Perfluorinated chemicals and fetal growth: a study within the Danish National Birth Cohort

Perfluoroalkyl compounds in dust from Asian, Australian, European, and North American homes and UK cars, classrooms, and offices

Perfluoroalkyl compounds (PFCs) were measured in dust from Australian, Canadian, French, German, Kazahkstani, Thai, UK, and US homes, and UK cars, classrooms, and offices. Most PFCs were significantly lower in Kazahkstan and Thailand than elsewhere; 2-(N-methylperfluoro-1-octanesulfonamido)-ethanol (MeFOSE) and 2-(N-ethylperfluoro-1-octanesulfonamido)-ethanol (EtFOSE) were significantly lower in Canada than in the UK and the US; perfluoro-1-hexanesulfonate (PFHxS) was significantly lower in Canada than in the UK, and N-ethylperfluoro-1-octanesulfonamide (EtFOSA) was significantly higher in Australia than in the UK. High EtFOSA concentrations in some samples may be consistent with its use as an insecticide. Perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), PFHxS, and MeFOSE were significantly higher in classrooms than in cars, homes, and offices; N-methylperfluoro-1-octanesulfonamide (MeFOSA) was significantly lower in classrooms than in homes and offices, and perfluoro-1-octanesulfonamide (FOSA) was significantly lower in classrooms than in cars, homes, and offices. While homes are usually the most important vector of dust exposure (typically > 60%), offices and classrooms make important contributions. While diet is usually the main exposure pathway for UK adults and children (~1-6 years) for PFOS, PFOA, and PFHxS; dust ingestion can be significant under high dust ingestion scenarios. Even under high-end exposure scenarios for dust and diet, PFOS and PFOA exposures are well within the European Food Safety Authority tolerable daily intakes.

Prenatal exposures to perfluorinated chemicals and anthropometric measures in infancy

Perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) are persistent chemicals that may affect growth early in life. The authors estimated the associations between maternal plasma levels of PFOS and PFOA and infants' weight, length, and body mass index development during the first year of life. Fourteen hundred women were randomly selected from the Danish National Birth Cohort among those who provided blood samples early in pregnancy and gave birth to liveborn singletons between 1996 and 2002. Weight and length information at 5 and 12 months of age was available for 1,010 children. Multiple linear regression models were used for analyses, and maternal PFOS and PFOA concentrations (ng/mL) were inversely related to children's weight in the first year of life: adjusted regression coefficients: 0.8 g (95% confidence interval(CI): 4.2, 2.6) at 5 months and 5.8 g (95% CI:10.4, 1.2) at 12 months for perfluorooctanesulfonate(PFOS); 9.4 g (95% CI: 28.6, 9.9) at 5 months and 19.0 g (95% CI: 44.9, 6.8) at 12 months for perfluorooctanoate(PFOA) [corrected]. A similar pattern was observed for body mass index measurements, and no associations with length were found. After sex stratification, the inverse associations with weight and body mass index were more pronounced in boys, and no clear association was seen for girls.

Prenatal exposure to PFOA and PFOS and risk of hospitalization for infectious diseases in early childhood

OBJECTIVES

To examine whether prenatal exposure to perfluorooctanesulfonate (PFOS) or perfluorooctanoate (PFOA) is associated with the occurrence of hospitalization for infectious diseases during early childhood.

METHODS

We randomly selected 1400 pregnant women and their offspring from the Danish National Birth Cohort (1996-2002) and measured PFOS and PFOA levels in maternal blood during early pregnancy. Hospitalizations for infection of the offspring were identified by the linkage to the National Hospital Discharge Register through 2008.

RESULTS

Hospitalizations due to infections were not associated with prenatal exposure to PFOA and PFOS. On the contrary, the relative risks of hospitalizations ranged from 0.71 to 0.84 for the three higher quartiles of maternal PFOA levels compared with the lowest, but no dose-response pattern was found. No clear pattern was observed when results were stratified by child's age at infection, with the exception of an inverse association between maternal PFC levels and risk of hospitalization during the child's first year of life.

CONCLUSIONS

These findings suggest that prenatal exposure to PFOA or PFOS is not associated with increased risk of infectious diseases leading to hospitalization in early childhood.

Maternal exposure to perfluorinated acids and fetal growth

The widespread detection of perfluorinated acids (PFAs) in humans and known developmental toxicity in animals has raised concern about their potential effects on human reproductive health. Our objective was to determine whether increasing maternal exposure to PFAs is associated with adverse effects on fetal growth and length of gestation in women giving birth in Alberta, Canada. We examined the concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) in a cohort of 252 pregnant women who gave birth to live singletons. Each of the women had undergone an early second trimester prenatal screen, and her serum was analyzed for PFA concentrations. Data on infant and maternal variables were collected from the delivery record completed at birth. Adjusted changes in birth weight per natural log (ng/ml) of PFOA (median 1.5 ng/ml), PFHxS (median 0.97 ng/ml), and PFOS (median 7.8 ng/ml) were -37.4 g (95% confidence interval (CI): -86.0 to 11.2 g), 21.9 g (-23.4 to 67.2 g), and 31.3 g (-43.3 to 105.9 g), respectively. Mean birth weight z-score, standardized for gestational age and gender, length of gestation, and risk of preterm birth did not appear to be influenced by maternal PFA exposure. When PFA concentrations were divided into tertiles, similar patterns were observed. These results suggest that maternal PFA exposure has no substantial effect on fetal weight and length of gestation at the concentrations observed in this population.

Environmental contaminants and human health in the Canadian Arctic

The third Canadian Arctic Human Health Assessment conducted under the Canadian Northern Contaminants Program (NCP), in association with the circumpolar Arctic Monitoring and Assessment Programme (AMAP), addresses concerns about possible adverse health effects in individuals exposed to environmental contaminants through a diet containing country foods. The objectives here are to: 1) provide data on changes in human contaminant concentrations and exposure among Canadian Arctic peoples; 2) identify new contaminants of concern; 3) discuss possible health effects; 4) outline risk communication about contaminants in country food; and 5) identify knowledge gaps for future contaminant research and monitoring. The nutritional and cultural benefits of country foods are substantial; however, some dietary studies suggest declines in the amount of country foods being consumed. Significant declines were found for most contaminants in maternal blood over the last 10 years within all three Arctic regions studied. Inuit continue to have the highest levels of almost all persistent organic pollutants (POPs) and metals among the ethnic groups studied. A greater proportion of people in the East exceed Health Canada's guidelines for PCBs and mercury, although the proportion of mothers exceeding these guidelines has decreased since the previous assessment. Further monitoring and research are required to assess trends and health effects of emerging contaminants. Infant development studies have shown possible subtle effects of prenatal exposure to heavy metals and some POPs on immune system function and neurodevelopment. New data suggest important beneficial effects on brain development for Inuit infants from some country food nutrients. The most successful risk communication processes balance the risks and benefits of a diet of country food through input from a variety of regional experts and the community, to incorporate the many socio-cultural and economic factors to arrive at a risk management decision that will be the most beneficial in Arctic communities.

Diet and particularly seafood are major sources of perfluorinated compounds in humans

Commercially used perfluorinated compounds (PFCs) have been widely detected in wildlife and humans, but the sources of human exposure are not fully characterized. The objectives of this study were to explore possible associations between concentrations of PFCs in serum and consumption of food with particular focus on seafood, and to compare estimated dietary intakes with determined serum PFC concentrations. Concentrations of 19 PFCs were determined in serum from 175 participants in the Norwegian Fish and Game Study and evaluated with respect to food consumption using multiple linear regression analysis. Associations between estimated individual total dietary intakes of PFCs and serum concentrations were also explored. PFC concentrations in serum were significantly associated (p<0.05) with the consumption of lean fish, fish liver, shrimps and meat, as well as age, breastfeeding history and area of residence (R(2) 0.35-0.63). The estimated dietary intakes of perfluorooctanoic acid (PFOA), perfluoroundecanoic acid (PFUnDA) and perfluorooctane sulfonic acid (PFOS) were 0.60, 0.34 and 1.5 ng/kg body weight/day, respectively. Seafood (fish and shellfish) was the major dietary source contributing 38% of the estimated dietary intakes of PFOA, 93% of PFUnDA and 81% of PFOS. The estimated dietary intakes of these three selected PFCs were significantly associated with the corresponding serum PFC concentrations (p<0.05). In conclusion, our results show that consumption of fish and shellfish is a major determinant of serum PFC concentrations. Further, significant relationships between estimated dietary intakes and serum concentrations have been demonstrated for the first time.

Obesogens

PURPOSE OF REVIEW

The environmental obesogen hypothesis postulates chemical pollutants that are able to promote obesity by altering homeostatic metabolic set-points, disrupting appetite controls, perturbing lipid homeostasis to promote adipocyte hypertrophy, or stimulating adipogenic pathways that enhance adipocyte hyperplasia during development or in adults. This review focuses on recent experimental advances for candidate obesogens that target nuclear hormone receptors when a direct link between exposure, modulation of transcriptional networks and adipogenic phenotypes can be rationalized.

RECENT FINDINGS

Various endocrine disrupting chemicals can disrupt hormonal signaling relevant to adipose tissue biology. In this review, progress on one identified obesogen, the organotin tributyltin, will be outlined to highlight principles and novel insights into its high-affinity nuclear hormone receptor-mediated mechanism, its effects on adipocyte biology, its potential to promote long-term obesogenic changes and its epidemiological relevance. When appropriate, important results for other suspected obesogenic ligands, including bisphenol A, phthalates, polybrominated diphenyl ethers and perfluoro-compounds, will highlight corroborating principles.

SUMMARY

These examples serve to provide perspective on the potential harm that man-made obesogenic pollutants pose to human health, focus attention on areas in which knowledge remains inadequate and prompt a re-evaluation of the causative risk factors driving the current changes in obesity rates.

Inhalation exposure to fluorotelomer alcohols yield perfluorocarboxylates in human blood?

Levels of perfluorinated carboxylates (PFCAs) in different environmental and biological compartments have been known for some time, but the routes of exposure still remain unclear. The opinions are divergent whether the exposure to general populations occurs mainly indirect through precursor compounds or direct via PFCAs. Previous results showed elevated blood levels of PFCAs in ski wax technicians compared to a general population. The objective of this follow-up study was to determine concentrations of PFCAs, perfluorosulfonates (PFSAs), and fluorotelomer alcohols (FTOHs), precursor compounds that are known to degrade to PFCAs, in air collected in the breathing zone of ski wax technicians during work. We collected air samples by using ISOLUTE ENV+ cartridges connected to portable air pumps with an air flow of 2.0 L min(-1). PFCAs C5-C11 and PFSAs C4, C6, C8, and C10 were analyzed using LC-MS/MS and FTOHs 6:2, 8:2, and 10:2 with GC-MS/MS. The results show daily inhalation exposure of 8:2 FTOH in μg/m(3) air which is up to 800 times higher than levels of PFOA with individual levels ranging between 830-255000 ng/m(3) air. This suggests internal exposure of PFOA through biotransformation of 8:2 FTOH to PFOA and PFNA in humans.

Gene Expression Profiling in Wild-Type and PPARα-Null Mice Exposed to Perfluorooctane Sulfonate Reveals PPARα-Independent Effects

Perfluorooctane sulfonate (PFOS) is a perfluoroalkyl acid (PFAA) and a persistent environmental contaminant found in the tissues of humans and wildlife. Although blood levels of PFOS have begun to decline, health concerns remain because of the long half-life of PFOS in humans. Like other PFAAs, such as, perfluorooctanoic acid (PFOA), PFOS is an activator of peroxisome proliferator-activated receptor-alpha (PPARα) and exhibits hepatocarcinogenic potential in rodents. PFOS is also a developmental toxicant in rodents where, unlike PFOA, its mode of action is independent of PPARα. Wild-type (WT) and PPARα-null (Null) mice were dosed with 0, 3, or 10 mg/kg/day PFOS for 7 days. Animals were euthanized, livers weighed, and liver samples collected for histology and preparation of total RNA. Gene profiling was conducted using Affymetrix 430_2 microarrays. In WT mice, PFOS induced changes that were characteristic of PPARα transactivation including regulation of genes associated with lipid metabolism, peroxisome biogenesis, proteasome activation, and inflammation. PPARα-independent changes were indicated in both WT and Null mice by altered expression of genes related to lipid metabolism, inflammation, and xenobiotic metabolism. Such results are similar to studies done with PFOA and are consistent with modest activation of the constitutive androstane receptor (CAR), and possibly PPARγ and/or PPARβ/δ. Unique treatment-related effects were also found in Null mice including altered expression of genes associated with ribosome biogenesis, oxidative phosphorylation, and cholesterol biosynthesis. Of interest was up-regulation of Cyp7a1, a gene which is under the control of various transcription regulators. Hence, in addition to its ability to modestly activate PPARα, PFOS induces a variety of PPARα-independent effects as well.

Pre- and postnatal exposure to perfluorinated compounds (PFCs)

Perfluorinated compounds (PFCs) are a group of chemicals widely used for many applications. In this study PFCs were investigated in maternal blood during pregnancy (at two time points) (n = 40 and 38) and 6 months after delivery (n = 47), in cord blood (n = 33) and in blood of infants six (n = 40) and nineteen months (n = 24) after birth, and monthly in breast milk samples in Germany. Concentrations in maternal serum ranged from 0.5 to 9.4 μg/L for perfluorooctane sulfonate (PFOS) and 0.7 to 8.7 μg/L for perfluorooctanoic acid (PFOA). In cord serum, the values ranged from 0.3 to 2.8 μg/L and from 0.5 to 4.2 μg/L for PFOS and PFOA, respectively. The median results from serum at six and nineteen months of age were 3.0 and 1.9 μg/L for PFOS and 6.9 and 4.6 μg/L for PFOA, respectively. In breast milk samples, PFOS ranged from <0.03 to 0.11 μg/L (median: 0.04 μg/L), while PFOA was detected only in some samples as were all other PFCs. Overall, we found low levels of PFCs in cord sera and an increase in concentrations through the first months of infant life. Although the concentrations in breast milk were low, this intake led to a body burden at the age of six months similar to (PFOS) or higher than (PFOA) that found in adults.

Effect of perfluorooctanesulfonate on osmoregulation in marine fish, Sebastes schlegeli, under different salinities

Effect of potassium salt of perfluorooctane sulfonic acid (PFOS) on the osmoregulation of marine teleost (blackrock fish), Sebastes schlegeli, was investigated under varying salinities, by monitoring serum osmolality, Na(+), K(+), Cl(-), Ca(2+) and Mg(2+) concentrations in serum, serum glucose, and gill Na(+)-K(+) ATPase (NKA) activity. The fish was acclimatized to four salinity levels (10, 17.5, 25, and 34 psu) for 2 weeks before a 6-d exposure to 100 or 1000 microg L(-1) of PFOS. Six fish from each exposure group were sampled at 24, 48, and 144 h after exposures, and serum, liver and gills were collected for analysis. NKA activity decreased by 34% and 31% relative to control at salinity levels of 25 and 34 psu, respectively, following exposure to 1000 microg L(-1) PFOS. PFOS did not affect serum osmolality, Na(+), Cl(-), Ca(2+) and Mg(2+) concentrations; however, serum K(+) concentration increased during initial exposure period and then decreased after 144 h. Serum glucose levels decreased with increasing PFOS concentrations, implying high energy demand in response to exposure. Overall, PFOS exposure impaired NKA activity, altered potassium ion concentrations in serum, and reduced serum glucose levels while no other effects on serum concentrations of ionic salts were observed.

Perfluorooctanesulfonate and perfluorooctanoic acid exposures of the Italian general population

The serum concentrations of perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA) were determined in 230 subjects of the Italian general population. Participants were enrolled in 2008 in two Italian towns (Brescia, Northern Italy, and Rome, Central Italy) and belonged to the three age ranges: 20-35 years, 36-50 years, and 51-65 years. PFOS and PFOA were quantified by HPLC interfaced to a mass spectrometer operating in the electrospray negative mode. Data were acquired using multiple reaction monitoring (MRM). The isotope dilution technique was applied throughout. The median serum concentrations of all participants were 6.31 ng g(-1) and 3.59 ng g(-1) for PFOS and PFOA, respectively, and the pertinent 90th percentiles were 12.38 and 6.92. Men had higher concentrations of PFOS and PFOA than women, regardless of age. The differences were statistically significant in the 20-35 and 36-50 years groups, but not in the 51-65 group. An increase of PFOS and PFOA serum concentrations with age was observed. The Median test showed a statistically significant difference (p<<0.01) between the three age groups for both PFOS and PFOA when applied to the entire dataset (males and females). When the test was applied to the groups of males and females separately, a significant difference was observed for females (p<<0.005) but not for males (p>0.1). The observed strong correlation between PFOS and PFOA concentrations suggests same or similar exposure routes.

Epidemiologic evidence on the health effects of perfluorooctanoic acid (PFOA)

OBJECTIVE AND SOURCES: We reviewed the epidemiologic literature for PFOA.

DATA SYNTHESIS

Perfluorooctanoic acid (PFOA) does not occur naturally but is present in the serum of most residents of industrialized countries (U.S. median, 4 ng/mL). Drinking water is the primary route of exposure in some populations, but exposure sources are not well understood. PFOA has been used to manufacture such products as Gore-Tex and Teflon. PFOA does not break down in the environment; the human half-life is estimated at about 3 years. PFOA is not metabolized in the body; it is not lipophilic. PFOA is not directly genotoxic; animal data indicate that it can cause several types of tumors and neonatal death and may have toxic effects on the immune, liver, and endocrine systems. Data on the human health effects of PFOA are sparse. There is relatively consistent evidence of modest positive associations with cholesterol and uric acid, although the magnitude of the cholesterol effect is inconsistent across different exposure levels. There is some but much less consistent evidence of a modest positive correlation with liver enzymes. Most findings come from cross-sectional studies, limiting conclusions. Two occupational cohort studies do not provide consistent evidence for chronic disease; both are limited by sample size and reliance on mortality data. Reproductive data have increased recently but are inconsistent, and any observed adverse effects are modest.

CONCLUSIONS

Epidemiologic evidence remains limited, and to date data are insufficient to draw firm conclusions regarding the role of PFOA for any of the diseases of concern.

Maternal pesticide use and birth weight in the agricultural health study

Studies examining the association between maternal pesticide exposure and low birth weight yield conflicting results. The authors examined the association between maternal pesticide use and birth weight among women in the Agricultural Health Study, a large study of pesticide applicators and their spouses in Iowa and North Carolina. The authors evaluated self-reported pesticide use of 27 individual pesticides in relation to birth weight among 2246 farm women whose most recent singleton birth occurred within 5 years of enrollment (1993-1997). The authors used linear regression models adjusted for site, preterm birth, medical parity, maternal body mass index, height, and smoking. The results showed that mean infant birth weight was 3586 g (+/- 546 g), and 3% of the infants were low birth weight (<2500 g). First-trimester pesticide-related tasks were not associated with birth weight. Ever use of the pesticide carbaryl was associated with decreased birth weight (-82 g, 95% confidence interval [CI] = -132, -31). This study thus provides limited evidence about pesticide use as a modulator of birth weight. Overall, the authors observed no associations between birth weight and pesticide-related activities during early pregnancy; however, the authors have no data on temporal specificity of individual pesticide exposures prior to or during pregnancy and therefore cannot draw conclusions related to these exposure windows. Given the widespread exposure to pesticide products, additional evaluation of maternal pregnancy exposures at specific time windows and subsequent birth outcomes is warranted.

The impact of environmental and occupational exposures on reproductive health

Environmental exposures during critical periods of susceptibility in utero may result in lifelong or intergenerational adverse health effects. Most chemicals in commercial use in the United States have not been tested for possible developmental toxicity to fetuses, infants, and children. Environmental and occupational exposures can result in adverse effects on female and male reproduction. Nurses can identify at-risk patients, provide education about the impact of chemical toxicants, and empower women to take precautionary action.

The occurrence of perfluorinated alkyl compounds in human milk from different regions of China

Perfluorinated compounds (PFCs), especially perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), are known to occur throughout the environment and in the human population (Houde et al., 2006). The occurrence of PFCs in human umbilical cord blood and human milk, coupled with the potential developmental toxicity of PFCs, suggests the need for determining the exposure sources and magnitudes of PFCs in infants. In this study, 10 PFCs were measured in 24 pooled samples consisting of 1237 individual human milk samples. The samples were collected from 12 provinces of China in 2007. PFOS and PFOA were the predominant PFCs found in all the samples tested. The geometric mean (GM) and median of the concentrations were 46 pg/mL and 49 pg/mL for PFOS, 46 pg/mL and 34.5 pg/mL for PFOA respectively. A large variation in geographical distribution was observed for PFCs in human milk. High concentrations of PFOA (814 pg/ml for the rural samples and 616 pg/ml for the urban samples) were found in human milk from Shanghai. Estimated dietary intakes (EDI) were established and the median, GM and the highest EDI of the total PFCs were 17.2 ng/kg/d, 17.8 ng/kg/d and 129.1 ng/kg/d respectively. The EDI for PFOA (88.4 ng/kg/d) for Shanghai was close to the tolerable daily intake (100 ng/kg/d) proposed by the German Federal Institute for Risk Assessment and the Drinking Water Commission. The results suggest both mothers and infants have a high exposure to PFCs in the Shanghai region. The potential health impact of postnatal exposure through breastfeeding to infants should therefore be comprehensively evaluated.

Levels of perfluorooctane sulfonate and perfluorooctanoic acid in female serum samples from Japan in 2008, Korea in 1994-2008 and Vietnam in 2007-2008

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have recently received attention owing to their widespread contamination in the environment. One of major manufacturers, 3M Company voluntarily phased out PFOS production in 2002. We measured the PFOS and PFOA concentrations in serum samples from Japan (Sendai, Takayama and Osaka), Korea (Busan and Seoul) and Vietnam (Hanoi) to evaluate the possible effects of the phase-out on the serum levels. There were spatial differences in both the serum PFOS and PFOA concentrations. The serum PFOS concentrations (ngmL(-1)) evaluated as the geometric mean (geometric standard deviation) in 2007-2008 ranged from 4.86 (1.45) in Sendai, Japan, to 9.36 (1.42) in Busan, Korea. The serum PFOA concentrations ranged from 0.575 (2.32) in Hanoi, Vietnam, to 14.2 (1.73) in Osaka, Japan. Historically archived samples collected from Korea in 1994-2008 revealed that the serum PFOA concentrations increased by 1.24-fold in Busan from 2000 to 2008 and 1.41-fold in Seoul from 1994 to 2007. On the other hand, the serum PFOS concentrations did not change from 1994 to 2007/2008. The serum PFOS levels in Japan in 2008 were significantly decreased compared with previously reported values (22.3-66.7% of the values in 2003/2004). However, the serum PFOA levels showed a clear decline from 2003 to 2008 in a high-exposed area, Osaka, but not in low-exposed areas in Japan. The trends toward decreases were not uniformly observed in Asian countries, unlike the case for the United States, suggesting that local factors associated with the production and introduction histories in each country overwhelm the effects of the phase-out.

A time trend study of significantly elevated perfluorocarboxylate levels in humans after using fluorinated ski wax

A time trend study focusing on ski waxing technicians' exposure to perfluorinated chemicals (PFCs) from fluorinated wax fumes was performed in 2007/2008. Levels of eight perfluorocarboxylates and three perfluorosulfonates were analyzed in monthly blood samples from eight technicians. Samples were collected before the ski season, i.e., preseason, then at four FIS World Cup competitions in cross country skiing, and finally during an unexposed 5-month postseason period. The perfluorinated carboxylates perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) bioaccumulate, and continued exposure may contribute to elevated levels in ski technicians compared to the general population. The wax technicians' median blood level of PFOA is 112 ng/mL compared to 2.5 ng/mL in the general Swedish population. A significant correlation was found between number of working years and levels of perfluorocarboxylates. The PFOA levels in three technicians with "low" initial levels of PFOA (<10.0 ng/mL in preseason blood) increased by 254, 134, and 120%, whereas five technicians with "high" initial levels (>100 ng/mL in preseason sample) were at steady state. PFHxA is suggested to have a short half-life in humans relative the other perfluorocarboxylates. The levels of perfluorosulfonates were unaffected by the wax exposure.

Exposure to polyfluoroalkyl chemicals and cholesterol, body weight, and insulin resistance in the general U.S. population

BACKGROUND

Polyfluoroalkyl chemicals (PFCs) are used commonly in commercial applications and are detected in humans and the environment worldwide. Concern has been raised that they may disrupt lipid and weight regulation.

OBJECTIVES

We investigated the relationship between PFC serum concentrations and lipid and weight outcomes in a large publicly available data set.

METHODS

We analyzed data from the 20032004 National Health and Nutrition Examination Survey (NHANES) for participants 1280 years of age. Using linear regression to control for covariates, we studied the association between serum concentrations of perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctane sulfonic acid (PFOS), and perfluorohexane sulfonic acid (PFHxS) and measures of cholesterol, body size, and insulin resistance.

RESULTS

We observed a positive association between concentrations of PFOS, PFOA, and PFNA and total and non-high-density cholesterol. We found the opposite for PFHxS. Those in the highest quartile of PFOS exposure had total cholesterol levels 13.4 mg/dL [95% confidence interval (CI), 3.823.0] higher than those in the lowest quartile. For PFOA, PFNA, and PFHxS, effect estimates were 9.8 (95% CI, 0.2 to 19.7), 13.9 (95% CI, 1.925.9), and 7.0 (95% CI, 13.2 to 0.8), respectively. A similar pattern emerged when exposures were modeled continuously. We saw little evidence of a consistent association with body size or insulin resistance.

CONCLUSIONS

This exploratory cross-sectional study is consistent with other epidemiologic studies in finding a positive association between PFOS and PFOA and cholesterol, despite much lower exposures in NHANES. Results for PFNA and PFHxS are novel, emphasizing the need to study PFCs other than PFOS and PFOA.

Association of endocrine disruptors and obesity: perspectives from epidemiological studies

Although changes in diet and physical activity are undoubtedly key causal factors related to the increase in obesity, there is growing interest in the possibility that endocrine disrupting chemicals (EDCs) may affect obesity-related pathways by altering cell signalling involved in weight and lipid homeostasis. Proposed mechanisms that could underlie associations between EDCs and obesity include effects on thyroid and steroid hormones, and activation of peroxisome proliferator-activated receptors, which play a major role in adipocyte differentiation and energy storage. Most evidence supporting the hypothesis that EDCs affect obesity comes from laboratory studies. We summarize the limited epidemiological literature on the topic, including prospective studies of human prenatal exposure to EDCs. We also present findings from a cross-sectional study of levels of six phthalate metabolites and body mass index (BMI) and waist circumference (WC), using data from the U.S. National Health and Nutrition Examination Survey. We found positive associations between BMI and WC among adult males for most phthalate metabolites. For example, in males aged 20-59, the adjusted mean BMI across quartiles of mono-benzyl phthalate was 26.7, 27.2, 28.4, 29.0 (p-trend = 0.0002). In females, BMI and WC increased with quartiles of mono-ethyl phthalate in 12-19 year olds (adjusted mean BMI = 22.9, 23.8, 24.1, 24.7, p-trend = 0.03), and a similar but less strong pattern was seen in 20-59 year olds. By contrast, higher levels of mono-2-ethylhexyl phthalate were associated with lower BMI in adolescent girls and females aged 20-59. This exploratory analysis found several associations between phthalate metabolites and obesity, including notable differences by gender. However, the cross-sectional data are a limitation. Additional prospective studies of the association between exposures to EDCs, especially during development, and obesity are warranted. As this field of research advances, there are challenging methodological questions that must be considered by both epidemiologists and toxicologists.

Dietary predictors and plasma concentrations of perfluorinated compounds in a coastal population from northern Norway

Dietary intake, age, gender, and body mass index were investigated as possible predictors of perfluorinated compounds in a study population from northern Norway (44 women and 16 men). In addition to donating a blood sample, the participants answered a detailed questionnaire about diet and lifestyle. Perfluorooctane sulfonate (PFOS) (29 ng/mL), perfluorooctanoate (PFOA) (3.9 ng/mL), perfluorohexane sulfonate (PFHxS) (0.5 ng/mL), perfluorononanoate (PFNA) (0.8 ng/mL), and perfluoroheptane sulfonate (PFHpS) (1.1 ng/mL) were detected in more than 95% of all samples. Of the dietary items investigated, fruit and vegetables significantly reduced the concentrations of PFOS and PFHpS, whereas fatty fish to a smaller extent significantly increased the levels of the same compounds. Men had significantly higher concentrations of PFOS, PFOA, PFHxS, and PFHpS than women. There were significant differences in PFOS isomer pattern between genders, with women having the largest proportion of linear PFOS. PFOS, PFHxS, and PFHpS concentrations also increased with age.

Association of perfluorooctanoic acid and perfluorooctane sulfonate with serum lipids among adults living near a chemical plant

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are compounds that do not occur in nature but have been widely used since World War II and persist indefinitely in the environment. They are present in the serum of Americans with median levels of 4 ng/mL and 21 ng/mL, respectively. PFOA has been positively associated with cholesterol in several studies of workers. A cross-sectional study of lipids and PFOA and PFOS was conducted among 46,294 community residents aged 18 years or above, who drank water contaminated with PFOA from a chemical plant in West Virginia. The mean levels of serum PFOA and PFOS in 2005-2006 were 80 ng/mL (median, 27 ng/mL) and 22 ng/mL (median, 20 ng/mL), respectively. All lipid outcomes except high density lipoprotein cholesterol showed significant increasing trends by increasing decile of either compound; high density lipoprotein cholesterol showed no association. The predicted increase in cholesterol from lowest to highest decile for either compound was 11-12 mg/dL. The odds ratios for high cholesterol (>/=240 mg/dL), by increasing quartile of PFOA, were 1.00, 1.21 (95% confidence interval (CI): 1.12, 1.31), 1.33 (95% CI: 1.23, 1.43), and 1.40 (95% CI: 1.29, 1.51) and were similar for PFOS quartiles. Because these data are cross-sectional, causal inference is limited. Nonetheless, the associations between these compounds and lipids raise concerns, given their common presence in the general population.

Congenital anomalies, labor/delivery complications, maternal risk factors and their relationship with perfluorooctanoic acid (PFOA)-contaminated public drinking water

BACKGROUND

We have previously examined the associations between perfluorooctanoic acid (PFOA) exposure, birth weight and gestational age in individuals exposed to PFOA-contaminated residential drinking water from the Little Hocking Water Association (LHWA). In this investigation, we expand the scope of our analysis to examine the associations between PFOA, congenital anomalies, labor and delivery complications and maternal risk factors.

OBJECTIVES

To compare the likelihood of congenital anomalies, labor and delivery complications and maternal risk factors in neonates and their mothers residing in zip codes with public water service provided completely, partially or not at all by the LHWA.

METHODS

Logistic regression analyses were performed on singleton neonatal birth outcome data supplied by the Ohio Department of Health to examine the associations between LHWA water service category and the outcomes of interest. When possible, models were adjusted for maternal age, preterm birth, neonatal sex, race, maternal education, alcohol use, tobacco use and diabetic status.

RESULTS

Increased PFOA exposure, as assessed by water service category, was not associated with an overall increase in the likelihood of congenital anomalies or any specific diagnosis (adjusted OR: 1.4, 95% CI: 0.34-3.3). The overall likelihood of labor and delivery complications was significantly lower among mothers with water service provided by the LHWA, as compared to mothers not serviced by the LHWA (adjusted OR: 0.65, 95% CI: 0.46-0.92). A significant increase in the likelihood of anemia (crude OR: 11, 95% CI: 1.8-64) and dysfunctional labor (crude OR: 5.3, 95% CI: 1.2-24) was noted for mothers residing within zip codes serviced by the LHWA, but the number of reported cases was very small.

CONCLUSION

At the levels measured in the LHWA, we conclude that PFOA is not associated with increased risk of congenital anomalies, most labor and delivery complications and maternal risk factors. Additional research is required to assess the observed associations between PFOA, anemia and dysfunctional labor.

Serum levels of perfluorooctanoic acid and perfluorooctane sulfonate and pregnancy outcome

The authors examined the association of serum perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) with self-reported pregnancy outcome in Mid-Ohio Valley residents (2000-2006) highly exposed to PFOA. Data on 1,845 pregnancies within the 5 years preceding exposure measurement were analyzed for PFOA, and data on 5,262 pregnancies were analyzed for PFOS. Generalized estimating equations were used to calculate adjusted odds ratios and 95% confidence intervals. Neither PFOA nor PFOS showed any association with miscarriage or preterm birth. Preeclampsia was weakly associated with PFOA (adjusted odds ratio = 1.3, 95% confidence interval: 0.9, 1.9) and PFOS (adjusted odds ratio = 1.3, 95% confidence interval: 1.1, 1.7) exposures above the median. PFOA was not associated with an increase in low birth weight, but PFOS showed an increased risk above the median (adjusted odds ratio = 1.5, 95% confidence interval: 1.1, 1.9) and a dose-response gradient. Birth defects were weakly associated with PFOA exposures above the 90th percentile (adjusted odds ratio = 1.7, 95% confidence interval: 0.8, 3.6). This study identified modest associations of PFOA with preeclampsia and birth defects and of PFOS with preeclampsia and low birth weight, but associations were small, limited in precision, and based solely on self-reported health outcomes.

Phthalate levels and low birth weight: a nested case-control study of Chinese newborns

OBJECTIVE

To assess maternal-fetal exposure to phthalates and investigate whether in utero phthalate exposure is associated with low birth weight (LBW).

STUDY DESIGN

A total of 201 newborn-mother pairs (88 LBW cases and 113 controls) residing in Shanghai were enrolled in this nested case-control study during 2005-2006. Maternal blood, cord blood, and meconium specimens were collected and analyzed for phthalates by high-performance liquid chromatography-mass spectrometry. Nonparametric tests were used to compare demographic characteristics in cases and controls. Conditional logistic regression and Spearman correlation were used to analyze the association between phthalate exposure and LBW.

RESULTS

No significant differences in gestational age, prepregnancy body mass index, prenatal care, vitamin supplementation, or socioeconomic levels were found between the LBW and control infants. More than 70% of the biosamples had quantifiable levels of phthalates, with higher levels in the LBW infants compared with the controls. Prenatal di-n-butyl phthalate (DBP) exposure was associated with LBW, and di-2-ethylhexyl phthalate (DEHP) was negatively associated with birth length. After adjusting for the potential confounders, DBP concentrations in the highest quartile were associated with an increased risk of LBW.

CONCLUSIONS

Newborns in China are ubiquitously exposed to phthalates; significantly higher phthalate levels were detected in LBW cases compared with controls. In utero DBP and DEHP exposures were associated with LBW in a dose-dependent manner. Prenatal phthalate exposure may be a risk factor for LBW.

Measuring outcomes in a longitudinal birth cohort

Longitudinal studies are often focussed on specific outcomes to address predetermined hypotheses. Nevertheless, many discoveries have been made with data collected that were not part of the original design. Measurement of a broad range of outcomes is therefore important. Here we describe examples of the types of outcome that a birth cohort should collect, with emphasis on accuracy. We emphasise the use of continuous traits as well as of dichotomous outcomes, using a variety of examples.

Occurrence and potential significance of perfluorooctanoic acid (PFOA) detected in New Jersey public drinking water systems

After detection of perfluorooctanoic acid (PFOA) in two New Jersey (NJ) public water systems (PWS) at concentrations up to 0.19 microg/L, a study of PFOA in 23 other NJ PWS was conducted in 2006. PFOA was detected in 15 (65%) of the systems at concentrations ranging from 0.005 to 0.039 microg/L. To assess the significance of these data, the contribution of drinking water to human exposure to PFOA was evaluated, and a health-based drinking water concentration protective for lifetime exposure of 0.04 microg/L was developed through a risk assessment approach. Both the exposure assessment and the health-based drinking water concentrations are based on the previously reported 100:1 ratio between the concentration of PFOA in serum and drinking water in a community with highly contaminated drinking water. The applicability of this ratio to lower drinking water concentrations was confirmed using data on serum levels and water concentrations from other communities. The health-based concentration is based on toxicological end points identified by U.S. Environmental Protection Agency (USEPA) in its 2005 draft risk assessment Recent information on PFOA's toxicity not considered in the USEPA risk assessment urther supports the health-based concentration of 0.04 microg/L. In additional sampling of 18 PWS in 2007-2008, PFOA in most systems was below the health-based concentration. However, PFOA was detected above the health-based concentration in five systems, including one not previously sampled.

Geographical distribution of perfluorinated compounds in human blood from Liaoning province, China

Perfluorinated compounds (PFCs), such as perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), have been identified widely in human. Monitoring of geographical distribution of PFCs in human blood can provide the information to better characterize the exposure source and pathway of these compounds. In this study, 13 PFCs were detected in 138 whole blood samples collected in 2008 from seven cities (Liaoning province, China) including Fuxin, Jinzhou, Shenyang, Anshan, Yingkou, Huludao, and Dalian. The highest geometric mean (GM) concentration of total PFCs was found in samples from Fuxin (17.27 ng/mL) followed by Shenyang (12.70 ng/mL) and Anshan (12.63 ng/mL). The composition profile of PFCs was varied in blood samples from seven cities. In Fuxin and Jinzhou, the percentage proportion of PFOA was significantly higher than that of perfluorohexanesulfonate (PFHxS) by about two times. By contrast, in Shenyang, Anshan, and Yingkou, the percentage proportion of PFHxS was about three times higher than that of PFOA. In Huludao and Dalian, the profile of PFCs in blood was very similar with comparable proportions of PFOA and PFHxS. The results suggested different human exposure sources and pathways of PFCs in Liaoning province, China.

Effects of perfluorooctanoic acid on mouse mammary gland development and differentiation resulting from cross-foster and restricted gestational exposures

The adverse consequences of developmental exposures to perfluorooctanoic acid (PFOA) are established in mice, and include impaired development of the mammary gland (MG). However, the relationships between timing or route of exposure, and consequences in the MG have not been characterized. To address the effects of these variables on the onset and persistence of MG effects in female offspring, timed pregnant CD-1 dams received PFOA by oral gavage over various gestational durations. Cross-fostering studies identified the 5mg/kg dose, under either lactational- or intrauterine-only exposures, to delay MG development as early as postnatal day (PND) 1, persisting beyond PND 63. Intrauterine exposure during the final days of pregnancy caused adverse MG developmental effects similar to that of extended gestational exposures. These studies confirm a window of MG sensitivity in late fetal and early neonatal life, and demonstrate developmental PFOA exposure results in early and persistent MG effects, suggesting permanent consequences.

Analysis of PFOA in dosed CD-1 mice. Part 2. Disposition of PFOA in tissues and fluids from pregnant and lactating mice and their pups

Previous studies in mice with multiple gestational exposures to perfluorooctanoic acid (PFOA) demonstrate numerous dose dependent growth and developmental effects which appeared to worsen if offspring exposed in utero nursed from PFOA-exposed dams. To evaluate the disposition of PFOA in the pregnant and lactating dam and her offspring, time-pregnant CD-1 mice received a single 0, 0.1, 1, or 5mg PFOA/kg BW dose (n=25/dose group) by gavage on gestation day 17. Maternal and pup fluids and tissues were collected over time. Pups exhibited significantly higher serum PFOA concentrations than their respective dams, and their body burden increased after birth until at least postnatal day 8, regardless of dose. The distribution of milk:serum PFOA varied by dose and time, but was typically in excess of 0.20. These data suggest that milk is a substantial PFOA exposure route in mice and should be considered in risk assessment modeling designs for this compound.

Do perfluoroalkyl compounds impair human semen quality?

BACKGROUND

Perfluoroalkyl acids (PFAAs) are found globally in wildlife and humans and are suspected to act as endocrine disruptors. There are no previous reports of PFAA levels in adult men from Denmark or of a possible association between semen quality and PFAA exposure.

OBJECTIVES

We investigated possible associations between PFAAs and testicular function. We hypothesized that higher PFAA levels would be associated with lower semen quality and lower testosterone levels.

METHODS

We analyzed serum samples for levels of 10 different PFAAs and reproductive hormones and assessed semen quality in 105 Danish men from the general population (median age, 19 years).

RESULTS

Considerable levels of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid were found in all young men (medians of 24.5, 4.9, and 6.6 ng/mL, respectively). Men with high combined levels of PFOS and PFOA had a median of 6.2 million normal spermatozoa in their ejaculate in contrast to 15.5 million among men with low PFOS-PFOA (p = 0.030). In addition, we found nonsignificant trends with regard to lower sperm concentration, lower total sperm counts, and altered pituitary-gonadal hormones among men with high PFOS-PFOA levels.

CONCLUSION

High PFAA levels were associated with fewer normal sperm. Thus, high levels of PFAAs may contribute to the otherwise unexplained low semen quality often seen in young men. However, our findings need to be corroborated in larger studies.

Polyfluoroalkyl chemicals in pooled blood serum from infants, children, and adults in Australia

Polyfluoroalkyl chemicals (PFCs) have been used worldwide for more than 50 years in a wide variety of industrial and consumer products. Limited data exist on human exposure to PFCs in the Southern Hemisphere. Human blood serum collected in southeast Queensland, Australia, in 2006-2007 from 2420 donors was pooled according to age (cord blood, 0-0.5, 0.6-1, 1.1-1.5, 1.6-2, 2.1-2.5, 2.6-3, 3.1-3.5, 3.6-4, 4.1-6, 6.1-9, 9.1-12, 12.1-15, 16-30, 31-45, 46-60, and > 60 years) and gender and was analyzed for eight PFCs. Across all pools, perfluorooctane sulfonate (PFOS) was detected at the highest mean concentration (15.2 ng/mL) followed by perfluorooctanoate (PFOA, 6.4 ng/mL), perfluorohexane sulfonate (PFHxS, 3.1 ng/mL), perfluorononanoate (PFNA, 0.8 ng/mL), 2-(N-methylperfluorooctance sulfonamide) acetate (Me-PFOSA-AcOH, 0.66 ng/mL), and perfluorodecanoate (PFDeA, 0.29 ng/mL). Perfluorooctane sulfonamide was detected in only 24% of the pools, and 2-(N-ethylperfluorooctane sulfonamide) acetate was detected in only one. PFOS concentrations were significantly higher in pools from adult males than from adult females (p = 0.002); no gender differences were apparent in the pools from children (< 12 years old). The highest mean concentrations of PFOA, PFHxS, PFNA, PFDeA, and Me-PFOSA-AcOH were found in children < 15 years, while PFOS was highest in adults > 60 years. Investigation into the sources and exposure pathways in Australia, in particular for children, is necessary as well as continued biomonitoring to determine the potential effects on human concentrations as a result of changes in the PFC manufacturing practices, including the cessation of production of several PFCs.

Relationship between dietary exposure and serum perfluorochemical (PFC) levels--a case study

Daily dietary intake of perfluorinated chemicals (PFCs) in relation to serum levels was assessed by determination of nine PFCs including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in matched daily diet duplicates and serum samples. Diet and serum were collected in year 2004 from 20 women in Osaka and Miyagi, Japan. Only PFOS and PFOA were detected in the diet samples and no significant difference between cities was seen. After adjusted by water content, diet concentration of PFOA was significantly higher in Osaka. The median daily intake calculated using the measured diet concentrations was 1.47 ng PFOS/kg b.w. and 1.28 ng PFOA/kg b.w. for Osaka, and 1.08 ng PFOS/kg b.w. and 0.72 ng PFOA/kg b.w. for Miyagi. A significant difference between cities was seen for the serum concentrations with median of 31 ng/mL PFOS and PFOA in Osaka, compared to 14 ng/mL PFOS and 4.6 ng/mL PFOA in Miyagi. Carboxylates such as perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUnDA) were also detected in serum at median levels 6.9 ng/mL and 3.2 ng/mL (Osaka), and 2.8 ng/mL and 5.1 ng/mL (Miyagi). Based on one-compartment model under steady state, dietary intake of PFOS and PFOA accounted for only 22.4% and 23.7% of serum levels in Osaka females, and in contrast 92.5% and 110.6% in Miyagi females, respectively.

Association among serum perfluoroalkyl chemicals, glucose homeostasis, and metabolic syndrome in adolescents and adults

OBJECTIVE

Perfluoroalkyl chemicals (PFCs) have been used worldwide in a variety of consumer products. The effect of PFCs on glucose homeostasis is not known.

RESEARCH DESIGN AND METHODS

We examined 474 adolescents and 969 adults with reliable serum measures of metabolic syndrome profile from the National Health and Nutrition Examination Survey 1999-2000 and 2003-2004.

RESULTS

In adolescents, increased serum perfluorononanoic acid (PFNA) concentrations were associated with hyperglycemia (odds ratio [OR] 3.16 [95% CI 1.39-7.16], P < 0.05). Increased serum PFNA concentrations also have favorable associations with serum HDL cholesterol (0.67 [0.45-0.99], P < 0.05). Overall, increased serum PFNA concentrations were inversely correlated with the prevalence of the metabolic syndrome (0.37 [0.21-0.64], P < 0.005). In adults, increased serum perfluorooctanoic acid concentrations were significantly associated with increased beta-cell function (beta coefficient 0.07 +/- 0.03, P < 0.05). Increased serum perfluorooctane sulfate (PFOS) concentrations were associated with increased blood insulin (0.14 +/- 0.05, P < 0.01), homeostasis model assessment of insulin resistance (0.14 +/- 0.05, P < 0.01), and beta-cell function (0.15 +/- 0.05, P < 0.01). Serum PFOS concentrations were also unfavorably correlated with serum HDL cholesterol (OR 1.61 [95% CI 1.15-2.26], P < 0.05).

CONCLUSIONS

Serum PFCs were associated with glucose homeostasis and indicators of metabolic syndrome. Further clinical and animal studies are warranted to clarify putative causal relationships.

Polyfluoroalkyl compounds in pooled sera from children participating in the National Health and Nutrition Examination Survey 2001-2002

To assess exposure of polyfluoroalkyl compounds (PFCs) among children, we measured the concentrations of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid, and 8 other PFCs in 24 pooled serum samples. The individual serum samples used to make the pools were collected from U.S. children who were participants in the 2001-2002 National Health and Nutrition Examination Survey. These children were from three major races/ethnicities (non-Hispanic blacks, non-Hispanic whites, and Mexican Americans), two age categories (3-5 and 6-11 years), and both sexes. PFCs were extracted from 100 microL of serum using online solid-phase extraction coupled to isotope dilution high performance liquid chromatography tandem mass spectrometry; detection limits ranged from 0.1 to 0.4 ng/mL In the final ANOVA models, race was the only significant demographic factor, and concentrations appeared to be lower for Mexican Americans than for the other two racial groups. For example, for Mexican American children 6-11 years old, the least-squares means (LSM) estimates were 30.45 ng/mL (PFOS) and 6.125 ng/mL (PFOA), while for non-Hispanic white children of the same age group, the LSM estimates were 42.45 ng/mL (PFOS) and 7.575 ng/mL (PFOA). However, after adjusting for the potential underestimation of variance associated with the sampling design, race did not remain a significantfactor. Nevertheless,these findings suggestthat human exposure to PFCs among the population groups of children examined may differ and stress the importance of identifying the environmental sources and routes of exposure to PFCs.