Dechlorane Plus Research Articles

Spatial distribution of Dechlorane Plus and dechlorane related compounds in European background air

The highly chlorinated chemical Dechlorane Plus (DP) was introduced as a replacement flame retardant for Mirex, which is banned through the Stockholm Convention (SC) for its toxicity (T), environmental persistence (P), potential for bioaccumulation (B) and long-range environmental transport potential (LRETP). Currently, Dechlorane Plus is under consideration for listing under the Stockholm Convention and by the European Chemical Agency as it is suspected to also have potential for P, B, T and LRET. Knowledge of atmospheric concentrations of chemicals in background regions is vital to understand their persistence and long-range atmospheric transport but such knowledge is still limited for Dechlorane Plus. Also, knowledge on environmental occurrence of the less described Dechlorane Related Compounds (DRCs), with similar properties and uses as Dechlorane Plus, is limited. Hence, the main objective of this study was to carry out a spatial mapping of atmospheric concentrations of Dechlorane Plus and Dechlorane Related Compounds at background sites in Europe. Polyurethane foam passive air samplers were deployed at 99 sites across 33 European countries for 3 months in summer 2016 and analyzed for dechloranes. The study showed that syn- and anti-DP are present across the European continent (<MDL-2.6 pg/m3 and <MDL-12.3 pg/m3, respectively), including parts of the Arctic. This supports that these compounds have potential for long-range atmospheric transport to remote regions. The highest concentrations of Dechlorane Plus were observed in central continental Europe, with anti-DP fractions close to the commercial mixture of Dechlorane Plus. The only detected Dechlorane Related Compounds was Dechlorane-602, which was found in 27% of the samples (<MDL-0.33 pg/m3). The measured concentrations and spatial patterns of Dechlorane Plus and Dechlorane-602 in air across Europe indicate the influence of primary sources of these compounds on background concentrations in European air. Future air monitoring efforts targeting dechloranes is needed in both background and source areas, including consistent temporal trends.

Disentangling Source Profiles and Time Trends of Halogenated Flame Retardants in the Great Lakes.

Thirty-five polybrominated diphenyl ethers (PBDEs) and eight other alternative flame retardants were measured in air samples (vapor plus particles) collected at six sites near the North American Great Lakes between 2005 and 2019 as part of the Integrated Atmospheric Deposition Network (IADN). These data were analyzed using a multiple linear regression model to determine spatial and temporal trends. Overall, the levels of flame retardants remain significantly higher in urban sites compared to rural and remote sites except for pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), and total Dechlorane Plus (ΣDP). Here, we report the first findings of decreasing levels of ΣDP at Sturgeon Point, New York. The atmospheric levels of total PBDEs remain unchanged over time near Lakes Michigan and Superior and declined near Lakes Erie and Ontario, with rate constants at the latter two lakes revealing halving times of approximately 7 to 14 years. This work presents results from the first investigation of PBDE source apportionment in the Great Lakes atmosphere. Source apportionment by use of positive matrix factorization (PMF) identified two legacy commercial technical mixtures (i.e., penta-BDE and deca-BDE mixes) and elucidated a factor representing ambient degradation. Our results show that weathered local sources of technical commercial mixtures, and their photolysis contribute most to the total PBDE burden in the Great Lakes atmosphere.

Exposure to flame retardants in European children - Results from the HBM4EU aligned studies.

Many legacy and emerging flame retardants (FRs) have adverse human and environmental health effects. This study reports legacy and emerging FRs in children from nine European countries from the HBM4EU aligned studies. Studies from Belgium, Czech Republic, Germany, Denmark, France, Greece, Slovenia, Slovakia, and Norway conducted between 2014 and 2021 provided data on FRs in blood and urine from 2136 children. All samples were collected and analyzed in alignment with the HBM4EU protocols. Ten halogenated FRs were quantified in blood, and four organophosphate flame retardants (OPFR) metabolites quantified in urine. Hexabromocyclododecane (HBCDD) and decabromodiphenyl ethane (DBDPE) were infrequently detected (<16% of samples). BDE-47 was quantified in blood from Greece, France, and Norway, with France (0.36ng/g lipid) having the highest concentrations. BDE-153 and -209 were detected in <40% of samples. Dechlorane Plus (DP) was quantified in blood from four countries, with notably high median concentrations of 16ng/g lipid in Slovenian children. OPFR metabolites had a higher detection frequency than other halogenated FRs. Diphenyl phosphate (DPHP) was quantified in 99% of samples across 8 countries at levels ∼5 times higher than other OPFR metabolites (highest median in Slovenia of 2.43ng/g lipid). FR concentrations were associated with lifestyle factors such as cleaning frequency, employment status of the father of the household, and renovation status of the house, among others. The concentrations of BDE-47 in children from this study were similar to or lower than FRs found in adult matrices in previous studies, suggesting lower recent exposure and effectiveness of PBDE restrictions.

Regional soil contamination by halogenated organic pollutants attributed to E‐waste recycling, scattered industrialization and urbanization

AbstractRapid urbanization and industrialization can lead to the accumulation of toxic halogenated organic pollutants (HOPs) in soil environments, which poses a risk to the wider eco‐environment. In this study, we explored the occurrence and health risks of halogenated organic pollutants by analysing surface soil samples (n = 209) collected from various E‐waste dismantling, industrialized and urban areas, rural areas and remote areas in Zhejiang Province, China. The mean average concentrations (d.w.) and range (min–max) of the HOPs were Dechlorane plus (DP) = 0.14 ng/g (below detection limit (&lt;DL) to 3.60 ng/g); short‐chain chlorinated paraffins (SCCPs) = 111.00 ng/g (&lt;DL to 1736.00 ng/g); polychlorinated biphenyls (PCBs) = 1.20 ng/g (&lt;DL to 15.00 ng/g); and polybrominated diphenyl ethers (PBDEs) = 21.30 ng/g (&lt;0.16–673.00 ng/g). In the different areas sampled, the soil pollution level of HOP was in the order of E‐waste dismantling areas &gt; industrialized and urban areas &gt; rural areas &gt; remote areas. Nevertheless, we observed high detection ratios in rural and remote areas, indicating scattered industrialization led to ubiquitous HOP soil pollution in the region.

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.

Occurrence and ecological risks of brominated flame retardants and dechlorane plus in sediments from the Pearl River Estuary and Daya Bay, South China.

Considering the phasing-out of polybrominated diphenyl ethers (PBDEs), environmental concerns of PBDE alternatives and dechlorane plus (DP) are rising. Accordingly, this study investigates occurrence and ecological risks of PBDEs, PBDE alternatives and DPs in sediments of two littoral regions, the Pearl River Estuary (PRE) and Daya Bay (DYB), in southern China. Total PBDEs concentrations in surface sediments of the PRE and DYB were in the range (mean) of 0.30-28.7 (8.71) and 0.29-43.4 (6.05) ng/g dw, respectively. DP levels in surface sediments of the PRE (0.004-0.27ng/g dw) were significantly higher than those in the DYB (0.005-0.24ng/g dw) (p<0.05). BDE 209 was the predominant component, followed by DBDPE, exhibiting regional variations in BFRs usage. Vertical profiles of BFRs and DP in the PRE and DYB sediment cores exhibited clear anthropogenic influences. Risk quotients suggest critical ecological risks of tetra-, penta- and deca-BDE congeners in all the surface sediments.

Phytotoxicity, uptake, and translocation of two halogenated flame retardants and cadmium in two rice varieties

Dechlorane Plus (DP) and Tetrabromobisphenol A (TBBPA) are the halogenated flame retardant with the highest production volume, cadmium (Cd) is regarded as one of the hazardous heavy metals due to its bio toxicity and bioaccumulation in the environment, and it will cause environmental pollution and affect human health, so a pot experiment was conducted to investigate the phytotoxicity on seed germination and seedling of two rice varieties. The results showed that with the increasing of DP, TBBPA and Cd concentrations in soil, the germination rate, germination index and vigor index of two rice varieties decreased, and the germination of Number 7 rice was affected more than Number 1 rice. Halogenated flame retardants and Cd in soil significantly promoted root activity and proline, and significantly inhibited protein and soluble sugar contents of two rice varieties. In addition, the responses of the two rice varieties seedlings to different pollutants were obviously different. The activity of superoxide dismutase (SOD) in two kinds of rice was improved, and a large amount of malonyldialdehyde (MDA) was induced. But the activity of catalase (CAT) in Number 7 rice was increased under the action of DP and TBBPA, while the activity of Number 1 rice was increased under the action of DP and inhibited under the pollution of TBBPA. Bioaccumulation factors of DP and Cd were 0.025–0.042 and 6.59–14.20, bio transport coefficients were 0.39–0.48 and 0.034–0.087. There was no significant difference in the bioaccumulation of DP in the two rice varieties, but TBBPA and Cd were more easily bio accumulated in the Number 1 rice. These findings would provide some essential information for interpreting the ecological risks of two halogenated flame-retardants and Cd in plants.

Composition profiles of halogenated flame-retardants in the surface soils and in-situ cypress leaves from two chemical industrial parks

There is limited information available regarding the investigation on typical organic pollutants between the soil and in-situ grown plant leaves. This study is to reveal whether the pollution characteristics of soil and leaves can reflect the long-term and short-term pollution situation, and to find the differences between halogenated flame-retardants in the surface soils and in-situ cypress leaves. Polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), and decabromodiphenyl ethane (DBDPE) in were investigated in two different industrial parks, which were located at the largest brominated flame-retardant-manufacturing center in Weifang, China. These chemicals were frequently detected with high median concentrations of PBDEs (1.22 × 103 ng/g) and DBDPE (227 ng/g) in the soil samples, and DBDPE (881 ng/g) and PBDEs (461 ng/g) in the in-situ cypress leaves. The DP concentration was 1–4 orders of magnitude lower than the other two chemicals in both the matrices. Different composition profiles of the chemicals in soil and cypress leaves were observed. The PBDEs and DBDPE were found to be the predominant species in soils and cypress leaves, respectively. In comparison, the LG industrial parks had higher concentrations of PBDEs and DBDPE in both the soils and cypress leaves. No significant correlations were observed for these chemicals between the soil and leaf samples, although significant correlations (p < 0.05) were observed for several PBDE congeners among all samples from the industrial parks and a separate industrial park. The results indicated that the soil was not the important source of these chemicals in leaves. A large proportion of DBDPE was preferentially present in cypress leaves, which revealed the situation of recent pollution. The results deepen the understanding of chemical distribution characteristics among different environmental matrices in soils and leaves.

Factors Influencing Dechlorane plus Distributions in Various Sheep Tissues.

Dechlorane plus (DP) is a potential persistent organic pollutant and its distribution in various tissues and organs of terrestrial organisms is currently unknown. DP concentrations in sheep tissues were determined in this study. The DP concentrations in the tissues decreased in the following order: abdominal fat > liver > stomach > heart > outer tenderloin > lung > hind leg meat > kidney > small intestine > tail fat > spleen > brain. Apart from brain and fat, anti-DP is enriched more readily than syn-DP in sheep tissues, but syn-DP is more readily enriched in brain and abdominal fat. The factors influencing DP distributions in sheep tissues were assessed by determining the DP to sheep serum albumin binding forces, binding types, and binding sites by fluorescence spectroscopy. The results indicated that anti-DP more readily binds to sheep serum albumin than does syn-DP. Therefore, sheep serum albumin will more readily transport anti-DP than syn-DP to sheep tissues, and anti-DP will be enriched more than syn-DP in the tissues. The molecular diameter of DP is the main factor affecting DP concentrations in sheep brain and fat because of the blood–brain barrier and because the main source of DP to abdominal fat is dermal contact.

Comparison of Dechlorane Plus Concentrations in Sequential Blood Samples of Pregnant Women in Taizhou, China.

To develop an appropriate sampling strategy to assess the intrauterine exposure to dechlorane plus (DP), we investigated DP levels in sequential maternal blood samples collected in three trimesters of pregnancy, respectively, from women living in Taizhou. The median concentration of DPs (sum of syn-DP and anti-DP) in all samples was 30.5 pg g−1 wet-weight and 5.01 ng g−1 lipid-adjusted weight, respectively. The trimester-related DP concentrations were consistently strongly correlated (p < 0.01), indicating that a single measurement of DP levels could represent intrauterine exposure without sampling from the same female repeatedly; however, the wet-weight levels significantly increased across trimesters (p < 0.05), while the lipid-adjusted levels did not significantly vary. Notably, whether lipid-adjusted weight or wet-weight levels, the variation extent of DP across trimesters was found to be less than 41%, and those for other persistent organic pollutants (POPs) reported in the literature were also limited to 100%. The limitation in variation extents indicated that, regardless of the time of blood collection during pregnancy and how the levels were expressed, a single measurement could be extended to screen for exposure risk if necessary. Our study provides different strategies for sampling the maternal blood to serve the requirement for assessment of in utero exposure to DP.

Historical record of legacy and alternative halogenated flame retardants in dated sediment from a highly industrialized saltwater lake in Korea

Legacy and alternative halogenated flame retardants (HFRs), such as polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs), and dechlorane plus (DP), were measured in dated sediments from a highly industrialized lake in Korea. All HFRs were detected in almost all of the sediment depth layers for more than 70 years, indicating a history of long-term contamination. Similar historical trends in PBDEs, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and DP were observed in dated sediments, whereas decabromodiphenylethane (DBDPE), and 2-ethylhexyl-2,3,4,5-octabromo-1,3,3-trimethyl-1-phenylindane (OBIND) concentrations sharply increased since the 1990s. Moreover, the concentration ratios of DBDPE/BDE 209 increased from the early 1990s to the present. Our findings suggest that DBDPE and OBIND have been used as HFR alternatives. The historical record of the concentrations and profiles of legacy and alternative HFRs corresponded with industrial activities, consumption of FRs, and coastal development activities. Inventories of legacy and alternative HFRs were similar to those reported for highly industrialized regions around the globe.

Effect of Affinity between Dechlorane Plus and Human Serum Albumin on Its Serum Concentration in a General Population.

Dechlorane Plus (DP) has been detected in human serum around the world. Determining how DP binds to human serum albumin (HSA) could improve our understanding of the effects of DP in humans. The results of a fluorescence titration experiment indicated that DP binds to HSA at the interface between domains IIA and IIB, and HSA has more affinity for anti-DP than syn-DP. The DP concentrations in serum from 33 people living in Wuxi City, China, were determined in five consecutive years (2012-2016). The total concentrations of the two DP isomers were 1.73-16.3 ng·g-1 lipid weight (mean 4.7 ng·g-1 lipid weight). No clear increasing or decreasing temporal trend was found in the DP concentrations in serum over the study period. The affinity between DP and HSA will increase as the amount of fatty acids combined with HSA increases. This explained the syn-DP and anti-DP concentrations in serum being higher for overweight people than for normal weight people. Ethanol can occupy the DP binding sites on HSA. This explained the syn-DP and anti-DP concentrations being lower for alcoholic people than for nonalcoholic people.

Increasing Trends of Legacy and Emerging Organic Contaminants in a Dated Sediment Core From East-Africa

Temporal trends of industrial organic contaminants can show how environmental burdens respond to changes in production, regulation, and other anthropogenic and environmental factors. Numerous studies have documented such trends from the Northern Hemisphere, while there is very limited data in the literature from sub-Saharan Africa. We hypothesized that the temporal trends of legacy and contemporary industrial contaminants in sub-Saharan Africa could greatly differ from the regions in which many of these chemicals were initially produced and more extensively used. For this purpose, a dated sediment core covering six decades from a floodplain system in urban Dar es Salaam, Tanzania, was analysed. The samples were analysed for selected legacy persistent organic pollutants (POPs) [polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs)] and chemicals of emerging concern (CECs) [alternative brominated flame retardants (aBFRs), chlorinated paraffins (CPs), and dechloranes]. All groups of chemicals showed a steep increase in concentrations towards the uppermost sediment layers reflecting the more recent years. Concentrations of the individual compound groups in surface sediment were found in the order CPs &amp;gt;&amp;gt; aBFRs ∼ ∑25PBDEs &amp;gt; dechloranes ∼ ∑32PCBs. Time trends for the individual compounds and compound groups differed, with ∑32PCBs showing presence in sediments since at least the early 1960s, while some CECs first occurred in sediments corresponding to the last decade. Investigations into potential drivers for the observed trends showed that socioeconomic factors related to growth in population, economy, and waste generation have contributed to increasing concentrations of PBDEs, aBFRs, CPs, and Dechlorane Plus. Further monitoring of temporal trends of industrial organic contaminants in urban areas in the Global South is recommended.

Sex- and size-dependent accumulation of Dechlorane Plus flame retardant in a wild frog-eating snake Amphiesma stolata

Despite several studies having addressed the bioaccumulation of Dechlorane Plus (DP) flame retardant in wildlife, there is still a dearth of information for reptiles in general and for snakes in particular. Here, we report the residue levels and trophic transfer of syn-, anti-, and anti-Cl11-DP in a frog-eating snake—namely, the striped keelback snake Amphiesma stolata—from a DP hotspot in South China. The concentrations of syn-, anti-, and anti-Cl11-DP in A. stolata ranged from 1.06–21.2, 2.13–21.5, and 0.16–10.6 ng/g lipid weight, respectively, with significantly higher levels in males compared with females. Statistical analysis showed that the concentrations of these chemicals were negatively correlated with body sizes (length and mass) of the snake. The fractional abundance of anti-DP (fanti) did not significantly differ either between the sexes or between A. stolata and its diet (i.e., frogs). However, fanti showed positive correlations with the snake's body size and negative correlations with ∑DP concentrations (summed concentrations of syn- and anti-DP), indicating that body size and DP residue levels are important factors influencing DP isomeric profiles in these snakes. Biomagnification factors estimated based on the relationship between A. stolata and frogs were 0.49 ± 0.01 (mean ± SE), 0.44 ± 0.09, and 1.79 ± 0.54 for syn-, anti-, and anti-Cl11-DP, respectively, suggesting trophic dilution of syn- and anti-DP and a mild biomagnification of anti-Cl11-DP from frogs to snakes.

Species-specific dechlorane plus isomer fractionation during bioaccumulation: phenomenon and potential mechanisms

The occurrence and behavior of dechlorane plus (DP), an additive chlorinated flame retardant, have been intensively studied since it was identified in 2006. The commercial products of DP are a mixture of two stereoisomers: syn-DP and anti-DP. Stereoselective bioaccumulation of DP isomers in biota was reported in field monitoring and laboratory experiments. This review summarizes stereoselective bioaccumulation of DP in biota samples and provides the potential mechanisms for this stereoselective bioaccumulation. Stereoselective enrichment of syn-DP was widely observed in fish, whereas selective enrichment of anti-DP was mainly found in some birds. This species-specific stereoselective enrichment of DP might reflect that two different types of DP isomer fractionation occurred in bioaccumulation between ectotherms and endotherms. Anti-DP is more readily metabolized through biotransformation in all animals. However, a preferential excretion of anti-DP in fish and syn-DP in birds was observed based on the available data. Both processes determine the DP isomer fractionation in bioaccumulation. A direct comparison in DP composition between biological samples and commercial products was conducted for most studies to determine the occurrence of stereoselective DP enrichment, which may lead to underestimating the potential stereoselective enrichment of DP in organisms. The factors which affected the DP isomer composition in organisms included the tissues or organs used, DP concentration, organisms’ trophic levels occupied, and sex. Inconsistent results were obtained considering the effects of these influence factors. The underlying cause of these inconsistent results is unclear based on present data. Further research on DP biotransformation and interactions between DP and biomacromolecule is needed.

Persistent and toxic chemical pollutants in fish consumed by Asians in Chicago, United States

Consumption of seafood brings health benefits but may increase the ingestion of contaminants. Compared with other ethnic groups in the U.S., Asians consume seafood more frequently. However, there is little information about how culturally specific fish consumption contributes to exposure to toxicants. In this work, we surveyed fish consumption among Chinese, Korean and Vietnamese communities and purchased 103 seafood samples from local markets in Chicago. Each sample was analyzed for mercury (Hg) and 92 organic chemicals including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), and Dechlorane Plus and related compounds (DPs). The rank order of pollutant concentration in all samples was Hg ≫ Σ66PCBs > Σ17OCPs > Σ8PBDEs > Σ8DPs. Positive correlations were noted among most contaminant groups. Bluefish, pike and tuna steak had the highest mean Hg (>1 mg/kg). The mean Σ66PCBs was highest in pike and bluefish (>100 ng/g) followed by pollock and mackerel (>40 ng/g). Overall, octopus, shrimp and tilapia were the least contaminated; while pike, bluefish, and pollock were the most contaminated. Omega-3 fatty acids were more strongly affiliated with the organic contaminants than mercury. A risk assessment identified seven types of fish that should have consumption limitations and six that should not be consumed. For these seafoods, consumption advice based on Hg levels would adequately protect health. In the survey participants, 17% of seafood mass consumed is from types of fish that should be limited to 1 or 2 meals/week, while 7% of the seafood mass consumed comes from types that should not be consumed at all. This work adds additional contaminants to the profile of health risks resulting from fish consumption among Asian Americans, which can be used in interventions aimed at conserving consumption of healthy fish while avoiding contaminants.

Biological response and phytoremediation of perennial ryegrass to halogenated flame retardants and Cd in contaminated soils

Two halogenated flame-retardants and cadmium in soil is harmful to human health, in order to study the biological response and bioaccumulation ability of ryegrass to pollution stress, the phytotoxicity to seedlings and the phytoremediation effect in contaminated soil were investigated. It showed that proline and malonaldehyde (MDA) contents and antioxidant enzyme activity of ryegrass seedlings were increased, cadmium was the most toxic to ryegrass seedlings. The bioconcentration factor (BCF) of roots is higher than shoot. Ryegrass could assimilate trace amount of Dechlorane Plus (DP) and Tetrabromobisphenol A (TBBPA), and its dissipation in soil mainly due to the root exudates and rhizosphere microorganisms. T1/2 of syn-DP, anti-DP and TBBPA was 42.01, 39.38 and 74.53 d in the single pollution, T1/2 prolonged in combined pollution. Cadmium in the roots and stems is 27.82 mg/kg and 10.25 mg/kg in the treatment of single pollution, biological accumulating coefficient (BAC) and biological transfer coefficient (BTC) were 2.16 and 0.37. Ryegrass could effectively reduce total cadmium in soil; the optimal bioremediation time was 60 days. The phytoremediation ability and phytoextraction efficiency of ryegrass in contaminated soil were clarified, which would be useful for understanding the fate of halogenated flame-retardants and Cd in phytoremediation for contaminated soil.

Spatial trends of chlorinated paraffins and dechloranes in air and soil in a tropical urban, suburban, and rural environment

There are large knowledge gaps concerning environmental levels and fate of many organic pollutants, particularly for chemicals of emerging concern in tropical regions of the Global South. In this study, we investigated the levels of chlorinated paraffins (CPs) and dechloranes in air and soil in rural, suburban, and urban regions in and around Dar es Salaam, Tanzania. Samples were also collected near the city's main municipal waste dumpsite and an electronic waste (e-waste) handling facility. In passive air samples, short chain CPs (SCCPs) dominated, with an average estimated concentration of 22 ng/m3, while medium chain CPs (MCCPs) had an average estimated concentration of 9 ng/m3. The average estimated air concentration of ∑dechloranes (Dechlorane Plus (DP) + Dechlorane 602 + Dechlorane 603) was three to four orders of magnitudes lower, 2 pg/m3. In soil samples, MCCPs dominated with an average concentration of 640 ng/g dw, followed by SCCPs with an average concentration of 330 ng/g dw, and ∑dechloranes with an average concentration of 0.9 ng/g dw. In both air and soil, DP was the dominating dechlorane compound. Urban pulses were observed for CPs and dechloranes in air and soil. CPs were in addition found in elevated levels at the municipal waste dumpsite and the e-waste handling facility, while DPs were found in elevated levels at the e-waste handling facility. This suggests that waste handling sites represent important emission sources for these pollutants. Investigations into seasonal trends and environmental fate of CPs and dechloranes showed that monsoonal rain patterns play a major role in governing air concentrations and mobility, particularly for the less volatile MCCPs and dechloranes. This study is the first to report levels of CPs in air from sub-Saharan Africa, and DP, Dechlorane 602, and Dechlorane 603 in soil from sub-Saharan Africa.

Halogenated flame retardants in wild, prey-sized mud carp from an e-waste recycling site in South China, 2006–2016: Residue dynamics and ecological risk assessment

The crude e-waste recycling has been regulated in China since the late 2000s; however, information on the recent levels and the ecological risks of e-waste derived contaminants such as halogenated flame retardants (HFRs) in the e-waste sites are limited. We therefore examined the concentrations of several HFRs in wild, prey-sized mud carps collected from a typical e-waste site in 2006, 2011 and 2016, to understand the exposure dynamics and ecological risk of these chemicals. Several ecological and biological parameters including δ15N, δ13C, body size and lipid content of the fish were also examined, to ensure an overall uniformity of the sample set among the sampling years. Among the HFRs measured, polybrominated diphenyl ethers (PBDEs) were detected at the highest concentrations (contributing >90% to ∑HFRs), followed by Dechlorane Plus (DPs), polybrominated biphenyls (PBBs), and alternative brominated flame retardants (ABFRs). The fish concentrations of ∑PBDEs, ∑PBBs and ∑DPs significantly dropped by 65%, 57% and 53% from 2006 to 2011, and 12%, 74% and 51% from 2011 to 2016, respectively; likely reflecting the positive impact of the environmental regulations on crude e-waste recycling. The ∑ABFRs concentrations were also decreased by 80% from 2006 to 2011, but increased by 127% from 2011 to 2016; suggesting possible fresh input of these novel HFRs in recent years. In addition to the changes in the HFR concentrations, contaminant profiles in the fish were also changed, possibly due to environmental degradation of the HFRs. Despite our conservative method of risk assessment, we found that PBDEs posed an important risk both for the mud carp and for piscivorous wildlife that inhabit the e-waste site.

Flame retardants and their associations with thyroid hormone-related variables in northern fulmars from the Faroe Islands

Flame retardants (FRs) are widely reported in tissues of seabirds including birds sampled from remote areas. There is evidence that FRs can disrupt the hypothalamic-pituitary-thyroid (HPT) axis in seabirds, although information is limited on thyroid-related mechanisms and effects. This study investigated the associations between concentrations of polybrominated diphenyl ethers (PBDEs) and other FRs, and changes in the HPT axis in northern fulmars (Fulmarus glacialis) from the Faroe Islands (North Atlantic). Plasma concentrations of thyroid hormones (THs), hepatic deiodinase type 1 (D1) activity, and transcription of selected TH-related genes in liver were used as markers of HPT axis changes. Liver concentrations of a certain PBDE congeners and other FRs including pentabromoethylbenzene (PBEB), dechlorane 602 (Dec-602), and dechlorane plus (DP) were associated with changes in thyroid status. Specifically, liver PBDE, PBEB and Dec-602 concentrations were associated with plasma TH levels (free thyroxine [FT4] and total triiodothyronine [TT3]). Liver DP concentrations were positively correlated with the TT4:FT4 ratios and mRNA levels of UDP-glucuronyltransferase-1, while those of PBEB were negatively associated with TT4:TT3 ratios and D1 activity. D1 activity was also positively associated with the tri-, tetra- and hexa-BDE congeners. Moreover, transcription of ABCC2, a hepatic TH transporter, was associated with certain liver PBDE concentrations. Although PBDEs and other FRs may be potential inhibitors of D1 activity, only a few of the targeted FRs had modest associations with hepatic D1 activity. Regardless, the relationships reported herein indicated that exposure to moderate levels of FRs can be associated with thyroid axis perturbation at the molecular/biochemical levels in this North Atlantic seabird species.