Epidemiological studies consistently link environmental toxicant exposure with increased Type 2 diabetes risk. Our study investigated the diabetogenic effects of a widely used flame retardant, Dechlorane Plus (DP), on pancreatic β-cells using rodent and human model systems. We first examined pancreas tissues from male mice exposed daily to oral gavage of either vehicle (corn oil) or DP (10, 100, or 1000 μg/kg per day) and fed chow or high fat diet for 28-days in vivo. DP exposure did not affect islet size or endocrine cell composition in either diet group. Next, we assessed the effect of 48-hour exposure to vehicle (DMSO) or DP (1, 10, or 100 nM) in vitro using immortalized rat β-cells (INS-1 832/3), primary mouse and human islets, and human stem-cell derived islet-like cells (SC-islets). In INS-1 832/3 cells, DP did not impact glucose-stimulated insulin secretion (GSIS) but significantly decreased intracellular insulin content. DP had no effect on GSIS in mouse islets or SC-islets but had variable effects on GSIS in human islets depending on the donor. DP alone did not affect insulin content in mouse islets, human islets, or SC-islets, but mouse islets co-exposed to DP and glucolipotoxic (GLT) stress conditions (28.7 mM glucose + 0.5 mM palmitate) had reduced insulin content compared to control conditions. Co-exposure of mouse islets to DP + GLT amplified the upregulation of Slc30a8 compared to GLT alone. Our study highlights the importance and challenges of using different in vitro models for studying chemical toxicity.

China, one of the two dechlorane plus (DP) producers, might have become a major area of DP pollution. The environmental contamination status of DP in sediments across the whole of China has not yet been studied. In the current study, the pollution levels, spatial distribution, and compositions of DP were investigated comprehensively in surface sediments from 173 black-odorous urban rivers across China for the first time. Total DP concentrations varied from not-detected to 39.71 ng/g dw, with an average concentration of 3.20 ± 4.74 ng/g dw, which was polluted by local emission sources and presented significant differences among different sampling cities. Among the seven administrative regions of China, DP concentrations were the highest in South China and showed a decreasing trend from southeastern coastal areas to northwest inland regions. Spearman\'s correlation analysis suggested that the gross industrial output, gross domestic product, and daily wastewater treatment capacity were not the principal factors controlling the spatial distribution of DP. The fanti values (the concentration ratios of anti-DP to the sum of anti-DP and syn-DP) varied from 0.19 to 0.88, with those in most sediments falling in the range of DP technical product (0.60 ~ 0.80), suggesting no apparent stereoselective enrichment occurred. Moreover, the anti-Cl11-DP was detected in sediments (n.d. ~ 0.40 ng/g dw), which showed significantly and insignificantly positive correlation with the anti-DP levels and fanti, respectively, implying it might mainly originate from the byproduct of DP technical product rather than the dechlorination of anti-DP.

Novel brominated flame retardants (NBFRs) and dechlorane plus (DP) have been widely used as alternatives to traditional BFRs. However, little is known about the temporal trends of NBFR and DP pollution in e-waste recycling sites. In the current study, three composite sediment cores were collected from an e-waste-polluted pond located in a typical e-waste recycling site in South China to investigate the historical occurrence and composition of NBFRs and DP. The NBFRs and DP were detected in all layers of the sediment cores with concentration ranges of 5.71~180,895 and 4.95~109,847 ng/g dw, respectively. Except for 2,3,5,6-tetrabromo-p-xylene (pTBX) and 2,3,4,5,6-pentabromoethylbenzene (PBEB), all the NBFR compounds and DP showed a clear increasing trend from the bottom to top layers. These results implied the long-term and severe contamination of NBFRs and DP. Decabromodiphenyl ethane (DBDPE) was the most abundant NBFR with the contribution proportions of 58 ± 15%, 73 ± 15%, and 71 ± 18% in three sediment cores, followed by 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) and pentabromobenzene (HBB). The ratios of BTBPE/Octa-BDEs and DBDPE/Deca-BDEs varied from 0.12 to 60 and from 0.03 to 0.49, respectively, which had no clear increase trends with a decrease in sediment depth. As for DP, the fanti values (the concentration ratios of anti-DP to the sum of anti-DP and syn-DP) in sediment cores ranged from 0.41 to 0.83, almost falling in the range of those in DP technical products, suggesting that DP degradation did not occur in sediment cores. The environmental burdens of DBDPE, BTBPE, HBB, PBT, PBEB, pTBX, and DP were estimated to be 34.0, 5.67, 10.1, 0.02, 0.02, 0.01, and 34.8 kg, respectively. This work provides the first insight into the historical contamination status of NBFRs and DP in the sediments of an e-waste recycling site.

The global presence of Dechlorane Plus (DP) in environmental and human samples highlights the need for further research into its ecological risks and health effects. This study determined DP concentrations in soil and air samples from an old electronic waste dismantling area (Fengjiang) and a new electronic waste dismantling area (Binhai) in Taizhou City, China. Both syn-DP and anti-DP isomers were found in all soil and air samples. The median concentrations of DP in soil and air were 90.5 ng/g and 48.4 pg/m3 in Fengjiang, and 6.69 ng/g and 28.8 pg/m3 in Binhai. DP were widespread in the local environment, and in general at moderate levels compared with reports from other electronic waste dismantling areas. The analysis of DP isomer profiles in different seasons and the calculation of related fugacity fraction showed that anti-DP perhaps easier than syn-DP to migrate from soil to air in summer. DP concentrations in serum of residents from Fengjiang (median 9.74 ng/g) were significantly higher than those from Huangyan (common control area, median 2.77 ng/g; p < 0.01), while the fanti value showed that Fengjiang was significantly lower than Huangyan (p < 0.05). This revealed that DP exposure levels in serum perhaps one of the crucial factors influencing fanti value. Moreover, DP concentrations in serum showed an increasing trend with increasing body mass index (BMI) or age. However, the relationship between DP and sex was not observed. The fanti values of serum samples were higher than those in soil and air samples, suggested that DP perhaps stereo-selectively absorbed into the body or stereo-selectively metabolised.

As pollution has attracted attention due to its wide distribution. An environmental concern that may be overlooked is that NPs additives are easily released into the environment due to their physical combination with NPs. However, the knowledge gaps still exist about the interfacial reactions of NPs and the additives (e.g. flame retardants) and the joint ecological effect. In the present study, fourier transform infrared (FTIR) spectrometer coupled with 2D correlation spectroscopy (2D-COS) analysis revealed the interfacial reactions between polystyrene nanoplastics (PSNPs) and Dechlorane Plus (DP). Results showed that carbon‑oxygen bonds and carbon‑chlorine bonds were the important binding sites during adhesion and DP could reduce the colloidal stability. Single and joint ecological effects of PSNPs and DP on the microalgae Chlorella vulgaris were further deliberated. Reduced photosynthetic efficiency (reduced Fv/Fm by 0.03 %), higher growth inhibition (16.15 %) and oxidative damage (increased ROS by 152 %) were observed in algae under co-exposure. Notably, DP could significantly increase the attachment of PSNPs to the surface of the algae. Metabolomics further revealed that co-exposure significantly down-regulated amino acid metabolism and tricarboxylic acid cycle (TCA) cycle, and up-regulated fatty acid metabolism. The present study provides new insights into the risk assessment of NPs in aquatic environment by investigating the interfacial reaction mechanism and combined ecotoxicity of NPs and additives.

The migration and transformation of Tetrabromobisphenol A (TBBPA), DechloranePlus (DP), and cadmium in soil-rice system was investigated, and the influence on the quality of two varieties of rice was studied. The degradation half-lives of TBBPA, BBPAs, syn-DP, and anti-DP were 23.18 ~ 26.36 days, 30.14 ~ 36.10 days, 72.96-81.55 days, and 169.06-198.04 days in the soil. TBBPA was gradually degraded to tri-BBPA, di-BBPA, mono-BBPA, and bisphenol A by the debromination. TBBPA and its bromide metabolites could be bioaccumulated in different tissues of rice; mono-BBPA and bisphenol A was easy to accumulate in the stems, and bisphenol A was easy to bioaccumulate in the grain. Comparing with single and compound pollution, there was no significant difference in bioaccumulation factors of two rice species. The grain of NO7 had stronger bioaccumulation ability to mono-BBPA and BPA than NO1, and there is no significant difference in TBBPA. Residual level of DP in the rice: roots > stems > grain; there was no significant difference in bioaccumulation of two varieties of rice. Cadmium was easily bioaccumulated in the roots of rice and translocated to the rice stems and grains. NO7 rice had stronger bioaccumulation and transport capacity than NO1. The effects of the three pollutants on the quality of two varieties of rice varied significantly; cadmium had the greatest effect on the iodine blue value (BV) and amylase activity of the grain. This study proved that selecting rice varieties with low bioaccumulation to polluters can effectively reduce the risk of the food chain harming human health.

Exposure of human tissues to Dechlorane Plus (DP) has raised public concern because of the multiple health threats it may pose to humans. Therefore, it is important to summarize the main findings of previous studies on DP in human tissues and to provide potential guidance for future studies. In this paper, DP levels in different populations and human tissues worldwide since 2009 were systematically reviewed. DP levels in human tissues of workers in e-waste dismantling sites in Guangdong Province, China (median 190 ng·g-1 lw in serum) and DP manufacturing plants in Jiangsu Province, China (mean 857 ng·g-1 lw in whole-blood) are the highest reported worldwide. DP levels in tissues of the general population in recent studies are close to those of residents near e-waste dismantling sites, which should be of concern. DP levels in different human tissues were found to be positively correlated with a pattern of blood > breast milk > adipose tissue. The distribution of DP in different human tissues is mainly lipid-driven and may also be influenced by the interaction of DP with proteins such as human serum albumin. Most of the past studies determined the isomer stereoselectivity of DP in human tissues only by comparing the composition of DP in commercial DP products and human tissues, which lacks evidence of mechanism. Recently, a significantly different affinity of DP isomers for proteins was found, which seems to confirm the isomer selectivity of DP in human tissues. We simulated the binding of DP to human serum albumin and DP to thyroid hormone receptor β by molecular docking and found differences in the binding behavior of syn-DP and anti-DP to the selected proteins. Molecular docking seems to be a feasible approach for future studies to predict and reveal the mechanisms of DP behavior and health effects in human tissues.

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 (Rrapid) 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 Rrapid 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.

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 (0.004-0.27 ng/g dw) were significantly higher than those in the DYB (0.005-0.24 ng/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.

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.