Species- and tissue-specific accumulation of Dechlorane Plus in three terrestrial passerine bird species from the Pearl River Delta, South China

Characterization, distribution, sources and health risks of Dechlorane Plus (DP) in urban street dust of Shenyang City, China

Dechlorane Plus (DP) is an emerging persistent organic pollutants, yet few studies have been conducted in China, especially in urban dust. DP was measured and detected in urban street dust samples collected from Shenyang City, China. Spatial distribution, potential sources, and health risks of DP in urban dust were assessed in this study. Results show that anti-DP was easier to detect than syn-DP due to the proportion of DP production, stability, migration capability, and physical and chemical properties of DP isomers. Mean ∑DP, syn-DP, and anti-DP concentrations were 25.95 ± 11.59 ng/g, 5.71 ± 3.78 ng/g, and 21.57 ± 9.19 ng/g, respectively. Results suggested that levels of DP pollution were influenced by land-use type, and differences in DP between the two major transportation networks in the city (e.g., first-ring road and second-ring road) were not significant. Results of correlation analysis and fractional abundance of DP isomers were consistent, indicating that PD in urban dust of Shenyang City is mainly derived from commercial DP products. Although the health risks of DP in the dust of Shenyang City were within acceptable levels, results of exposure doses and health risks suggested that children were more susceptible to the impacts of DP than adults, with oral ingestion being a more important exposure pathway than dermal absorption.

Contamination Level, Distribution, and Inventory of Dechlorane Plus (DP) in the Surface Soil of Shenyang City, China

Dechlorane Plus (DP), an emerging type of persistent organic pollutant (POP), poses potential harmful effects on plants, animals, and humans alike, garnering increasing attention. Urban surface soil is easily accessible to urban residents, and its environmental conditions have a more significant impact on urban residents. However, there are few studies on related DP contamination. In this study, the contamination of DP in surface soil from Shenyang City, Liaoning Province, China, was investigated. Soil samples were collected from 33 different locations in May and June 2023. The total DP (∑DP), anti-DP, and syn-DP were determined by gas chromatography and ranged from not detected (ND) to 77.80 ng/g, from ND to 61.50 ng/g, and from ND to 16.30 ng/g, respectively. The mean values were 33.60 ± 18.93 ng/g, 27.01 ± 14.32 ng/g, and 8.57 ± 4.55 ng/g. The findings indicate that anti-DP is more readily detectable than syn-DP, attributable to the lower proportion of syn-DP in the overall DP production and the distinct physicochemical properties of DP isomers. The fsyn [syn-DP/(anti-DP + syn-DP)] is 0.14-0.40, with a mean value of 0.22. This aligns closely with the values observed in commercial DP formulations, suggesting that the primary sources are derived from commercial DP products. Contour maps show that DP concentrations are influenced by urban land use and DP production. Based on the Tyson polygon method, the DP inventory was calculated at approximately 1.18 tons, with the unit area load exceeding previously reported values. The results also show that the health risks of DP are minimal, but children are more susceptible to the impacts of DP than adults, and oral ingestion is a more critical exposure pathway.

Tissue-specific and stereoselective accumulation of Dechlorane Plus isomers in two predator fish in a laboratory feeding study

The tissue-specific bioaccumulation of Dechlorane Plus (DP) isomers was investigated in two predator fish species (redtail catfish, RF; and oscar fish, OF) that were feeding on tiger barb (TB), which was exposed to syn-DP and anti-DP isomers. The biotransformation potential of DP isomers was examined by in vitro metabolism using fish liver microsomes. No difference in accumulation behaviors of DP isomers was observed between RF and OF, and the accumulation of both syn- and anti-DP isomers exhibiting a linear increase trend with the exposure time in all fish tissues. The assimilation efficiencies and depuration rates for syn-DP and anti-DP were determined to be the highest in the liver. Biomagnification factors (BMFs) for both syn-DP and anti-DP were higher than one in the serum and gastrointestinal tract of fish, whereas were less than one in the other tissues. The wet-weight concentrations of DP isomers in tissues were significantly correlated with the lipid contents in both fish species, indicating that the tissue distribution of DP isomers occurred through passive diffusion to the lipid compartments in vivo. Tissue-specific compositions of DP isomers were observed, with anti-DP selectively accumulating in the liver, gonad, serum, and gills, whilst syn-DP in the carcass and GI tract. However, after being normalized of all tissues, the fish showed no selective accumulation of DP isomers during the exposure period, and selective accumulation of syn-DP was observed during the depuration period. No potential DP metabolites were detected in the fish tissues and in vitro metabolism systems. The main cause of this stereoselective DP isomer accumulation could have been the selective excretion of anti-DP isomer through the fish feces.

Dechlorane Plus as an emerging environmental pollutant in Asia: a review

Dechlorane Plus (DP) is an unregulated, highly chlorinated flame retardant. It has been manufactured from past 40 years but its presence in the environment was initially reported in 2006. Later, it has been found in various biotic and abiotic environmental matrices. However, little attention has been paid to monitor its presence in Asia. Many studies have reported the occurrence of DP in the environment of Asia, yet the data are scarce, and studies are limited to few regions. The objective of present review is to summarize the occurrence, distribution, and toxicity of this ubiquitous pollutant in various environmental matrices (biotic and abiotic). DP has also been reported in the areas with no emission sources, which proves its long-range transport. Moreover, urbanization and industrialization also affect the distribution of DP, i.e., high levels of DP have been found in urban areas relative to the rural. Tidal movement also incorporates in transport of DP across the aquatic system. Further, bioaccumulation trend of DP in various tissues is kidney > liver > muscle tissues, whereas, blood brain barrier resists its accumulation in brain tissues. Additionally, gender-based accumulation trends revealed high DP levels in females in comparison to males due to strong metabolism of males. Furthermore, methodological aspects and instrumental analysis used in previous studies have also been summarized here. However, data on biomagnification in aquatic ecosystem and bioaccumulation of DP in terrestrial food web are still scarce. Toxicity behavior of syn-DP and anti-DP is still unknown which might gain the interest for future studies.

Alternative halogenated flame retardants (AHFRs) in green mussels from the south China sea

Restrictions of legacy brominated flame retardants, such as polybrominated diphenyl ether (PBDE) and polybrominated biphenyl (PBB), have resulted in increased usage of alternative halogenated flame retardants (AHFRs). Consequently, AHFRs contamination has caused a major concern in the scientific community. However, there is limited information on their presence in marine mussels. In this study, we investigated the occurrence and distribution of polybrominated biphenyls (PBBs), AHFRs and dehalogenated products in green mussels collected from 22 locations in the northern South China Sea (SCS). Our results revealed that ∑AHFRs were ubiquitous in green mussels with concentrations in the range of 1.08-7.71 ng/g lipid weight (lw). Among target AHFRs, hexabromobenzene (HBB), decabromodiphenyl (DBDPE) and dechlorane plus (DP) were predominant with their mean values of 1.19, 1.00 and 0.82 ng/g lw, respectively. There were negligible stereoisomer enrichments of DP in green mussels based on f_anti values, indicating a limited bioaccumulation and metabolism of DP in green mussels. In comparison with other locations, concentrations of the AHFRs in green mussels determined here were at moderate levels. Additionally, there were significant linear relationships between some AHFRs (e.g., HBB and PBEB), suggesting their similar commercial applications and sources in the environment. The estimated daily intakes of AHFRs through consumption of green mussels by the local population in South China were 0.05-0.14 ng/kg body weight/day and 0.17-0.44 ng/kg body weight/day based on the mean and 95th concentrations, respectively. To the best of our knowledge, the present study is the first to report AHFRs and dehalogenated products in green mussels.

Comparative study of dechlorane plus (DP) in adult chickens and developing embryos: Stereo-selective bioaccumulation of DP in chickens

Although isomer-specific bioaccumulation of dechlorane plus (DP) has been addressed in many studies, it remains unclear which factors determine this process and whether biotransformation of DP occurs in organisms. Comparative experiments were conducted in both in vivo and in ovo incubation using hens and eggs to identify the dominant factors determining the bioaccumulation of DP. Hens and fertilized eggs were exposed to DP isomers (syn- and anti-DP) by feeding and spiking, respectively, to investigate absorption, elimination, and metabolism. No significant differences were found between absorption efficiencies of DP isomers in the adult hens. Following first-order kinetics, anti-DP exhibited a slightly longer half-life than syn-DP as well as an elevated anti-DP fraction in laid eggs, thereby suggesting selective enrichment of anti-DP in adult hens. However, chicken embryos metabolized approximately 12% and 28% of the absorbed syn- and anti-DP, respectively, thereby verifying that anti-DP was preferably metabolized. This result indicated that stereo-selective excretion of syn-DP, rather than preferred metabolism of anti-DP, played a more prominent role in isomer-specific bioaccumulation of DP in chickens. Further studies on metabolites of DP are crucial to understanding the fate of DP in organisms.

Accumulation and exposure assessment of persistent chlorinated and fluorinated contaminants in Korean birds

To date, information is scarce on the accumulation and potential risks of persistent chlorinated and fluorinated contaminants in birds. In this study, organohalogen contaminants (OHCs), such as polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), and perfluoroalkyl substances (PFASs), were measured in the liver tissues of 10 bird species (n = 69) from Korea. Among the OHCs, PFASs showed the highest concentration, ranging from 5.40 to 11,300 (median: 294) ng/g wet weight. The median concentrations of OCPs and PCBs in all the bird samples were 147 and 81.9 ng/g lipid weight, respectively. The maximum concentration of perfluorooctane sulfonate (PFOS) observed in our bird samples was highest reported so far. Concentrations of OHCs in predatory birds were significantly greater than those measured in non-predatory birds, indicating the importance of diet and trophic position for bioaccumulation of these contaminants. In addition, different accumulation patterns of OHCs were found between predatory and non-predatory birds. Significant correlations were found between organochlorine concentrations and stable nitrogen isotope ratio (δ¹⁵N) measurements, whereas no correlation was found between PFASs and δ¹⁵N. Although the concentrations of PCBs and DDTs in birds were lower than the threshold levels, 25% and 49% of birds exceeded the toxicity reference value and predicted no effect concentration for PFOS, respectively, implying potential health risks to Korean birds.

Halogenated organic pollutants in aquatic, amphibious, and terrestrial organisms from an e-waste site: Habitat-dependent accumulation and maternal transfer in watersnake

Dichlorodiphenyltrichloroethanes (DDTs), Polychlorinated biphenyls (PCBs), and halogenated flame retardants (HFRs) were measured in aquatic, amphibious, and terrestrial wildlife collected from an e-waste contaminated pond and its surrounding region. The species-specific bioaccumulation and maternal transfer of chemicals in the watersnake were investigated. Total concentrations of target chemicals ranged from 1.3 × 10³ to 4.8 × 10⁵ ng g^-1 lipid weight. PCBs were the predominant (72-95%) contaminants, followed by polybrominated biphenyl ethers (PBDEs, 4-27%). The concentrations of PCBs and HFRs except decabromodiphenyl ethane (DBDPE) were higher in aquatic organisms and terrestrial birds than in amphibians and lizards. Relatively high DDT levels were observed in the terrestrial birds and toads, but high DBDPE was found in the aquatic species except for waterbird eggs. Species-specific congeners profiles for PCB and PBDE and isomeric composition for dechlorane plus were observed. These results indicated a habitat-dependent accumulation among different species. Maternal transfer examined by the ratio of egg to carcass for watersnakes indicated multi-linear correlations between maternal transfer potential and octanol-water partition coefficient (log K_OW) of chemicals. The same maternal transfer efficiencies were found for chemicals with log K_OW between 6 and 8, then the maternal transfer potential rapidly decreased with increasing of log K_OW.

Dechlorinated Analogues of Dechlorane Plus

Degradation products of the chlorinated additive flame retardant Dechlorane Plus (DP) have been discovered globally. However, the identity of many of these species remains unknown due to a lack of available analytical standards, hindering the ability to quantitatively measure the amounts of these compounds in the environment. In the present study, synthetic routes to possible dechlorinated DP derivatives were investigated in an effort to identify the environmentally significant degradation products. The methano-bridge chlorines of anti- and syn-DP were selectively replaced by hydrogen atoms to give six new hydrodechlorinated DP analogues. The identity and absolute configuration of all of these compounds were confirmed by GC-MS, NMR spectroscopy, and X-ray diffraction studies. These compounds were observed in sediment samples from streams and rivers in relatively rural areas of Ontario and are thus environmentally relevant.

Stereoselective bioaccumulation of syn- and anti-Dechlorane plus isomers in different tissues of common carp (Cyprinus carpio)

Common carps (Cyprinus carpio) were exposed to syn- and anti-Dechlorane Plus (DP) isomers to investigate absorption, tissue distribution, and stereoselective bioaccumulation of DP isomers. The absorption efficiencies of anti-DP in the gastrointestinal system were higher than those of syn-DP. A linear accumulation was found for both isomers in all fish tissues except for serum; and the liver and gill exhibited the highest and lowest DP assimilation efficiency, respectively. The elimination of DP isomers in all tissues followed first-order kinetics, with the fastest depuration rate occurring in the liver and serum. The biomagnification factors (BMFs) of both isomers were less than one in all tissues, except for serum. Anti-DP was preferably accumulated in the liver, gill, and serum, whereas syn-DP was selectively accumulated in the carcass and gastrointestinal tract. As a whole, fish did not show selective accumulation of the syn- or anti-DP isomer in the uptake stage, whereas a selective accumulation of syn-DP in fish was observed during the depuration period, which could be due to a selective excretion of anti-DP. Metabolism cannot be ruled out as a possible reason considering the high f_anti values and the high elimination rate of DPs in the liver.

Distribution and region-specific sources of Dechlorane Plus in marine sediments from the coastal East China Sea

Dechlorane Plus (DP) is a highly chlorinated flame retardant and found to be ubiquitously present in the environment. We reported here the first record of DP in sediments from the coastal East China Sea (ECS). DP was detected in most of the surface sediments, and the concentrations ranged from 14.8 to 198pg/g dry weight (dw) with a mean value of 64.4pg/g dw. Overall, DP levels exhibited a seaward decreasing trend from the inshore toward outer sea. The fractional abundance of anti-DP (f_anti) showed regional discrepancies, attributing to different environmental behaviors of DP isomers. Depth profiles of DP in a sediment core from estuarine environment showed distinct fluctuation, and the core in open sea had stable deposition environment with two peak values of DP in ~1978 and 2000. The f_anti exhibited downward decreasing trend prior to mid-1950s, indicating a preferential degradation of anti-DP and/or a greater adsorption capacity of syn-DP after its burial. Lignin and lipid biomarkers (∑C₂₇+C₂₉+C₃₁n-alkanes) of terrestrial organic matters were introduced to identify region-specific sources of DP, and the results showed that DP in the northern inner shelf, southern inner shelf of 29 °N and mud area southwest of Cheju Island was mainly come from Yangtze River (YR) input, surface runoffs after discharge of local sources close to the Taizhou-Wenzhou Region and the atmospheric deposition from the North China and East Asia, respectively. The coastal ECS was an important reservoir of DP in the world, with mass inventory of approximately 310.7kg in the surface sediments (0-5cm).

Extensive organohalogen contamination in wildlife from a site in the Yangtze River Delta

The environmental and human health concerns for organohalogen contaminants (OHCs) extend beyond the 23 persistent organic pollutants (POPs) regulated by the Stockholm Convention. The current, intense industrial production and use of chemicals in China and their bioaccumulation makes Chinese wildlife highly suitable for the assessment of legacy, novel and emerging environmental pollutants. In the present study, six species of amphibians, fish and birds were sampled from paddy fields in the Yangtze River Delta (YRD) were screened for OHCs. Some extensive contamination was found, both regarding number and concentrations of the analytes, among the species assessed. High concentrations of chlorinated paraffins were found in the snake, Short-tailed mamushi (range of 200-340 μg g(-)(1)lw), Peregrine falcon (8-59 μg g(-1)lw) and Asiatic toad (97 μg g(-)(1)lw). Novel contaminants and patterns were observed; octaCBs to decaCB made up 20% of the total polychlorinated biphenyls (PCBs) content in the samples and new OHCs, substituted with 5-8 chlorines, were found but are not yet structurally confirmed. In addition, Dechlorane 602 (DDC-DBF) and numerous other OHCs (DDTs, hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), hexbromocyclododecane (HBCDD), chlordane, heptachlor, endosulfan and Mirex) were found in all species analyzed. These data show extensive chemical contamination of wildlife in the YRD with a suite of OHCs with both known and unknown toxicities, calling for further in-depth studies.

Maternal transfer of dechloranes and their distribution among tissues in contaminated ducks

The tissue concentrations of dechlorane plus and its analogues were determined in ducks collected from several e-waste recycling villages of Taizhou, China. Compared with the published literature, the relatively high concentrations of these compounds were detected in ducks, indicating serious DP contamination. Since both the duck meat and eggs were important components for diet, this result reminded us of keeping a watchful eye on human dietary exposure to DP and its analogues in this study area. The wet-weight concentrations of DP and its analogues were significantly related to tissue lipid content (p < 0.05), indicating that the lipid pools predominantly impacted the distribution of DPs in ducks. On the basis of lipid adjustment, the significantly lower levels in brain than those in liver and blood, displayed the occurrence of liver sequestration and blood-brain barrier to DP and its analogues in the duck (p < 0.05). The maternal transfer of DP and Mirex was not obviously limited, and the transferring extent of Dec 602 was over one. The stereo-selected accumulation of two DP isomers occurred among tissues with preference to syn-DP in blood, and to anti-DP in brain. The values of lipid-adjusted monodechlorinated products mainly originated from the exterior environment in ducks.

Microscopic anthropogenic litter in terrestrial birds from Shanghai, China: Not only plastics but also natural fibers

The level of contamination by microscopic anthropogenic litter (0.5-5mm) in terrestrial ecosystems is not well understood. After chemical digestion in 10% KOH, microscopic anthropogenic litter from the gastrointestinal tracts of 17 terrestrial birds was identified and categorized under a stereomicroscope based on its physical properties and melting tests. In total, 364 items from 16 birds were identified as microscopic anthropogenic litter, ranging in size from 0.5 to 8.5mm. No relationship between plastic load and body condition was found. Natural fibers, plastic fibers and fragmented plastics represented, respectively, 37.4% (136 items), 54.9% (200 items) and 7.7% (28 items) of total litter items. Small sample sizes limited our ability to draw strong conclusions about the metabolism of natural fibers, but the decline in the proportion of natural fibers from the esophagus to stomach to intestine suggested that they may be digestible. Particles smaller than 5mm represented more than 90% of the total number of pollutant items. Particles with colors in the mid-tones and fibrous shapes were overwhelmingly common particles. The results reflect pollution by microscopic anthropogenic litter in the terrestrial ecosystem of the study area. Microscopic natural fibers, which may disperse and adsorb chemical pollutants differently from microplastic and may pose an even greater risk, are in urgent need of further research.

Sources and environmental behaviors of Dechlorane Plus and related compounds - A review

Although Dechlorane Plus (DP) has been used as a polychlorinated flame retardant for almost half a century, its detection in the environment was not reported until 2006. The subsequent intensive research has confirmed its global ubiquity. A few reviews have presented the properties, analytical methods and environmental occurrence of DP and related compounds in the past several years. The present review emphasizes on the environmental behavior of DP isomers which is assessed by the variation of the isomer ratio of DP in various matrices. Other aspects including the analytical methods, emission sources, general environmental occurrence and bioaccumulation of DP are also summarized. In this review, three typical emission sources in the environment are categorized after introducing the measurement method of DP. The temporal-spatial distribution is then evaluated at the global scale, which provides an integrated representation of the environmental occurrence of DP and potential impact on the human health and ecosystems. The variations of DP isomer ratio in various matrices reinforce its source related distribution and their stereoselective bioaccumulation. Thereafter, DP related compounds and dechlorinated analogs are briefly summarized in regards to their occurrence in various matrices, suggesting their ubiquity in the environment and bioavailability. Further studies are required to better assess the exposures and toxicological effects of DP and its analogs. A special concern is the serious contamination in e-waste recycling areas in developing countries, where long-term monitoring data on the association of DP exposure and adverse effects to human health and ecosystems is urgently needed.

Determination of Dechlorane Plus and related compounds (dechlorane 602, 603 and 604) in fish and vegetable oils

Dechlorane Plus (DP) is a flame retardant used as a substitute of Mirex since 1970s, but it was not detected in the environment until 2006. Since then, this compound and its main relatives, Dechlorane 602, 603 and 604, have been mainly studied in environmental matrices for monitoring purposes, but the dietary exposure to them has been hardly investigated so far. In the present study, we determined this family of compounds in fish and vegetable oil samples from Catalonia (Spain), most of them used as health supplements. Determination was carried out by gas chromatography-high resolution mass spectrometry (GC-HRMS), after a clean up in a multilayer silica column and preparative high performance liquid chromatography (HPLC) equipped with a pyrenyl(ethyl) column. Concentrations of Dechlorane compounds were between below the limit of detection and 384.2 pg g(-1). Although there are only few studies about the presence of these pollutants in food or feed, concentrations obtained indicated that these compounds are in the same order in fish and vegetable oil health supplements as the few other food and feed studies.

A review on current knowledge and future prospects of organohalogen contaminants (OHCs) in Asian birds

The release of harmful chemicals in the Asian environment has recently increased dramatically due to rising industrial and agricultural activities. About 60% of the global human population is currently living on the Asian continent and may thus be exposed to a large range of different chemicals. Different classes of organohalogen chemicals have indeed been reported in various environmental compartments from Asia including humans and wildlife, but this issue has received less attention in birds. In this article, we reviewed the available literature on levels of legacy persistent organic pollutants (POPs) and various flame retardants (FRs) in Asian avifauna to analyze the existing pool of knowledge as well as to identify the gaps that should be addressed in future research. Furthermore, we discussed the variation in levels of organohalogens based on differences in regions, trophic level, dietary sources and migratory behaviors of species including distribution patterns in different tissues of birds. Although the mass of published literature is very low and even absent in many important regions of Asia, we deduced from the reported studies that levels of almost all classes of organohalogens (OHCs) including FRs were highest in East Asian countries such as Japan, China and South Korea, except for HCHs that were found at maximum levels in birds of South India. Concentrations (ng/g LW) of different OHCs in Asian birds ranged between <LOD (limit of detection) to 14,000,000 for polychlorinated biphenyls (PCBs), <LOD to 790,000 for dichlorodiphenyltrichloroethane (DDTs), <LOD to 12,000 for hexachlorobenzene (HCB), <LOD to 29,000 for hexachlorocyclohexanes (HCHs), <LOD to 47,000 for chlordanes (CHLs) and <LOD to 4600 for total cyclodienes. Further, ranges (ng/g LW) of 1.1 to 150,000 for Co-PCBs; <LOD to 27 for polychlorinated dibenzo-p-dioxins (PCDDs); <LOD to 45 for polychlorinated dibenzofurans (PCDFs) and 0.02 to 73 for PCDD/DFs have been reported in Asian aves. Among emerging FRs, levels of total polybrominated diphenyl ethers (PBDEs), total dechlorane plus (DPs) [syn and anti DPs] and hexabromocyclododecane (HBCDs) oscillated between <LOD to 134,000, <LOD to 3820 [<0.1-920 and <0.1-2900], and <LOD to 11,800 ng/g LW, respectively. Corresponding ranges of novel brominated flame retardants (nBFRs) such as decabromodiphenyl ethane (DBDPE) and 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) were <LOD to 820 and <LOD to 89 ng/g LW. Other nBFRs such as tetrabromobisphenol-A (TBBPA) hexabromobenzene (HBB) and pentabromoethylbenzene (PBEB) in Asian avifauna have been reported in very few studies. Dependence of organohalogens on dietary sources and subsequent biomagnification in the food chain has been corroborated through δ(15)N and δ(13)C stable isotope proxies. In general, tissues with higher fat content accumulated more organohalogens and vice versa. Aspects such as maternal transfer of OHCs and temporal trends have rarely been discussed in reported literature from Asia. The mobility of birds, vicinity to sources and trans-boundary movement of pollutants were identified as key exposure routes and subsequent OHCs contamination in Asian birds. There is extreme scarcity of literature on organohalogen contamination in birds from Northern, South-eastern and west Asian countries where an industrial boom has been witnessed in the past few decades. Current scenarios suggest that levels of OHCs, particularly the FRs, are rising in birds of Asia and it would be wise to develop baseline information and to regulate the OHCs emission accordingly.

Accumulation of Dechlorane Plus flame retardant in terrestrial passerines from a nature reserve in South China: the influences of biological and chemical variables

Although a number of studies have addressed the bioaccumulation of Dechlorane Plus (DP) flame retardant in wildlife, few data are available on terrestrial organisms. This study examined the presence of DP isomers in the muscle tissue of seven terrestrial resident passerine species, i.e., the great tit (Parus major), the oriental magpie-robin (Copsychus saularis), the red-whiskered bulbul (Pycnonotus jocosus), the light-vented bulbul (Pycnonotus sinensis), the streak-breasted scimitar babbler (Pomatorhinus ruficollis), the long-tailed shrike (Lanius schach), and the orange-headed thrush (Zoothera citrina), from a national nature reserve located in South China. The ∑DP (sum of syn-DP and anti-DP) concentrations ranged from 1.2 to 104 ng/g lipid weight, with significantly higher levels in insectivorous birds than in omnivorous birds. The overall exposure to DP isomers of the current passerines may be attributed to the intensive release of this pollutant from electronic waste recycling sites and industrial zones in the vicinity of the nature reserve. Species-specific DP isomeric profiles were also found, with significantly greater fanti values (the isomer fractions of anti-DP) in the red-whiskered bulbul and the oriental magpie-robin. Additionally, the fanti values were significantly negatively correlated to ∑DP concentrations for the individual bird samples, suggesting the influence of DP concentrations on the isomeric profiles.

Sources, gastrointestinal absorption and stereo-selective and tissue-specific accumulation of Dechlorane Plus (DP) in chicken

Dechlorane Plus (DP) isomers, along with two dechlorinated metabolites were measured in environmental matrices, chyme and digestive tract contents and tissues of chicken from an e-waste recycling site located in South China. Soil is proved to be the main source of DP in chicken rather than food because soil contributes more than 94% of total DP in chyme. In the gastrointestinal tract absorption processes, no selective absorption was observed for DP isomers during the ingestion processes. The tissue distribution of DP isomers in chicken exhibits complicated characteristics. The lipid contents in tissues are the main factors in the tissue distribution of DP, while the different blood perfusion state and the different tissue functions also seem to influence the tissue distribution of DP. The fat, brain, and liver exhibit higher fanti values (0.65, 0.64, and 0.64) than the other tissues (0.54-0.59). The elevated fanti values of DP from the contamination source (0.52 in soil) to chicken suggest stereoselective bioaccumulation of anti-DP in chicken. The similar ratios of anti-Cl11-DP to anti-DP between soil and chicken imply that anti-Cl11-DP mainly derives from the uptake from environment rather than in vivo dechlorination.

Kinetics of stereoselective enrichment of Dechlorane Plus in Ulva Pertusa

Dechlorane Plus (DP) has been detected extensively in both biotic and abiotic matrices, and stereoselective enrichment of Dechlorane Plus isomers has also been observed in organisms. In this laboratory study, Ulva pertusa were firstly exposed to known Dechlorane Plus concentrations for 21d (uptake period), and then transferred to clean seawater for 14d (depuration period) to investigate the kinetics of Dechlorane Plus isomers in U. pertusa. Dechlorane Plus isomers reached steady-state after 21d of exposure. The mean fractional abundance of syn-DP (fsyn) exceeded than that of 0d (0.23±0.02) during uptake, but decreased during depuration. This study is the first to define the kinetics of stereoselective enrichment of Dechlorane Plus isomers in U. pertusa using two-box kinetic model. The uptake rate constants of the syn- and anti-DP were 0.164±0.056d(-1) and 0.083±0.071d(-1), respectively. The depuration rate constants were 0.337±0.057d(-1) (syn-DP) and 0.236±0.095d(-1) (anti-DP), suggesting that syn-DP is eliminated quicker than anti-DP by U. pertusa. These results are consistent with observation of fsyn and stereoselective enrichment of Dechlorane Plus isomers in U. pertusa.

Trophic transfer of dechloranes in the marine food web of Liaodong Bay, north China

Dechloranes are of particular concern because of their ubiquity in environmental matrices, but little is known about their trophic transfer in aquatic food web. This study investigated the trophic transfer of seven dechloranes in a marine food web from Liaodong Bay, China. Dechloranes were determined in sediments and 15 marine species including benthic invertebrates, fish and gulls collected from Liaodong Bay. Biomagnification factors (BMFTL) of dechloranes in black-headed gulls were calculated to be 6.4, 1.7, 0.45, 0.36, 0.14, and 0.11 for mirex, Dechlorane 602 (Dec 602), Dechlorane 603 (Dec 603), antiundecachloropentacyclooctadecadiene (anti-Cl11DP), syn-dechlorane plus (syn-DP), and anti-DP. Significantly positive relationships were found between lipid equivalent concentrations of mirex, Dec 602, and anti-Cl11DP and trophic levels, and the trophic magnification factors (TMFs) were 13, 3.7, and 5.6, respectively, indicating that these compounds undergo trophic magnification in the aquatic food web. Lipid equivalent concentrations of Dec 603 and DP isomers did not exhibit a statistically significant correlation with trophic levels. The relatively low trophic magnification potentials of Dec 603 and DP isomers were possibly due to their extreme hydrophobicity (logKOW: 11.2-11.3) and subsequent low bioavailabilities compared with mirex (7.0), Dec 602 (8.1) and anti-Cl11DP. The results provided important information for understanding the ecological risk of dechloranes.

Organohalogen contamination in passerine birds from three metropolises in China: geographical variation and its implication for anthropogenic effects on urban environments

Contamination of organohalogen pollutants (OHPs), including dichlorodiphenyl trichloroethane and its metabolites (DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenylethane (DBDPE), hexabromocyclododecanes (HBCDs), and dechlorane plus (DP) in three metropolises of China, Beijing, Wuhan, and Guangzhou, and a reference rural site were determined using terrestrial residential passerine species as bioindicator. DDTs dominated in Wuhan whereas flame retardants dominated in Guangzhou and Beijing. No geographical variation was found for PCB levels but it exhibited different homologue profiles among different sites which could be attributed to different dietary sources of birds. Industry characteristics of the sampling location contributed to the geographical differences in the occurrence and contamination profile of OHPs. The transformation of traditional agriculture characterized contamination profiles to industry characterized profiles in Beijing and Guangzhou implicates significantly environmental concern on the flame retardants contamination in non-hot-spot regions of China.

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.

Species-specific accumulation of halogenated flame retardants in eggs of terrestrial birds from an ecological station in the Pearl River Delta, South China

Little information is available on the bioaccumulation of halogenated flame retardants (HFRs) in terrestrial ecosystem. Eggs of light-vented bulbul, yellow-bellied prinia, plain prinia, and dark green white-eye were collected from an ecological station in the Pearl River Delta, South China to investigate the occurrence of polybrominated diphenyl ethers (PBDEs) and several alternative HFRs, including decabromodiphenyl ethane (DBDPE), dechlorane plus (DP), hexabromobenzene (HBB), pentabromoethylbenzene (PBEB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), pentabromotoluene (PBT), and 2,3,5,6-tetrabromo-p-xylene (pTBX). Concentrations of PBDEs, DBDPE, DP, HBB, PBEB, BTBPE, PBT, and pTBX ranged from 53-423, 6.1-609, 4.6-268, not detected (nd)-10, nd-1.4, nd-1.7, nd-7.5, and nd-3.2 ng g(-1) lw, respectively. Light-vented bulbul exhibited significantly lower levels of PBDEs, DBDPE, DP, and HBB than other three bird species due to its phytophagy and the other three bird species' insectivores. PBDEs were the predominant HFRs in bird eggs, followed by DBDPE and DP. Significant negative relationship between the fraction of anti-DP and DP concentrations was observed in bird eggs, suggesting that DP levels play an important role in determining the isomeric composition. Anti-Cl11-DP, the dechlorinated products of DP, was found in bird eggs with concentrations ranging from nd to 0.86 ng g(-1) lw and its source is worth further research.

Levels and profiles of Dechlorane Plus in a major E-waste dismantling area in China

Dechlorane Plus (DP) is a high-production volume, chlorinated flame retardant comprising two major isomers, syn- and anti-DP. In this study, levels of DP were measured in soil and earthworm samples in farmland from a typical E-waste dismantling area in China. The concentrations of total DP ranged from 0.17 to 1,990 ng g(-1) dw in soil samples and 3.43 to 89.2 ng g(-1) lw in earthworm samples. Higher DP levels were found in some main E-waste dismantling sites than those in other sites. The ratios of anti-DP to total DP (f anti) ranged from 0.57 to 0.80 in soil samples and 0.47 to 0.81 in earthworm samples, respectively. The f anti in most samples in this study was in the range of the reported technical DP values. These results showed that improper E-waste dismantling activities could result in the emission of DP. Most earthworm samples showed very low BSAFs (biota-to-soil accumulation factors) for total DP. The values of BSAF were in the range of 0.0007-1.85, with an average value of 0.23. This study presents the first report of the DP in earthworms, which would be useful for ecological risk assessment of DP in terrestrial ecosystem.

Tissue distribution, maternal transfer, and age-related accumulation of dechloranes in Chinese sturgeon

While dechloranes have been detected in environmental media and wildlife, limited information was available on their tissue distribution in wildlife. Syn-dechlorane plus (syn-DP), anti-DP, syn-undecachloropentacyclooctadecadiene (syn-Cl(11)DP), anti-Cl(11)DP, dechlorane 602, dechlorane 603 and mirex were measured in 13 organs of 17 female Chinese sturgeon (Acipenser sinensis). Dechloranes were detected in all tissues and the highest concentrations of total dechloranes were detected in heart (87 pg/g ww, 4.5-645 pg/g ww), followed by adipose (61 pg/g ww, 14-531 pg/g ww) and eggs (57 pg/g ww, 13-261 pg/g ww). The tissue distribution of DP was mainly determined by lipid partition, while Dec 602 and Dec 603 preferred to accumulate in the intestine and stomach. The values of f(anti) (the concentration of anti-DP relative to the sum concentration of DP) in maternal tissues (0.72 ± 0.03 in muscle) were significantly higher than those found in eggs (0.65 ± 0.04) (p < 0.001), while f(anti-Cl11DP) (the concentration of anti-Cl(11)DP relative to the sum concentration of Cl(11)DP) in maternal tissues (0.59 ± 0.10 in muscle) was significantly lower than that in eggs (0.75 ± 0.13) (p < 0.05). High maternal transfer efficiencies of dechloranes were observed in eggs, which accounted for 49% of the total body burden, and the ratios of concentrations in eggs to maternal tissues (EMR) for mirex, Dec 602, Dec 603, syn-Cl(11)DP, anti-Cl(11)DP, syn-DP, and anti-DP were 18, 8.8, 5.2, 2.6, 5.2, 5.5 and 3.7, respectively, which are dependent on their K(OW) values (r = -0.66, p < 0.01). Negative age-related trends were observed for mirex, Dec 603, syn-Cl(11)DP and anti-Cl(11)DP in eggs (R(2) = 0.28-0.38, p = 0.02-0.05), which were possibly due to their high transfer efficiencies to eggs from maternal body (49%).