Time trends of polybrominated diphenyl ethers in sediment cores from the Pearl River Estuary, South China

The present study provides information on the time trend of PBDEs in three sediment cores from the Pearl River Estuary (PRE), South China, using 210Pb dating technique. The sigmaPBDEs (except for BDE 209) concentrations in all sediment cores increased gradually from the bottom (mid-1970s) to the middle layer (later 1980s and early 1990s) followed by different temporal trends in different locations to the surface sediments, reflecting the variations in the consumption of commercial penta-BDEs mixture in different regions of the Pearl River Delta. The BDE 209 concentrations remained constant until 1990 and thereafter increased exponentially to the present, with doubling times of 2.6 +/- 0.5-6.4 +/- 1.6 years, suggesting the increasing market demands for deca-BDE mixture after 1990 in China. The inventories of sigmaPBDEs and BDE 209 in sediments of the PRE were 56.0 and 368.2 ng cm(-2), respectively, and the total burden of PBDEs in the PRE were estimated at 8.6 metric tons. The current sigmaPBDEs and BDE 209 fluxes to the PRE were 2.1 and 29.7 ng cm(-2) yr(-1), respectively. The concurrent increase of BDE 209 fluxes and the annual gross industrial output values of electronics manufacturing revealed that the rapid growth of electronics manufacturing in this region since the early 1990s was responsible for the sharp rise of BDE 209 fluxes in the past decade. The PBDE congener compositions of the cores indicated the various input pathways for PBDEs transport to different locations of the estuary.     

Reductive debromination of polybrominated diphenyl ethers in anaerobic sediment and a biomimetic system

Because of the bioaccumulation of penta- and tetrapolybrominated diphenyl ether (PBDE) flame retardants in biota,the environmental biotransformation of decabromodiphenyl ether (BDE-209) is of interest. BDE-209 accounts for more than 80% by mass of PBDE production and is the dominant PBDE in sediments. Most sediments are anaerobic and reports of microbial reductive dehalogenation of hydrophobic persistent organohalogen pollutants are numerous. Reductive debromination of BDE-209 in the environment could provide a significant source of lesser-brominated PBDEs to biota. Moreover, a recent study showed that BDE-209 debrominates in sewage sludge, and another demonstrated that some halorespiring bacteria will debrominate BDE-209. To determine whether reductive debromination of BDE-209 occurs in sediments, parallel experiments were conducted using anaerobic sediment microcosms and a cosolvent-enhanced biomimetic system. In the biomimetic system, reductive debromination occurred at rates corresponding to bromine substitution levels with a BDE-209 half-life of only 18 s compared with a halflife of almost 60 days for 2,2',4,4'-tetrabromodiphenyl ether. In sediment, the measured debromination half-life of BDE-209 was well over a decade and was in good agreement with the predicted value obtained from the biomimetic experiment. Product congeners were predominantly double para-substituted. BDE-209 debrominated in sediment with a corresponding increase in nona-, octa-, hepta-, and hexa-PBDEs. Nine new PBDE congeners appeared in sediment from reductive debromination. Given the very large BDE-209 burden already in sediments globally, it is important to determine whether this transformation is a significant source of lesser-brominated PBDEs to the environment.     

Polybrominated diphenyl ethers in watershed soils of the Pearl River Delta, China: occurrence, inventory, and fate

Soils play an important role in the distribution and biogeochemical cycling of polybrominated diphenyl ethers (PBDEs) as they are a major reservoir and sink for PBDEs due to their large sorption capacity. In this study, concentrations, compositional profiles, mass inventories, and fate of sigma9PBDEs (28, 47, 66, 100, 99, 154, 153, 138, 183) and BDE 209 were investigated in 33 surface soils, six profile soils, and three point-source polluted soils (close to e-waste dismantling sites) from the Pearl River Delta (PRD), China. The concentrations of sigma9PBDEs and BDE 209 in the surface soils ranged from 0.13 to 3.81 ng/g with an average of 1.02 ng/g and from 2.38 to 66.6 ng/g with an average of 13.8 ng/g, respectively, and ranged from 1.93 to 19.5 ng/g and from 25.7 to 102 ng/g, respectively, in the point-source contaminated soils. The PBDE compositional patterns in the surface soils indicated deca-BDE, penta-BDE, and octa-BDE products as the main sources, but those in the point-source samples suggested deca-BDE and octa-BDE technical mixtures as the dominant sources. The mass inventories of PBDEs in soils of the PRD were estimated at 3.98 and 44.4 t for sigma9PBDEs and BDE 209, respectively. The average loading of PBDEs in the soils was comparable to that in the sediments of the Pearl River Estuary, suggesting that soil erosion and surface runoff are an important mode to transport PBDEs from terrestrial sources to oceans in the PRD. Individual BDE congeners, sigma9PBDEs, and PBDE 209, were significantly correlated with total organic carbon (TOC), and a good regression (except for BDE 47) between the logarithms of TOC-normalized BDE average concentrations and their log K(ow) was also obtained, indicating that sorption of PBDEs on soil organic matter governed their spatial distribution, transportation, and fate in the soils. Predicted aqueous and gaseous concentrations of PBDEs were derived from the soil-water and soil-air partitioning models, respectively, and good agreements were obtained between the predicted and previously reported values. BDE 47 and/or 28 did not appear to follow the same trend for these models, an indication that an portion of them was likely the biodegradation byproducts in soils.     

Tracking polybrominated diphenyl ether releases in a wastewater treatment plant effluent, Palo Alto, California

Polybrominated diphenyl ethers (PBDEs) are commonly used flame-retardants that are now ubiquitous environmental contaminants. Wastewater treatment plants are one source of PBDEs to the environment through their discharge of treated effluent and land application of sewage sludge. Effluent and sludge were collected and analyzed for PBDEs at a wastewater treatment plant in California. The total concentration of PBDEs ranged from 61 to 1440 microg/kg dry wt in the sludge and from 4 to 29,000 pg/L in discharged effluent. The congeners with the highest abundance in sludge were BDE-47, BDE-99, and BDE-209, while in treated effluent BDE-47 and BDE-99 were the most abundant. BDE-47 and BDE-99 are major congeners of the penta-formulation, while BDE-209 composes the deca-formulation. The sum of the major congeners in the penta-formulation (BDE-47, 99, 100, 153, and 154) comprises 88% of the total PBDEs in the effluent, while BDE-209 is only 6%. Based on the loading analysis, the total PBDE concentrations loaded to the San Francisco Estuary through effluent discharge from this wastewater treatment plant is 2 lb/year (0.9 kg/year).     

Riverine inputs of polybrominated diphenyl ethers from the Pearl River Delta (China) to the coastal ocean

Riverine runoff is an important mode to transport anthropogenic pollutants from terrestrial sources to oceans. Polybrominated diphenyl ethers (PBDEs) were measured in riverine runoff samples from the eight major outlets within the Pearl River Delta (PRD), China, an economically fast developing region housing a vast number of electronics manufacturing and assembling plants. The sigma 17PBDEs (sum of 17 BDE congeners, i.e., BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, -183, -196, -197, -203, -206, -207, -208, and -209) concentrations varied from 344 to 68,000 pg/L, with those of BDE-209, BDE-47, and BDE-99 being 335-65200, 3-143, and <1-200 pg/L, respectively. These levels were in the high end of the global PBDEs concentrations in the aquatic environments. The monthly inputs of sigma 17PBDEs ranged from 0.21 to 215 kg at individual outlets, and the annual input of sigma 17PBDEs from all the outlets was estimated at 2140 kg/year. Of the target BDE congeners, BDE-209 was the most predominant component with an annual input of 1960 kg/year, followed by BDE-47 (13.3 kg/year) and BDE-99 (11.7 kg/year). An extrapolation of the past use of PBDEs in the region concluded that 23 metric tons of sigma 17PBDEs have been discharged into the coastal ocean from the PRD in the last 20 years. The amount of PBDEs imported to China in the form of e-waste was estimated at 35000 metric tons/year, higher than the annual domestic production of brominated fire retardants (approximately 10000 metric tons/year) and the annual riverine input of total PBDEs from the PRD, suggesting that the majority of PBDEs inventory has been accumulated from importation of e-wastes. Because of the continuous importation of e-wastes and strong demand for brominated fire retardants, the impact of PBDEs on China's and the world's environments is expected to persist for many years to come.     

Concentration levels, compositional profiles, and gas-particle partitioning of polybrominated diphenyl ethers in the atmosphere of an urban city in South China

Air samples were collected in June of 2004 from four sites in the city of Guangzhou, a typical urban center in South China, to determine the levels, compositional profiles, and gas-particle distribution of 11 polybrominated diphenyl ether (PBDE) congeners (BDE-28, -47, -66, -100, -99, -85, -154, -153, -138, -183, and -209). The arithmetic mean atmospheric concentrations of sigmaPBDEs (sum of all target PBDE congeners except for BDE-209) in samples from the urban and city background sites were comparable to or slightly higher than those from other places around the world. The arithmetic mean atmospheric concentrations of BDE-209, however, were higherthan those in North America and Europe, and similar to the values from Japan. Congener compositions were dominated by BDE-209 in all (>70%) but an industrial site, with an average abundance of 48% for BDE-209. The PBDE patterns were generally similar to that in the technical penta-BDE mixture, Bromkal 70-5DE. Partitioning of PBDEs between the gas and particle phases (Kp) was well correlated with the subcooled liquid vapor pressure (PLO) for all of the samples, but the relationship differed between samples from different sites. The measured fractions of PBDEs in the particulate phase were compared to the predictions from the Junge-Pankow adsorption and KOA-based absorption models. The results indicated that the KOA-based model worked better than the Junge-Pankow model that tended to overestimate the particulate fractions for most PBDE congeners.     

Polybrominated diphenyl ethers in peregrine falcon (Falco peregrinus) eggs from the northeastern U.S

A total of 114 peregrine falcon eggs from nests in Connecticut, Massachusetts, Maine, New Hampshire, Rhode Island, and Vermont were analyzed for polybrominanted diphenyl ethers (PBDEs). Eggs were collected from 1996 to 2006, excluding 1997 and 1998. Total PBDE concentrations ranged from 74.5 to 6610 ng/g wet weight, with a median of 440. These levels were generally higher than those observed in European peregrine eggs, but comparable to those in North American seabird eggs. Congener patterns differed from such seabirds and were dominated by BDE-153, followed by BDE-99, -183, -209, -197, -207, -154, -100, and -196; with lesser contributions from BDE-47, -208, -203, -201, -206, -202, -138, and -119. Urban and rural falcon eggs contained similar total PBDE concentrations but different congener profiles. Urban eggs exhibited higher BDE-209 concentrations and greater percentages of other highly brominated congeners. BDE-209 was detectable in all eggs, with concentrations ranging from 1.4 to 420 ng/g wet weight Five octa- and three nona-brominated congeners were also frequently detected, some likely derived from the biodegradation of BDE-209. Temporal analyses indicated no significant changes in concentrations of total PBDEs, or most individual congeners, during the study period. An exception was BDE-209. It exhibited a significant increase, with a doubling time of 5 years. Current PBDE burdens may be insufficient to cause noticeable adverse effects at the population level, as the number of territorial pairs increased in the past decade. However, the high BDE-209 concentrations, short doubling time, and likely biodegradation observed in peregrine eggs from the northeastern U.S. may supportthe need for additional deca-BDE regulations.     

Deposition versus photochemical removal of PBDEs from Lake Superior air

Analysis of a sediment core collected from Siskiwit Lake, located on a remote island in Lake Superior, provides evidence that polybrominated diphenyl ethers (PBDEs) are removed effectively from the atmosphere via deposition processes during long-range transport. A mass balance model based on photochemical rate constants and data from atmospheric samples was created to understand the relative importance of various photochemical and deposition processes in removing PBDEs from the atmosphere. Photolysis rate constants were derived from UV absorption spectra of 25 PBDEs recorded in isooctane over the range of 280-350 nm at 298 K. Photolysis decays measured for BDE-3 and -7 in the gas phase were substantial compared to a well-defined chemical actinometer, indicating that their photolysis quantum yields are significant. Dibenzofuran production was observed when PBDE congeners containing ortho-bromines were photolyzed in helium. From estimates of removal rates of PBDEs from the lower troposphere, we find that wet and dry deposition accountfor >95% of the removal of BDE-209, while photolysis accounts for -90% of the removal of gas-phase congeners such as BDE-47. These results help explain the deposition patterns of PBDEs found in lake and river sediments and have important implications concerning the inclusion of photolysis as a fate process in multimedia models.     

Polybrominated diphenyl ethers in the sediments of the Great Lakes. 2. Lakes Michigan and Huron

Sediment cores were taken in 2002 in Lakes Michigan and Huron at six locations. A total of 75 samples were characterized, dated using 210Pb, and analyzed for 10 congeners of polybromodiphenyl ether (PBDE) including BDE209, as well as 39 congeners of polychlorinated biphenyls (PCBs). The concentrations of nine tri- through hepta-BDE congeners (Sigma9PBDE) in the surficial sediments range from 1.7 to 4 ng g(-1) for Lake Michigan and from 1.0 to 1.9 ng g(-1) for Lake Huron, on the basis of the dry sediment weight. The Sigma9PBDEs fluxes to the sediment around the year 2002 are from 36 to 109 pg cm(-2) yr(-1) in Lake Michigan and from 30 to 73 pg cm(-2) yr(-1) in Lake Huron, with spatial variations in both lakes. The flux of BDE209 ranges from 0.64 to 2.04 ng cm(-2) yr(-1) and from 0.67 to 1.41 ng cm(-2) yr(-1) in Lake Michigan and Lake Huron, respectively. Dramatic increases in PBDE concentrations and fluxes upward toward the sediment surface and the present time are evident at all locations. The inventory of PBDEs in both lakes appears to be dependent upon latitude and the proximity to populated areas, implying that north-bound air plumes from urban areas are the major sources of PBDEs found in the lake sediments at locations away from the shores. Heavier congeners are more abundant in the sediments than in air and fish samples in the region. BDE209 is about 96% and 91% of the total PBDEs on a mass basis in Lake Michigan and Lake Huron, respectively; both are higher than the 89% found in Lake Superior, although a t test shows that the value for Lake Huron is not statistically different from that for Lake Superior at the 95% confidence level.     

Antarctic research bases: local sources of polybrominated diphenyl ether (PBDE) flame retardants

Contemporary studies of chemical contamination in Antarctica commonly focus on remnants of historical local releases or long-range transport of legacy pollutants. To protect the continent's pristine status, the Antarctic Treaty's Protocol on Environmental Protection prohibits importation of persistent organic pollutants. However, some polybrominated diphenyl ether (PBDE) congeners exhibit similar properties. Many modern polymer-containing products, e.g., home/office furnishings and electronics, contain percent levels of flame retardant PBDEs. PBDE concentrations in indoor dust and wastewater sludge from the U.S. McMurdo and New Zealand-operated Scott Antarctic research bases were high. Levels tracked those in sludge and dust from their respective host countries. BDE-209, the major constituent in the commercial deca-PBDE product, was the dominant congener in sludge and dust, as well as aquatic sediments collected near the McMurdo wastewater outfall. The pattern and level of BDE-209 sediment concentrations, in conjunction with its limited environmental mobility, suggest inputs from local sources. PBDE concentrations in fish and invertebrates near the McMurdo outfall rivaled those in urbanized areas of North America and generally decreased with distance. The data indicate that reliance on wastewater maceration alone, as stipulated by the Protocol, may permit entry of substantial amounts of PBDEs and other chemicals to the Antarctic environment.     

Polybrominated diphenyl ethers in the sediments of the Great Lakes. 1. Lake Superior

Sediment cores were taken in 2001 and 2002 in Lake Superior at six locations away from lakeshores and segmented at 0.5-5 cm intervals. The year of sediment deposition was estimated for each segment of four cores using the 210Pb dating technique. Samples were Soxhlet-extracted and cleaned up by silica gel fractionation, and the concentrations of 10 polybrominated diphenyl ethers (PBDEs) and 19 polychlorinated biphenyls (PCBs) were measured by GC-MS in SIM mode. In contrast to recent declining or level-off trends in PCB fluxes, the sedimentary records of PBDEs generally show a significant increase in recent years. The load of total PBDEs to Lake Superior was estimated to be 2-6 metric tons, and the current loading rate was about 80-160 kg yr(-1). With the exclusion of decabromodiphenyl ether (BDE209), the surficial concentration of sumPBDE (sum of 9 congeners) ranged from 0.5 to 3 ng g(-1), and the current sumPBDEs flux was 8-31 pg cm(-2) yr(-1). The concentrations of BDE209 were about an order of magnitude higher than the sum of other congeners, comprising 83-94% of the total PBDE inventory in the sediments. Among the other nine PBDEs detected, congeners 47 and 99 were the most abundant, and congeners 100, 153, 154, and 183 were also detected in all the cores. Congener analysis demonstrated that the pattern of PBDEs in Lake Superior sediments differs from those in air and fish.     

Evidence of debromination of decabromodiphenyl ether (BDE-209) in biota from a wastewater receiving stream

Decabromodiphenyl ether (BDE-209) is a high production volume flame retardant. To date, regulation and control of its environmental release have been minimal. Once in the environment, BDE-209 may encounter conditions favoring debromination, potentially forming congeners with greater toxicity, bioaccumulation potential, and persistence. However, (photolytic and in vivo) debromination has only been demonstrated under laboratory scenarios. To examine whether debromination was likely in the field, PBDE congener profiles were tracked from a wastewater treatment plant (sludge) to receiving stream sediments and associated aquatic biota. BDE-209 and 23 additional PBDEs were detected. Sludge congener profiles resembled the commercial penta- and deca- formulations, suggesting minimal -209 debromination during wastewater treatment. Similar profiles were observed in surficial sediments at the outfall and downstream. However, sunfish (Lepomis gibbosus), creek chub (Semotilus atromaculatus), and crayfish (Cambarus puncticambarus sp. c) collected near the outfall contained tri- through deca-PBDEs, including congeners not detected in the commercial deca-mixture, sludges or sediments (BDE-179, -184, -188, -201, and -202). A previous in vivo laboratory study identified these as -209 debromination products. This supports the hypothesis that metabolic debromination of -209 does occur in the aquatic environment under realistic conditions. Hence assessments that assume no BDE-209 debromination may underestimate associated bioaccumulation and toxicity attributable to the less brominated congeners produced.     

Air-water exchange and dry deposition of polybrominated diphenyl ethers at a coastal site in Izmir Bay, Turkey

The air-water exchange of polybrominated diphenyl ethers (PBDEs), an emerging class of persistent organic pollutants (POPs), was investigated using paired air-water samples (n = 15) collected in July and December, 2005 from Guzelyali Port in Izmir Bay, Turkey. Total dissolved-phase water concentrations of PBDEs (sigma7PBDEs) were 212 +/- 65 and 87 +/- 57 pg L(-1) (average +/- SD) in summer and winter, respectively. BDE-209 was the most abundant congener in all samples, followed by BDE-99 and -47. Average ambient gas-phase sigma7PBDE concentrations were between 189 +/- 61 (summer) and 76 +/- 65 pg m(-3) (winter). Net air-water exchange fluxes ranged from -0.9 +/- 1.0 (BDE-28) (volatilization) to 11.1 +/- 5.4 (BDE-209) ng m(-2) day(-1) (deposition). The BDE-28 fluxes were mainly volatilization while the other congeners were deposited. Gas- and dissolved-phase concentrations were significantly correlated (P = 0.33-0.55, p < 0.05, except for BDE-209, r = 0.05, p > 0.05) indicating thatthe atmosphere controls the surface water PBDE levels in this coastal environment. Estimated particulate dry deposition fluxes ranged between 2.7 +/- 1.9 (BDE-154) and 116 +/- 84 ng m(-2) day(-1) (BDE-209) indicating that dry deposition is also a significant input to surface waters in the study area.     

Polybrominated diphenyl ethers in the sediments of the Great Lakes. 3. Lakes Ontario and Erie

Sediment cores were taken in 2002 in Lakes Ontario and Erie at four locations. A total of 48 sediment samples were characterized, dated using 210Pb, and analyzed for 10 congeners of polybrominated diphenyl ethers (PBDEs) including BDE209 as well as 39 congeners of polychlorinated biphenyls (PCBs). The surficial concentrations of nine tri- through hepta-BDE congeners (sigma9PBDE) are 4.85 and 6.33 ng g(-1), at sampling sites ON40 and ON30 in Lake Ontario, and 1.83 and 1.95 ng g(-1) at ER37 and ER09 in Lake Erie, respectively, based on dry sediment weight. The surficial BDE209 concentrations are 242 and 211 ng g(-1) at ON40 and ON30 and 50 and 55 ng g(-1) at ER37 and ER09. The sigma(9-) PBDEs fluxes to the sediment around 2002 are 147 and 195 pg cm(-2) year(-1) at ON40 and ON30 and 136 and 314 pg cm(-2) year(-1) at ER37 and ER09, respectively. The fluxes of BDE209 are 6.5 and 7.3 ng cm(-2) year(-1) at ON30 and ON40 and 3.7 and 8.9 ng cm(-2) year(-1) at ER37 and ER09, respectively. Dramatic increases in PBDE concentrations and fluxes upward toward the sediment surface and the present time are evident at both locations in Lake Ontario, while PCBs concentrations peak in the middle of sediment cores around the dated time of 1970s and 1960s. For both locations of Lake Erie, the increasing trends of both PBDEs and PCBs from the bottom to the surficial segments were distorted by sediment mixing. BDE209 is the most abundant congener among PBDEs in the sediments, constituting about 96 and 91% of the total PBDEs on mass basis in Lakes Ontario and Erie, respectively.     

Bioaccumulation and metabolism of polybrominated diphenyl ethers in carp (Cyprinus carpio) in a water/sediment microcosm: important role of particulate matter exposure

Microcosms were built up to simulate a pond system with polybrominated diphenyl ether (PBDE) contaminated sediment and bioorganisms. The microcosms were divided into groups A and B. In group A, both benthic invertebrates (tubificid worms) and carp (Cyprinu carpio) were added, while in group B, only fish were added. After exposure for 20 d, the fish were sampled (exposure I). A net was fixed in the microcosms, and new fish were added (exposure II). These fish were prohibited from contacting the sediment by the net, and the accumulation and depuration of PBDEs in the fish were investigated. Among 11 monitored PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, BDE-183, BDE-206, BDE-207, BDE-208, and BDE-209), only 5 congeners (BDE-28, BDE-47, BDE-100, BDE-153, and BDE-154) were detected in the carp fillets and liver. BDE-99 and BDE-183 were not detected in the fish because of the efficient metabolic debromination in carp tissues. The uptake of PBDEs in exposure I was significantly higher/faster than that in exposure II, since the fish in exposure I had an opportunity to take in more of the highly contaminated particles. The uptake kinetics (k(s)) and elimination (k(e)) rate coefficients showed a general trend of decreasing with increasing log K(ow). No significant difference was observed in uptake/depuration kinetics between groups A and B, indicating that the tubificids' reworking does not affect the bioaccumulation of sediment-associated PBDEs in fish significantly. All the PBDE congeners, including nona- and deca-BDEs, were bioaccumulated in the tubificid worms. The PBDE concentrations in the worms were significantly higher than those in the fish, and the congener profile of the sevem major congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) was distinctly different from that of fish tissues. The biota-sediment accumulation factors in the worms ranged from 0.01 to 5.89 and declined with increasing bromination and log K(ow.).     

Levels and distribution of polybrominated diphenyl ethers in water, surface sediments, and bivalves from the San Francisco Estuary

Polybrominated diphenyl ethers (PBDEs) were found in water, surface sediments, and bivalve samples that were collected from the San Francisco Estuary in 2002. sigmaPBDE concentrations in water samples ranged from 3 to 513 pg/ L, with the highest concentrations found in the Lower South Bay (range 103-513 pg/L) region, which receives approximately 26% of the Estuary's wastewater treatment plant effluents. The sigmaPBDEs in sediments ranged from below detection limits to 212 ng/g dry wt, with the highest concentration found at a South Bay station (212 ng/g dry wt), which was up to 3 orders of magnitude higher than other stations. The sigmaPBDE concentrations ranged from 9 to 64 ng/g dry wt in oysters (Crassostrea gigas), from 13 to 47 ng/g dry wt in mussels (Mytilus californianus), and from 85 to 106 ng/g dry wt in clams (Corbicula fluminea). Only three PBDE congeners were detected in bivalves, BDE-47, BDE-99, and BOE-100; these are the most bioaccumulative congeners from the commercial Penta-BDE mixture.     

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.     

Indoor air is a significant source of tri-decabrominated diphenyl ethers to outdoor air via ventilation systems

Ventilation of indoor air has been hypothesized to be a source of PBDEs to outdoors. To study this, tri-decabrominated diphenyl ethers were analyzed in outgoing air samples collected inside ventilation systems just before exiting 33 buildings and compared to indoor air samples from microenvironments in each building collected simultaneously. Median ∑(10)PBDE (BDE- 28, -47, -99, -153, -183, -197, -206, -207, -208, -209) concentrations in air from apartment, office and day care center buildings were 93, 3700, and 660 pg/m(3) for outgoing air, and 92, 4700, and 1200 pg/m(3) for indoor air, respectively. BDE-209 was the major congener found. No statistically significant differences were seen for individual PBDE concentrations in matched indoor and outgoing air samples, indicating that outgoing air PBDE concentrations are equivalent to indoor air concentrations. PBDE concentrations in indoor and outgoing air were higher than published outdoor air values suggesting ventilation as a conduit of PBDEs, including BDE-209, from indoors to outdoors. BDE-209 and sum of BDE-28, -47, -99, and -153 emissions from indoor air to outdoors were roughly estimated to represent close to 90% of total emissions to outdoor air for Sweden, indicating that contaminated indoor air is an important source of PBDE contamination to outdoor air.     

High postnatal exposures to polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) via breast milk in California: does BDE-209 transfer to breast milk?

Breast milk samples collected during 2003-2005 from 82 first-time mothers in 24 communities located throughout California contained levels of polybrominated diphenyl ethers (∑(tri-hexa (8))PBDEs; median = 53.3 ng/g lw, range = 9.60-1291) and polychlorinated biphenyls (∑(12)PCBs; median = 73.4 ng/g lw, range = 22.2-433) that are among the highest in the world. PBDE levels varied 100-fold. BDE-47 was the dominant PBDE congener, with levels exceeding the U.S.EPA Reference Dose (RfD) for neurodevelopmental toxicity (100 ng/kg/day) in most (60%) breast milk samples. In some samples, BDE-209 (2/82) and/or BDE-153 (5/82) were the dominant congeners, suggesting that BDE-209 can transfer to breast milk and/or break down in the mother and transfer to the nursing infant as the lower-brominated PBDEs associated with adverse effects. PBDE levels in California breast milk are approaching those of PCBs, and the trend PBDEs > PCBs may continue as PBDEs migrate from products to the indoor and outdoor environments.     

Effects of deBDE and PCB-126 on hepatic concentrations of PBDEs and methoxy-PBDEs in Atlantic tomcod

The biotransformation of high bromosubstituted polybrominated diphenyl ethers (PBDEs) congeners contained in a commercial deca mixture (DeBDE) is of environmental concern because it might lead to the increase of toxic low brominated PBDEs in biota. A few studies have reported that freshwater fish dietary exposed to DeBDE or its main constituent, decabrominated PBDE congener (BDE-209), had their tissues enriched with PBDEs not initially present in fish or feed. In the present study, Atlantic tomcod (Microgadus tomcod) were intraperitoneally (IP) injected with DeBDE to assess hepatic concentration changes of PBDEs and methoxy polybrominated diphenyl ethers (MeO-PBDEs) in a marine fish species. Tomcod were also IP injected with polychlorinated biphenyl (PCB)-126 to evaluate the impact of cytochrome P4501A (CYP1A) induction on the biotransformation of injected PBDEs contained in DeBDE and PBDEs initially present in fish. Besides BDE-209, concentrations of BDE-203 and three other unidentified octabrominated PBDEs and the nonabrominated PBDEs (BDE-206, -207, and -208) were enriched in the liver of fish injected with DeBDE. All these PBDE congeners, essentially absent in control fish, were identified as impurities in DeBDE, and, thus, their presence could not be attributed exclusivelyto biotransformation. Despite a 4.3times increase of EROD activity in the liver of tomcod injected with both PCB-126 and DeBDE, compared to DeBDE alone, no further increases of PBDE hepatic concentrations were observed. However, depleted concentrations of BDE-17 (x 1.5) and 6-MeO-BDE-47 (x 1.4) were found in fish IP injected with DeBDE compared to control fish, likely due to activated hepatic metabolic enzymes other than CYP1A. Fish injected with PCB-126 showed an even more significant depletion of BDE-17 hepatic concentrations (x 3.5) than the one associated with the DeBDE treatment and a significantly lower proportion of fish with quantifiable concentrations of BDE-203. Thus, CYP1A inducers can promote the biotransformation of PBDEs in fish liver. This study shows that exposure of fish to DeBDE is expected to result in the enrichment of high brominated PBDEs in fish liver and that metabolic activities in fish can affect their PBDE bioaccumulation pattern and possibly the toxicity of PBDEs to fish.