Circulating maternal perfluoroalkyl substances during pregnancy in the C8 Health Study

Gestational and childhood exposure to per- and polyfluoroalkyl substances and cardiometabolic risk at age 12 years

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) may adversely influence cardiometabolic risk. However, few studies have examined if the timing of early life PFAS exposure modifies their relation to cardiometabolic risk. We examined the influence of gestational and childhood PFAS exposure on adolescents' cardiometabolic risk.

METHODS

We quantified concentrations of four PFAS (perfluorooctanoate [PFOA], perfluorooctane sulfonate [PFOS], perfluorononanoate [PFNA], and perfluorohexane sulfonate [PFHxS]) in sera collected during pregnancy, at birth, and at ages 3, 8, and 12 years from 221 mother-child pairs in the HOME Study (enrolled 2003-06, Cincinnati, Ohio). We measured cardiometabolic risk factors using physical examinations, fasting serum biomarkers, and dual-energy X-ray absorptiometry scans at age 12 years. Cardiometabolic risk summary scores were calculated by summing age- and sex-standardized z-scores for individual cardiometabolic risk factors. We used multiple informant models to estimate covariate-adjusted associations of serum PFAS concentrations (log2-transformed) at each visit with cardiometabolic risk scores and their individual components, and tested for differences in associations across visits.

RESULTS

The associations of serum PFOA concentrations with cardiometabolic risk scores differed across visits (P for heterogeneity = 0.03). Gestational and cord serum PFOA concentrations were positively associated with cardiometabolic risk scores (βs and 95% confidence intervals [95% CIs]: gestational 0.8 [0.0, 1.6]; cord 0.9 [-0.1, 1.9] per interquartile range increase). These positive associations were primarily driven by homeostatic model assessment for insulin resistance index (β = 0.3 [0.1, 0.5]) and adiponectin to leptin ratio (β = -0.5 [-1.0, 0.0]). Other individual cardiometabolic risk factors associated with gestational PFOA included insulin and waist circumference. Gestational and cord PFHxS were also associated with higher cardiometabolic risk scores (βs: gestational 0.9 [0.2, 1.6]; cord 0.9 [0.1, 1.7]).

CONCLUSION

In this cohort of children with higher gestational PFOA exposure, fetal exposure to PFOA and PFHxS was associated with unfavorable cardiometabolic risk in adolescence.

The association between perfluoroalkyl substances and lipid profile in exposed pregnant women in the Veneto region, Italy

BACKGROUND

Residents of a large area of North-Eastern Italy were exposed for decades to high concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS) via drinking water. Serum PFAS levels have been consistently associated with elevated serum lipids, but few studies have been conducted among pregnant women, and none has stratified analyses by trimester of gestation. Elevated serum lipid levels during pregnancy can have both immediate and long-lasting effects on pregnant women and the developing fetus. We evaluated the association between perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluoro-hexanesulfonate (PFHxS) levels in relation to lipid profiles in highly-exposed pregnant women.

METHODS

A cross-sectional analysis was conducted in 319 pregnant women (age 14-48 years) enrolled in the Regional health surveillance program. Non-fasting blood samples were obtained in any trimester of pregnancy and analyzed for PFOA, PFOS and PFHxS, total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C). Low-density lipoprotein cholesterol (LDL-C) was calculated. The associations between ln-transformed PFAS (and categorized into quartiles) and lipids were assessed using generalized additive models. Analyses were adjusted for potential confounders and stratified according to pregnancy trimester.

RESULTS

The geometric means of PFOA, PFOS and PFHxS were 14.78 ng/mL, 2.67 ng/mL and 1.89 ng/mL, respectively. The plasma levels of TC, HDL-C and LDL-C increased steadily throughout the trimesters. In the 1st trimester, PFOS was positively associated with TC and PFHxS with HDL-C. In the 3rd trimester, instead, an inverse relationship was seen between PFOA and PFHxS and both TC and LDL-C.

CONCLUSIONS

Results suggest the associations between PFAS concentrations and lipid profiles in pregnant women might differ by trimesters of pregnancy. In the first trimester, patterns are similar to those of non-pregnant women, while they differ late in pregnancy. Different independent behavior of PFAS and lipid levels throughout the pregnancy might explain our observations. These findings support the ubiquitous exposure to PFAS and possible influence on lipid metabolisms during pregnancy and suggest a careful evaluation of the timing of PFAS measurement, when examining effects of PFAS during pregnancy on gestational outcomes related to serum lipids amounts.

Rubella immunity and serum perfluoroalkyl substances: Sex and analytic strategy

Background

Perfluoroalkyl substances (PFASs) have been associated with decreased immunity to childhood tetanus and diphtheria immunizations. If these vaccinations are vulnerable to influence from PFASs, questions arise about associations with other common inoculations.

Objective

To examine whether serum PFASs were associated with reduced immunity to rubella immunization, and whether interactions with sex or ethnicity warranted analytic stratification. Usually, toxicology analyses are calculated controlling for race and sex. However, sex differences in immune function have been reported and a reduction of immunity to rubella in women could pose risks such miscarriage.

Methods

We analyzed a nationally representative sample of individuals ≥ 12 years from the National Health and Nutrition Examination Survey (NHANES) for years 1999–2000 and 2003–2004 for whom PFAS measures were available. Our analytic strategy was to start with separate analyses for youth and adults controlling for several covariates including ethnicity and sex, as well as the interaction of these terms with PFASs. If there was a main effect of PFASs and an interaction term, we would stratify analyses of effect size. The outcome variable was Rubella IgG titers by quartile of perfluoroalkyl substances.

Results

After exclusion for missing data, the analyzed sample contained 581 adult women, 621 adult men, and 1012 youth. There was no significant effect of PFASs on immunity in youths but a significant effect of both PFOA and PFOS in adults, as well as a significant interaction of PFOA x sex and a borderline significant interaction of PFOS x sex. When effect size analyses were stratified by sex, a significant association between rubella titres and PFOA was found in men but not women and PFOS was not significant in either sex.

Conclusions

These results support our earlier studies showing sex specific responses to PFASs and indicate the importance of thinking carefully about analytic strategies in population based toxicology research.

Association of perfluorinated chemical exposure in utero with maternal and infant thyroid hormone levels in the Sapporo cohort of Hokkaido Study on the Environment and Children's Health

OBJECTIVES

Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) have been widely used as industrial products, and are persistent organic pollutants due to their chemical stability. Previous studies suggested that PFOS and PFOA might disrupt thyroid hormone (TH) status. Although TH plays an important role in fetal growth during pregnancy, little attention has been paid to the relationships between maternal exposure to perfluorocarbons and TH statuses of mothers and fetuses. We investigated the effects of low levels of environmental PFOS and PFOA on thyroid function of mothers and infants.

METHODS

Of the eligible subjects in a prospective cohort, 392 mother-infant pairs were selected. Concentration of maternal serum PFOS and PFOA was measured in samples taken during the second and third trimesters or within 1 week of delivery. Blood samples for measuring thyroid stimulating hormone (TSH) and free thyroxine (FT4) levels were obtained from mothers at early gestational stage (median 11.1 weeks), and from infants between 4 and 7 days of age, respectively.

RESULTS

Median concentrations of PFOS and PFOA were 5.2 [95 % confidence interval (CI) 1.6-12.3] and 1.2 (95 % CI limitation of detection-3.4) ng/mL, respectively. Maternal PFOS levels were inversely correlated with maternal serum TSH and positively associated with infant serum TSH, whereas maternal PFOA showed no significant relationship with TSH or FT4 among mothers and infants.

CONCLUSIONS

These findings suggest that PFOS may independently affect the secretion and balances of maternal and infant TSH even at low levels of environmental exposure.