Serum levels of polybrominated diphenyl ethers (PBDEs) in foam recyclers and carpet installers working in the United States

Increased exposure to the flame retardants known as polybrominated diphenyl ethers (PBDEs) may be expected to occur during the recycling of polyurethane foam containing these chemicals. To date, no studies in the United States have investigated occupational exposure to these flame retardants during recycling processes. The objective of the present study was to determine if individuals working in foam recycling facilities, and/or carpet installers who may install carpet padding manufactured from recycled foam, possess significantly higher PBDE serum levels relative to that of the general U.S. population. As a control group, serum was collected from four spouses and one clerical worker. In addition, levels in workers were also compared to the recently published national health and nutrition examination survey (NHANES) data set on PBDEs in the general U.S. population. Serum samples were collected in duplicate and analyzed by two different laboratories as quality control. Total PBDE levels were found to be significantly higher (p < 0.05) in the individuals recycling foam and installing carpet (n = 15) relative to the control group (n = 5). Median sigmaPBDE levels in the foam recyclers, carpet layers, and control group were 160, 178, and 19 ng/g lipid, respectively. In contrast, concentrations of a polybrominated biphenyl (BB-153) and a polychlorinated biphenyl (CB-153) were equivalent among all groups tested. The PBDE congeners BDE-47, 99, 100, and 153 contributed 90% of the sigmaPBDE concentration in serum and no differences in congener patterns were apparent among the different groups. Relative to concentrations measured in the NHANES, foam recyclers and carpet layers have body burdens that are an order of magnitude higher. These data suggest individuals recycling foam-containing products, and/ or using products manufactured from recycled foam (i.e., carpet padding), have higher body burdens of PBDEs, and thus may be at higher risk from adverse health effects associated with brominated flame retardant exposure.     

Microbial reductive debromination of polybrominated diphenyl ethers (PBDEs)

Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants that have recently been detected in environmental samples, diverse biota, human blood serum, and breast milk at exponentially increasing concentrations. Currently, little is known about the fate of these compounds, and in particular, about the microbial potential to degrade them. In this study, debromination of deca-BDE and an octa-BDE mixture is demonstrated with anaerobic bacteria including Sulfurospirillum multivorans and Dehalococcoides species. Hepta- and octa-BDEs were produced by the S. multivorans culture when it was exposed to deca-BDE, although no debromination was observed with the octa-BDE mixture. In contrast, a variety of hepta- through di-BDEs were produced by Dehalococcoides-containing cultures exposed to an octa-BDE mixture, despite the fact that none of these cultures could debrominate deca-BDE. The more toxic hexa-154, penta-99, tetra-49, and tetra-47 were identified among the debromination products. Because the penta-BDE congeners are among the most toxic PBDEs, debromination of the higher congeners to more toxic products in the environment could have profound implications for public health and for the regulation of these compounds.     

Personal exposure to polybrominated diphenyl ethers (PBDEs) in residential indoor air

We used personal air samplers to measure indoor air exposure to polybrominated diphenyl ethers (PBDEs) for 20 residents of the Greater Boston Area (Massachusetts). Area air measures were simultaneously collected from two rooms in each participant's home. Total personal air concentrations (particulate + vapor) were 469 pg/m3 for non-209 BDEs and 174 pg/m3 for BDE 209, significantly higher than bedroom and main living room concentrations (p = 0.01). The ratio of personal air to room air increased from 1 for vapor-phase congeners to 4 for fully particulate-bound congeners, indicating a personal cloud effect. Bedroom and main living area air samples were moderately correlated for non-209 BDEs (r = 0.45, p = 0.045) and BDE 209 (r = 0.58, p = 0.008). Use of personal air concentrations increased estimates of inhalation exposure over those previously reported. Inhalation may account for up to 22% of the total BDE 209 exposure in U.S. adults.     

Genotoxicity of several polybrominated diphenyl ethers (PBDEs) and hydroxylated PBDEs, and their mechanisms of toxicity

Polybrominated diphenyl ethers (PBDEs) have been extensively utilized as flame retardants, and recently there has been concern about potential adverse effects in humans and wildlife. Their hydroxylated analogs (OH-BDEs) have received increasing attention due to their potential for endocrine and neurological toxicities. However, the potentials and mechanisms of genotoxicity of these brominated compounds have scarcely been investigated. In the present study, genotoxicity of tetra-BDEs, penta BDE, octa-BDE, deca-BDE, and tetra-OH-BDEs were investigated by use of chicken DT40 cell lines including wild-type cells and a panel of mutant cell lines deficient in DNA repair pathways. Tetra-BDEs have greater genotoxic potential than do the other BDEs tested. OH-tetra-BDEs were more genotoxic than tetra-BDEs. DT40 cells, deficient in base excision repair (Polβ(-/-)) and translesion DNA synthesis (REV3(-/-)) pathways, were hypersensitive to the genotoxic effects of tetra-BDEs and OH-tetra-BDEs. The observation of chromosomal aberrations and gamma-H2AX assay confirmed that the studied brominated compounds caused double strand breaks. Pretreatment with N-acetyl-l-cysteine (NAC) significantly rescued the Polβ(-/-) and REV3(-/-) mutants, which is consistent with the hypothesis that PBDEs and OH-BDEs cause DNA damage mediated through reactive oxygen species (ROS). Some tetra-BDEs and OH-tetra-BDEs caused base damage through ROS leading to replication blockage and subsequent chromosomal breaks.     

Parental transfer of polybrominated diphenyl ethers (PBDEs) and thyroid endocrine disruption in zebrafish

Polybrominated diphenyl ethers (PBDEs) have the potential to disrupt the thyroid endocrine system. The objective of the present study was to characterize the disrupting effects of long-term exposure on the thyroid endocrine system in adult fish and their progeny following parental exposure to PBDEs. Zebrafish (Danio rerio) embryos were exposed to environmentally relevant concentrations (1, 3, and 10 μg/L) of the PBDE mixture DE-71 for 5 months until sexual maturation. In the F0 generation, exposure to DE-71 significantly increased plasma thyroxine (T4) but not 3,5,3'-triiodothyronine (T3) in females. This increased T4 was accompanied by decreased mRNA levels of corticotropin-releasing hormone (CRH) and thyrotropin β-subunit (TSHβ) in the brain. The F1 generation was further examined with or without continued DE-71 treatment conditions. Exposure to DE-71 in the F0 fish caused significant increases in T4 and T3 levels in the F1 larvae and modified gene expressions in the hypothalamic-pituitary-thyroid axis (HPT axis) under both conditions. Decreased hatching and inhibition of growth in the F1 offspring were observed in the condition without DE-71 treatment. Continued DE-71 treatment in the F1 embryos/larvae resulted in further decreased hatching, and increased malformation rates compared with those without DE-71 exposure. Analysis of F1 eggs indicated that parental exposure to DE-71 could result in a transfer of PBDEs and thyroid hormones (THs) to their offspring. For the first time, we demonstrated that parental exposure to low concentrations of PBDEs could affect THs in the offspring and the transgenerational PBDE-induced toxicity in subsequent nonexposed generations.     

Comparison of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) in Lake Michigan salmonids

Polybrominated diphenyl ethers (PBDEs) have been used extensively over the past two decades as flame retardants in most types of polymers. Many measurements of PBDEs in various environmental matrices from Sweden, Holland, Japan, and elsewhere have been reported, but few measurements are available for North America. PBDEs in 21 coho and chinook salmon taken from Lake Michigan tributaries in 1996 were measured for this study. The salmon samples were extracted and initially analyzed for polychlorinated biphenyl (PCB) congeners. It was demonstrated for these samples that the same extract fraction contains PBDEs. Six PBDE congeners were observed in all 21 samples, and the rank order of concentration of these congeners was similar to that in commercial mixtures of PBDEs. The average concentration across all samples of the sum of PBDE congeners was 80.1 ng/g of wet weight or 2,440 ng/g of lipid. This is much less than the average sum PCB concentration (1,450 ng/g of wet weight; 43,100 ng/g of lipid). However, the average concentration of the most abundant PBDE congener (IUPAC BDE-49: 52.1 ng/g wet, 1,590 ng/g of lipid) was about one-third of the average concentration of the most abundant PCB congener (IUPAC CB-153: 149 ng/g wet, 4,550 ng/g of lipid). On the basis of an extensive literature survey, the concentrations of PBDEs reported here are among the highest in the world for salmon in open waters. The concentrations of PBDEs and PCBs are both correlated with fish length and mass, but not with lipid content. The concentrations of PBDEs and PCBs are highly correlated in individual fish, implying that PBDEs are as prevalent as PCBs in Lake Michigan.     

Particle-phase dry deposition and air-soil gas-exchange of polybrominated diphenyl ethers (PBDEs) in Izmir, Turkey

The particle-phase dry deposition and soil-air gas-exchange of polybrominated diphenyl ethers (PBDEs) were measured in Izmir, Turkey. Relative contributions of different deposition mechanisms (dry particle, dry gas, and wet deposition) were also determined. BDE-209 was the dominating congener in all types of samples (air, deposition, and soil). Average dry deposition fluxes of total PBDEs (sigma7PBDE) for suburban and urban sites were 67.6 and 128.8 ng m(-2) day(-1), respectively. Particulate dry deposition velocities ranged from 11.5 (BDE-28) to 3.9 cm s(-1) (BDE-209) for suburban sites and 7.8 (BDE-28) to 2.8 cm s(-1) (BDE-154) for urban sites with an overall average of 5.8 +/- 3.7 cm s(-1). The highest sigma7PBDE concentration (2.84 x 10(6) ng kg(-1) dry wt) was found around an electronic factory among the 13 soil samples collected from different sites. The concentration in a bag filter dust from a steel plant was also high (2.05 x 10(5) ng kg(-1)), indicating that these industries are significant PBDE sources. Calculated net soil-air gas exchange flux of sigma7PBDE ranged from 11.8 (urban) to 23.4 (industrial) ng m(-2) day(-1) in summer, while in winter it ranged from 3.2 (urban) to 11.6 (suburban) ng m(-2) day(-1). All congeners were deposited at all three sites in winter and summer. It was estimated that the wet deposition also contributes significantly to the total PBDE deposition to soil. Dry particle, wet, and gas deposition contribute 60, 32, and 8%, respectively, to annual PBDE flux to the suburban soil.     

Dietary exposure of the Hong Kong adult population to polybrominated diphenyl ethers (PBDEs): results of the first Hong Kong Total Diet Study

Polybrominated diphenyl ethers (PBDEs) are a group of industrial chemicals that are persistent and can bioaccumulate. In the first Hong Kong Total Diet Study, the dietary exposure of Hong Kong adults to PBDEs was estimated to assess the associated health risks. Food samples, which represented the Hong Kong people’s diet, were collected and prepared in table-ready form for analysis. Concentrations of PBDEs were determined in 142 composite samples. The dietary exposures were estimated by combining the analytical results with the local food consumption data of the adults. The mean and 95th percentile of dietary PBDEs exposures of the Hong Kong people were 1.34 and 2.90 ng kg^?1 body weight day^?1, respectively. The main dietary source of PBDEs was “fish and seafood and their products”, which contributed 27.3% of the total exposure, followed by “meat, poultry and game and their products” (20.7%), “cereals and their products” (15.9%), and “fats and oils” (15.9%). The large margins of exposure (MOE) (>2.5) calculated following the European Food Safety Authority (EFSA) approach for four important congeners, BDE-47, BDE-99, BDE-153 and BDE-209, indicate that the estimated dietary exposures are unlikely to be a significant health concern.     

Dramatic changes in the temporal trends of polybrominated diphenyl ethers (PBDEs) in herring gull eggs from the Laurentian Great Lakes: 1982-2006

DecaBDE is a current-use, commercial formulation of an additive, polybrominated diphenyl ether (PBDE) flame retardant composed of > 97% 2,2',3,3',4,4',5,5',6,6'-decabromoDE (BDE-209). Of the 43 PBDE congeners monitored, we report on the temporal trends (1982-2006) of quantifiable PBDEs, and specifically BDE-209, in pooled samples of herring gull (Larus argentatus) eggs from seven colonies spanning the Laurentian Great Lakes. BDE-209 concentrations in 2006 egg pools ranged from 4.5 to 20 ng/g wet weight (ww) and constituted 0.6-4.5% of sigma39PBDE concentrations among colonies, whereas sigma(octa)BDE and sigma(nona)BDE concentrations constituted from 0.5 to 2.2% and 0.3 to 1.1%, respectively. From 1982 to 2006, the BDE-209 doubling times ranged from 2.1 to 3.0 years, whereas for sigma(octa)BDEs and sigma(nona)BDEs, the mean doubling times ranged from 3.0 to 11 years and 2.4 to 5.3 years, respectively. The source of the octa- and nona-BDE congeners, e.g., BDE-207 and BDE-197, are the result of BDE-209 debromination, and they are either formed metabolically in Great Lakes herring gulls and/or bioaccumulated from the diet and subsequently transferred to their eggs. In contrast to BDE-209 and the octa- and nona-BDEs, congeners derived mainly from PentaBDE and OctaBDE mixtures, e.g., BDE-47, -99, and -100, showed rapid increases up until 2000; however, there was no increasing trend post-2000. The data illustrates that PBDE concentrations and congener pattern trends in the Great Lakes herring gull eggs have dramatically changed between 1995 and 2006. Regardless of BDE-209 not fitting the pervasive criteria as a persistent and bioaccumulative substance, it is clearly of increasing concern in Great Lake herring gulls, and provides evidence that regulation of DecaBDE formulations is warranted.     

Modeling the importance of biota and black carbon as vectors of polybrominated diphenyl ethers (PBDEs) in the Baltic Sea ecosystem

The POPCYCLING-Baltic model, a nonsteady state spatially resolved mass balance model of chemical transport in the Baltic Sea environment was modified to include black carbon (BC), dissolved organic carbon (DOC) and food-web bioaccumulation. The importance of these modifications to the transport of PBDE congeners BDE-47, -99, -153, and -209 was assessed by comparing time-series simulated with and without black carbon and biota between 1970 and 2005. Inclusion of black carbon improved the model fit to measurements from air, soil, and biota, and had a major effect on the mass balance. Modeled bulk concentrations of PBDEs in sediments and soils increased by a factor of 3 while concentrations in biota decreased by a factor of 2-5. Black carbon also doubled the recovery time of the system due to the limited availability of PBDEs for degradation. In comparison, the inclusion of biota had only a minor effect on the overall mass balance and recovery times. The modified model is constructed as a flexible matrix and can also be applied to persistent organic pollutants in other ecosystems besides the Baltic Sea.     

Concentrations and spatial variations of polybrominated diphenyl ethers and several organochlorine compounds in fishes from the northeastern United States

Fish from four lakes, two small lakes in the northeastern United States and two of the Great Lakes, were analyzed to determine the concentrations and spatial variations of polybrominated diphenyl ethers (PBDE) in this region. Three of the lakes were considered to have background levels of PBDEs; one lake was close to a suspected source. The PBDE concentrations were compared to organochlorine pesticide and PCB concentrations. Age and trophic position did not influence the organohalogen concentrations in the fish collected from the four locations. At the three background locations, the sum of PBDE concentrations ranged from 6.9 +/- 1.4 to 18 +/- 1 ng/g wet weight, or 150 +/- 9 to 300 +/- 80 ng/g lipid, and these values were similar to those of some of the organochlorine pesticides, such as total chlordane, but lower than sum of PCB concentrations. At the lake near the suspected source, the sum of PBDE concentration was 65 +/- 8 ng/g wet weight, or 2,400 +/- 600 ng/g lipid, and it exceeded the sum of PCB concentration. The hexabrominated congeners made up 43% of the total mass of PBDEs at this lake, and 7% at the background locations. Fish to sediment concentration ratios indicated that the tetra- through hexa-substituted congeners have a similar bioavailability, while the deca-substituted congener does not seem to be bioavailable at all.     

Fate, partitioning, and mass loading of polybrominated diphenyl ethers (PBDEs) during the treatment processing of municipal sewage

Sewage treatment plant (STP) effluents are likely a major source of contamination for PBDEs, especially in the receiving water bodies of local aquatic environments surrounding the location of these discharges. Congeners of the pentaBDE mixture, 2,2,',4,4'-tetrabromodiphenyl ether (BDE47), 2,2,',4,4',5-pentabromodiphenyl ether (BDE99), 2,2,',4,4',6-pentabromodiphenyl ether (BDE100), 2,2,',4,4',5,5'-hexabromodiphenyl ether (BDE153), and 2,2,',4,4',5,6'-hexabromodiphenyl ether (BDE154), are of great environmental concern in North America due to their persistence, potential for bioaccumulation, and >97% use of the global production of the mixture in the region. Detailed characterization of the distribution of eight PBDE congeners (2,4,4'-tribromoDE (BDE28) and BDE47, 99, 100, 138, 153, 154, and 183) was carried out at five sites along the treatment process at an activated sludge-type secondary treatment municipal STP facility. PentaBDE mixture congeners, sigma5PBDE (sum of BDE47, 99, 100, 153, and 154) accounted for >98% of the total (sigma 8) PBDE concentration at all sites, with over 80% of the composition being BDE47 and BDE99. Presence of dissolved organic matter affected the mobility of PBDEs during the initial stages of the treatment process. About 9% of the influent mass of sigma5PBDE to the facility is estimated to be discharged into the Little River (leading to the Detroit River) with the final effluent, resulting in an estimated mass loading of approximately 0.7 kg/year. The total mass loading of sigma5PBDE to the Detroit River is expected to be much larger as effluent from this facility accounts for <10% of the total STP discharges to the river.     

Dietary intake estimations of polybrominated diphenyl ethers (PBDEs) based on a total diet study in Osaka,Japan

This study presents the results of a total diet study performed for estimating the dietary intake of polybrominated diphenyl ethers (PBDEs) in Osaka, Japan. The concentrations of 36 PBDEs were measured in samples from 14 food groups (Groups I–XIV). PBDEs were detected only in Groups IV (oils and fats), V (legumes and their products), X (fish, shellfish, and their products), and XI (meat and eggs) at concentrations of 1.8, 0.03, 0.48, and 0.01 ng g^?1, respectively. For an average person, the lower bound dietary intakes of penta- and deca-formulations were estimated to be 46 and 21 ng day^?1, respectively. A high proportion of the decabrominated congener (DeBDE-209) was observed in Group IV. To confirm the presence of DeBDE-209 in vegetable oils, an additional analysis was performed using 18 vegetable oil samples. Of these, seven contained ng g^?1 levels of DeBDE-209.     

Temporal trends of polybrominated diphenyl ethers and hexabromocyclododecane in milk from Stockholm mothers, 1980-2004

Environmental and human exposures to brominated flame retardants (BFR) have been of emerging concern since some BFR are persistent and bioaccumulative compounds. Among those, polybrominated diphenyl ethers (PBDE) have frequently been reported in low to high ng/g concentrations in human blood around the world while hexabromocyclododecane (HBCDD) only occasionally has been reported and then in the low ppb concentrations in human blood. The present study concerns PBDE congener and HBCDD concentrations in human milk from Stockholm from 1980 to 2004. HBCDD concentrations has increased four to five times since 1980 until 2002 but seems to have stabilized at this concentration in the last years (2003/04). Similarly, BDE-153 has continued to increase at least to 2001, after which it has stabilized in the mother's milk. Other PBDE congeners with four to five bromine substituents peaked 5 years earlier (1995) and are all decreasing. DecaBDE (BDE-209) is not a suitable biomarker for time trend studies according to the present results, showing no changes over time. This is likely due to its short apparent half-life in humans and poor transfer from blood to milk.     

European-scale modeling of concentrations and distribution of polybrominated diphenyl ethers in the pentabromodiphenyl ether product

The results from a modeling exercise utilizing the European variant (EVn) BETR multimedia environmental fate model are presented for selected polybrominated diphenyl ethers (PBDEs) of the technical penta- (Pe-) bromodiphenyl ether (BDE) product. The objectives of this study were to test PeBDE emission estimates from the literature for Europe by investigating the consistency between model predictions and ambient measurements to address the ability of the model to predict spatial variability and differences between congeners. Concurrently sampled and analyzed passive sampling air data, together with soil and grass data, were used as key model validation tools. The model steady-state simulations gave generally good agreement with measured data for BDE-47 and -99 with greater discrepancies for heavier congeners (e.g., BDE-153). To predict future atmospheric concentration trends, the model was used in its fully dynamic mode over the period 1970--2010. It was predicted that atmospheric concentrations peaked around 1997, declining with an overall "disappearance" half-life of 4.8 years. Soil and grass levels were underestimated by the model; possible reasons for differences with measurement data are further explored. Finally, the importance of temporally and spatially resolved environmental data sets is highlighted, while improved quantification of degradation half-lives is essential to better understand and predict the behavior of BDE congeners in PeBDE.     

Causes of variability in concentrations of polychlorinated biphenyls and polybrominated diphenyl ethers in indoor air

Airborne concentrations of PCBs and PBDEs were measured in offices, homes, public environments, and cars. Variations in concentrations between different rooms in the same domestic and office buildings, showed some intra-building variability for both compound groups. Stepwise multiple linear regression analysis revealed no clear and consistent relationships between log-normalized concentrations of PCBs and PBDEs in homes and offices and factors such as the number of personal computers. This is considered to reflect the complexity of relationships between indoor air contamination and microenvironment characteristics. The influence of personal computers was demonstrated when PBDE concentrations in one office fell appreciably following the exchange of a computer constructed in 1998 for one dating from 2003. Concentrations of PCBs in buildings constructed between 1950 and 1979 were significantly higher (p < 0.001) than in those constructed since. When two of the most contaminated cars were omitted as outliers, a significant (p < 0.01) positive linear relationship was detected between PBDE concentrations and vehicle age. Concentrations of PCBs and PBDEs were monitored throughout a calendar year in four homes and four offices. Although concentrations in warmer months usually exceeded those in colder months, seasonal variability in indoor contamination appears less significant than observed previously for outdoor air.     

Dehalogenation of polybrominated diphenyl ethers and polychlorinated biphenyl by bimetallic, impregnated, and nanoscale zerovalent iron

Nanoscale zerovalent iron particles (nZVI), bimetallic nanoparticles (nZVI/Pd), and nZVI/Pd impregnated activated carbon (nZVI/Pd-AC) composite particles were synthesized and investigated for their effectiveness to remove polybrominated diphenyl ethers (PBDEs) and/or polychlorinated biphenyls (PCBs). Palladization of nZVI promoted the dehalogenation kinetics for mono- to tri-BDEs and 2,3,4-trichlorobiphenyl (PCB 21). Compared to nZVI, the iron-normalized rate constants for nZVI/Pd were about 2-, 3-, and 4-orders of magnitude greater for tri-, di-, and mono-BDEs, respectively, with diphenyl ether as a main reaction product. The reaction kinetics and pathways suggest an H-atom transfer mechanism. The reaction pathways with nZVI/Pd favor preferential removal of para-halogens on PBDEs and PCBs. X-ray fluorescence mapping of nZVI/Pd-AC showed that Pd mainly deposits on the outer part of particles, while Fe was present throughout the activated carbon particles. While BDE 21 was sorbed onto activated carbon composites quickly, debromination was slower compared to reaction with freely dispersed nZVI/Pd. Our XPS and chemical data suggest about 7% of the total iron within the activated carbon was zerovalent, which shows the difficulty with in-situ synthesis of a significant fraction of zerovalent iron in the microporous material. Related factors that likely hinder the reaction with nZVI/Pd-AC are the heterogeneous distribution of nZVI and Pd on activated carbon and/or immobilization of hydrophobic organic contaminants at the adsorption sites thereby inhibiting contact with nZVI.     

Indoor and outdoor air concentrations and phase partitioning of perfluoroalkyl sulfonamides and polybrominated diphenyl ethers

Perfluoroalkyls (PFAs) and polybrominated diphenyl ethers (PBDEs) are two classes of emerging persistent organic pollutants (POPs) that are widely used in domestic and workplace products. These compounds also occur in remote locations such as the Arctic where they are accumulated in the food chain. This study makes connections between indoor sources of these chemicals and the potential and mode for their transport in air. In the case of the PFAs, three perfluoralkyl sulfonamides (PFASs) were investigated--N-methyl perfluorooctane sulfonamidoethanol (MeFOSE), N-ethyl perfluorooctane sulfonamidoethanol (EtFOSE), and N-methyl perfluorooctane sulfonamidethylacrylate (MeFOSEA). These are believed to act as precursors that eventually degrade to perfluorooctane sulfonate (PFOS), which is detected in samples from remote regions. High-volume samples were collected for indoor and outdoor air to investigate the source signature and strength. Mean indoor air concentrations (pg/m3) were 2590 (MeFOSE), 770 (EtFOSE), and 630 (sigmaPBDE). The ratios of concentration between indoor and outdoor air were 110 for MeFOSE, 85 for EtFOSE, and 15 for sigmaPBDE. The gas and particle phases were collected separately to investigate the partitioning characteristics of these chemicals. Measured particulate percentages were compared to predicted values determined using models based on the octanol-air partition coefficient (K(OA)) and supercooled liquid vapor pressure (pL(o)); these models were previously developed for nonpolar, hydrophobic chemicals. To make this comparison for the three PFASs, it was necessary to measure their K(OA) and vapor pressure. K(OA) values were measured as a function of temperature (0 to +20 degrees C). Values of log K(OA) at 20 degrees C were 7.70, 7.78, and 7.87 for MeFOSE, EtFOSE, and MeFOSEA, respectively. Partitioning to octanol increased at colder temperatures, and the enthalpies associated with octanol-air transfer (deltaH(OA), kJ/mol) were 68-73 and consistent with previous measurements for nonpolar hydrophobic chemicals. Solid-phase vapor pressures (pS(o)) were measured at room temperature (23 degrees C) by the gas saturation method. Values of pS(o) (Pa) were 4.0 x 10(-4), 1.7 x 10(-3), and 4.1 x 10(-4), respectively. These were converted to pL(o) for describing particle-gas exchange. Both the pL(o)-based model and the K(OA) model worked well for the PBDEs but were not valid for the PFASs, greatly underpredicting particulate percentages. These results suggest that existing K(OA)- and pL(o)-based models of partitioning will need to be recalibrated for PFASs.     

Latitudinal fractionation of polybrominated diphenyl ethers and polychlorinated biphenyls in frogs (Rana temporaria)

The flame retardant polybrominated diphenyl ethers (PBDEs) have become ubiquitous environmental pollutants. The environmental distribution of PBDEs is much less studied than that of the polychlorinated biphenyls (PCBs). To compare the environmental fate of the PCBs with their partial substitute, the PBDEs, common frogs (Rana temporaria)were collected along a approximately 1,500-km-long latitudinal gradient of the Scandinavian Peninsula and their livers analyzed for PCBs and PBDEs. Mean concentrations of total PCBs and BDE47 ranged from 9200 to 92 900 and 30 to 120 ng kg(-1) fresh weight, respectively, whereas BDE99 was detected in less than 50% of the frogs. PCB concentrations were higher than that of the PBDEs, and the differences decreased in the northern latitudes. Moreover, the pollutant concentrations in frog livers were negative functions of latitude. The observed scatter and regression slopes imply several influencing factors (such as habitat, exposure route, uptake, metabolism, excretion, etc.) and indicate release events instead of the grasshopper effect Biological variables such as gender, age, body size, and lipid content did not influence pollutant concentrations in the frog livers. The total PCB and BDE47 concentrations in frogs were highly correlated. Hence, their environmental fate is analogous and our results highlight the need to examine the potential role of xenobiotics on amphibian populations.     

Global assessment of polybrominated diphenyl ethers in farmed and wild salmon

We have shown recently that levels of persistent, bioaccumulative contaminants (polychlorinated biphenyls, dioxins, and several chlorinated pesticides) are significantly higher in farmed than in wild salmon and that European farm-raised salmon have significantly greater toxic contaminant loads than those raised in North and South America. In this paper, we extend these results to polybrominated diphenyl ethers (PBDEs) and show that farm-raised salmon have higher levels of these compounds than wild salmon. We also show that farm-raised salmon from Europe have higher PBDE levels than those raised in North America and that both European and North American farm-raised salmon have higher PBDE levels than those farm-raised in Chile. Among the species of wild salmon, chinook had significantly elevated PBDE levels relative to the other wild species. These elevated PBDE levels may be related to chinook's feeding behavior and trophic level. Among all of the wild species we studied, chinook tend to feed higher in the food web throughout their adult life and grow to be larger individuals.