Investigating Dechlorane Plus (DP) distribution and isomer specific adsorption behavior in size fractionated marine sediments

Primary emissions or environmental persistence contribute to the present DDTs: Evidence from sediment records in Tibetan lakes

Dichlorodiphenyltrichloroethane (DDT) compounds are still circulating the global environment even though the technical DDT has been restricted in agriculture since the last century. The persistent presence of DDTs worldwide remains uncertain, as it is unclear whether their existence is primarily due to ongoing use or the prolonged persistence in soils and sediments that result in continuous reemission into the atmosphere. The present study applied a sequential extraction procedure to determine the DDT concentrations in rapid desorption, slow desorption, and bound residue fractions in the dated sediment cores from distinct regions of Tibet. The temporal variation of total DDTs (sum of three fractions) in sediments from southern and eastern Tibet respectively revealed the different DDT usage histories in India and China mainland. Nevertheless, the current application volumes of DDT-containing products in these regions were found to decrease significantly. The reversible transformations among three fractions of DDTs with aging time was observed along sediment profile, including the back conversion from bound residue. This process may be the key driver to prolong the half-life of sediment p,p'-DDT, resulting in the persistence of secondary sources of this persistent organic pollutant in the global environment for a longer duration than previously expected.

Aging affects isomer-specific occurrence of dechlorane plus in soil profiles: A case study in a geographically isolated landfill from the Tibetan Plateau

Two major structural isomers in commercial dechlorane plus (DP) mixtures, anti-DP and syn-DP, generally displayed varied desorption and partitioning efficiencies in soils, which may be linked to their different aging rates. However, the molecular parameters that govern the degree of aging and its associated effects on the occurrence of DP isomers have not been comprehensively investigated. In this study, the relative abundance of rapid desorption concentration (R_rapid) was measured for anti-DP, syn-DP, anti-Cl₁₁-DP, anti-Cl₁₀-DP, Dechlorane-604 (Dec-604), and Dechlorane-602 (Dec-602) at a geographically isolated landfill area in the Tibetan Plateau. The R_rapid values were used as an indicator of aging degree, exhibiting a close correlation with the three-dimension conformation of the molecules for the dechlorane series compounds. This observation suggested that planar molecules may have a greater tendency to accumulate in the condensed phase of organic matter and undergo more rapid aging. The fractional abundances and dechlorinated products of anti-DP were found to be predominantly controlled by the aging degree of DP isomers. The multiple nonlinear regression model indicated that differences in aging between anti-CP and syn-DP were primarily driven by the total desorption concentration and soil organic matter content. Aging plays a significant role in both the transport processes and metabolism of DP isomers and should be taken into account to refine the assessment of their environmental behaviors.

Source and Distribution of Emerging and Legacy Persistent Organic Pollutants in the Basins of the Eastern Indian Ocean

Persistent organic pollutants (POPs) have received significant and ongoing attention. To establish favorable regulatory policies, it is vital to investigate the occurrence, source, and budgets of POPs worldwide. POPs including phthalic acid esters (PAEs), organophosphate esters (OPEs), brominated flame retardants (BFRs), and highly chlorinated flame retardants (HFRs) have not yet been examined in the Eastern Indian Ocean (EIO). In this study, the distribution of POPs has been investigated from surface sediments with the depth of 4369-5742 m in the Central Indian Ocean Basin (CIOB) and Wharton Basin (WB) of EIO. The average (±SD) concentrations of ∑₁₁PAEs, ∑₁₁OPEs, ∑₄ BFRs, and ∑₅HFRs were 1202.0 ± 274.36 ng g^-1 dw, 15.3 ± 7.23 ng g^-1 dw, 327.6 ± 211.74 pg g^-1 dw, and 7.9 ± 7.45 pg g^-1 dw, respectively. The high abundance of low-molecular-weight (LMW) PAEs, chlorinated OPEs, LMW BDEs, and anti-Dechlorane Plus indicated the pollution characteristics in the EIO. Correlation analysis demonstrated that LMW compounds may be derived from the high-molecular-weight compounds. The monsoon circulation, currents, and Antarctic Bottom Water may be the main drivers. POP accumulation rate, depositional flux, and mass inventory in the Indian Ocean were also estimated.

Current pollution status, spatial features, and health risks of legacy and emerging halogenated flame retardants in agricultural soils across China

Soil is a major reservoir and a secondary source of semi-volatile organic chemicals, while studies on the pollution status of halogenated flame retardants (HFRs) in agricultural soils are limited. In this study, a total of twenty-five chemicals including novel brominated flame retardants (NBFRs), polybrominated diphenyl ethers (PBDEs), and dechlorane plus (DPs) was analyzed in the agricultural soils across China to investigate the occurrence, spatial distribution, potential sources, influencing factors and their associated human health risks. The results showed that BDE-209 (125-130,183 pg/g, dry weight, d.w.) was the most abundant flame retardant of PBDEs, followed by decabromodiphenyl ethane (DBDPE) (9.27-22,864 pg/g, d.w.). Meanwhile, the DPs (anti-DP plus syn-DP) were in the range of ND-1229 pg/g (d.w.), and the range of f_anti values (the concentration of anti-DP divided by the sum of the concentrations of two isomers) in this study greatly matched those of commercial products, suggesting the effect of proximity to the source region. The higher levels of HFRs were found in Eastern and Southern regions of China. Spatial distribution implied that e-waste recycling activities and plastic processing have shown more importance in releasing legacy flame retardants (FRs) into the environment than the manufacturing process, while all are important for novel FRs. Correlation analysis between influencing factors and HFRs indicated that the distribution of most pollutants was more affected by anthropogenic source factors than environmental factors. The results of the principal component analysis demonstrated that deca-BDE and its alternative products were the major contributors to the sources of HFRs pollution. Human health risks assessment via oral intake and dermal contact pathways presented that the selected pollutants posed a no-carcinogenic risk to children and adults. It is worth noting that supervision of the disposal process of the NBFRs should be strengthened in the future.

Source, fate and budget of Dechlorane Plus (DP) in a typical semi-closed sea, China

Dechlorane Plus (DP), which has severe effects on marine ecosystems, has been proposed for listing under the Stockholm Convention as a persistent organic pollutant (POPs). This study was the first comprehensive investigation of the concentration and fate of DP in the Bohai Sea (BS) based on determination of river estuary water, river estuary sediment, surface seawater, bottom seawater, and sea sediments samples. The highest water DP levels were found in river estuary in Tianjin in North China due to the huge usage of DP in recent years, and spatial distribution analysis indicates it was mainly affected by regional high urbanization and emission of E-waste. The spatial distribution of DP in the BS was mainly affected by a combination of coastal hydrodynamics and land anthropogenic activities. On the basis of multi-box mass balance, simulations of DP in seawater showed an increase from 2014 to 2025, before leveling off at 184 pg L ^-1 by a constant DP input to the BS. Riverine discharge almost contributed to the total input (∼99%) and dominated the DP levels in the BS. Degradation of DP accounted for 55.3% and 78.1% of total DP output in seawater and sediment, respectively, indicating that degradation mainly affected decline of DP in the environment.

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.

Global emissions of Dechlorane Plus

Dechlorane Plus (DP) is a chlorinated flame retardant applied in parallel to or as a replacement product for regulated flame retardants. Detection of DP in environmental media all over the world in recent years necessitates the development of detailed global emission estimates for environmental model studies. Based on production, usage and disposal data two global atmospheric emission scenarios were made with a detailed geographical distribution. The total DP emission is estimated to be 0.02 t/year and 3.2 t/year in a low and high emission scenario, respectively, reflecting the uncertainties in production volumes and emission factors. The emission estimates are tested by implementation in the Danish Eulerian Hemispheric Model, an advanced chemistry-transport model. An evaluation against measurements in the Arctic from the early 2010s, considered to represent background concentrations, shows that the predicted concentration range for the high emission scenario is in line with the measured range, whereas the predicted concentrations for the low emission estimate are more than a factor of 100 lower than the measurements, rendering the high emission estimate most probable.

Assessment of Dechlorane Plus and related compounds in foodstuffs and estimates of daily intake from Lebanese population

Dechlorane Related Compounds (DRCs), including Dechlorane Plus (syn/anti-DP or syn/anti-DDC-CO) and related compounds (Dec-601 or DDC-ID, Dec-602 or DDC-DBF, Dec-603 or DDC-Ant and Chlordene Plus or DDC-PDD), are a group of polychlorinated flame retardants of concern since they were first reported in various environmental and biota matrices about one decade ago. In this work, we investigated the dietary intake of the Lebanese population to these lipophilic environmental contaminants upon the evaluation of selected foodstuff contamination. Collected food samples (n = 58) were selected to be representative of the lipid fraction of the whole diet of the Beiruti population. The samples were analysed using pressurized liquid extraction, silica multilayer column followed by gel permeation chromatography for purification and GC-EI-HRMS for separation and detection. Detection frequency of at least one compound among Dechlorane Plus (syn-DP and anti-DP), Dechlorane 602, 603 and Chlordene Plus) was 91%. The mean concentrations of ∑₆DRCs, by food group, ranged from 4.7 to 29.5 pg g^-1 wet weight in lowerbound (LB) and from 6.7 to 76.9 pg g^-1 wet weight in upperbound (UB). Based on food habits, the dietary intake of Beiruti adults was estimated to be between 3.71 (LB) and 5.61 (UB) ng day^-1. Dechlorane Plus and Dechlorane 602 were the dominant compounds, contributing to 70 and 24% of the total intake (LB value), respectively. This study reports for the first time the occurrence of Dechloranes in Lebanese foods and proposes corresponding deterministic dietary exposure scenario.

Assessment of selected chlorinated and brominated flame retardants in human plasma samples among co-residing family members

Three hexachloronorbornene-based flame retardants and five polybrominated diphenyl ethers (PBDEs) were measured in 414 human plasma samples, (169 from children, 167 from mothers, and 78 from fathers), collected from 200 families between 2014 and 2016. The median concentration of ∑PBDEs (sum of BDE-47, -99, -100, -153 and -183) was 13.2 ng/g lipid for child, 9.03 ng/g lipid for mother and 12.7 ng/g lipid for father, respectively. Among the hexachloronorbornene-based flame retardants, Dec 602 was the most frequently detected chemical. Significant and positive correlations between the concentrations of PBDE congeners as well as between Dec 602 and Dec 603 were observed. Concentrations of PBDE congeners also showed significant and positive correlations in paired samples from family members (child-mother-father), while Dec 602 was the only hexachloronorbornene-based flame retardant whose concentrations correlated between family members, and only in mother-father paired samples. This is the largest study to date focusing on measuring and correlating HRFs in children and their parents living in the same household. The results convey important information on human exposure to measured HFRs, which can help researchers and regulators more clearly understand the influence of diet and the home environment.

Characterization of brominated, chlorinated, and phosphate flame retardants in San Francisco Bay, an urban estuary

Flame retardant chemical additives are incorporated into consumer goods to meet flammability standards, and many have been detected in environmental matrices. A uniquely wide-ranging characterization of flame retardants was conducted, including polybrominated diphenyl ethers (PBDEs) and 52 additional brominated, chlorinated, or phosphate analytes, in water, sediment, bivalves, and harbor seal blubber of San Francisco Bay, a highly urbanized estuary once considered a hot spot for PBDE contamination. Among brominated flame retardants, PBDEs remained the dominant contaminants in all matrices, though declines have been observed over the last decade following their phase-out. Hexabromocyclododecane (HBCD) and other hydrophobic, brominated flame retardants were commonly detected at lower levels than PBDEs in sediment and tissue matrices. Dechlorane Plus (DP) and related chlorinated compounds were also detected at lower levels or not at all across all matrices. In contrast, phosphate flame retardants were widely detected in Bay water samples, with highest median concentrations in the order TCPP > TPhP > TBEP > TDCPP > TCEP. Concentrations in Bay water were often higher than in other estuarine and marine environments. Phosphate flame retardants were also widely detected in sediment, in the order TEHP > TCrP > TPhP > TDCPP > TBEP. Several were present in bivalves, with levels of TDCPP comparable to PBDEs. Only four phosphate flame retardants were detected in harbor seal blubber: TCPP, TDCPP, TCEP, and TPhP. Periodic, multi-matrix screening is recommended to track contaminant trends impacted by changes to flammability standards and manufacturing practices, with a particular focus on contaminants like TDCPP and TPhP that were found at levels comparable to thresholds for aquatic toxicity.

Bioaccumulation and cycling of polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DP) in three natural mangrove ecosystems of South China

Polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DP) in mangrove sediments and tissues of nine species from three Mangrove Reserves of Hainan Island were studied. The average concentrations of PBDEs and DP in mangrove leaves, branches, roots and fruits were 1048, 498, 546 and 364 pg g^-1 dw, and 294, 181, 108 and 165 pg g^-1 dw, respectively. The elevated PBDEs and DP concentrations in mangrove leaves may be caused by atmospheric sedimentation. The predominant PBDE congeners in sediments were BDE-209 and those in mangrove tissues were BDE-28. The average f_anti (ratio of [anti-DP]/[DP]) of DP in sediments and tissues were 0.47 and 0.32, respectively. Sonneratia hainanensis, a fast growing mangrove plant, has a relatively high tolerance and absorptive capacity to PBDEs and DP in sediments, suggesting that it could be used as an effective plant for phytoremediation. The biota sediment accumulation factors (BSAFs) of PBDEs in mangrove branches were positively correlated with log K_OW (R² = 0.43, p < 0.05). The standing accumulation, annual absorption, annual net retention, annual return, and turnover period of PBDEs and DP in mangrove tissues of the ecosystems were estimated, and the results indicated that mangroves are playing an important role in retaining PBDEs and DP.

Validation and Application of a 3-Step Sequential Extraction Method to Investigate the Fraction Transformation of Organic Pollutants in Aging Soils: A Case Study of Dechlorane Plus

A 3-step sequential extraction method was developed to characterize the "labile," "stable-adsorbed," and "bound-residue" fractions of Dechlorane Plus (DP) in aging soils. Afterward, the proposed method was used to observe the transformation of DP fractions during aging. Slight decrease of total DP concentrations suggested there was a rather limited degradation, with only 4.2-8.2% of initial DP having degraded after 260 days. The labile fraction, which indicated the bioavailability of DP, decreased from 25.5% to 8.2%. The bound-residue fraction, usually regarded as a route for detoxification, increased from 0.1% to 18.5%. Model simulations were then developed to investigate the transformation, indicating that transformation rates were inconstant and distinguishable over time. Half-lives of DP were estimated to range from 1325 to 2948 days, indicating its environmental persistence in aging soils. Through Sobol Global Sensitivity Analysis (SGSA), degradation was evaluated to be the most sensitive factor of effecting the DP transformation in aging soils. Furthermore, the f_syn values increased from 0.26 to 0.37 in the labile fraction and decreased from 0.25 to 0.18 in the bound-residue fraction. The observed stereoselectivity difference might be the cause of the stereoselective accumulation of DP in terrestrial organisms.

Distributions, influencing factors, and risk assessment of Dechlorane Plus and related compounds in surficial water and sediment from the Jiulong River Estuary, Southeast China

Dechloranes, a type of additive polychlorinated flame retardant, which include Dechlorane (Dec) Plus (DP), Dec 602, Dec 603, and Dec 604, were detected in surficial water and sediment from the Jiulong River Estuary (JRE). The total concentration of dechloranes in the water and sediments ranged from 1.4 to 4.1 ng/L and 9.3 to 36.2 ng/g dry weight, respectively. The distribution patterns of dechloranes in the water and sediments were both dominated by DP. The average values of the anti-DP fractional abundances (f_anti) in the water and sediment samples both were fell in the range of commercial DP mixtures. The relationships of DP in the water with suspended particulate matter (SPM), total organic carbon (TOC), and tides indicated that the combined actions of these environmental factors influenced the distribution of DP in the JRE. The deleterious risk associated with exposure to dechloranes via the water for adults was very low, suggesting that exposure of the local population of dechloranes via water is relatively safe in the JRE.

Enrichment and physiological responses of dechlorane plus on juvenile marine macroalgae (Ulva pertusa)

Dechlorane Plus (DP), a chlorinated flame retardant, is increasingly reported in aquatic ecosystems worldwide. But little information is available regarding the toxicity of DP in marine organisms, especially in macroalgae. The objective of this study was to investigate effects of DP exposure on photosynthesis, oxidative stress and its enrichment in juvenile marine macroalgae (Ulva pertusa). Following 21- day uptake and 21- day depuration (10^-8 mol/L), algae accumulated 1.18 times of DP compared to the initial concentration. Anti-DP was prone to accumulate in juvenile macroalgae. The enrichment of DP affected the physiological responses in algae. After 1, 7 and 14 days DP exposure (10^-8, 10^-7 and 10^-6 mol/L), antioxidant enzymes (SOD and CAT) activities and MDA content changed in a dose and time depended manner. Chlorophyll fluorescence parameters, including F_v/F_m, Φ_PSII and ETR decreased with the increasing DP concentration. It indicated that DP leads to a low rate of light energy utilization in algae which may ascribe to the oxidative damage induced by DP enrichment. Present study provides insight into the toxicological effects of DP on marine macroalgae, which is useful for risk assessment of DP in intertidal zone ecosystems.

E-Waste Driven Pollution in Pakistan: The First Evidence of Environmental and Human Exposure to Flame Retardants (FRs) in Karachi City

Informal e-waste recycling activities have been shown to be a major emitter of organic flame retardants (FRs), contributing to both environmental and human exposure to laborers at e-waste recycling sites in some West African countries, as well as in China and India. The main objective of this study was to determine the levels of selected organic FRs in both air and soil samples collected from areas with intensive informal e-waste recycling activities in Karachi, Pakistan. Dechlorane Plus (DP) and "novel" brominated flame retardants (NBFRs) were often detected in high concentrations in soils, while phosphorus-based FRs (OPFRs) dominated atmospheric samples. Among individual substances and substance groups, decabromodiphenyl ether (BDE-209) (726 ng/g), decabromodiphenyl ethane (DBDPE) (551 ng/g), 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) (362 ng/g), and triphenyl-phosphate (∑TPP) (296 ng/g) were found to be prevalent in soils, while OPFR congeners (5903-24986 ng/m³) were prevalent in air. The two major e-waste recycling areas (Shershah and Lyari) were highly contaminated with FRs, suggesting informal e-waste recycling activities as a major emission source of FRs in the environment in Karachi City. However, the hazards associated with exposure to PM_2.5 appear to exceed those attributed to exposure to selected FRs via inhalation and soil ingestion.

Dechlorane Plus induces oxidative stress and decreases cyclooxygenase activity in the blue mussel

Dechlorane Plus (DP) is a chlorinated flame retardant used mainly in electrical wire and cable coating, computer connectors, and plastic roofing materials. Concentrations of DP (syn and anti isomers) are increasingly being reported in aquatic ecosystems worldwide. However, there is exceedingly little information on the exposure-related toxicity of DP in aquatic organisms, especially in bivalves. The objective of this study was to investigate the in vivo and in vitro effects of DP exposure on histopathology, lipid peroxidation (LPO) levels, cyclooxygenase (COX) activity, phagocytosis capacity and efficiency, and DNA strand breakage in the blue mussel (Mytilus edulis) following a 29days exposure (0.001, 0.01, 0.1 and 1.0μg DP/L). Blue mussels accumulated DP in muscle and digestive gland in a dose-dependent manner. LPO levels in gills were found to increase by 82% and 67% at the 0.01 and 1.0μg DP/L doses, respectively, while COX activity in gills decreased by 44% at the 1μg/L dose. No histopathological lesion was found in gonads following DP exposure. Moreover, no change in hemocyte DNA strand breakage, phagocytosis rate, and viability was observed following DP exposure. Present study showed that toxicity of DP may occur primarily via oxidative stress in the blue mussel and potentially other bivalves, and that gills represent the most responsive tissue to this exposure.

Atmospheric deposition of PBDEs and DPs in Dongjiang River Basin, South China

The atmospheric deposition fluxes of polybrominated diphenyl ethers (PBDEs) and Dechlorane Plus (DPs) in Dongjiang River Basin of the Pearl River Delta in South China were investigated during winter and summer, respectively. The total deposition fluxes varied from 4.74 to 27.0 ng/m²/day for PBDEs and 8.77 to 206 ng/m²/day for DPs, respectively. The fractions of anti-DP to the total DPs (f _anti) varied from 0.28 to 0.63 (mean = 0.43 ± 0.06), i.e., generally lower than those in commercial products, which might be attributed to the different environmental fates of the two isomers. Significant seasonal and spatial variations of PBDEs and DPs were observed. The deposition fluxes in summer were generally higher than those in winter, which may be due to the relatively high temperature and rainfall in summer under the influence of prevailing subtropical monsoon climate. Moreover, high deposition fluxes of PBDEs and DPs in urban areas and significant urban/rural gradient implied that local industrial activities in the urban areas were primary sources, which were further confirmed by the results of principal component analysis. The highest deposition of PBDE and DP fluxes was found at different sampling sites, suggesting PBDEs and DPs may be derived from different industries or products.

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).

Occurrence of Dechlorane compounds and polybrominated diphenyl ethers (PBDEs) in the Korean general population

Dechlorane compounds, including Dechlorane Plus (DP), mirex, and Dechlorane (Dec) 602, 603 and 604, were measured in 61 serum samples collected from a Korean urban area (Seoul) in 2013. Dechlorane Plus and Dec 602 were dominant in most samples, whereas Dec 604 was not detected in any samples. The median value of DP was 0.75 ng/g lipid, which was comparable with the levels observed in Europe and Canada, but lower than that observed in China. Statistically significant correlations among Dechlorane compounds were observed. The median anti-isomer fractional abundance (fanti) was 0.74, and a negative correlation between fanti and the DP concentration in serum samples was observed. Polybrominated diphenyl ethers (PBDEs) were also measured for comparison with Dechlorane compounds, and BDE-153 was found the most abundant congener with a median value of 1.43 ng/g lipid. A time trend of Dechlorane compounds was investigated in 7 pooled serum samples to cover the period from 2006 to 2013. A distinct trend of Dechlorane compounds was not observed, while PBDEs steadily decreased with time.

Toxicological responses following short-term exposure through gavage feeding or water-borne exposure to Dechlorane Plus in zebrafish (Danio rerio)

Dechlorane Plus (DP) is a chlorinated flame retardant widely used worldwide, and has been reported in environment and humans. However, only limited information is currently available on its toxicity on aquatic organisms. In this study, we employed zebrafish to evaluate possible toxicological responses including oxidative stress and endocrine disruption following exposure to DP. DP was dissolved in corn oil and was delivered to adult male zebrafish via gavage feeding. Delivery of DP was carried out twice on days 0 and 2, at up to 3 μg/g fish wet weight. Body residue level of DP in the fish at day 6 was within a range that has been reported in hot spot areas of China. On day 6, blood, liver, testis, and brain were collected and were evaluated for oxidative damage and endocrine disruption. Following DP exposure, hepatic catalase activity significantly increased, implying its oxidative damage potential. In addition, plasma thyroxine (T4) concentrations increased along with up-regulation of corticotropin releasing hormone and thyroid stimulating hormone β genes in brain. Following DP exposure, transcriptional responses of sex hormone related genes in brain were observed, suggesting possible sex hormone disrupting potentials of DP. However, water-borne exposure to DP up to 267 μg/L among the embryo and larval fish did not show any adverse effects on hatching time and transcription of thyroid hormone related genes. Our observations indicate for the first time that DP disrupts thyroid hormone balance of zebrafish by altering regulatory pathways in the brain. Handling editor: David Volz.

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.

Levels and distribution of dechloranes in sediments of Lake Taihu, China

The occurrence and spatial distribution of dechloranes including mirex, dechlorane plus (DP), dechlorane (Dec) 602, Dec 603, and Dec 604 in surficial sediments of Lake Taihu were investigated in this study. The concentrations of mirex and DP ranged from below detection limit (BDL) to 1.29 ng g(-1) dw and 0.051 to 2.10 ng g(-1) dw, respectively. Dec 602, Dec 603, and Dec 604 on the other hand, were BDL in any of the samples. The contamination levels of DP were higher than that of Mirex at 21 of all 22 sampling sites. Levels of mirex and DP in the lake sediments were correlated when an extremely high mirex value was removed. Both mirex and DP levels were correlated with the amount of organic matters in the sediment samples. Spatial distribution of mirex and DP suggested that these two chemicals in the lake had similar input sources except for one site. Comparison to previously reported flame retardants' levels in the sediments shows that DP levels were similar with the levels of tetrabromobisphenol A, hexabromocyclododecane but lower than PBDEs and organophosphates levels in Lake Taihu. The higher levels in the north-east part of Lake Taihu adjacent to two major cities: Wuxi and Suzhou, indicated that city effluent might be a major source for DP contamination in the lake.