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BACKGROUND: In December 2013, it was discovered that drinking water supplied to one third of the households in Ronneby, southern Sweden, was highly contaminated by PFAS (sum level >10,000 ng/L) originated from firefighting foams used at a nearby military airport.OBJECTIVES: To report serum PFAS levels of Ronneby residents participating in a biomonitoring program, and to describe the variation by age, sex and calendar period for residential exposure. In addition, a reference group living in a neighboring municipality without PFAS contaminated drinking water was examined.METHODS: Blood samples and demographic data were collected for 3297 Ronneby residents and 226 individuals from the reference group. Yearly residence addresses were available for 3086 Ronneby residents from the national population registry. Serum concentrations of PFHxS, PFOS and PFOA were determined in all participants, with additional PFHpA, PFNA and PFDA in subsets of the participants.RESULTS: The population geometric means for serum PFHxS, PFOS and PFOA were 114, 135 and 6.8 ng/mL for all Ronneby residents, i.e.135, 35 and 4.5 times higher than for the reference group. Ronneby residents who resided in the area with contaminated water supply during 2005-2013 showed much higher PFAS levels in 2014 than those exposed only before 2005. Ronneby residents who never resided in the area with contaminated water supply also had higher serum PFAS levels than the reference group. All three PFAS were highly correlated (rs > 0.9 for each pair). Serum PFAS levels were lowest in teenage years and then increased with age. Adult females had lower PFAS levels on average than males under the age of 60 but higher above 60.DISCUSSION: The results reveal high serum PFAS levels dominated by PFHxS and PFOS in the Ronneby residents highly exposed to PFAS originated from firefighting foams. The PFAS exposure in Ronneby permits studies of associations to a range of health parameters, as well as studies of the toxicokinetics of PFAS exposure. (Less)

Background: Perfluoroalkyl substances (PFAS) are widespread synthetic substances with various adverse health effects. A potential mechanism of toxicity for PFAS is via epigenetic changes, such as DNA methylation. However, few studies have evaluated associations between PFAS exposure and DNA methylation among adults, and data is especially scarce for women. Furthermore, exposure to environmental pollutants has been associated with epigenetic age acceleration, but no studies have yet evaluated whether PFAS is associated with epigenetic age acceleration. Objectives: To investigate whether exposure to PFAS is associated with alteration of DNA methylation and epigenetic age acceleration among women. Methods: In this observational pilot study, 59 women (aged 20–47 years at enrollment in 2014) from Ronneby, Sweden, an area with historically high PFAS exposure due to local drinking water contamination, were divided into three PFAS exposure groups (low, medium, and high). Genome-wide methylation of whole-blood DNA was analyzed using the Infinium MethylationEPIC BeadChip. Ingenuity Pathway Analysis was used for in silico functional assessment. Epigenetic age acceleration was derived from the DNA methylation data using Horvath's epigenetic skin and blood clock. Results: 117 differentially methylated positions (q < 0.017) and one near-significantly differentially methylated region (S100A13, FWER = 0.020) were identified. In silico functional analyses suggested that genes with altered DNA methylation (q < 0.05) were annotated to cancer, endocrine system disorders, reproductive system disease, as well as pathways such as estrogen receptor signaling, cardiac hypertrophy signaling, PPARα/RXRα activation and telomerase signaling. No differences in epigenetic age acceleration between PFAS exposure groups were noted (p = 0.43). Conclusion: The data suggests that PFAS exposure alters DNA methylation in women highly exposed to PFAS from drinking water. The observed associations should be verified in larger cohorts, and it should also be further investigated whether these changes in methylation also underlie potential phenotypic changes and/or adverse health effects of PFAS. (Less)

Background The C8 Science Panel was composed of three epidemiologists charged with studying the possible health effects of PFOA in a highly exposed population in the mid-Ohio Valley. The Panel determined in 2012 there was a ‘probable link’ (i.e., more probable than not based on the weight of the available scientific evidence) between PFOA and high cholesterol, thyroid disease, kidney and testicular cancer, pregnancy-induced hypertension, and ulcerative colitis. Objective Here, former C8 Science Panel members and collaborators comment on the PFOA literature regarding thyroid disorders, cancer, immune and auto-immune disorders, liver disease, hypercholesterolemia, reproductive outcomes, neurotoxicity, and kidney disease. We also discuss developments regarding fate and transport, and pharmacokinetic models, and discuss causality assessment in cross-sectional associations among low-exposed populations. Discussion For cancer, the epidemiologic evidence remains supportive but not definitive for kidney and testicular cancers. There is consistent evidence of a positive association between PFOA and cholesterol, but no evidence of an association with heart disease. There is evidence for an association with ulcerative colitis, but not for other auto-immune diseases. There is good evidence that PFOA is associated with immune response, but uneven evidence for an association with infectious disease. The evidence for an association between PFOA and thyroid and kidney disease is suggestive but uneven. There is evidence of an association with liver enzymes, but not with liver disease. There is little evidence of an association with neurotoxicity. Suggested reductions in birthweight may be due to reverse causality and/or confounding. Fate and transport models and pharmacokinetic models remain central to estimating past exposure for new cohorts, but are difficult to develop without good historical data on emissions of PFOA into the environment. Conclusion Overall, the epidemiologic evidence remains limited. For a few outcomes there has been some replication of our earlier findings. More longitudinal research is needed in large populations with large exposure contrasts. Additional cross-sectional studies of low exposed populations may be less informative.

Highlights • The literature on PFASs and circulating levels of immune cells is scarce. • Study of the association between PFASs and white blood cells at two different time points. • Cross-sectional study on the association between PFASs and lymphocyte subsets. • Positive association between PFHxS and total lymphocytes, especially for cell count. • Positive, but less consistent, association between PFOA and PFOS and total lymphocytes., 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.

Perfluoroalkyl acids (PFAAs) are persistent, synthetic compounds that are used in a number of consumer products. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been associated with cardiovascular risk factors, and changes in gene expression and DNA methylation in animals and cellular systems. However, whether PFAA exposure is associated with LINE-1 DNA methylation, a potential marker of cardiovascular risk, in humans remains unknown. We sought to evaluate the cross-sectional associations between serum PFAAs and LINE-1 DNA methylation in a population highly exposed to PFOA. We measured serum PFAAs twice four to five years apart in 685 adult participants (47% male, mean age ± SD = 42 ± 11 years). We measured percent LINE-1 DNA methylation in peripheral blood leukocytes at the second time point (follow-up), and estimated absolute differences in LINE-1 methylation associated with an interquartile (IQR) shift in mean PFAA serum levels. IQR increases in mean serum PFOA, PFOS, perfluorononanoic acid (PFNA), and perfluorohexane sulfonate (PFHxS) were associated with differences of −0.04 (p = 0.16), 0.20 (p = 0.001), 0.06 (p = 0.19), and 0.02 (p = 0.57), respectively, in % LINE-1 methylation at follow-up after adjustment for potential confounders. We observed a monotonic increase in LINE-1 DNA methylation across tertiles of PFOS and PFNA (ptrend = 0.02 for both associations), but not across tertiles of PFOA or PFHxS (ptrend = 0.71 and 0.44, respectively). In summary, serum PFOS was associated with LINE-1 methylation, while serum PFOA, PFHxS, and PFNA were not. Additional research is needed to more precisely determine whether these compounds are epigenetically active. Keywords: Perfluorooctanoic acid, Perfluorooctane sulfonate, Epigenetics, DNA methylation, LINE-1, Cardiovascular disease

Perfluorooctanoic acid (PFOA, ‘C8’) and perfluoroctane sulphonate (PFOS) are environmentally stable compounds with industrial and consumer uses and long half-lives in humans. Concern has been raised over chronic exposure effects to human health, especially in relation to cholesterol metabolism. Here, we explore the association between exposure to PFOA and PFOS and the in vivo expression of genes involved in cholesterol metabolism. We studied 290 individuals exposed to background levels of PFOS and elevated concentrations of PFOA through drinking water. Using adjusted linear regression models, we found inverse associations between serum PFOA levels and the whole blood expression level of genes involved in cholesterol transport (NR1H2, NPC1 and ABCG1; p = 0.002, 0.026 and 0.014 respectively). A positive association was seen between PFOS and a transcript involved in cholesterol mobilisation (NCEH1; p = 0.018), and a negative relationship with a transcript involved in cholesterol transport (NR1H3; p = 0.044). When sexes were analysed separately, reductions in the levels of mRNAs involved in cholesterol transport were seen with PFOA in men (NPC1, ABCG1, and PPARA; p = 0.025, 0.024 and 0.012 respectively) and in women (NR1H2 expression; p = 0.019), whereas an increase in the levels of a cholesterol mobilisation transcript (NCEH1; p = 0.036) was noted in women alone. PFOS was positively associated with expression of genes involved in both cholesterol mobilisation and transport in women (NCEH1 and PPARA; p = 0.003 and 0.039 respectively), but no effects were evident in men. This is the first report of associations between the in vivo expression of genes involved in cholesterol metabolism and exposure to PFOA or PFOS, suggested that exposure to these compounds may promote a hypercholesterolaemic environment, with wider implications for human disease. Keywords: PFOA, PFOS, Cholesterol, Human, Toxicogenomics

Introduction: Thyroid hormones (THs) are especially important for brain maturation and development during the fetal period and childhood. Several epidemiological studies have assessed the possible association between exposure to perfluoroalkyl substances (PFAS) and thyroid outcomes during the early stages of life. We aimed to review this evidence. Methods: We conducted a systematic review in compliance with the PRISMA Statement (search conducted in PubMed and Embase, as well as in the citations of the selected articles). We chose studies if they dealt with thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxin (T4), or thyroid dysfunctions, and perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS) or perfluorononanoic acid (PFNA) measured in the blood of pregnant women and/or children up to 19 years old. Results: We included in this review three cross-sectional, one case-control, and six cohort studies (publication: 2011–2015), focusing on prenatal life (n = 7), childhood (n = 2) or both periods (n = 1). We observed a high degree of heterogeneity across studies in terms of sampling time (different gestational weeks, at birth, or childhood), outcomes, adjustment for potential confounders, and statistical approach. We found some evidence of a positive association between PFHxS and PFOS exposure and TSH levels measured in maternal blood, and PFNA and TSH levels measured in the blood of boys aged ≥11 years. Conclusion: Although there is a small number of studies with comparable data, we found some consistency of a positive association between maternal or teenage male exposure to some PFAS and TSH levels based on the current literature. However, further studies are required to confirm these possible relationships. Keywords: Prenatal and infant exposure, Perfluorohexane sulfonate (PFHxS), Perfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA), Perfluorononanoic acid (PFNA), Thyroid