Perfluoroalkyl substances and immune cell counts in adults from the Mid-Ohio Valley (USA)

Background: Although perfluoroalkyl substances (PFASs) may be immunotoxic, evidence for this in humans is scarce. We studied the association between 4 PFASs (perfluorohexane sulfonate [PFHxS], perfluorooctanoic acid [PFOA], perfluorooctane sulfonate [PFOS] and perfluorononanoic acid [PFNA]) and circulating levels of several types of immune cells. Methods: Serum PFASs and white blood cell types were measured in 42,782 (2005-2006) and 526 (2010) adults from an area with PFOA drinking water contamination in the Mid-Ohio Valley (USA). Additionally, the major lymphocyte subsets were measured in 2010. Ln(cell counts) and percentages of cell counts were regressed on serum PFAS concentrations (ln or percentiles). Adjusted results were expressed as the percentage difference (95% CI) per interquartile range (IQR) increment of each PFAS concentration. Results: Generally positive monotonic associations between total lymphocytes and PFHxS, PFOA, and PFOS were found in both surveys (difference range: 1.12-7.33% for count and 0.36-1.77 for percentage, per PFAS IQR increment), and were stronger for PFHxS. These associations were reflected in lymphocyte subset counts but not percentages, with PFHxS positively and monotonically associated with T, B, and natural killer (NK) cell counts (range: 5.51-8.62%), PFOA and PFOS with some T-cell phenotypes, and PFOS with NK cells (range: 3.12-12.21%), the associations being monotonic in some cases. Neutrophils, particularly percentage (range: -1.74 to -0.36), showed decreasing trends associated with PFASs. Findings were less consistent for monocytes and eosinophils. Conclusion: These results suggest an association between PFHxS and, less consistently, for PFOA and PFOS, and total lymphocytes (although the magnitudes of the differences were small). The increase in absolute lymphocyte count appeared to be evenly distributed across lymphocyte subsets since associations with their percentages were not significant.