and polyfluoroalkyl substances (PFAS) are a class of persistent organic pollu-tants. Industrial production and consumer use of PFAS are the primary sources of exposure in urban areas. E-waste recycling activities are also a significant source of environmental PFAS exposure.

Objective To compare exposure profiles between traditional and emerging PFAS in neonatal cord blood collected from an e-waste recycling area and a general exposure area characterized by modern economic development (hereafter referred to as general exposure area).

Methods Based on a birth cohort study conducted in 2018, 85 pregnant women were recruited (36 participants from an e-waste recycling area and 49 participants from a general exposure area). Neonatal cord blood was collected at delivery. Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was used to detect 28 common PFAS in the blood. A structured questionnaire was used to gather sociodemographic characteristics of the pregnant women. Mann-Whitney U tests were used to compare PFAS exposure levels in neonatal cord blood between the e-waste recycling area and the general exposure area. Multiple linear regression models were used to explore the influence of residing in the e-waste recycling area on neonatal PFAS exposure, with area as the independent variable and the natural logarithm of PFAS exposure levels as the dependent variable.

Results A total of 22 PFAS were positive in neonatal cord blood, of which 13 congeners were 100% detectable in the samples from both areas. The median ∑PFAS exposure levels in neonatal cord blood were 14.19 ng·mL⁻¹ and 14.02 ng·mL⁻¹ for the e-waste recycling area and the general exposure area, respectively, with linear perfluorooctanoic acid (L-PFOA) showing the highest median concentration (5.49 ng·mL⁻¹ and 6.39 ng·mL⁻¹, respectively). The results of Mann-Whitney U tests showed that the median exposure levels of long-chain perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), and perfluorotridecanoic acid (PFTrDA), as well as emerging alternatives 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and 8:2 chlorinated polyfluorinated ether sulfonate (8:2 Cl-PFESA), were higher in the e-waste recycling area than in the general exposure area. In contrast, the median exposure levels of short-chain perfluoropentanoic acid (PFPeA) and perfluorohexanoic acid (PFHxA), as well as perfluorooctanoic acid (PFOA) branched isomers, including perfluoro-6-methylheptanoic acid (iso-PFOA), perfluoro-5-methylheptanoic acid (5m-PFOA), and perfluoro-4-methylheptanoic acid (4m-PFOA), were lower in the e-waste recycling area than in the general exposure area (P<0.05). The multiple linear regression models showed that, compared to the general exposure area, neonatal cord blood in the e-waste recycling area had significantly higher exposure levels of long-chain PFDA, PFUnDA, PFDoDA, PFTrDA, and emerging alternatives 6:2 Cl-PFESA and 8:2 Cl-PFESA, with odds ratios of 1.95 (95%CI: 1.39-2.75), 2.10 (95%CI: 1.58-2.75), 2.12 (95%CI: 1.39-3.25), 2.64 (95%CI: 1.63-4.22), 3.46 (95%CI: 2.34-5.10), and 3.25 (95%CI: 2.01-5.26), respectively. Conversely, the exposure levels of short-chain PFPeA, PFHxA, and branched PFOA (br-PFOA) were significantly lower, with odds ratios of 0.44 (95%CI: 0.38-0.52), 0.30 (95%CI: 0.16-0.57), and 0.50 (95%CI: 0.38-0.67), respectively.

Conclusion PFAS are widely present in neonatal cord blood in both the e-waste recycling area and the general exposure area. Compared to the general exposure area, the neonatal cord blood samples in the e-waste recycling area show higher exposure levels of certain long-chain perfluoroalkyl carboxylic acids (PFCA) and emerging PFAS alternatives, while the neonatal cord blood samples in the general exposure area show higher exposure levels of some short-chain PFCA and PFOA branched isomers.