The effect of prenatal perfluorinated chemicals exposures on pediatric atopy

Fish intake during pregnancy or infancy and allergic outcomes in children: A systematic review and meta-analysis

It has been suggested that n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) have anti-inflammatory properties and may reduce the risk of allergic disease. Fish is a great source of n-3 LC-PUFAs. However, the effect of fish on allergic disease remains controversial. PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were searched for randomized controlled trials (RCTs) and prospective cohort studies regarding the effect of fish intake during pregnancy or infancy on allergic outcomes in children. The outcomes of interest were atopy, eczema, allergic rhinitis, wheeze, asthma, and food allergy. One RCT and 17 publications from 13 prospective cohort studies were included for maternal fish intake during pregnancy, and eight publications from five prospective cohort studies for fish intake in infancy. Pooled analysis suggested that maternal fish intake during pregnancy was not associated with lower risk of any allergic outcome, both in RCT and observational studies. Consumption of fish during the first year of life reduced the risk of eczema (RR 0.61; 95% CI 0.47, 0.80; p = 0.0003; I²  = 68%) and allergic rhinitis (RR 0.54; 95% CI 0.36, 0.81; p = 0.003; I²  = 74%). Current evidence indicates that fish intake in infancy could reduce the risk of eczema and allergic rhinitis in children, whereas maternal fish intake during pregnancy does not affect any atopic outcome. The intake of fish per se in infancy, not specially n-3 LC-PUFAs, may have an allergy protective effect. High-quality and adequately powered RCTs are warranted to confirm this.

Association between perfluoroalkyl substance exposure and asthma and allergic disease in children as modified by MMR vaccination

Perfluoroalkyl substances (PFASs) are highly persistent chemicals that might be associated with asthma and allergy, but the associations remain unclear. Therefore, this study examined whether pre- and postnatal PFAS exposure was associated with childhood asthma and allergy. Measles, mumps, and rubella (MMR) vaccination in early life may have a protective effect against asthma and allergy, and MMR vaccination is therefore taken into account when evaluating these associations. In a cohort of Faroese children whose mothers were recruited during pregnancy, serum concentrations of five PFASs - Perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) - were measured at three timepoints (maternal serum in pregnancy week 34-36 and child serum at ages 5 and 13 years) and their association with immunoglobulin E (IgE) (cord blood and at age 7 years) and asthma/allergic diseases (questionnaires at ages 5 and 13 years and skin prick test at age 13 years) was determined. A total of 559 children were included in the analyses. Interactions with MMR vaccination were evaluated. Among 22 MMR-unvaccinated children, higher levels of the five PFASs at age 5 years were associated with increased odds of asthma at ages 5 and 13. The associations were reversed among MMR-vaccinated children. Prenatal PFAS exposure was not associated with childhood asthma or allergic diseases regardless of MMR vaccination status. In conclusion, PFAS exposure at age 5 was associated with increased risk of asthma among a small subgroup of MMR-unvaccinated children but not among MMR-vaccinated children. While PFAS exposure may impact immune system functions, this study suggests that MMR vaccination might be a potential effect-modifier.

Occurrence investigation of perfluorinated compounds in surface water from East Lake (Wuhan, China) upon rapid and selective magnetic solid-phase extraction

Using a novel magnetic nanocomposite as adsorbent, a convenient and effective magnetic solid-phase extraction (MSPE) procedure was established for selective separation and concentration of nine perfluorinated compounds (PFCs) in surface water sample. Then an ultra high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) system was employed for detection of PFCs. Good linearity of the developed analytical method was in the range of 0.5-100 ng L^-1 with R² > 0.9917, and the limits of detection (LODs) ranged from 0.029 to 0.099 ng L^-1. At three fortified concentrations of 0.5, 5 and 50 ng L^-1, the spiked recoveries of PFCs were in the range of 90.05-106.67% with RSDs < 12.62% (n = 3). The proposed analytical method was applied for determination of PFCs in surface water from East Lake (Wuhan, China). The total concentrations of nine PFCs ranged from 30.12 to 125.35 ng L^-1, with perfluorooctane sulfonate and perfluoroctanoic acid as the most prevalent PFCs, and the greatest concentrations of PFCs were observed in Niuchao lakelet. The concentrations of the PFCs (C ≥ 11) were mostly less than the limits of quantification (LOQs), attributed to the possibility that the more hydrophobic long-chain PFCs are potential to accumulate in sediment and aquatic biota.

Association between prenatal exposure to perfluorinated compounds and symptoms of infections at age 1-4years among 359 children in the Odense Child Cohort

INTRODUCTION

Perfluorinated alkylated substances (PFAS) are persistent industrial chemicals that have resulted in global environmental exposures. Previous epidemiological studies have reported possible effects on the immune system after developmental PFAS exposure, but the possible impact on childhood infectious disease is unclear.

OBJECTIVES

To investigate the association between prenatal exposure to PFAS and symptoms of infections at age 1-4years.

METHODS

The Odense Child Cohort is an on-going prospective study on children's health, where serum concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA) were measured in 649 pregnant women before gestational week 16. Of these women, 359 reported on symptoms of infection in their child every two weeks for a one-year period. The association between prenatal exposure to PFAS and the symptoms was estimated using a logistic regression model and a negative binomial regression model. For the latter, the outcome was reported as an incidence rate-ratio (IRR), and all models were adjusted for maternal age, educational level, parity and child age.

RESULTS

On average, the children experienced symptoms of infection 23% of the time during one year. PFOS exposure in the high tertile compared to the low tertile was associated with a statistically significant increased proportion of days with fever (IRR: 1.65 (95% CI: 1.24, 2.18), P-trend<0.001) and an increased odds of experiencing days with fever above the median (OR: 2.35 (95% CI: 1.31, 4.11). The latter tendency was also apparent for PFOA (OR: 1.97 (95% CI: 1.07, 3.62). Further, higher concentrations of PFOS and PFOA tended to increase the number of episodes of co-occurrence of fever and coughing and fever and nasal discharge during the one-year study period.

CONCLUSION

We found a positive association between prenatal exposure to PFOS and PFOA and the prevalence of fever, which may be a sensitive marker of infection. This finding is in agreement with an immunotoxic effect of prenatal exposure to PFAS. The wider implications for childhood infectious disease deserve attention.

Testosterone-Mediated Endocrine Function and TH1/TH2 Cytokine Balance after Prenatal Exposure to Perfluorooctane Sulfonate: By Sex Status

Little information exists about the evaluation of potential developmental immunotoxicity induced by perfluorooctane sulfonate (PFOS), a synthetic persistent and increasingly ubiquitous environmental contaminant. To assess potential sex-specific impacts of PFOS on immunological health in the offspring, using male and female C57BL/6 mice, pups were evaluated for developmental immunotoxic effects after maternal oral exposure to PFOS (0.1, 1.0 and 5.0 mg PFOS/kg/day) during Gestational Days 1-17. Spontaneous TH1/TH2-type cytokines, serum levels of testosterone and estradiol were evaluated in F1 pups at four and eight weeks of age. The study showed that male pups were more sensitive to the effects of PFOS than female pups. At eight weeks of age, an imbalance in TH1/TH2-type cytokines with excess TH2 cytokines (IL-4) was found only in male pups. As for hormone levels, PFOS treatment in utero significantly decreased serum testosterone levels and increased estradiol levels only in male pups, and a significant interaction between sex and PFOS was observed for serum testosterone at both four weeks of age (pinteraction = 0.0049) and eight weeks of age (pinteraction = 0.0227) and for estradiol alternation at four weeks of age (pinteraction = 0.0351). In conclusion, testosterone-mediated endocrine function may be partially involved in the TH1/TH2 imbalance induced by PFOS, and these deficits are detectable among both young and adult mice and may affect males more than females.

Effects of prenatal exposure to perfluoroalkyl acids on prevalence ofallergic diseases among 4-year-old children

Perfluoroalkyl acids (PFAAs) are ubiquitous chemicals extremely resistant and widespread throughout the environment, frequently being detected in human blood samples. Animal studies have revealed that exposure to PFAAs results in immunotoxicity. However, the association between PFAAs, especially long-chain PFAAs, and allergies in humans is not well established. We examined whether prenatal exposure to PFAAs is associated with allergic diseases among 4-year-old children in a large-scale prospective birth cohort in Hokkaido, Japan. In total, 1558 mother-child pairs were included in this study and prenatal levels of eleven PFAAs were measured in maternal plasma samples obtained between 28 and 32weeks of pregnancy by using ultra-performance liquid chromatography-tandem mass spectrometry. Participant demographic and characteristic information were obtained from self-administered pre- and postnatal questionnaires and medical birth records. Infant allergies were assessed using the Japanese version of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three questionnaire, which was administered 4years post-delivery. Symptoms included eczema, wheezing and rhinoconjunctivitis with a prevalence of 19.0%, 18.7%, and 5.4%, respectively. Associations of PFAA quartiles with allergic outcomes were examined using logistic models. Adjusted odds ratios (ORs) in the 4th quartile vs. 1st quartile (Q4 vs. Q1) for total allergic diseases (including at least one allergic outcome) significantly decreased for perfluorododecanoic acid (PFDoDa) (Q4 vs. Q1 OR: 0.621; 95% confidence interval (CI): 0.454, 0.847) and perfluorotridecanoic acid (PFTrDA) (Q4 vs. Q1 OR: 0.712; 95% CI: 0.524, 0.966) in all children. We obtained similar results when examining the association between PFAAs and eczema. The adjusted OR (Q4 vs. Q1) for wheezing in relation to higher maternal PFHxS levels was 0.728 (95% CI: 0.497, 1.06) in all children. In conclusion, prenatal exposure to long-chain PFAAs, such as PFDoDa and PFTrDA may have an immunosuppressive effect on allergic diseases in 4-year-old children.

Exposure to perfluoroundecanoic acid (PFUnDA) accelerates insulitis development in a mouse model of type 1 diabetes

Perfluoralkylated substances (PFAS) are classified as persistent, bioaccumulative and toxic substances and are widespread environmental contaminants. Humans are exposed through food, drinking water and air. We have previously reported that bisphenol A accelerates spontaneous diabetes development in non-obese diabetic (NOD) mice and observed in the present study that perfluoroundecanoic acid, PFUnDA, increased insulitis development, a prerequisite for diabetes development in NOD mice. We exposed NOD mice to PFUnDA in drinking water (3, 30 and 300 μg/l) at mating, during gestation and lactation and until 30 weeks of age. After 300 μg/l PFUnDA exposure, we report (i) increased pancreatic insulitis, (ii) increased number of apoptotic cells in pancreatic islets prior to insulitis and (iii) decreased phagocytosis in peritoneal macrophages. There was also a trend of decreased number of tissue resident macrophages in pancreatic islets prior to insulitis after exposure to 300 μg/l, and altered cytokine secretion in activated splenocytes after exposure to 3 μg/l PFUnDA. Although insulitis is a prerequisite for autoimmune diabetes, the accelerated insulitis was not associated with accelerated diabetes development. Instead, the incidence of diabetes tended to be reduced in the animals exposed to 3 and 30 μg/l PFUnDA, suggesting a non-monotonic dose response. The effects of PFUnDA exposure on increased apoptosis in pancreas and reduced macrophage function as well as accelerated insulitis development in NOD mice, may also be relevant for human insulitis. Further observational autoimmune diabetes clinical cohort studies and animal experiments for PFUnDA as well as other PFASs are therefore encouraged.

Perfluoroalkyl substance serum concentrations and immune response to FluMist vaccination among healthy adults

Perfluoroalkyl substances (PFAS) were shown to be immunotoxic in laboratory animals. There is some epidemiological evidence that PFAS exposure is inversely associated with vaccine-induced antibody concentration. We examined immune response to vaccination with FluMist intranasal live attenuated influenza vaccine in relation to four PFAS (perfluorooctanoate, perfluorononanoate, perfluorooctane sulfonate, perfluorohexane sulfonate) serum concentrations among 78 healthy adults vaccinated during the 2010-2011 influenza season. We measured anti-A H1N1 antibody response and cytokine and chemokine concentrations in serum pre-vaccination, 3 days post-vaccination, and 30 days post-vaccination. We measured cytokine, chemokine, and mucosal IgA concentration in nasal secretions 3 days post-vaccination and 30 days post-vaccination. Adults with higher PFAS concentrations were more likely to seroconvert after FluMist vaccination as compared to adults with lower PFAS concentrations. The associations, however, were imprecise and few participants seroconverted as measured either by hemagglutination inhibition (9%) or immunohistochemical staining (25%). We observed no readily discernable or consistent pattern between PFAS concentration and baseline cytokine, chemokine, or mucosal IgA concentration, or between PFAS concentration and change in these immune markers between baseline and FluMist-response states. The results of this study do not support a reduced immune response to FluMist vaccination among healthy adults in relation to serum PFAS concentration. Given the study's many limitations, however, it does not rule out impaired vaccine response to other vaccines or vaccine components in either children or adults.

Perfluoroalkyl substances in cord blood and attention deficit/hyperactivity disorder symptoms in seven-year-old children

OBJECTIVE

The effect of perfluoroalkyl substances (PFASs) on the development of neurotoxicity in children is still controversial. This study aimed to evaluate the association between in utero exposure to four PFASs and the development of neurobehavioral symptoms related to attention deficit hyperactivity disorder (ADHD) in early childhood.

METHODS

Eligible study subjects were selected from the Taiwan Birth Panel Study and the Taiwan Early-Life Cohort, which enrolled a total of 1526 mother-infant pairs during 2004 and 2005. We collected umbilical cord blood and analyzed perfluorooctanoic acid (PFOA), perfluorooctanyl sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUA) levels. When a child was 7 years old, to evaluate ADHD related neurobehavioral symptoms, their parents completed the Swanson, Nolan, and Pelham IV scale (SNAP-IV), the Child Behavior Checklist (CBCL), and the Strengths and Difficulties Questionnaire (SDQ) questionnaires. We used linear regression models with inverse probability weighting to explore the association between prenatal exposure to four PFASs and ADHD rating scores.

RESULTS

A total of 282 subjects have completed the PFASs analysis and questionnaire survey. After adjusted for potential confounders, we observed that PFNA is inversely associated with inattention and oppositional defiant disorder of SNAP-IV, and hyperactivity/inattention of SDQ. No association between PFOA, PFOS, or PFUA and ADHD symptoms was found.

CONCLUSIONS

Prenatal exposure to PFNA was found to associate with neurobehavioral symptoms related to ADHD among Asian seven-year-old children. Further studies are needed to elucidate the causal relationship.

Associations of serum perfluoroalkyl acid levels with T-helper cell-specific cytokines in children: By gender and asthma status

Perfluoroalkyl acids (PFAAs) are a group of common chemicals that ubiquitously exist in wildlife and humans. Experimental data suggest that they may alter T-lymphocyte functioning in situ by preferentially enhancing the development of T-helper 2 (TH2)- and inhibiting TH1-lymphocyte development and might increase allergic inflammation, but few human studies have been conducted. To evaluate the association between serum PFAAs concentrations and T-lymphocyte-related immunological markers of asthma in children, and further to assess whether gender modified this association, 231 asthmatic children and 225 non-asthmatic control children from Northern Taiwan were recruited into the Genetic and Biomarker study for Childhood Asthma. Serum concentrations of ten PFAAs and levels of TH1 [interferon (IFN)-γ, interleukin (IL)-2] and TH2 (IL-4 and IL-5) cytokines were measured. The results showed that asthmatics had significantly higher serum PFAAs concentrations compared with the healthy controls. When stratified by gender, a greater number of significant associations between PFAAs and asthma outcomes were found in males than in females. Among males, adjusted odds ratios for asthma among those with the highest versus lowest quartile of PFAAs exposure ranged from 2.59 (95% CI: 1.14, 5.87) for the perfluorobutanesulfonate (PFBS) to 4.38 (95% CI: 2.02, 9.50) for perfluorooctanesulfonate (PFOS); and serum PFAAs were associated positively with TH2 cytokines and inversely with TH1 cytokines among male asthmatics. Among females, no significant associations between PFAAs and TH2 cytokines could be detected. In conclusion, increased serum PFAAs levels may promote TH cell dysregulation and alter the availability of key TH1 and TH2 cytokines, ultimately contributing to the development of asthma that may differentially impact males to a greater degree than females. These results have potential relevance in asthma prevention.

Prenatal Exposure to Perfluoroalkyl Substances and Behavioral Development in Children

Background: In recent years, prevalence rates of behavioral disorders in children have increased. One factor possibly implied in the etiology of behavioral disorders is exposure to perfluoroalkyl substances (PFASs). The use of PFASs is highly integrated into everyday life, and exposure is ubiquitous. Exposure to PFASs during early life may be particularly harmful, as it represents a critical time window for brain development. However, research in the area is limited, especially among preschool children. The objective of the current study was to explore the relationship between prenatal exposure to several PFASs and behavioral development at the age of 18 months. Methods: Data from the Dutch cohort LINC (Linking Maternal Nutrition to Child Health) were used. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were measured in cord plasma. The total exposure of PFASs was also calculated (ΣPFASs). Behavioral development was assessed with the Child Behavior Checklist 1.5–5 (CBCL 1.5–5). The CBCL scales “Attention Deficit Hyperactivity Disorder” (ADHD) and “Externalizing problems” were used for further analysis. Separate regression models were composed for each combination, in which exposure levels were classified in tertiles. Both whole population and sex-stratified analyses were performed. A family history of ADHD, the educational level, smoking or using alcohol or illicit drugs during pregnancy were considered as confounders. In total, data from 76 mother-child pairs was included. Results: No significant associations were found between prenatal PFAS exposure and ADHD scores in the whole population and in the sex-stratified analyses. With regard to externalizing behavior, a significant negative association was found between the highest levels of ΣPFAS exposure and externalizing problem behavior in the whole population, but only in the crude model. After stratifying for sex, boys in the second and third tertile of exposure to PFOA presented significantly lower scores on the Externalizing Problem Scale than boys with the lowest exposure levels in the adjusted model. Girls exposed to higher levels of ΣPFAS exposure (T2) showed significantly lower scores on the Externalizing Problem Scale, in both crude and adjusted models. No significant associations with PFOS were found. Conclusions: Results from the current study show that prenatal exposure to PFOA was negatively related to externalizing behavior in boys. Results were different for boys and girls, emphasizing that mechanisms at work might be sex-dependent. However, results should be interpreted with caution as the sample size was small.

Childhood Atopic Dermatitis in Taiwan

The prevalence of atopic dermatitis (AD) appears to have increased dramatically over the past decades. It is generally believed that such rapid increase in prevalence cannot be explained fully by genetic factors. Environmental factors might play a role in such an increment. Children with AD are most likely to suffer considerable school absences, family stress, and health care expenditures. Because the onset of AD occurs relatively early in life, identification of early life risk factors and early management for AD to prevent the development of atopic march are of critical importance. However, there is still no consensus on coordinated prevention and management for AD in Taiwan. In this review, we discuss the specific risk factors of AD and important results of recent articles on AD from Taiwan. The management and prevention strategies of AD for Asian skin are also discussed.

Perfluoroalkyl substances and food allergies in adolescents

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are a class of organic compounds that are persistent in the environment due to their stable carbon-fluorine backbone, which is not susceptible to degradation. Research suggests these chemicals may exert an immunotoxic effect. The aim of this study is to investigate the associations between four PFASs - perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) - with food sensitization and food allergies in adolescent participants (ages 12-19years) in the National Health and Nutrition Examination Survey (NHANES) 2005-2006 and 2007-2010, respectively. We performed multivariate logistic regression to analyze the association between individual PFASs with food sensitization (defined as having at least 1 food-specific IgE level≥0.35kU/L) in NHANES 2005-2006 and food allergies (self-reported) in NHANES 2007-2010. Serum PFOA, PFOS, and PFHxS were statistically significantly associated with higher odds to have self-reported food allergies in NHANES 2007-2010. When using IgE levels as a marker of food sensitization, we found that serum PFNA was inversely associated with food sensitization (NHANES 2005-2006). In conclusion, we found that serum levels of PFASs were associated with higher odds to have self-reported food allergies. Conversely, adolescents with higher serum PFNA were less likely to be sensitized to food allergens. These results, along with previous studies, warrant further investigation, such as well-designed longitudinal studies.

Perfluoroalkyl and polyfluoroalkyl substances and indicators of immune function in children aged 12-19 y: National Health and Nutrition Examination Survey

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are immunotoxic in laboratory studies. Human studies of immune effects are inconsistent. Using the US National Health and Nutrition Examination Survey (NHANES), we examined PFAS serum concentration and indicators of prevalent immune function among 12-19-y-old children.

METHODS

In this cross-sectional study, we examined PFAS serum concentration in relation to measles, mumps, and rubella antibody concentrations in NHANES 1999-2000 and 2003-2004 (n = 1,191) and to allergic conditions and allergic sensitization in NHANES 2005-2006 (n = 640).

RESULTS

In adjusted, survey-weighted models, a doubling of perfluorooctane sulfonate (PFOS) concentration among seropositive children was associated with a 13.3% (95% confidence interval (CI): -19.9, -6.2) decrease in rubella antibody concentration and a 5.9% decrease in mumps antibody concentration (95% CI: -9.9, -1.6). We observed no adverse association between exposure and current allergic conditions, including asthma. Children with higher PFOS concentration were less likely to be sensitized to any allergen (odds ratio (OR): 0.74; 95% CI: 0.58, 0.95).

CONCLUSION

Increased exposure to several PFAS was associated with lower levels to mumps and rubella antibody concentrations, especially among seropositive individuals. These lower antibody concentrations may indicate a less robust response to vaccination or greater waning of vaccine-derived immunity over time.

A critical review of perfluorooctanoate and perfluorooctanesulfonate exposure and immunological health conditions in humans

Whether perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), two widely used and biopersistent synthetic chemicals, are immunotoxic in humans is unclear. Accordingly, this article systematically and critically reviews the epidemiologic evidence on the association between exposure to PFOA and PFOS and various immune-related health conditions in humans. Twenty-four epidemiologic studies have reported associations of PFOA and/or PFOS with immune-related health conditions, including ten studies of immune biomarker levels or gene expression patterns, ten studies of atopic or allergic disorders, five studies of infectious diseases, four studies of vaccine responses, and five studies of chronic inflammatory or autoimmune conditions (with several studies evaluating multiple endpoints). Asthma, the most commonly studied condition, was evaluated in seven studies. With few, often methodologically limited studies of any particular health condition, generally inconsistent results, and an inability to exclude confounding, bias, or chance as an explanation for observed associations, the available epidemiologic evidence is insufficient to reach a conclusion about a causal relationship between exposure to PFOA and PFOS and any immune-related health condition in humans. When interpreting such studies, an immunodeficiency should not be presumed to exist when there is no evidence of a clinical abnormality. Large, prospective studies with repeated exposure assessment in independent populations are needed to confirm some suggestive associations with certain endpoints.

Prenatal exposure to phthalates, bisphenol A and perfluoroalkyl substances and cord blood levels of IgE, TSLP and IL-33

The fetal time period is a critical window of immune system development and resulting heightened susceptibility to the adverse effects of environmental exposures. Epidemiologists and toxicologists have hypothesized that phthalates, bisphenol A (BPA) and perfluoroalkyl substance have immunotoxic properties. Immunotoxic effects of chemicals may manifest in an altered immune system profile at birth. Immunoglobulin E, thymic stromal lymphopoietin (TSLP), and interleukin-33 (IL-33) are integral in the etiology of childhood allergy and detectable at birth. The objective of this study was to determine the association between maternal levels of phthalates, bisphenol A (BPA), and perfluoroalkyl substances and elevated umbilical cord blood levels of IgE, TSLP, and IL-33. This study utilized data collected in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada cohort study of 2001 pregnant women. Of these women, 1258 had a singleton, term birth and cord blood sample. A Bayesian hierarchical model was employed to determine associations between log-transformed continuous variables and immune system biomarkers while adjusting for potential confounding from correlated environmental contaminants. Inverse, nonlinear associations were observed between maternal urinary MCPP levels and elevated levels of both IL-33/TSLP and IgE and between maternal urinary BPA levels and elevated levels of IL-33/TSLP. In this primarily urban Canadian population of pregnant women and their newborns, maternal urinary and plasma concentrations of phthalate metabolites, BPA, and perfluoroalkyl substances were not associated with immunotoxic effects that manifest as increased odds of elevated levels of IgE, TSLP or IL-33.

Maternal exposure to metals and persistent pollutants and cord blood immune system biomarkers

BACKGROUND

The fetal time period is a critical window of immune system development and resulting heightened susceptibility to the adverse effects of environmental exposures. Epidemiologists and toxicologists have hypothesized that persistent organic pollutants, pesticides and metals have immunotoxic properties. Immunotoxic effects may manifest as an altered immune system profile at birth. Immunoglobulin E, thymic stromal lymphopoietin (TSLP), and interleukin-33 (IL-33) may be implicated in the etiology of childhood allergy and are detectable at birth. The objective of this study was to examine the potential relationship between maternal concentrations of metals, persistent organic pollutants, and pesticides and elevated umbilical cord blood concentrations of IgE, TSLP, and IL-33 in a Canadian birth cohort.

METHODS

This study utilized data collected in the Maternal-Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada cohort study of 2,001 pregnant women. Of these women, 1258 had a singleton, term birth and cord blood sample. Logistic regression was used to determine associations between log-transformed continuous variables and immune system biomarkers.

RESULTS

Inverse relationships were observed between lead, DDE, PCB-118, and a summary index of organophosphorous metabolites and jointly elevated concentrations of IL-33 and TSLP. None of the environmental contaminants were associated with increased odds of a high cord blood immune system biomarker concentration.

CONCLUSIONS

In this primarily urban Canadian population of pregnant women and their newborns, maternal blood or urine concentrations of persistent organic pollutants, pesticides, and metals were not associated with immunotoxic effects that manifest as increased odds of elevated concentrations of IgE, TSLP or IL-33.

Prenatal exposure to environmental chemical contaminants and asthma and eczema in school-age children

BACKGROUND

Emerging evidence suggests that prenatal or early-life exposures to environmental contaminants may contribute to an increased risk of asthma and allergies in children. We aimed to the explore associations of prenatal exposures to a large set of environmental chemical contaminants with asthma and eczema in school-age children.

METHODS

We studied 1024 mother-child pairs from Greenland and Ukraine from the INUENDO birth cohort. Data were collected by means of an interview-based questionnaire when the children were 5-9 years of age. Questions from the ISAAC study were used to define asthma, eczema, and wheeze. We applied principal components analysis (PCA) to sixteen contaminants in maternal serum sampled during pregnancy, including perfluoroalkyl substances (PFASs), metabolites of diethylhexyl (DEHP) and diisononyl (DiNP) phthalates, PCB-153, and p,p'-DDE. Scores of five principal components (PCs) explaining 70% of the variance were included in multiple logistic regression models.

RESULTS

In a meta-analysis that included both populations, the PC2 score, reflecting exposure to DiNP, was negatively associated with current eczema (OR 0.71, 95% CI 0.52-0.96). Other associations were not consistent between the two populations. In Ukrainian children, the PC3 score (DEHP) was positively associated with current wheeze (adjusted OR 1.56, 95% CI 1.03-2.37), whereas the PC5 score, dominated by perfluorooctanoic acid (PFOA), was inversely associated with current wheeze (OR 0.64, 0.41-0.99). In Greenlandic children, a negative association of PC4 (organochlorines) with ever eczema (OR 0.78, 0.61-0.99) was found.

CONCLUSIONS

We found limited evidence to support a link between prenatal exposure to environmental chemical contaminants and childhood asthma and eczema.

Cord blood gene expression supports that prenatal exposure to perfluoroalkyl substances causes depressed immune functionality in early childhood

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a class of synthetic compounds that have widespread use in consumer and industrial applications. PFAS are considered environmental pollutants that have various toxic properties, including effects on the immune system. Recent human studies indicate that prenatal exposure to PFAS leads to suppressed immune responses in early childhood. In this study, data from the Norwegian BraMat cohort was used to investigate transcriptomics profiles in neonatal cord blood and their association with maternal PFAS exposure, anti-rubella antibody levels at 3 years of age and the number of common cold episodes until 3 years. Genes associated with PFAS exposure showed enrichment for immunological and developmental functions. The analyses identified a toxicogenomics profile of 52 PFAS exposure-associated genes that were in common with genes associated with rubella titers and/or common cold episodes. This gene set contains several immunomodulatory genes (CYTL1, IL27) as well as other immune-associated genes (e.g. EMR4P, SHC4, ADORA2A). In addition, this study identified PPARD as a PFAS toxicogenomics marker. These markers can serve as the basis for further mechanistic or epidemiological studies. This study provides a transcriptomics connection between prenatal PFAS exposure and impaired immune function in early childhood and supports current views on PPAR- and NF-κB-mediated modes of action. The findings add to the available evidence that PFAS exposure is immunotoxic in humans and support regulatory policies to phase out these substances.

Domestic exposure to volatile organic compounds in relation to asthma and allergy in children and adults

Over the past decades, the prevalence of asthma, allergic disease and atopy has increased significantly and in parallel with the increased use of products and materials emitting volatile organic compounds (VOCs) in the indoor environment. The purpose of this review is to examine the evidence of the relationship between quantitatively measured domestic exposure to VOCs and allergic diseases and allergy in children and adults. Sources, potential immune-inflammatory mechanisms and risks for development and severity of asthma and allergy have been addressed. Available evidence is based on studies that have mainly used observational designs of variable quality. Total, aromatic, aliphatic, microbial VOCs and aldehydes have been the most widely investigated VOC classes, with formaldehyde being the most commonly examined single compound. Overall, the evidence is inadequate to draw any firm conclusions. However, given indicative evidence from a few high-quality studies and significant potential for improvements in asthma outcomes in those with established disease, there is a need to consider undertaking further investigation of the relationship between domestic VOC exposure and asthma/allergy outcomes that should encompass both high-quality, robust observational studies and ultimately clinical trials assessing the impact of interventions that aim to reduce VOC exposure in children and adults with asthma.

Perfluoroalkyl chemicals and asthma among children 12-19 years of age: NHANES (1999-2008)

BACKGROUND

Perfluoroalkyl chemicals (PFCs) are a family of commonly used industrial chemicals whose persistence and ubiquity in human blood samples has led to concern about possible toxicity. Several animal studies and one recent human study have suggested a link between exposure to PFCs and asthma, although few epidemiologic studies have been conducted.

OBJECTIVES

We investigated children's PFC serum concentrations and their associations with asthma-related outcomes.

METHODS

We evaluated the association between serum concentrations of eight PFCs, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS), with self-reported lifetime asthma, recent wheezing, and current asthma using data from participants 12-19 years of age from the 1999-2000 and 2003-2008 National Health and Nutrition Examination Surveys.

RESULTS

In multivariable-adjusted models, PFOA was associated with higher odds of ever having received a diagnosis of asthma [odds ratio (OR) = 1.18; 95% CI: 1.01, 1.39 for a doubling in PFOA], whereas for PFOS there were inverse relationships with both asthma and wheezing (OR = 0.88; 95% CI: 0.74, 1.04, and OR = 0.83; 95% CI: 0.67, 1.02, respectively). The associations were attenuated after accounting for sampling weights. No associations were seen between the other PFCs and any outcome.

CONCLUSIONS

This cross-sectional study provides some evidence for associations between exposure to PFCs and asthma-related outcomes in children. The evidence is inconsistent, however, and prospective studies are needed.

The Navigation Guide - evidence-based medicine meets environmental health: systematic review of human evidence for PFOA effects on fetal growth

BACKGROUND

The Navigation Guide methodology was developed to meet the need for a robust method of systematic and transparent research synthesis in environmental health science. We conducted a case study systematic review to support proof of concept of the method.

OBJECTIVE

We applied the Navigation Guide systematic review methodology to determine whether developmental exposure to perfluorooctanoic acid (PFOA) affects fetal growth in humans.

METHODS

We applied the first 3 steps of the Navigation Guide methodology to human epidemiological data: 1) specify the study question, 2) select the evidence, and 3) rate the quality and strength of the evidence. We developed a protocol, conducted a comprehensive search of the literature, and identified relevant studies using prespecified criteria. We evaluated each study for risk of bias and conducted meta-analyses on a subset of studies. We rated quality and strength of the entire body of human evidence.

RESULTS

We identified 18 human studies that met our inclusion criteria, and 9 of these were combined through meta-analysis. Through meta-analysis, we estimated that a 1-ng/mL increase in serum or plasma PFOA was associated with a -18.9 g (95% CI: -29.8, -7.9) difference in birth weight. We concluded that the risk of bias across studies was low, and we assigned a "moderate" quality rating to the overall body of human evidence.

CONCLUSION

On the basis of this first application of the Navigation Guide systematic review methodology, we concluded that there is "sufficient" human evidence that developmental exposure to PFOA reduces fetal growth.

The Navigation Guide systematic review methodology: a rigorous and transparent method for translating environmental health science into better health outcomes

BACKGROUND

Synthesizing what is known about the environmental drivers of health is instrumental to taking prevention-oriented action. Methods of research synthesis commonly used in environmental health lag behind systematic review methods developed in the clinical sciences over the past 20 years.

OBJECTIVES

We sought to develop a proof of concept of the "Navigation Guide," a systematic and transparent method of research synthesis in environmental health.

DISCUSSION

The Navigation Guide methodology builds on best practices in research synthesis in evidence-based medicine and environmental health. Key points of departure from current methods of expert-based narrative review prevalent in environmental health include a prespecified protocol, standardized and transparent documentation including expert judgment, a comprehensive search strategy, assessment of "risk of bias," and separation of the science from values and preferences. Key points of departure from evidence-based medicine include assigning a "moderate" quality rating to human observational studies and combining diverse evidence streams.

CONCLUSIONS

The Navigation Guide methodology is a systematic and rigorous approach to research synthesis that has been developed to reduce bias and maximize transparency in the evaluation of environmental health information. Although novel aspects of the method will require further development and validation, our findings demonstrated that improved methods of research synthesis under development at the National Toxicology Program and under consideration by the U.S. Environmental Protection Agency are fully achievable. The institutionalization of robust methods of systematic and transparent review would provide a concrete mechanism for linking science to timely action to prevent harm.

Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: high seafood consumers, high freshwater fish consumers and pregnant women

Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC-MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values<LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg(-1) bw.d(-1)), PFUnA (1.3 ng.kg(-1) bw.d(-1)), PFDA (0.4 ng.kg(-1) bw.d(-1)) and PFHpS (0.03 ng.kg(-1) bw.d(-1)) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg(-1) bw.d(-1)), PFNA (0.2 ng.kg(-1) bw.d(-1)) and PFHxS (0.06 ng.kg(-1) bw.d(-1)). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals.

Perfluorinated compounds in serum and urine samples from children aged 5-13 years in South Korea

Serum and urine samples from 120 children aged 5-13 years from Dae-gu, Korea, were analyzed for 16 perfluorinated compounds (PFCs). The total PFC concentrations in the serum were 4.26-29.70 ng/mL, and perfluorohexanesulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS, which was dominant overall, at 6.58 ng/mL), and perfluoroundecanoic acid (PFUndA) were detected in all serum samples. The total PFC concentrations in the urine ranged from below the detection limit to 14.9 ng/mL, and perfluoropentanoic acid (PFPeA) was predominant. The PFOS (p < 0.005) concentration was higher in the serum of children than that of Korean adults aged 20-29. Some of the PFC concentrations in the serum correlated negatively with body mass index and tended to increase with the duration of breastfeeding. However, there were no gender-specific differences in the PFC concentrations and no correlations between PFC concentrations in serum and urine.

Ten years of progress in the Hokkaido birth cohort study on environment and children's health: cohort profile--updated 2013

The Hokkaido Study on Environment and Children's Health is an ongoing cohort study that began in 2002. The study consists of two prospective birth cohorts, the Sapporo cohort (n = 514) and the Hokkaido large-scale cohort (n = 20,940). The primary goals of this study are to first examine the potential negative effects of perinatal environmental chemical exposures on birth outcomes, including congenital malformations and growth retardation; second, to evaluate the development of allergies, infectious diseases and neurodevelopmental disorders and perform longitudinal observations of the children's physical development to clarify the causal relationship between these outcomes and environmental chemicals; third, to identify individuals genetically susceptible to environmental chemicals; finally, to identify the additive effects of various environmental factors in our daily life, such as secondhand smoke exposure or low folate intake during early pregnancy. In this paper, we introduce our recent progress in the Hokkaido study with a cohort profile updated in 2013. For the last ten years, we followed pregnant women and their offspring, measuring various environmental chemicals, i.e., PCB, OH-PCB and dioxins, PFCs (Perfluorinated Compounds), Organochlorine pesticides, Phthalates, bisphenol A and mercury. We discovered that the concentration of toxic equivalents (TEQ) of dioxin and other specific congeners of PCDF or PCDD have effects on birth weight, infants' neurodevelopment and immune function. There were significant gender differences in these effects; our results suggest that male infants have more susceptibility to those chemical exposures than female infants. Interestingly, we found maternal genetic polymorphisms in AHR, CYP1A1 or GSTs that significantly modified the dioxin concentrations in maternal blood, suggesting different dioxin accumulations in the bodies of individuals with these genotypes, which would lead to different dioxin exposure levels. These genetic susceptibility factors influenced the body size of children born from mothers that either smoked or were passively exposed to tobacco smoke. Further studies investigating the correlation between epigenetics, the effects of intrauterine exposure to environmental chemicals and developmental factors related to health and disease are warranted.

Prenatal exposure to perfluoroalkyl acids and allergic diseases in early childhood

Perfluoroalkyl acids (PFAAs) are persistent organic pollutants that are detected in humans worldwide. Laboratory animal studies have shown that PFAAs are associated with immunotoxic effects. However, epidemiological studies investigating the role of PFAAs, in particular PFAAs with longer chains than perfluorooctanoic acid, are scarce. We investigated associations between prenatal exposure to PFAAs, including long-chain compounds, and infant allergic diseases at 12 and 24months in a large study population. The participants included mothers and their infants who enrolled in the Hokkaido Study on Environment and Children's Health 2003-2009. Eleven PFAAs were measured in maternal plasma taken at 28-32weeks of gestation using ultra-performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry. Characteristics of participants and information on infant allergic diseases were obtained from self-administered questionnaires and medical records. At 24months, the adjusted odds ratio (OR) (first vs. fourth quartiles) for eczema in association with higher maternal perfluorotridecanoic acid (PFTrDA) levels was 0.62 (95% confidence interval (CI) 0.45, 0.86). After stratification by gender, the adjusted ORs in female infants from mothers with higher maternal perfluoroundecanoic acid (PFUnDA) and PFTrDA levels were also statistically significant (PFUnDA: OR=0.50; 95% CI, 0.30, 0.81; PFTrDA: OR=0.39; 95% CI, 0.23, 0.64). Our findings suggest that lower prenatal exposure to PFTrDA may decrease the risk of developing eczema in early childhood, only in female infants.

Uptake of perfluorinated compounds by plants grown in nutrient solution

The uptake rates of three perfluorinated carboxylates and three perfluorinated sufonates by a grass (B diandrus) grown in nutrient solution at two different perfluorinated compounds (PFCs) concentrations were assessed. Grass can be ingested by grazing animals causing the PFCs to enter the food chain, which is a pathway of human exposure to these compounds. A rapid and miniaturized method was developed to determine PFCs in plants, based on a matrix solid-phase dispersion (MSPD) extraction procedure followed by quantitation by HPLC-MS/MS with an MQL in the range from 1 to 9 ng/g. An increase of PFCs levels in plant was observed along the exposure time. Differences in uptake for studied perfluorinated carboxylates were found, showing a decrease with carbon chain length (from 3027 to 1,167 ng/g at the end of assay), whereas no significant differences in absorption were obtained between perfluorinated sulfonates (about 1,700 ng/g). Initially, higher PFC transfer factors (ratio between concentration in plant and concentration in initial nutrient solution) were obtained for plants growing in the nutrient solution at the highest PFC concentration, but these factors became similar with time to plants exposed to the lowest concentration.

Perfluorinated compounds: emerging POPs with potential immunotoxicity

Perfluorinated compounds (PFCs) have been recognized as an important class of environmental contaminants commonly detected in blood samples of both wildlife and humans. These compounds have been in use for more than 60 years as surface treatment chemicals, polymerization aids, and surfactants. They possess a strong carbon-fluorine bond, which leads to their environmental persistence. There is evidence from both epidemiology and laboratory studies that PFCs may be immunotoxic, affecting both cell-mediated and humoral immunity. Reported effects of PFCs include decreased spleen and thymus weights and cellularity, reduced specific antibody production, reduced survival after influenza infection, and altered cytokine production. Immunosuppression is a critical effect associated with exposure to PFCs, as it has been reported to reduce antibody responses to vaccination in children. Mounting evidence suggests that immunotoxicity in experimental animals can occur at serum concentrations below, within, or just above the reported range for highly exposed humans and wildlife. Considering bioaccumulation and exposure to multiple PFCs, the risk of immunotoxicity for humans and wildlife cannot be discounted. This review will discuss current and recently published work exploring the immunomodulatory effects of PFCs in experimental animals and humans.

Potential risk of asthma associated with in utero exposure to xenobiotics

The incidence of asthma, a complex disease and significant public health problem, has been increasing over the last 30 years for unknown reasons. Changes in environmental exposures or lifestyle may be involved. In some cases asthma may originate in utero or in early life. Associations have been found between in utero exposures to several xenobiotics and increased risk of asthma. There is convincing evidence that maternal smoking and/or in utero and perinatal exposure to environmental tobacco smoke are associated with increased risk of asthma. Similar effects have been demonstrated in animal models of allergic asthma. Evidence also suggests that in utero and/or early-life exposures to various ambient air pollutants may increase the risk of asthma although supporting animal data are very limited. A few studies have suggested that in utero exposure to acetaminophen is associated with increased risk of asthma; however, animal data are lacking. Various vitamin deficiencies and supplements during pregnancy have been studied. In general, it appears that vitamins A, C, and E have protective effects and vitamins D and B may, in some instances, increase the risk, but the data are not conclusive. Some studies related to in utero exposures to polychlorinated biphenyls and bisphenol A and asthma risk are also reported. The underlying mechanisms for an association between xenobiotic exposures and asthma remain a matter of speculation. Genetic predisposition and epigenetic changes have been explored. The developing immune, respiratory, and nervous systems are potential targets. Oxidative stress and modulation of inflammation are thought to be involved.

Prenatal environmental factors influencing IgE levels, atopy and early asthma

PURPOSE OF REVIEW

There is increasing evidence that the prenatal window represents a critical period in which the developing immune system may be primed toward an allergic phenotype. Studies have investigated the role of a number of maternal environmental exposures on subsequent allergic disorders in the offspring. We summarize findings from recent studies on prenatal environmental factors influencing IgE levels, atopy, and early asthma.

RECENT FINDINGS

A building literature supports the influence of maternal exposure to environmental pollutants, such as allergens, traffic-related air pollution, tobacco smoke, and organochlorine compounds and social factors on allergic outcomes. More novel associations have been investigated, such as the effect of prenatal exposures to phthalates, bisphenol A, and magnetic fields. There is also rising interest in epigenetics as a pathway of action by which maternal exposure affect immune health.

SUMMARY

Emerging research highlights the challenges of investigating in-utero exposures and of relating exposures to such a heterogeneous and complex outcome as allergic disease. Further research is needed on the mechanisms by which prenatal exposure influences allergic response in childhood and how postnatal, familial and social factors, and sex can modify disease outcomes. Epigenetics is a promising new frontier, and likely one of several explanatory factors.

Neonatal-maternal factors and perfluoroalkyl substances in cord blood

Perfluoroalkyl substances (PFASs) can cross the placenta, enter fetal circulation, and were found to correlate with adverse fetal growth. However, determinants of cord blood PFASs are not fully characterized. The study aimed to explore the association between PFASs and neonatal-maternal factors within a Taiwanese birth cohort. We selected subjects from Taiwan Birth Panel Study, which enrolled 486 infant-mother pairs in 2004-2005. We collected cord blood and analyzed perfluorooctanoic acid (PFOA), perfluorooctanyl sulfonate (PFOS), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUA) using a simple protein precipitation and an ultra-high performance liquid chromatography/tandem mass spectrometry. We retrieved information pertaining to maternal socio-demographics, lifestyle- and dietary-related factors through structured questionnaires during the postpartum hospital stay. A total of 439 subjects, with 90% response rate, have completed serum analysis and questionnaire survey. The median concentrations for PFOA, PFOS, PFNA, and PFUA in cord blood were 1.86, 5.67, 3.00, and 13.5ngmL(-1), respectively. After adjusting for potential confounders, multiple linear regression models revealed that log10-PFOA was positively associated with maternal age (β=0.011) and negatively associated with multiparity (β=-0.044). Log10-PFOS was negatively correlated with birth weight (β=-0.011) and higher maternal education (senior high school: β=-0.067; university: β=-0.088). Log10-PFUA tended to negatively associate with gender, male infants (β=-0.075), and using cosmetics during pregnancy (β=-0.065). Interestingly, presence of cockroaches in the home was positively associated with log10-PFOA (β=0.041) and 1og10-PFNA (β=0.123). In conclusion, this study demonstrated several factors to correlate with cord blood PFASs and further investigation are still needed for confirmation of exposure routes.

Serum polyfluoroalkyl concentrations, asthma outcomes, and immunological markers in a case-control study of Taiwanese children

BACKGROUND

Perfluorinated compounds (PFCs) are ubiquitous pollutants. Experimental data suggest that they may be associated with adverse health outcomes, including asthma. However, there is little supporting epidemiological evidence.

METHODS

A total of 231 asthmatic children and 225 nonasthmatic controls, all from northern Taiwan, were recruited in the Genetic and Biomarkers study for Childhood Asthma. Structure questionnaires were administered by face-to-face interview. Serum concentrations of 11 PFCs and levels of immunological markers were also measured. Associations of PFC quartiles with concentrations of immunological markers and asthma outcomes were estimated using multivariable regression models.

RESULTS

Nine PFCs were detectable in most children (≥ 84.4%), of which perfluorooctane sulfonate (PFOS) was the most abundant (median serum concentrations of 33.9 ng/mL in asthmatics and 28.9 ng/mL in controls). Adjusted odds ratios for asthma among those with the highest versus lowest quartile of PFC exposure ranged from 1.81 (95% CI: 1.02, 3.23) for the perfluorododecanoic acid (PFDoA) to 4.05 (95% CI: 2.21, 7.42) for perfluorooctanic acid (PFOA). PFOS, PFOA, and subsets of the other PFCs were positively associated with serum IgE concentrations, absolute eosinophil counts (AEC), eosinophilic cationic protein (ECP) concentrations, and asthma severity scores among asthmatics.

CONCLUSIONS

This study suggests an association between PFC exposure and juvenile asthma. Because of widespread exposure to these chemicals, these findings may be of potential public health concern.

Associations between perfluoroalkyl compounds and immune and clinical chemistry parameters in highly exposed bottlenose dolphins (Tursiops truncatus)

Perfluoroalkyl compounds (PFCs) are ubiquitous, persistent chemical contaminants found in the environment, wildlife, and humans. Despite the widespread occurrence of PFCs, little is known about the impact these contaminants have on the health of wildlife populations. The authors investigated the relationship between PFCs (including ∑perfluorocarboxylates, ∑perfluoroalkyl sulfonates, perfluorooctane sulfonate, perfluorooctanoic acid, and perfluorodecanoic acid) and the clinocopathologic and immune parameters in a highly exposed population (n = 79) of Atlantic bottlenose dolphins (mean ∑PFCs = 1970 ng/ml; range 574-8670 ng/ml) sampled from 2003 to 2005 near Charleston, South Carolina, USA. Age-adjusted linear regression models showed statistically significant positive associations between exposure to one or more of the PFC totals and/or individual analytes and the following immunological parameters: absolute numbers of CD2+ T cells, CD4+ helper T cells, CD19+ immature B cells, CD21+ mature B cells, CD2/CD21 ratio, MHCII+ cells, B cell proliferation, serum IgG1, granulocytic, and monocytic phagocytosis. Several PFC analyte groups were also positively associated with serum alanine aminotransferase, gamma-glutamyltransferase, creatinine, phosphorus, amylase, and anion gap and negatively associated with cholesterol levels, creatinine phosphokinase, eosinophils, and monocytes. Based on these relationships, the authors suggest that the PFC concentrations found in Charleston dolphins may have effects on immune, hematopoietic, kidney, and liver function. The results contribute to the emerging data on PFC health effects in this first study to describe associations between PFCs and health parameters in dolphins.

River water contaminated with perfluorinated compounds potentially posing the greatest risk to young children

Although, humans are exposed to perflourinated compounds (PFCs) from various media, water consumption could be an important source for the residents living near to contaminated areas. Since comprehensive multimedia exposure model has not been developed for PFCs, assessment of the potential risk due to exposure to PFCs through direct water consumption could be a conservative estimate. The human health risks derived from the exposure to PFCs through water consumption were assessed for different age groups of general population in Taiwan using probabilistic approach. Based on available data on concentrations of PFCs in river water, exposure to PFOS, PFOA and PFDA via water consumption for different age groups were calculated using deterministic and probabilistic risk assessment methods. The oral non-cancer risks from PFOS, PFOA and their combination, expressed as a Hazard Index (HI), was determined by comparing oral exposure dose (through water intake) with the oral Reference Dose (RfD). The average exposure to PFOS, PFOA and PFDA via water consumption for adults ranged from 0.16 to 220.15, 0.43 to 12.5 and 0.43 to 2.36 ng kg-bw(-1) d(-1) and for children 0.13-354.3, 0.35-20.17 and 0.35-3.79 ng kg-bw(-1) d(-1), respectively. Probabilistic values of total HIs for all age groups reside near to Keya River exceed the RfD 2.4-4.8 times, corresponding mainly to PFOS with a percentage of 97%. In conclusions, children aged 1-3 years old and the residents reside near to Keya River are at the highest risk of exposure to PFCs via water consumption.

Effects of persistent organic pollutants on the developing respiratory and immune systems: a systematic review

BACKGROUND

Disruption of developing immune and respiratory systems by early-life exposure to persistent organic pollutants (POPs) could result into reduced capacity to fight infections and increased risk to develop allergic manifestations later in life.

OBJECTIVES

To systematically review the epidemiologic literature on the adverse effects of early-life exposure to POPs on respiratory health, allergy and the immune system in infancy, childhood and adolescence.

METHODS

Based on published guidelines for systematic reviews, two independent researchers searched for published articles in MEDLINE and SCOPUS using defined keywords on POPs and respiratory health, immune function and allergy. Study eligibility criteria were defined to select the articles.

RESULTS

This review of 41 studies finds limited evidence for prenatal exposure to DDE, PCBs and dioxins and risk of respiratory infections. Evidence was limited also for postnatal exposure to PCBs, specifically ndl-PCBs, and reduced immune response after vaccination in childhood. The review indicates lack of association between postnatal exposure to PCBs/ndl-PCBs and risk of asthma-related symptoms. For the other exposure-outcome associations reviewed evidence was inadequate.

DISCUSSION AND CONCLUSION

Current epidemiological evidence suggests that early-life exposure to POPs can adversely influence immune and respiratory systems development. Heterogeneity between studies in exposure and outcome assessment and the small number of studies for any given exposure-outcome relationship currently make comparisons difficult and meta-analyses impossible. Also, mechanisms remain largely unexplored. Recommendations for significantly improving our understanding thus include harmonization of exposure and outcome assessment between studies, conduct of larger studies, long-term assessment of respiratory infections and asthma symptoms in order to identify critical periods of susceptibility, integration of the potential immunotoxic mechanisms of POPs, and use of new statistical tools to detangle the role of multiple exposures on multiple outcomes.

Pre-natal exposure to perfluoroalkyl substances may be associated with altered vaccine antibody levels and immune-related health outcomes in early childhood

Perfluoroalkyl substances (PFAS) are suggested to have immunosuppressive effects; exposure in utero and in the first years of life is of special concern as fetuses and small children are highly vulnerable to toxicant exposure. The objective of this study was to investigate the effect of pre-natal exposure to PFAS on responses to pediatric vaccines and immune-related health outcomes in children up to 3 years of age. In the prospective birth-cohort BraMat, a sub-cohort of the Norwegian Mother and Child Cohort Study (MoBa), pregnant women from Oslo and Akershus, Norway, were recruited during 2007-2008. Three annual questionnaire-based follow-ups were performed. Blood samples were collected from the mothers at the time of delivery and from the children at the age of 3 years. As a measure of pre-natal exposure to PFAS, the concentrations of perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) were determined in maternal blood from 99 BraMat participants. Main outcome measures were anti-vaccine antibody levels, common infectious diseases and allergy- and asthma-related health outcomes in the children up to the age of 3 years. There was an inverse association between the level of anti-rubella antibodies in the children's serum at age 3 years and the concentrations of the four PFAS. Furthermore, there was a positive association between the maternal concentrations of PFOA and PFNA and the number of episodes of common cold for the children, and between PFOA and PFHxS and the number of episodes of gastroenteritis. No associations were found between maternal PFAS concentrations and the allergy- and asthma-related health outcomes investigated. The results indicate that pre-natal exposure to PFAS may be associated with immunosuppression in early childhood.

Perfluorooctanoic acid (PFOA), an emerging drinking water contaminant: a critical review of recent literature

Perfluorooctanoic acid (PFOA) is an anthropogenic contaminant that differs in several ways from most other well-studied organic chemicals found in drinking water. PFOA is extremely resistant to environmental degradation processes and thus persists indefinitely. Unlike most other persistent and bioaccumulative organic pollutants, PFOA is water-soluble, does not bind well to soil or sediments, and bioaccumulates in serum rather than in fat. It has been detected in finished drinking water and drinking water sources impacted by releases from industrial facilities and waste water treatment plants, as well as in waters with no known point sources. However, the overall occurrence and population exposure from drinking water is not known. PFOA persists in humans with a half-life of several years and is found in the serum of almost all U.S. residents and in populations worldwide. Exposure sources include food, food packaging, consumer products, house dust, and drinking water. Continued exposure to even relatively low concentrations in drinking water can substantially increase total human exposure, with a serum:drinking water ratio of about 100:1. For example, ongoing exposures to drinking water concentrations of 10 ng/L, 40 ng/L, 100 ng/L, or 400 ng/L are expected to increase mean serum levels by about 25%, 100%, 250%, and 1000%, respectively, from the general population background serum level of about 4 ng/mL. Infants are potentially a sensitive subpopulation for PFOA's developmental effects, and their exposure through breast milk from mothers who use contaminated drinking water and/or from formula prepared with contaminated drinking water is higher than in adults exposed to the same drinking water concentration. Numerous health endpoints are associated with human PFOA exposure in the general population, communities with contaminated drinking water, and workers. As is the case for most such epidemiology studies, causality for these effects is not proven. Unlike most other well-studied drinking water contaminants, the human dose-response curve for several effects appears to be steepest at the lower exposure levels, including the general population range, with no apparent threshold for some endpoints. There is concordance in animals and humans for some effects, while humans and animals appear to react differently for other effects such as lipid metabolism. PFOA was classified as "likely to be carcinogenic in humans" by the USEPA Science Advisory Board. In animal studies, developmental effects have been identified as more sensitive endpoints for toxicity than carcinogenicity or the long-established hepatic effects. Notably, exposure to an environmentally relevant drinking water concentration caused adverse effects on mammary gland development in mice. This paper reviews current information relevant to the assessment of PFOA as an emerging drinking water contaminant. This information suggests that continued human exposure to even relatively low concentrations of PFOA in drinking water results in elevated body burdens that may increase the risk of health effects.

In vitro characterization of the immunotoxic potential of several perfluorinated compounds (PFCs)

We have previously shown that PFOA and PFOS directly suppress cytokine secretion in immune cells, with different mechanisms of action. In particular, we have demonstrated a role for PPAR-α in PFOA-induced immunotoxicity, and that PFOS has an inhibitory effect on LPS-induced I-κB degradation. These studies investigate the immunomodulatory effects of four other PFCs, namely PFBS, PFOSA, PFDA, and fluorotelomer using in vitro assays. The release of the pro-inflammatory cytokines IL-6 and TNF-α was evaluated in lipolysaccharide (LPS)-stimulated human peripheral blood leukocytes (hPBL) and in the human promyelocytic cell line THP-1, while the release of IL-10 and IFN-γ was evaluated in phytohemagglutinin (PHA)-stimulated hPBL. All PFCs suppressed LPS-induced TNF-α production in hPBL and THP-1 cells, while IL-6 production was suppressed by PFOSA, PFOS, PFDA and fluorotelomer. PFBS, PFOSA, PFOS, PFDA and fluorotelomer inhibited PHA-induced IL-10 release, while IFN-γ secretion was affected by PFOSA, PFOS, PFDA and fluorotelomer. Leukocytes obtained from female donors appear to be more sensitive to the in vitro immunotoxic effects of PFCs when their responses are compared to the results obtained using leukocytes from male donors. Mechanistic investigations demonstrated that inhibition of TNF-α release in THP-1 cells occurred at the transcriptional level. All PFCs, including PFOA and PFOS, decreased LPS-induced NF-κB activation. With the exception of PFOA, none of the PFCs tested was able to activate PPARα driven transcription in transiently transfected THP-1 cells, excluding a role for PPARα in the immunomodulation observed. PFBS and PFDA prevented LPS-induced I-κB degradation. Overall, these studies suggest that PFCs affect NF-κB activation, which directly suppresses cytokine secretion by immune cells. Our results indicate that PFOA is the least active of the PFCs examined followed by PFBS, PFDA, PFOS, PFOSA and fluorotelomer.

Comparative pharmacokinetics of perfluorohexanesulfonate (PFHxS) in rats, mice, and monkeys

Perfluorohexanesulfonate (PFHxS) has been found in biological samples from wildlife and humans. The human geometric mean serum PFHxS elimination half-life has been estimated to be 2665days. A series of studies was undertaken to establish pharmacokinetic parameters for PFHxS in rats, mice, and monkeys after single administration with pharmacokinetic parameters determined by WinNonlin(®) software. Rats and mice appeared to be more effective at eliminating PFHxS than monkeys. With the exception of female rats, which had serum PFHxS elimination half-life of approximately 2 days, the serum elimination half-lives in the rodent species and monkeys approximated 1month and 4months, respectively, when followed over extended time periods (10-24weeks). Collectively, these studies provide valuable insight for human health risk assessment regarding the potential for accumulation of PFHxS in humans.