Abstract
Perfluorinated alkylate substances (PFASs) are highly persistent and may cause immunotoxic effects. PFAS-associated attenuated antibody responses to childhood vaccines may be affected by PFAS exposures during infancy, where breastfeeding adds to PFAS exposures. Of 490 members of a Faroese birth cohort, 275 and 349 participated in clinical examinations and provided blood samples at ages 18 months and 5 years. PFAS concentrations were measured at birth and at the clinical examinations. Using information on duration of breastfeeding, serum-PFAS concentration profiles during infancy were estimated. As outcomes, serum concentrations of antibodies against tetanus and diphtheria vaccines were determined at age 5. Data from a previous cohort born eight years earlier were available for pooled analyses. Pre-natal exposure showed inverse associations with the antibody concentrations five years later, with decreases by up to about 20% for each two-fold higher exposure, while associations for serum concentrations at ages 18 months and 5 years were weaker. Modeling of serum-PFAS concentration showed levels for age 18 months that were similar to those measured. Concentrations estimated for ages 3 and 6 months showed the strongest inverse associations with antibody concentrations at age 5 years, particularly for tetanus. Joint analyses showed statistically significant decreases in tetanus antibody concentrations by 19–29% at age 5 for each doubling of the PFAS exposure in early infancy. These findings support the notion that the developing adaptive immune system is particularly vulnerable to immunotoxicity during infancy. This vulnerability appears to be the greatest during the first 6 months after birth, where PFAS exposures are affected by breast-feeding.
Highlights
Industrial chemicals are not routinely tested for immunotoxicity, but recent evidence suggests that some environmental chemicals may harm immune functions, perhaps in particular during early development of the adaptive immune system (Dietert and Dewitt 2010; Dietert 2014)
With human milk being a main source of exposure early postnatally, serum-perfluorinated alkylate substances (PFASs) concentrations in infancy could potentially be estimated from the exposure level at birth and the duration of breastfeeding
Experimental evidence so far supports the possibility that early development of the adaptive immune system may be vulnerable to PFAS exposure (Dietert 2014), but the U.S National Toxicology Program recently concluded that specific immune cell vulnerabilities and their dependence upon developmental stages are unclear so far (National Toxicology Program 2016)
Summary
Industrial chemicals are not routinely tested for immunotoxicity, but recent evidence suggests that some environmental chemicals may harm immune functions, perhaps in particular during early development of the adaptive immune system (Dietert and Dewitt 2010; Dietert 2014). Women eliminate PFASs via lactation (Mondal et al 2014), and a child’s exposure in infancy is strongly affected by transfer via human milk (Liu et al 2011; Mogensen et al 2015b). Experimental evidence so far supports the possibility that early development of the adaptive immune system may be vulnerable to PFAS exposure (Dietert 2014), but the U.S National Toxicology Program recently concluded that specific immune cell vulnerabilities and their dependence upon developmental stages are unclear so far (National Toxicology Program 2016). Epidemiology studies of toxicant exposures in infancy are problematic due to the difficulty in obtaining blood samples from small children
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