Human exposure pathways to organophosphate triesters — A biomonitoring study of mother–child pairs

The worldwide ban of several formulations of brominated flame retardants has caused an increase in the production of organophosphorus flame retardants (PFRs) to meet the existing fire regulations for a wide range of household products. This biomonitoring study surveys the occurrence of the metabolites from PFRs and related plasticizers (dialkyl and diaryl phosphates; DAPs) in urine from a Norwegian mother–child cohort (48 mothers and 54 children). Concentrations of DAPs were higher in the children than in their mothers (Wilcoxon signed-rank test p = 0.001). Median urinary concentrations of diphenyl phosphate (DPHP) were 1.1 and 0.51 ng/mL in children and mothers, respectively, followed by bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) with medians of 0.23 and 0.12 ng/mL, respectively. Detection frequencies for bis(2-butoxyethyl) phosphate (BBOEP) in urine from children and mothers were 32 and 1%, respectively (median < 0.18 ng/mL), and for di-n-butyl phosphate (DNBP) 15 and 8%, respectively (median < 0.12 ng/mL). The concentrations of DPHP and BDCIPP in urine from children were significantly correlated with those found for their parent compounds in air and dust from the households (Spearman's rank correlations 0.30 < R_s < 0.36; p < 0.05). For mothers, only the urinary concentration of BDCIPP was correlated to its precursor in dust from the households (R_s = 0.40; p < 0.01), which might indicate higher impact of the household environment on children than mothers. A diurnal variability study of the mothers' urinary concentrations of DPHP and BDCIPP showed lower concentrations at time periods when women were likely to be outside the household. In contrast, no relevant associations between organophosphate metabolites in urine and food consumption data obtained through a 24 hour recall were seen. This suggests that the residential environment is a more important exposure pathway to PFRs than the diet.     

Daily intake of bisphenol A and triclosan and their association with anthropometric data,thyroid hormones and weight loss in overweight and obese individuals

Bisphenol A (BPA) and triclosan (TCS) were determined in urine of Belgian overweight and obese (n = 151) and lean (n = 43) individuals. After the first urine collection (0 M), obese patients started a diet program or have undergone bariatric surgery. Hereafter, three additional urine samples from obese patients were collected after 3 (3 M), 6 (6 M) and 12 (12 M) months. Both compounds were detected in > 99% of the samples. BPA had median concentrations of 1.7 and 1.2 ng/mL in obese and lean groups, respectively, while TCS had median concentrations of 1.5 and 0.9 ng/mL in the obese and lean groups, respectively. The obese group had higher urinary concentrations (ng/mL) of BPA (p < 0.5), while no significant differences were found for TCS between the obese and lean groups. No time trends between the different collection moments were observed. The BPA concentrations in the obese group were negatively associated with age, while no gender difference or relationship with body mass index was observed. For TCS, no relationships with gender, BMI, or age were found. The temporal variability of BPA and TCS was assessed with calculation of the intraclass correlation coefficient, Spearman rank correlation coefficients, and surrogate category analysis. We observed evidence that single spot urine samples might be predictive of exposure over a longer period of time. Dietary intakes of BPA and TCS did not differ significantly among the time points considered after obese individuals started losing weight (6 and 12 months). Multiple linear regression analyses after adjusting for age and weight loss revealed negative associations between urinary TCS and serum FT4 in the 0 M and 3 M female obese individuals and positive associations between urinary BPA and serum TSH in the lean group.     

Assessment of human hair as an indicator of exposure to organophosphate flame retardants. Case study on a Norwegian mother–child cohort

A major challenge of non-invasive human biomonitoring using hair is to assess whether it can be used as an indicator of exposure to Flame Retardants, such as Organophosphate Flame Retardants (PFRs), since the contribution of atmospheric deposition (air and/or dust) cannot be neglected. Therefore, the aim of this study was to evaluate the suitability of using human hair more thoroughly by comparison of (i) levels of PFRs in human hair (from 48 mothers and 54 children), with levels measured in dust and air in their respective households; and (ii) levels of selected PFRs in hair with the levels of corresponding PFR metabolites in matching urine samples collected simultaneously. Most PFRs (tri-n-butyl phosphate (TNBP), 2-ethyl-hexyldiphenyl phosphate (EHDPHP), tri-phenyl phosphate (TPHP), tri-iso-butyl phosphate (TIBP), and tris(2-butoxyethyl) phosphate (TBOEP)) were detected in all human hair samples, tris(2-ethylhexyl) phosphate (TEHP) and tris(1,3-dichloro-iso-propyl) phosphate (TDCIPP) in 93%, tri-cresyl-phosphate (TCP) in 69% and tris(2-chloroethyl) phosphate (TCEP) in 21% of the samples. Levels of individual PFRs ranged between < 1 and 3744 ng/g hair and were lower than in indoor dust from the participants' homes. Several statistically significant associations between PFR levels in human hair and PFR levels in house dust and/or air were found, e.g. Spearman correlation (r_S = 0.561, p < 0.05) between TBOEP in children's hair and in indoor air. Also, associations were found between TDCIPP in hair and its metabolite bis(1,3-dichloro-iso-propyl) phosphate (BDCIPP) in urine; they were stronger for children (e.g. Pearson correlation r_P = 0.475; p = 0.001) than for mothers (r_P = 0.395, p = 0.01). Levels of diphenyl phosphate (DPHP) in mothers' and children's urine were slightly correlated (r_S = 0.409, p = 0.008), suggesting similar sources of exposure. To the best of our knowledge, this is the first study with such design and our findings might help to understand human exposure to and body burdens of PFRs.     

Concentrations of polybrominated diphenyl ethers (PBDEs) and 2,4,6-tribromophenol in human placental tissues

Legacy environmental contaminants such as polybrominated diphenyl ethers (PBDEs) are widely detected in human tissues. However, few studies have measured PBDEs in placental tissues, and there are no reported measurements of 2,4,6-tribromophenol (2,4,6-TBP) in placental tissues. Measurements of these contaminants are important for understanding potential fetal exposures, as these compounds have been shown to alter thyroid hormone regulation in vitro and in vivo. In this study, we measured a suite of PBDEs and 2,4,6-TBP in 102 human placental tissues collected between 2010 and 2011 in Durham County, North Carolina, USA. The most abundant PBDE congener detected was BDE-47, with a mean concentration of 5.09 ng/g lipid (range: 0.12–141 ng/g lipid; detection frequency 91%); however, 2,4,6-TBP was ubiquitously detected and present at higher concentrations with a mean concentration of 15.4 ng/g lipid (range:1.31–316 ng/g lipid; detection frequency 100%). BDE-209 was also detected in more than 50% of the samples, and was significantly associated with 2,4,6-TBP in placental tissues, suggesting they may have a similar source, or that 2,4,6-TBP may be a degradation product of BDE-209. Interestingly, BDE-209 and 2,4,6-TBP were negatively associated with age (r_s = − 0.16; p = 0.10 and r_s = − 0.17; p = 0.08, respectively). The results of this work indicate that PBDEs and 2,4,6-TBP bioaccumulate in human placenta tissue and likely contribute to prenatal exposures to these environmental contaminants. Future studies are needed to determine if these joint exposures are associated with any adverse health measures in infants and children.     

Identification of fipronil metabolites by time-of-flight mass spectrometry for application in a human exposure study

Fipronil is a phenylpyrazole insecticide commonly used in residential and agricultural applications. To understand more about the potential risks for human exposure associated with fipronil, urine and serum from dosed Long Evans adult rats (5 and 10 mg/kg bw) were analyzed to identify metabolites as potential biomarkers for use in human biomonitoring studies. Urine from treated rats was found to contain seven unique metabolites, two of which had not been previously reported—M4 and M7 which were putatively identified as a nitroso compound and an imine, respectively. Fipronil sulfone was confirmed to be the primary metabolite in rat serum. The fipronil metabolites identified in the respective matrices were then evaluated in matched human urine (n = 84) and serum (n = 96) samples from volunteers with no known pesticide exposures. Although no fipronil or metabolites were detected in human urine, fipronil sulfone was present in the serum of approximately 25% of the individuals at concentrations ranging from 0.1 to 4 ng/mL. These results indicate that many fipronil metabolites are produced following exposures in rats and that fipronil sulfone is a useful biomarker in human serum. Furthermore, human exposure to fipronil may occur regularly and require more extensive characterization.     

Predictors of exposure to organophosphate pesticides in schoolchildren in the Province of Talca,Chile

BackgroundFew data exist in Latin America concerning the association between organophosphate (OP) urinary metabolites and the consumption of fruits and vegetables and other exposure risk variables in schoolchildren.MethodsWe collected samples of urine from 190 Chilean children aged 6–12 years, fruits and vegetables, water and soil from schools and homes, and sociodemographic data through a questionnaire. We measured urinary dialkylphosphate (DAP) OP metabolites and OP pesticide residues in food consumed by these 190 children during two seasons: December 2010 (summer) and May 2011 (fall). We analyzed the relationship between urinary DAP concentrations and pesticide residues in food, home pesticide use, and residential location.ResultsDiethylalkylphosphates (DEAP) and dimethylalkylphosphates (DMAP) were detected in urine in 76% and 27% of the samples, respectively. Factors associated with urinary DEAP included chlorpyrifos in consumed fruits (p < 0.0001), urinary creatinine (p < 0.0001), rural residence (p = 0.02) and age less than 9 years (p = 0.004). Factors associated with urinary DMAP included the presence of phosmet residues in fruits (p < 0.0001), close proximity to a farm (p = 0.002), home fenitrothion use (p = 0.009), and season (p < 0.0001).ConclusionsUrinary DAP levels in Chilean school children were high compared to previously reported studies. The presence of chlorpyrifos and phosmet residues in fruits was the major factor predicting urinary DAP metabolite concentrations in children.     

Selective transfer of persistent organic pollutants and their metabolites in grey seals during lactation

Twenty grey seal (Halichoerus grypus) mother–pup pairs from the colony of the Isle of May (Scotland) were sampled at early and late lactation in order to study the transfer of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and their metabolites (HO-PCBs and HO-PBDEs) as well as organochlorine pesticides (OCPs), such as DDT and metabolites (DDXs) and hexachlorobenzene (HCB). The transfer of the naturally produced MeO-PBDEs was also investigated. Generally, concentrations (on a lipid weight basis) of the sum of PCBs, PBDEs and DDXs tended to be higher in all tissues at late lactation (for maternal outer blubber ΣPCBs = 3860 ± 2091 ng/g, ΣPBDEs = 120 ± 74 ng/g and ΣDDXs = 559 ± 207 ng/g; for maternal inner blubber ΣPCBs = 4229 ± 3274 ng/g, ΣPBDEs = 148 ± 118 ng/g and ΣDDXs = 704 ± 353 ng/g; for maternal serum ΣPCBs = 1271 ± 796 ng/g, ΣPBDEs = 27 ± 16 ng/g and ΣDDXs = 242 ± 125 ng/g; for milk ΣPCBs = 1190 ± 747 ng/g, ΣPBDEs = 55 ± 36 ng/g and ΣDDXs = 357 ± 160 ng/g; for pup serum ΣPCBs = 1451 ± 901 ng/g, ΣPBDEs = 48 ± 31 ng/g and ΣDDXs = 395 ± 201 ng/g). In all tissues, ΣMeO-PBDEs were found at very low levels or even undetected and their concentrations appeared to increase at late lactation only in maternal inner blubber (2.7 ± 1.3 to 5.3 ± 2.9 ng/g for early and late lactation, respectively) and milk (0.6 ± 0.3 to 1.1 ± 0.5 ng/g for early and late lactation, respectively). The transfer from inner blubber to maternal serum was selective and strongly depended on the log K_ow value of the compounds, with less lipophilic compounds being more efficiently released. Only a limited amount of HO-PCBs was transferred during lactation as 4-HO-CB-107 was the only metabolite detected in milk (29 to 40 pg/g lw). On the contrary, most of HO-PCB metabolites found in maternal serum were also detected in pup serum. These findings suggest not only a transplacental transfer of HO-PCBs from mothers to pups but also the possibility of endogenous biotransformation in suckling pups or accumulation of undetectable low amounts from milk.     

Hydroxylated PCB metabolites (OH-PCBs) in archived serum from 1950–60s California mothers: A pilot study

We are studying participants selected from the Child Health and Development Studies (CHDS), a longitudinal birth cohort of over 20,000 California pregnancies between 1959 and 1967, for associations between maternal body burden of organochlorine contaminants and thyroid function. We designed a pilot study using 30 samples selected among samples with high and low PCB concentrations to evaluate the feasibility of measuring OH-PCBs in the larger study population. GC-ECD and GC-NCI/MS were used to determine PCBs and OH-PCBs as methyl derivatives, respectively. Maternal serum levels of Σ₁₁PCBs and Σ₈OH-PCB metabolites varied from 0.74 to 7.99 ng/mL wet wt. with a median of 3.05 ng/mL, and from 0.12 to 0.98 ng/mL wet wt. with a median of 0.39 ng/mL, respectively. Average concentrations of Σ₈OH-PCB metabolites in the high PCB group were significantly higher than those in the low PCB group (p < 0.05). The levels of OH-PCB metabolites were dependent on PCB levels (r = 0.58, p < 0.05) but approximately an order of magnitude lower (p < 0.05). The average ratio of Σ₈OH-PCBs to Σ₁₁PCBs was 0.14 ± 0.08. The primary metabolite was 4-OH-CB187 followed by 4-OH-CB107. Both of these metabolites interfere with the thyroid system in in vitro, animal, and human studies. OH-PCBs were detectable in all archived sera analyzed, supporting the feasibility to measure OH-PCB metabolites in the entire cohort.     

Biomonitoring short- and long-term exposure to the herbicide terbuthylazine in agriculture workers and in the general population using urine and hair specimens

The aim of this work was to evaluate short-term and long-term exposure to terbuthylazine (TBA) in agriculture workers (AW), rural residents (RR), and urban residents (UR) using urine and hair specimens. Twelve AW, 13 RR, and 17 UR were included in the study. Urine spot samples were collected with two different protocols. AW urine samples were collected before the application season (February, U₀), at bedtime on the day of TBA application (March–May, U₁), and prior to the next shift on the day after TBA application (U₂). RR and UR urine samples were collected on any day during the application season (U_e). Hair samples were collected for all subjects before the application season (February, H₀) and at the end of the season (June, H₁). TBA and its metabolite desethylterbuthylazine (DET) were measured by liquid chromatography coupled with triple quadrupole mass spectrometry detection. DET was exclusively found in urine, while TBA was mostly found in the hair. In the AW, the urinary levels of DET were not detected in the U₀ samples, and they increased to median levels of 1.81 and 2.94 μg/L in the U₁ and U₂ samples, respectively (p < 0.001). In the RR and UR, DET was not detected in the U_e samples. In the UR, TBA was not detected in the H₀ samples, and the median levels of TBA were 0.01 ng/mg hair in both the AW and RR. In the H₁ samples, the median TBA levels were not detected, 0.01, and 0.08 ng/mg hair in the UR, RR, and AW, respectively (p < 0.001). Urinary DET and hair TBA are promising candidates for biomonitoring short- and long-term exposure to TBA. The use of this herbicide in agriculture leads to exposure in rural residents.     

Acute respiratory response to traffic-related air pollution during physical activity performance

BackgroundPhysical activity (PA) has beneficial, whereas exposure to traffic related air pollution (TRAP) has adverse, respiratory effects. Few studies, however, have examined if the acute effects of TRAP upon respiratory outcomes are modified depending on the level of PA.ObjectivesThe aim of our study was to disentangle acute effects of TRAP and PA upon respiratory outcomes and assess the impact of participants TRAP pre-exposure.MethodsWe conducted a real-world crossover study with repeated measures of 30 healthy adults. Participants completed four 2-h exposure scenarios that included either rest or intermittent exercise in high- and low-traffic environments. Measures of respiratory function were collected at three time points. Pre-exposure to TRAP was ascertained from land-use-modeled address-attributed values. Mixed-effects models were used to estimate the impact of TRAP and PA on respiratory measures as well as potential effect modifications.ResultsWe found that PA was associated with a statistically significant increases of FEV₁ (48.5 mL, p = 0.02), FEV₁/FVC (0.64%, p = 0.005) and FEF_25–75% (97.8 mL, p = 0.02). An increase in exposure to one unit (1 μg/m³) of PM_coarse was associated with a decrease in FEV₁ (− 1.31 mL, p = 0.02) and FVC (− 1.71 mL, p = 0.01), respectively. On the other hand, for an otherwise equivalent exposure an increase of PA by one unit (1%Heart rate max) was found to reduce the immediate negative effects of particulate matter (PM) upon PEF (PM_2.5, 0.02 L/min, p = 0.047; PM₁₀, 0.02 L/min p = 0.02; PM_coarse, 0.03 L/min, p = 0.02) and the several hours delayed negative effects of PM upon FVC (PM_coarse, 0.11 mL, p = 0.02). The negative impact of exposure to TRAP constituents on FEV₁/FVC and PEF was attenuated in those participants with higher TRAP pre-exposure levels.ConclusionsOur results suggest that associations between various pollutant exposures and respiratory measures are modified by the level of PA during exposure and TRAP pre-exposure of participants.     

Temporal trends in concentrations and total serum burdens of organochlorine compounds from birth until adolescence and the role of breastfeeding

Introduction: The aims of the present study are to assess the temporal trends of organochlorine compounds (OCs) concentrations and total serum burdens from birth until adolescence and the influence of breastfeeding in these temporal trends. Methods: In 1997 two birth cohort studies were set up in Ribera d'Ebre (N = 102) and the island of Menorca (N = 482), Spain. Concentrations (ng/mL) of OCs [pentachlorobenzene (PeCB), four isomers of hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), dichlorodiphenyltrichloroethane (4,4′-DDT), dichlorodiphenyldichloroethylene (4,4′-DDE) and seven polychlorobiphenyl congeners (Σ₇PCBs)] were measured in cord blood and at the age of 4 and 14 years. The total serum burdens (ng) of these compounds were estimated based on the total blood volume (mL) of children at the different ages. We compared median concentrations and total serum burdens of these OCs at the different time-points of follow-up between children of Ribera d'Ebre and Menorca and between breastfed and non-breastfed children. Results: From birth until adolescence concentrations of all OCs drastically reduced. These reductions were mainly derived from the dilution of OCs, associated to an increase in total blood volume of children at the age of 4 and 14 years. Despite the reduction in OCs concentrations, the total serum burdens of 4,4′-DDE and Σ₇PCBs, were higher in adolescents than at birth. Increases in OCs total serum burden occurred both in breastfed and non-breastfed children, but were significantly higher in the first. Conclusions: Even after decades of banning OCs production and use, current young generations in westernized countries are still bioaccumulating these compounds. Given the potential health effects of OCs, especial attention should be paid in the control of secondary emissions in the environment and in the control of food production and contamination. In countries with endemic malaria it is important to work towards effective alternatives to the use of DDT.     

Age as a determinant of phosphate flame retardant exposure of the Australian population and identification of novel urinary PFR metabolites

The demand for alternative flame retardant materials such as phosphate flame retardants and plasticizers (PFRs) is increasing, although little is known of their possible effects on human health and development. To date, no information on the exposure of children or general Australian population to PFRs is available. The objectives of this study were to characterize the average levels and age-related patterns of PFR metabolites in urine in the general Australian population and to identify novel hydroxylated PFR metabolites in urine. Surplus pathology urine samples from Queensland, Australia were stratified and pooled by age and sex (3224 individuals aged 0 to 75 years into 95 pools) according to two different pooling strategies at two different time periods. Samples were analyzed by solid phase extraction and liquid chromatography–tandem mass spectrometry following enzymatic treatment. Nine PFR metabolites were measured in the Australian population, including the first report of a hydroxylated metabolite of TCIPP (BCIPHIPP). Diphenyl phosphate (DPHP), BCIPHIPP and bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) were detected in > 95% of samples. DPHP, a metabolite of aryl-PFRs, was found in several samples at levels which were one order of magnitude higher than previously reported (up to 730 ng/mL). Weighted linear regression revealed a significant negative association between log-normalized BDCIPP and DPHP levels and age (p < 0.001). Significantly greater levels of BDCIPP and DPHP were found in children's urine compared with adults, suggesting higher exposure to PFRs in young children. BCIPHIPP was identified for inclusion in future PFR biomonitoring studies.     

Monitoring exposure to polycyclic aromatic hydrocarbons in an Australian population using pooled urine samples

Integrated exposure to polycyclic aromatic hydrocarbons (PAHs) can be assessed through monitoring of urinary mono-hydroxylated PAHs (OH-PAHs). The aim of this study was to provide the first assessment of exposure to PAHs in a large sample of the population in Queensland, Australia including exposure to infant (0–4 years). De-identified urine specimens, obtained from a pathology laboratory, were stratified by age and sex, and pooled (n = 24 pools of 100) and OH-PAHs were measured by gas chromatography–isotope dilution–tandem mass spectrometry. Geometric mean (GM) concentrations ranged from 30 ng/L (4-hydroxyphenanthrene) to 9221 ng/L (1-naphthol). GM of 1-hydroxypyrene, the most commonly used PAH exposure biomarker, was 142 ng/L. The concentrations of OH-PAHs found in this study are consistent with those in developed countries and lower than those in developing countries. We observed no association between sex and OH-PAH concentrations. However, we observed lower urinary concentrations of all OH-PAHs in samples from infants (0–4 years), children (5–14 years) and the elderly (> 60 year old) compared with samples from other age groups (15–29, 30–44 and 45–59 years) which may be attributed to age-dependent behaviour-specific exposure sources.     

Fate,distribution, and contrasting temporal trends of perfluoroalkyl substances (PFASs) in Lake Ontario,Canada

Lake Ontario water and sediment collected from tributary, nearshore, and open lake sites were analyzed for perfluoroalkyl substances (PFASs), namely perfluoroalkyl carboxylic acids (PFCAs, F(CF₂)_nCO₂⁻; n = 6-11,13) and perfluoroalkane sulfonic acids (PFSAs, F(CF₂)_nSO₃⁻; n = 6,8,10). Survey results of surface sediment and water indicated that shorter chained PFASs were predominant in and near urban/industrial area watersheds, while longer chained PFASs were predominant in fine-grained sediment from major depositional basins. Niagara River suspended solids (1981–2006) demonstrated temporal trends that may have been influenced by recent changes in North American production and use of PFASs. Perfluorooctane sulfonate (PFOS) reached a peak concentration in 2001 of 1.1 ng/g, followed by a decrease from 2001 to 2006 (half-life = 9 years). Perfluorooctanoic acid (PFOA) increased from 2001 to 2006 (doubling time = 2 years) reaching a peak concentration of 0.80 ng/g. In contrast, three sediment cores from western, central, and eastern Lake Ontario showed increasing temporal trends to surface sediment for all PFASs. PFOA and PFOS concentrations increased from 1988 to 2004 (doubling time = ~ 4 years) in the western Lake Ontario core. The observed variations in temporal trends from different environmental compartments may be a result of the physico-chemical properties of PFASs, ongoing emissions, and the environmental transformation and degradation of PFAS precursor compounds.     

Pyrethroids in house dust from the homes of farm worker families in the MICASA study

Indoor pesticide exposure is a growing concern, particularly for pyrethroids, a commonly used class of pesticides. Pyrethroid concentrations may be especially high in homes of immigrant farm worker families, who often live in close proximity to agricultural fields and are faced with poor housing conditions, potentially causing high pest infestation and pesticide use. We investigate levels of pyrethroids in the house dust of farm worker family homes in a study of mothers and children living in Mendota, CA, within the population-based Mexican Immigration to California: Agricultural Safety and Acculturation (MICASA) Study. We present pesticide use data and levels of pyrethroid pesticides in indoor dust collected in 2009 as measured by questionnaires and a GC/MS analysis of the pyrethroids cis- and trans-permethrin, cypermethrin, deltamethrin, esfenvalerate and resmethrin in single dust samples collected from 55 households. Cis- and trans-permethrin had the highest detection frequencies at 67%, with median concentrations of 244 and 172 ng/g dust, respectively. Cypermethrin was detected in 52% of the homes and had a median concentration of 186 ng/g dust. Esfenvalerate, resmethrin and deltamethrin were detected in less than half the samples. We compared the pyrethroid concentrations found in our study to other studies looking at both rural and urban homes and daycares. Lower detection frequencies and/or lower median concentrations of cis- and trans-permethrin and cypermethrin were observed in our study as compared to those studies. However, deltamethrin, esfenvalerate and resmethrin were detected more frequently in the house dust from our study than in the other studies. Because households whose children had higher urinary pyrethroid metabolite levels were more likely to be analyzed in this study, a positive bias in our estimates of household pyrethroid levels may be expected. A positive association was observed with reported outdoor pesticide use and cypermethrin levels found in the indoor dust samples (r_s = 0.28, p = 0.0450). There was also a positive association seen with summed pyrethroid levels in house dust and the results of a pesticide inventory conducted by field staff (r_s = 0.32, p = 0.018), a potentially useful predictor of pesticide exposure in farm worker family homes. Further research is warranted to fully investigate the utility of such a measure.     

Pharmacokinetics of bisphenol A in humans following a single oral administration

BackgroundHuman exposures to bisphenol A (BPA) are widespread. The current study addresses uncertainties regarding human pharmacokinetics of BPA.ObjectiveTo reduce uncertainties about the metabolism and excretion of BPA in humans following oral administration.MethodsWe exposed six men and eight women to 100 μg/kg bw of deuterated BPA (d6-BPA) by oral administration and conducted blood and urine analysis over a three day period. The use of d6-BPA allowed administered d6-BPA to be distinguished from background native (unlabeled) BPA. We calculated the rate of oral absorption, serum elimination, half-life, area under the curve (AUC), urinary excretion, and metabolism to glucuronide and sulfate conjugates.ResultsMean serum total (unconjugated and conjugated) d6-BPA C_max of 1711 nM (390 ng/ml) was observed at T_max of 1.1 ± 0.50 h. Unconjugated d6-BPA appeared in serum within 5–20 min of dosing with a mean C_max of 6.5 nM (1.5 ng/ml) observed at T_max of 1.3 ± 0.52 h. Detectable blood levels of unconjugated or total d6-BPA were observed at 48 h in some subjects at concentrations near the LOD (0.001–0.002 ng/ml). The half-times for terminal elimination of total d6-BPA and unconjugated d6-BPA were 6.4 ± 2.0 h and 6.2 ± 2.6 h, respectively. Recovery of total administered d6-BPA in urine was 84–109%. Most subjects (10 of 14) excreted > 90% as metabolites within 24 h.ConclusionsUsing more sensitive methods, our study expands the findings of other human oral pharmacokinetic studies. Conjugation reactions are rapid and nearly complete with unconjugated BPA comprising less than 1% of the total d6-BPA in blood at all times. Elimination of conjugates into urine largely occurs within 24 h.     

Exposure to per- and polyfluoroalkyl substances through the consumption of fish from lakes affected by aqueous film-forming foam emissions — A combined epidemiological and exposure modeling approach. The SAMINOR 2 Clinical Study

Releases of aqueous film-forming foams (AFFFs) from airport firefighting activities have been identified as important local point sources of per- and polyfluoroalkyl substances (PFASs) in nearby waterways. PFASs can be taken up by fish, and in turn by the humans that consume them. Despite the global extent of AFFF emissions, few studies exist on related impacts on humans. We aimed to investigate the associations between the consumption of fish from AFFF-affected waters and serum PFAS concentrations in humans using a combination of statistical tools, empirical data, and toxicokinetic modeling. Participants of the SAMINOR 2 Clinical Study were the basis for this study sample, which comprised 74 persons. Fifty-nine participants who reported consuming fish from AFFF-affected waters and 15 nonconsumers completed a questionnaire and gave serum samples. Participants were classified based on their consumption of trout and char: high (n = 16), moderate (n = 16), low (n = 27), and nonconsumers (n = 15); and serum samples were tested for the presence of 15 PFASs. Perfluorooctane sulfonic acid (PFOS) was found in all participants, with the highest concentrations detected in the high consumption group (geometric means, 28 ng/mL) compared to the low consumption group and nonconsumers (10 and 11 ng/mL, respectively). In an analysis of variance contrast model, a significant, positive increasing trend was seen for fish consumption and PFOS, perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA). Toxicokinetic modeling allowed us to predict the median increases in serum concentrations of PFOS, PFHxS, and PFNA among high consumers within a factor of 2.2. The combination of statistical evaluation and toxicokinetic modeling clearly demonstrated a positive relationship between consumption of fish from AFFF-affected waters and serum PFAS concentrations. Further studies on dietary exposure to other PFASs present in AFFF and its consequences on human health are warranted.     

Associations between PBDEs in office air,dust, and surface wipes

Increased use of flame-retardants in office furniture may increase exposure to PBDEs in the office environment. However, partitioning of PBDEs within the office environment is not well understood. Our objectives were to examine relationships between concurrent measures of PBDEs in office air, floor dust, and surface wipes.We collected air, dust, and surface wipe samples from 31 offices in Boston, MA. Correlation and linear regression were used to evaluate associations between variables. Geometric mean (GM) concentrations of individual BDE congeners in air and congener specific octanol–air partition coefficients (K_oa) were used to predict GM concentrations in dust and surface wipes and compared to the measured concentrations.GM concentrations of PentaBDEs in office air, dust, and surface wipes were 472 pg/m³, 2411 ng/g, and 77 pg/cm², respectively. BDE209 was detected in 100% of dust samples (GM = 4202 ng/g), 93% of surface wipes (GM = 125 pg/cm²), and 39% of air samples. PentaBDEs in dust and air were moderately correlated with each other (r = 0.60, p = 0.0003), as well as with PentaBDEs in surface wipes (r = 0.51, p = 0.003 for both dust and air). BDE209 in dust was correlated with BDE209 in surface wipes (r = 0.69, p = 0.007). Building (three categories) and PentaBDEs in dust were independent predictors of PentaBDEs in both air and surface wipes, together explaining 50% (p = 0.0009) and 48% (p = 0.001) of the variation respectively. Predicted and measured concentrations of individual BDE congeners were highly correlated in dust (r = 0.98, p < 0.0001) and surface wipes (r = 0.94, p = 002). BDE209 provided an interesting test of this equilibrium partitioning model as it is a low volatility compound.Associations between PentaBDEs in multiple sampling media suggest that collecting dust or surface wipes may be a convenient method of characterizing exposure in the indoor environment. The volatility of individual congeners, as well as physical characteristics of the indoor environment, influence relationships between PBDEs in air, dust, and surface wipes.     

Perfluoroalkyl acids in subarctic wild male mink (Neovison vison) in relation to age,season and geographical area

This study investigates the influence of biological and environmental factors on the concentrations of perfluoroalkyl acids (PFAAs) in a top predator; the American mink. Perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS) and perfluoroalkyl carboxylates (PFCAs) with C₈–C₁₃ perfluorinated carbon chains were analyzed in livers from wild male mink liver (n = 101) from four areas in Sweden representing two inland environments (rural and highly anthropogenic, respectively) and two different coastal environments. Mean PFOS concentrations were 1250 ng/g wet weight and some mink from the urban inland area had among the highest PFOS concentrations ever recorded in mink (up to 21 800 ng/g wet weight). PFBS was detected in 89% of the samples, but in low concentrations (mean 0.6 ng/g ww). There were significant differences in PFAA concentrations between the geographical areas (p < 0.001–0.01). Age, body condition and body weight did not influence the concentrations significantly, but there was a seasonal influence on the concentrations of perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnDA) (p < 0.01 and p < 0.05, respectively), with lower concentrations in autumn samples than in samples taken in the winter and spring. It is thus recommended to take possible seasonal differences into account when using mink exposure data. The overall results suggest that the mink is a suitable sentinel species for assessing and monitoring environmental levels of PFAAs.     

Intake of phthalate-tainted foods and microalbuminuria in children: The 2011 Taiwan food scandal

BackgroundA major threat to public health involving phthalate-tainted foodstuffs occurred in Taiwan in 2011. Phthalates, mainly di-(2-ethylhexyl) phthalate (DEHP), were intentionally added to several categories of food commonly consumed by children. This study investigated the relationship between intake of the phthalate-tainted foods and renal function in children.MethodsChildren aged ≤ 10 years with possible phthalate exposure were enrolled in this study between August 2012 and January 2013. Questionnaires were used to collect details of exposure to phthalate-tainted foodstuffs, and blood and urine samples were collected for clinical biochemical workup. The clinical biomarkers of renal injury, including urinary microalbumin, N-acetyl-beta-d-glucosaminidase (NAG), and β2-microglobulin were measured. Exposure was categorized based on recommended tolerable daily intake level defined by the U.S. Environmental Protection Agency (0.02 mg/kg/day) and the European Food Safety Authority (0.05 mg/kg/day).ResultsWe analyzed intake and renal function of 184 children whose intake of DEHP-tainted foods was known. Higher DEHP exposure to DEHP-tainted foods was significantly associated with increase of urine albumin/creatinine ratio (ACR). Children in the high-exposed group (daily DEHP intake (DDI) > 0.05 mg/kg/day) had 10.395 times the risk of microalbuminuria than the low-exposed group (DDI ≤ 0.02 and > 0 mg/kg/day) and no-exposed group combined after adjustment (95% CI = 1.096–98.580, P = 0.04).ConclusionIntake of DEHP from phthalate-tainted foods may be a potential risk factor for microalbuminuria, a marker of glomerular injury in children.