Residues of polybrominated diphenyl ethers in frogs (Rana limnocharis) from a contaminated site, South China: tissue distribution, biomagnification, and maternal transfer

Polybrominated diphenyl ether accumulation in an agricultural soil ecosystem receiving wastewater sludge amendments

Few studies have addressed bioaccumulation of organic pollutants associated with land-application of biosolids. We thus examined PBDE burdens within a soil ecosystem receiving long-term sludge amendments and a reference soil ecosystem receiving only manure inputs. No PBDEs were detected in reference site samples, but sludge-amended soils contained 17 600 ± 2330 μg/kg ∑3-7PBDE (total organic carbon (TOC) basis). ∑3-7PBDE burdens were highest in soil invertebrates with the greatest contact with sludge-amended soil (e.g., ∑3-7PBDE of 10 300 ± 2670 and 3000 ± 200 μg/kg lipid for earthworms and detritivorous woodlice, respectively). PBDEs were below quantitation limits in vegetation from the sludge-amended site. Surprisingly, we measured quantifiable PBDE burdens in only a single sample of predaceous ground spiders from the sludge-amended site. BDE-209 burdens in sludge-amended soil and earthworms were 7500 ± 2800 μg/kg TOC and 6500 ± 4100 μg/kg lipid, respectively. BDE 209 was detected in fewer taxa, but the burden in a detritivorous millipede composite was high (86 000 μg/kg lipid). PBDE congener patterns differed among species, with worms and ground beetles exhibiting Penta-BDE-like patterns. Penta-BDE biota-soil accumulation factors (BSAFs) ranged from 0.006 to 1.2, while BDE-209 BSAFs ranged from 0.07 to 10.5. δ(13)C and δ(15)N isotope signatures were poorly correlated with PBDE burdens, but sludge-amended samples were significantly δ(15)N enriched.

Endocrine disruption and reproduction impairment in zebrafish after long-term exposure to DE-71

The objective of the present study was to investigate the impact of polybrominated diphenyl ethers (PBDEs) on fish reproduction over 2 generations. Zebrafish (Danio rerio) embryos (F0) were exposed to low concentrations (3 µg/L, 10 µg/L, and 30 µg/L) of the PBDE mixture DE-71 until they were sexually mature, and steroid hormone production, expression of genes involved in steroidogenesis, gonadal development, and gamete characteristics were examined. Exposure of female zebrafish to DE-71 resulted in lower estradiol production and downregulation of cytochrome P450 aromatase mRNA. In males, exposure to DE-71 resulted in greater testosterone production and greater cytochrome P450 c17 α-hydroxylase,17,20-lase mRNA expression. Moreover, hepatic vitellogenin mRNA and estrogenic receptor β gene transcription were downregulated in females and males. Expression of the follicle-stimulating hormone β gene in the pituitary was upregulated, and the expression of luteinizing hormone β was downregulated in both sexes. Histological examination showed inhibition of oocyte maturation in females and retarded spermiation in males. The average number of eggs (F1) produced was also reduced. Additionally, exposure of F0 embryos to DE-71 did not result in developmental toxicity, whereas delayed hatching, reduced survival, and decreased growth were observed in the F1 embryos derived from parent fish exposed to DE-71. Therefore, long-term exposure to low concentrations of PBDEs in zebrafish could cause reproductive impairment, suggesting that PBDEs might have significant adverse effects on fish population in the highly PBDEs-contaminated aquatic environment.

Polybrominated diphenyl ethers in residential and agricultural soils from an electronic waste polluted region in South China: distribution, compositional profile, and sources

A detailed investigation was conducted to understand the concentration, distribution, profile and possible source of polybrominated diphenyl ethers (PBDEs) in residential and agricultural soils from Guiyu, Shantou, China, one of the largest electronic waste (e-waste) recycling and dismantling areas in the world. Ten PBDEs were analyzed in 46 surface soil samples in terms of individual and total concentrations, together with soil organic matter concentrations. Much higher concentrations of the total PBDEs were predicted in the residential areas (more than 2000 ng g(-1)), exhibiting a clear urban source, while in the agricultural areas, concentrations were lower than 1500 ng g(-1). PBDE-209 was the most dominant congener among the study sites, indicating the prevalence of commercial deca-PBDE. However signature congeners from commercial octa-PBDE were also found. The total PBDE concentrations were significantly correlated with each individual PBDE. Principal component analysis indicated that PBDEs were mainly distributed in three groups according to the number of bromine atoms on the phenyl rings, and potential source. This study showed that the informal e-waste recycling has already introduced PBDEs into surrounding areas as pollutant which thus warrants an urgent investigation into the transport of PBDEs in the soil-plant system of agricultural areas.

Bioavailability and tissue distribution of Dechloranes in wild frogs (Rana limnocharis) from an e-waste recycling area in Southeast China

Dechlorane Plus (DP), a flame retardant used as an alternative to decabromodiphenylether, has been frequently detected in organisms, indicating its bioaccumulation and biomagnification potential in aquatic and terrestrial species. However, little data is available on the bioaccumulation of DP in amphibians. Dechlorane Plus and its analogs (DPs) were detected in the liver, muscle and brain tissues of wild frogs (Rana limnocharis), which were collected from an e-waste recycling site, Southeast China. DP, Mirex, Dec 602 and a dechlorinated compound of DP (anti-Cl11-DP) varied in the range of 2.01-291, 0.650-179, 0.260-12.4, and not detected (nd)-8.67 ng/g lipid weight, respectively. No difference of tissue distribution was found for syn-DP, Mirex and Dec 602 between the liver and muscle tissue (liver/muscle concentration ratio close to 1, p > 0.05). However, higher retention was observed for anti-DP and anti-Cl11-DP in the frog muscle relative to the liver tissue (liver/muscle concentration ratio < 1, p < 0.05). Additionally, the blood-brain barrier was found to work efficiently to suppress these compounds entering brain tissues in this species (liver/brain concentration ratio > 1, p < 0.05), and the molecular weight was a key factor impacting the extent of the blood-brain barrier. Compared to levels in the muscle and brain tissue, a preferential enrichment of syn-DP was observed in the liver tissue, suggesting the occurrence of stereo-selective bioaccumulation in the wild frog.

A review of environmental and human exposure to persistent organic pollutants in the Pearl River Delta, South China

Rapid economic growth in South China (including Guangdong Province, Hong Kong, and Macau), particularly within the Pearl River Delta region, has resulted in severe pollution of the natural eco-environment in the last three decades. Large amounts of monitoring data on organic pollution in the Pearl River Delta have been accumulated, which allows us to conduct a fairly comprehensive assessment of the state of the Pearl River Delta and elucidate spatial and temporal patterns of pollution on a regional scale. Of various causes for environmental deterioration, negative impact from persistent organic pollutants (POPs) is a global concern. This review examines the current levels and distribution patterns of several POPs, namely DDT (and its metabolites DDD and DDE), hexachlorocyclohexanes, and polybrominated diphenyl ethers, in various environmental compartments of South China. The general information on environmental occurrence, regional behaviors, ecological effects, and human exposure of these POPs in this region are reviewed.

Residues, sources and tissue distributions of organochlorine pesticides in dog sharks (Mustelus griseus) from Zhoushan Fishing Ground, China

Ten dog sharks (Mustelus griseus) collected from Zhoushan Fishing Ground, China, were analysed for organochlorine pesticides in various tissues, including muscle, liver, skin, gill and fin, with the aim to study the residues, sources and tissue distributions of these chemicals in high trophic level marine fishes. The concentrations of DDTs, HCHs, and chlordanes varied from 7.27-26.62, 2.67-3.35, and 0.54-0.61 ng/g wet weight, respectively, with the estimated daily intake far below the acceptable daily intake and Chinese edible hygienic criteria. Data from the tissue distribution suggested a tendency of DDTs and chlordanes to accumulate in the liver, but for HCHs, direct gill penetration may be an important means of entrance. In addition, the compositional profiles indicated that the residues of HCHs and chlordanes mainly originated from the historical usage of these chemicals. However, the predominant maternal compounds and the o,p'-DDT/p,p'-DDT ratios reflected a recent use of dicofol.

Occurrence of polybrominated diphenyl ethers (PBDEs) and 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) in water samples from the Diep River, Cape Town, South Africa

Until recently, studies reporting the concentrations of polybrominated diphenyl ethers (PBDEs) as well as polybrominated biphenyls (PBBs) are generally scarce in the literature. Consequently, this study was aimed to investigate the occurrence and concentrations of certain PBDE congeners (BDE 28, 47, 100, 99, 154, 153, 183 and 209) and BB 153 in river water samples collected bi-monthly from the Diep River. The routine analyses of the target compounds were performed using a high-capillary GC-microelectron capture detection, while their structural elucidation was assessed using GC-TOF-MS technique. The overall mean concentrations of the sum of the eight PBDE congeners were 2.60, 4.83 and 4.29 ng/L for the upstream, point of discharge and downstream sampling points, respectively. Similarly, the overall mean concentrations of BB 153 were 0.25, 4.85 and 1.56 ng/L for the upstream, point of discharge and downstream sampling points, respectively. BDE 47 was the dominant congener found in these samples contributing between 19 and 26 % to the total PBDEs across the sampling points. The statistical analyses performed on the results obtained showed that all the congeners, except BDE 209 in certain instances, had strong positive correlations with one another, thus suggesting that these contaminants could be emanating from the same source. In this study, potential sources of these pollutants other than WWTP discharges into the investigated river were also identified. However, the relatively high concentrations of the target compounds found at the point of discharge sampling point coupled with the large volume of treated effluent being discharged suggested that the contributions from this source could be very significant over time.

Toxicokinetics of polybrominated diphenyl ethers across life stages in the northern leopard frog (Lithobates pipiens)

Polybrominated diphenyl ethers (PBDEs), a class of flame retardants, are bioaccumulative toxins that can biomagnify in food webs. However, little is known about the toxicokinetics of total and congener-specific BDEs in lower vertebrates. The authors exposed northern leopard frog (Lithobates (Rana) pipiens) tadpoles to diets containing DE-71 (a pentabromodiphenyl ether mixture (0 ng/g as control, 71.4 ng/g, and 634 DE-71 ng/g wet mass)) for 50 d, followed by a period of depuration during which they were fed only undosed (control) food. After 28 d, tadpoles eliminated over 94% of the ΣPBDEs from their tissues (t½  = 5.9 ± 1.9 d) with no significant differences in elimination rates for the predominant congeners. Elimination of BDE-99 was independent of dose, indicating first-order kinetics. It did not fit a biexponential model significantly better than a monoexponential model, indicating single-compartment elimination. To compare developmental life-stage kinetics following larval exposure, the authors collected individuals at the beginning and end of metamorphosis and at 70 d postmetamorphosis. During metamorphosis, total-body residues per individual did not significantly change, implying little to no elimination. After 70 d, juvenile frogs eliminated 89.7% of the ΣPBDEs from their tissues, and BDE-47 was eliminated at a faster rate (t½ = 17.3 d) than BDE-99 and BDE-100 (t½  = 63.0 d and 69.3 d, respectively). Because the kinetics of PBDEs in L. pipiens differed among life stages, developmental life stage-especially for species that undergo metamorphosis-should be considered when determining the toxicity of persistent organic pollutants.

Sex-dependent accumulation and maternal transfer of Dechlorane Plus flame retardant in fish from an electronic waste recycling site in South China

Knowledge is limited on sex-related accumulation and maternal transfer of Dechlorane Plus (DP) flame retardant in wildlife. In the present study, DP isomers were examined in liver and eggs of two fish species, northern snakehead and crucian carp, from an electronic waste recycling site in China. Hepatic ∑DP (sum of syn- and anti-DP) concentrations ranged 260-1920 ng/g lipid in northern snakehead and 340-1670 ng/g in crucian carp, with significantly higher levels in males relative to females. ∑DP concentrations ranged 4.6-310 ng/g lipid in the eggs, demonstrating their maternal transfer in the female fish. The mean eggs to liver concentration ratios (E/L ratios) were 0.03 and 0.03 in northern snakehead, and 0.26 and 0.25 in crucian carp, for syn- and anti-DP, respectively. A significantly negative correlation between the E/L ratios and the hepatic DP concentrations was observed, indicating a dose-dependent maternal transfer of DP isomers in the fish.

Maternal transfer of contaminants and reduced reproductive success of southern toads ( Bufo [Anaxyrus] terrestris ) exposed to coal combustion waste

Bioaccumulation of contaminants and subsequent maternal transfer to offspring are important factors that affect the reproductive success of wildlife. However, maternal transfer of contaminants has rarely been investigated in amphibians. We examined maternal transfer of trace elements in southern toads ( Bufo[Anaxyrus] terrestris) residing in two locations: (1) an active coal combustion waste (CCW) disposal basin and adjacent 40-ha floodplain contaminated with CCW over 35 years ago and (2) an uncontaminated reference site. Our study is among the few to document tissue concentration-dependent maternal transfer of contaminants and associated adverse effects in amphibians. We found that females collected from the CCW-contaminated area had elevated concentrations of Ni, Se, and Sr; these females also transferred elevated levels of Cu, Pb, Se, and Sr to their eggs compared to females from the reference site. Overall reproductive success, estimated as a function of clutch size and offspring viability, was reduced by 27% in clutches collected from parents from the contaminated site compared to the reference site. Offspring viability negatively correlated with female and/or egg concentrations of Se and Ni. Reproductive success negatively correlated with Se and Cu concentrations in females, and Se concentrations in eggs. Our study highlights how exposure to CCW can negatively affect amphibian reproduction.

Tissue concentrations, bioaccumulation, and biomagnification of synthetic musks in freshwater fish from Taihu Lake, China

Synthetic musks are ubiquitous pollutants in aquatic environments. As hydrophobic chemicals, they can accumulate in terrestrial and aquatic organisms. Investigations into the bioaccumulation of these chemicals in aquatic ecosystem have, however, been limited, and previous results were inconsistent among species and ecosystem. Studies on this topic have been carried out in European countries, the USA, and Japan, but very few are known of the situation in China. The aim of this study was to investigate contaminant levels of musks in fish from Taihu Lake, the second largest freshwater lake in China, as well as bioaccumulation and biomagnification of the pollutants in the freshwater food chain. Five polycyclic musks and two nitro musks were determined in 24 fish species and nine surface sediment samples from Taihu Lake. HHCB (1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta[γ]-2-benzopyran) and AHTN (7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene) were the predominant contaminants in the fish samples, with concentrations ranging from below the limit of detection (LOD) to 52.9 and from <LOD to 7.5 ng/g lipid weight, respectively. Other contaminants were at low detection frequencies. The results indicated low concentrations of musks yet widespread occurrence of these contaminants in fish from Taihu Lake. Species-specific and lipid-related bioaccumulation characteristics were suggested, but no significant region-specific differences were observed. Normalized biota-sediment accumulation factors for HHCB and AHTN were noted to increase with trophic levels in fish. Trophic magnification factors were estimated at 1.12 for HHCB and 0.74 for AHTN. A biomagnification for HHCB, and probably biodilution for AHTN, in the freshwater food chain are indicated, when trophic magnification factors were concerned. However, the correlations between logarithmic concentrations of the chemicals and trophic levels were not statistically significant. Further study using long food chains in this lake is still needed.

Hydroxylated and methoxylated polybrominated diphenyl ethers in blood plasma of humans in Hong Kong

Hydroxylated (OH-) and methoxylated (MeO-) polybrominated diphenyl ethers (PBDE) are suspected endocrine disruptors. Little is known about the accumulation or sources of these chemicals in tissues of humans, particularly those residing in Hong Kong, which is one of the most densely populated cities in the world. Seven MeO-BDEs, fifteen OH-BDEs and three bromophenols (BRPs) were analyzed in blood plasma of 116 humans that had been collected by the Hong Kong Red Cross. Total concentrations of MeO-BDEs, OH-BDEs and BRPs ranged from 3.8×10² to 52×10³ pg g⁻¹ lipid (median 4.5×10³ pg g⁻¹), 5.3 to 4.9×10² pg g⁻¹ lipid (81 pg g⁻¹) and ND to 1.1×10² pg g⁻¹ lipid (3.7 pg g⁻¹), respectively. 3-MeO-BDE-47, 6-OH-BDE-47 and 2, 4, 5-TBP were the predominant MeO-BDEs, OH-BDEs and BRPs, respectively. These results are consistent with accumulation of MeO-BDEs, OH-BDEs and BRPs in human plasma being primarily from natural products and inter-conversion of natural products. Coefficients of determination for some pairs of congeners such as 3-OH-BDE-100 and 6-OH-BDE-47, 6-OH-BDE-85 and 5'-OH-BDE-99, and 2, 4-DBP and 6-OH-BDE-85, were near 1.0, which is consistent with them having common sources. Patterns of relative concentrations of the target analytes were similar in the diet, particularly fish, as in blood plasma of humans, which suggests that the diet and particularly seafood might be a source of these compounds and PBDEs. Furthermore, biotransformation of natural chemicals such as OH-BDEs to BRPs might be the primary route of their elimination from humans.

Prenatal transfer of polybrominated diphenyl ethers (PBDEs) results in developmental neurotoxicity in zebrafish larvae

Parental exposure to polybrominated diphenyl ethers (PBDEs) in animals has been found to be transferred to the offspring. The environmental health risk and toxicity to the offspring are still unclear. The objective of the present study was to identify environmentally relevant concentrations of PBDEs for parental exposure that would cause developmental neurotoxicity in the offspring. Adult zebrafish were exposed to environmentally relevant concentrations of DE-71 (0.16, 0.8, 4.0 μg/L) via water. The results showed that PBDE exposure did not affect larvae hatching, malformation, or survival. The residue of PBDEs was detected in F1 eggs upon parental exposure. Acetylcholinesterase (AChE) activity was significantly inhibited in F1 larvae. Genes of central nervous system development (e.g., myelin basic protein, synapsin IIa, α1-tubulin) were significantly downregulated in larvae. Protein levels of α1-tubulin and synapsin IIa were also reduced. Decreased locomotion activity was observed in the larvae. This study provides the first evidence that parental exposure to environmentally relevant concentrations of PBDEs could cause adverse effects on neurodevelopment in zebrafish offspring.

Occurrence of (anti)estrogenic effects in surface sediment from an e-waste disassembly region in East China

Because of the report on the abnormal local fertility rate at Taizhou area, which is a famous e-waste disassembly center in China, the hormone-like effects in the surface sediment from the local river was investigated. Compared to the control site DG, significant estrogenic effects (p < 0.01) were observed at e-waste recycling sites ranging from 6.01 to 29.31 nmol/kg dw E2 equivalents by water extraction while ranging from 20.47 to 135.02 nmol/kg dw by organic extraction. When coincubated with E2, the water and the organic extractions displayed significant (p < 0.01) synergistic and anti-estrogenic effects respectively.

DDTs in rice frogs (Rana limnocharis) from an agricultural site, South China: tissue distribution, biomagnification, and potential toxic effects assessment

Contamination with agricultural pesticides such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), is among several proposed stressors contributing to the global declines in amphibian populations and species biodiversity. These chemicals were examined in insects and in the muscle, liver, and eggs of rice frogs (Rana limnocharis) from the paddy fields of an agricultural site in South China. The ΣDDT (sum of DDT, DDE, and DDD) concentrations ranged from 154 to 915, 195 to 1,400, and 165 to 1,930 ng/g lipid weight in the muscle, liver, and eggs, respectively. All the DDTs (DDT, DDE, and DDD) showed higher affinity for the liver relative to muscle tissue and can be maternally transferred to eggs in female frogs. The average biomagnification factors for DDTs ranged from 1.6 to 1.9 and 1.5 to 2.9 in female and male frogs, respectively, providing clear evidence of their biomagnification from insects to frogs. Compared with the reported DDT levels demonstrated to have toxic effects on frogs, DDTs in the present frogs are unlikely to constitute an immediate health risk. However, the adverse impacts of high DDT residues in eggs on the hatching success and their potential toxicity to the newly metamorphosed larval frogs should be assessed further.

Polybrominated diphenyl ethers and polychlorinated biphenyls in freshwater fish from Taihu Lake, China: their levels and the factors that influence biomagnification

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs), two types of persistent organic pollutants that have been used widely, can be released into the environment and accumulate in organisms. To obtain a better understanding of the biomagnification of PBDEs and PCBs in fish, as well as the influences on biomagnification by fish size and physical properties of PBDEs and PCBs, a total of 200 samples of 24 fish species were collected and analyzed from Taihu Lake, the second largest freshwater lake in China. The concentrations of PBDEs and PCBs ranged from 8.59 to 74.28 ng/g lipid weight (lw) and from 10.30 to 165.20 ng/g lw, respectively. Trophic magnification factors (TMFs) were used to estimate the PBDE and PCB biomagnification potentials. The TMF values of PBDEs and PCBs ranged from 0.78 to 2.95 and from 0.92 to 2.60, respectively. Most of the TMFs were greater than 1, indicating that these contaminants were biomagnified in food chains. Fish size might influence the biomagnification evaluation, because different sized fish had different lipid content, leading to different lipid-based concentrations of PBDEs and PCBs. Parabolic relationships were observed between the TMFs and logK(OW) , as well as between the TMFs and the molecular volumes of PBDE and PCB congeners. The congeners with logK(OW) values of approximately 7 or molecular volumes of approximately 8 × 10⁻⁵  nm³ had the greatest biomagnification potentials. Compared to molecular weight, molecular volume seems to be the better standard for analyzing the influence of molecular size on biomagnification.

Toxicokinetic of benzo[a]pyrene and fipronil in female green frogs (Pelophylax kl. esculentus)

A general consensus that an increased logK(ow) led to an increase in xenobiotic uptake and bioaccumulation is accepted. In this study we compared the toxicokinetics of two chemically different xenobiotics, i.e. benzo[a]pyrene and fipronil in female green frogs. Surprisingly, the uptake rates and the bioconcentration factors (BCF) of the two contaminants were not predicted by their logK(ow). The uptake rates obtained were of the same order of magnitude for the two contaminants and the BCFs measured for fipronil were about 3-fold higher than those obtained for benzo[a]pyrene. Fipronil appeared to be more recalcitrant than benzo[a]pyrene to detoxification processes leading to the accumulation of sulfone-fipronil especially in the ovaries. This phenomenon may explain reproductive influence of this contaminant described in other studies. Detoxification processes, including metabolism and the excretion of pollutants, are of importance when considering their persistence in aquatic organisms and trying to quantify their risks.

Effects of chronic polybrominated diphenyl ether exposure on gonadal development in the northern leopard frog, Rana pipiens

Polybrominated diphenyl ethers (PBDEs) are bioaccumulative, persistent organic pollutants used as flame retardants in consumer goods. Concentrations of PBDEs in North American wildlife have been increasing for decades and been shown to have estrogenic effects on sexual development. No studies, however, have examined the effects of PBDEs on the sexual development of North American frogs at ecologically relevant concentrations. This study examined the effects of five dietary concentrations of DE-71 (0, 1.1, 6.1, 71.4, and 634 ng ΣPBDEs/g diet), a technical PBDE mixture, on the gonadal development of the northern leopard frog, Rana pipiens. Tadpoles were exposed chronically from the time they became free-swimming until metamorphosis. Frogs were killed either at metamorphic climax or 10 weeks after completing metamorphosis, processed for histology, and examined for alterations in sexual development. The experimental group exposed to PBDEs at 1.1 ng/g had a significantly larger proportion of females compared with the expected 50:50 sex ratio. At 10 weeks post-metamorphosis, male frogs exposed to 6.1 and 71.4 ng/g had significantly smaller testes, but all other measure of gonadal development tested showed no effects. No intersex or increased incidence of gonadal abnormality were detected. These findings indicate that PBDEs may disrupt sexual differentiation in frogs at low, environmentally relevant concentrations.

House crickets can accumulate polybrominated diphenyl ethers (PBDEs) directly from polyurethane foam common in consumer products

Polybrominated diphenyl ether (PBDE) flame retardants are added at percent levels to many polymers and textiles abundant in human spaces and vehicles, wherein they have been long assumed to be tightly sequestered. However, the mgkg(-1) burdens recently detected in indoor dust testify to substantial releases. The bulk of released PBDEs remain in the terrestrial environment, yet comparatively little research focuses on this compartment. There, insects/arthropods, such as crickets, are the most abundant invertebrate organisms and facilitate the trophic transfer of contaminants by breaking down complex organic matter (including discarded polymers) and serving as food for other organisms. Our experiments revealed that house crickets (Acheta domesticus) provided uncontaminated food and free access to PUF containing Penta-BDE (8.7%drywt) for 28 d accumulated substantial PBDE body burdens. Crickets allowed to depurate gut contents exhibited whole body burdens of up to 13.4 mg kg(-1) lipid ΣPenta-BDE, 1000-fold higher than typically reported in humans. Non-depurated crickets and molted exoskeletons incurred even higher ΣPenta-BDE, up to 80.6 and 63.3 mg kg(-1) lipid, respectively. Congener patterns of whole crickets and molts resembled those of PUF and the commercial Penta-BDE formulation, DE-71, indicative of minimal discrimination or biotransformation. Accumulation factor (AF) calculations were hampered by uncertainties in determining actual PUF ingestion. However, estimated AFs were low, in the range of 10(-4)-10(-3), suggesting that polymer-PBDE interactions limited uptake. Nonetheless, results indicate that substantial PBDE burdens may be incurred by insects in contact with current-use and derelict treated polymers within human spaces and solid waste disposal sites (e.g. landfills, automotive dumps, etc.). Once ingested, even burdens not absorbed across the gut wall may be dispersed within proximate terrestrial food webs via the insect's movements and/or predation.

A review of polybrominated diphenyl ethers and alternative brominated flame retardants in wildlife from China: levels, trends, and bioaccumulation characteristics

Accelerated industrialization and urbanization, and unregulated disposal of waste of electric and electronic equipment (e-waste) in China have caused environmental pollution of brominated flame retardants (BFRs). This review summarized the levels, trends, and bioaccumulation characteristics of polybrominated diphenyl ethers (PBDEs) and other potential alternative BFRs including hexabromocyclododecanes (HBCDs), 1,2-bis(2,4,6-dibromophenoxy) ethane (BTBPE) and decabromodiphenylethane (DBDPE) in wildlife from China. PBDE levels in wildlife from China were generally higher than those from other parts in Asia, and were comparable to those from Europe but were lower than those from North America. However, wildlife from the e-waste recycling sites in South China and East China contained much higher PBDEs compared to other reports around the world, suggesting the heavy contamination of PBDEs in these regions. The alternative BFRs were also detected in wildlife, revealing that the animals are exposed to these chemicals, in addition to PBDEs. Temporal trends indicated by levels in marine mammals from South China suggested that PBDE levels increased from the beginning of 1990s to 2000s, but decreased from the middle of 2000s, followed by relatively steady levels. In contrast, HBCDs were found to be continuously increasing from 1997 to 2007, indicating the increasing usage of HBCDs in China in recent years. Compared to PBDE profiles found in other parts, aquatic species and birds from China contained relatively higher contributions of BDE-28 and 209, respectively, suggesting the possible different usage pattern of PBDEs. Future works including keeping monitoring at a reasonable scale and frequency to make sure levels near urban centers indicative of population do not increase are needed. Additionally, focus effort on e-waste recycling regions to look for impacts and to determine if regulation/controls are resulting in lower environmental contamination, and incorporation of sentinel species in monitoring efforts are recommended.

Regional dynamics of persistent organic pollutants (POPs) in the Pearl River Delta, China: implications and perspectives

The mass transport budgets of 1,1,1-trichloro-2,2-bis(chlorophenyl)ethane (p,p'-DDT) and decabromodiphenyl ether (BDE-209) in the Pearl River Delta, South China were calculated based on previously collected data. Residual p,p'-DDT, mostly related to historical use, has largely settled into soil (780,000 kg), while the soil BDE-209 inventory (44,000 kg) is considerably smaller. Conversely, large amounts of BDE-209 currently used in numerous commercial products have resulted in a much higher atmospheric depositional flux of BDE-209 (28,100 kg/yr) relative to p,p'-DDT (310 kg/yr). The soil inventory of p,p'-DDT is predicted to decrease to half of its current value after 22 years, and the percent area containing soil p,p'-DDT at levels exceeding the effects range-medium (27 ng/g) will decrease from 40% to 20%. Finally, soil BDE-209 inventory will reach an equilibrium value of 940 tons in ~60 years, when BDE-209 levels in 50% of soil will be above an equivalent risk guideline value (125 ng/g).

Sorption of PBDE in low-density polyethylene film: implications for bioavailability of BDE-209

The coefficients of partitioning (K(pew) ) between low-density polyethylene (LDPE) film (50-µm thickness) and water for 23 polybrominated diphenyl ether (PBDE) congeners were determined based on a regression analysis of sorption kinetics over an extended exposure period (up to 365 d). A curvilinear relationship between log K(pew) and log K(OW) (octanol-water partition coefficient) was obtained for the target BDE congeners with the turning point at log K(OW) approximately 8. Previously obtained dietary uptake efficiencies of BDE congeners in common carp (Cyprinus carpio) were also found to relate curvilinearly to log K(OW) . In addition, field-measured relative abundances of BDE-209 compiled from previous investigations conducted in the Pearl River Delta of South China were significantly (p < 0.001) higher in abiotic samples (n = 79 from 11 matrices) than in biotic samples (n = 73 from 12 matrices), suggesting the likelihood for reduced bioavailability of BDE-209 in certain biota. Finally, a molecular-scale analysis indicated that the curvilinear relationship between log K(pew) and log K(OW) can be attributed to the energy barrier that a molecule has to overcome as it attempts to diffuse into the LDPE structure, which can become significant for larger molecules. Similarly, the reduced bioavailability of BDE-209 in many biological species can be regarded as a reflection of the magnitude of molecular interactions between cell membranes and BDE-209.

Bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers in wild frogs

To investigate bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers (PBDEs) in amphibians, we collected adult frogs (Rana limnocharis) from a rice field in an e-waste recycling site in China. We found that ∑PBDEs in the whole frogs and various tissues (brain, liver, testis and egg) ranged from 17.10 to 141.11 ng g(-1) wet weight. Various tissues exhibited a similar PBDE congener profile, which was characterized by intermediate brominated congeners (BDE-99 and BDE-153) as the largest contributors, with less lower brominated congeners (BDE-28 and BDE-47) and higher brominated congeners (BDE-209). The maternal transfer capacity of PBDEs declined with the increase in bromine numbers of PBDE congeners. We suggest that the bromine atom number (the molecular size, to some degree) might be a determining factor for the maternal transport of a PBDE congener rather than K(ow) (Octanol-Water partition coefficient), which expresses a compound's lipophilicity. ∑PBDEs concentrations in frogs decreased over time during a depuration period of 54 days when these wild frogs were brought to the lab from the e-waste recycling site. The half-life of ∑PBDEs was 35 days, with about 14 days for BDE-47, and 36 and 81 days for BDE-99 and BDE-153, respectively. The data shows that the elimination of PBDEs has no essential difference from aquatic and terrestrial species.

Biomagnification of higher brominated PBDE congeners in an urban terrestrial food web in north China based on field observation of prey deliveries

As an important group of brominated flame retardants, polybrominated diphenyl ethers (PBDEs) persist in the wildlife food webs. However, the biomagnification of PBDEs has not been adequately studied in the terrestrial food webs. In this study, a terrestrial food web composed of common kestrels, sparrows, rats, grasshoppers, and dragonflies in the urban environment from northern China was obtained. A field prey delivery study, reinforced by δ¹³C and δ¹⁵N analyses, indicates that sparrows are the primary prey items of common kestrels. Concentrations of PBDEs were in the following order: common kestrel > sparrow > rat > grasshopper and dragonfly with BDE-209 as the dominant congener. Biomagnification factors (BMFs) were calculated as the ratio between the lipid normalized concentrations in the predator and prey. The highest BMF (6.9) was determined for BDE-153 in sparrow/common kestrel food chain. Other higher brominated congeners, such as BDE-202, -203, -154, -183, -197, and -209, were also biomagnified in this terrestrial food chain with BMF of 1.3-4.7. BDE-47, -99, and -100 were found to be biodiluted from sparrow to common kestrel (BMFs < 1). Measured BMF values for BDE-153, -47, -99, and -100 were consistent with predicted values from a nonsteady-state model in American kestrels from another study. Retention factors and metabolism of BDE congeners may be confounding factors influencing the measured BMFs in this current study.

Environmental issues and management strategies for waste electronic and electrical equipment

Issues surrounding the impact and management of discarded or waste electronic and electrical equipment (WEEE) have received increasing attention in recent years. This attention stems from the growing quantity and diversity of electronic and electrical equipment (EEE) used by modern society, the increasingly rapid turnover of EEE with the accompanying burden on the waste stream, and the occurrence of toxic chemicals in many EEE components that can pose a risk to human and environmental health if improperly managed. In addition, public awareness of the WEEE or "e-waste" dilemma has grown in light of popular press features on events such as the transition to digital television and the exportation of WEEE from the United States and other developed countries to Africa, China, and India, where WEEE has often not been managed in a safe manner (e.g., processed with proper safety precautions, disposed of in a sanitary landfill, combusted with proper air quality procedures). This paper critically reviews current published information on the subject of WEEE. The definition, magnitude, and characteristics of this waste stream are summarized, including a detailed review of the chemicals of concern associated with different components and how this has changed and continues to evolve over time. Current and evolving management practices are described (e.g., reuse, recycling, incineration, landfilling). This review discusses the role of regulation and policies developed by governments, institutions, and product manufacturers and how these initiatives are shaping current and future management practices.

Predominance of BDE-209 and other higher brominated diphenyl ethers in eggs of white stork (Ciconia ciconia) colonies from Spain

Polybrominated diphenyl ethers (PBDEs) are ubiquitous pollutants for which there is still a lack of knowledge about the environmental behavior and fate of the higher brominated congeners (octa- to deca-BDEs). In this study, the PBDE content and congener profiles in failed eggs from two colonies of white stork (Ciconia ciconia) in Spain were studied. The average total PBDE concentration was 1.64ng/g (wet weight, w.w.) for the rural colony and 9.08ng/g (w.w.) for the urban colony. Higher brominated BDEs dominated the congener profiles of both colonies. Of particular interest was the determination of BDE-209 as the dominant congener accounting for 44.1% and 38.6% of the total PBDE content in the rural and urban colonies, respectively. BDE-202, considered an indicator of BDE 209 debromination, was detected in 83% and all of the samples from rural and urban colonies, respectively. The observed congener profile in which BDE-207>BDE-208>BDE-206 does not correspond to any known technical PBDE mixture and is evidence for possible BDE-209 degradation.

Does maternal exposure to an environmental stressor affect offspring response to predators?

There is growing recognition of the ways in which maternal effects can influence offspring size, physiological performance, and survival. Additionally, environmental contaminants increasingly act as stressors in maternal environments, possibly leading to maternal effects on subsequent offspring. Thus, it is important to determine whether contaminants and other stressors can contribute to maternal effects, particularly under varied ecological conditions that encompass the range under which offspring develop. We used aquatic mesocosms to determine whether maternal effects of mercury (Hg) exposure shape offspring phenotype in the American toad (Bufo americanus) in the presence or absence of larval predators (dragonfly naiads). We found significant maternal effects of Hg exposure and significant effects of predators on several offspring traits, but there was little evidence that maternal effects altered offspring interactions with predators. Offspring from Hg-exposed mothers were 18% smaller than those of reference mothers. Offspring reared with predators were 23% smaller at metamorphosis than those reared without predators. There was also evidence of reduced larval survival when larvae were reared with predators, but this was independent of maternal effects. Additionally, 5 times more larvae had spinal malformations when reared without predators, suggesting selective predation of malformed larvae by predators. Lastly, we found a significant negative correlation between offspring survival and algal density in mesocosms, indicating a role for top-down effects of predators on periphyton communities. Our results demonstrate that maternal exposure to an environmental stressor can induce phenotypic responses in offspring in a direction similar to that produced by direct exposure of offspring to predators.

The hypothalamus-pituitary-thyroid axis in teleosts and amphibians: endocrine disruption and its consequences to natural populations

Teleosts and pond-breeding amphibians may be exposed to a wide variety of anthropogenic, waterborne contaminants that affect the hypothalamus-pituitary-thyroid (HPT) axis. Because thyroid hormone is required for their normal development and reproduction, the potential impact of HPT-disrupting contaminants on natural teleost and amphibian populations raises special concern. There is laboratory evidence indicating that persistent organic pollutants, heavy metals, pharmaceutical and personal care products, agricultural chemicals, and aerospace products may alter HPT activity, development, and reproduction in teleosts and amphibians. However, at present there is no evidence to clearly link contaminant-induced HPT alterations to impairments in teleost or amphibian population health in the field. Also, with the exception of perchlorate for which laboratory studies have shown a direct link between HPT disruption and adverse impacts on development and reproductive physiology, little is known about if or how other HPT-disrupting contaminants affect organismal performance. Future field studies should focus on establishing temporal associations between the presence of HPT-disrupting chemicals, the occurrence of HPT alterations, and adverse effects on development and reproduction in natural populations; as well as determining how complex mixtures of HPT contaminants affect organismal and population health.