Presence of novel and legacy flame retardants and other pollutants in an e-waste site in China and associated risks.

Electrical and Electronic Equipment (EEE) residues and their management have been widely identified as potential sources of plasticizers and flame retardants to the environment, especially in non-formal e-waste facilities. This study evaluates the distribution, partitioning and environmental and human impact of organophosphate esters (OPEs), legacy polychlorinated biphenyls (PCBs), polybromodiphenyl ethers (PBDEs) and organochlorine pesticides (OCPs) in the e-waste recycling area of Baihe Tang village, in the Qingyuan county, Guangdong province, China. A plastic debris lump accumulated in a small pond during years was identified as the main source of pollution with ∑pollutants of 8400 µg/g dw, being OPEs the main contaminants detected, followed by PBDEs. This lump produced the contamination of water, sediments, soils and hen eggs in the surrounding area at high concentrations. Plastic-water and water-sediment partitioning coefficients explained the migration of OPEs to the water body and accumulation in sediments, with a strong dependence according to the KOW. Triphenyl phosphate (TPhP), tricresyl phosphate (TCPs) and high chlorination degree PCBs produced a risk in soils and sediments, considering the lowest predicted no effect concentration, while the presence of PCBs and PBDEs in free range hen eggs exceeded the acceptable daily intake. OCPs were detected at low concentrations in all samples. The presence of organic contaminants in e-waste facilities worldwide is discussed to highlight the need for a strict control of EEE management to minimize environmental and human risks.

Mechanistic Aspects Regarding the Ultraviolet Degradation of Polychlorinated Biphenyls in Different Media: Insights from Carbon and Chlorine Isotope Fractionation.

In this study, the carbon and chlorine isotope fractionation during ultraviolet-photolysis of polychlorinated biphenyls (PCBs, including PCB18, PCB77, PCB110, and PCB138) in n-hexane (Hex), methanol/water (MeOH/H2O), and silica gel was first investigated to explore their mechanistic processes. We observed a significant variation in ΛCl-C (εCl/εC) for the same PCBs in different photochemical systems, implying that PCB degradation processes in various photoreaction systems could differ. Although all substrates showed normal apparent carbon/chlorine kinetic isotope effects (C-/Cl-AKIE >1), the putative inverse C-AKIE of nondechlorinated pathways was suggested by 13C depletion of the average carbon isotope composition of PCB138 and corresponding dechlorinated products in MeOH/H2O, which might originate from the magnetic isotope effect. Significant negative correlations were found between C-AKIE and relative disappearance quantum yields ("Φ") of ortho-dechlorinated substrates (PCB18, PCB110, and PCB138) in Hex and MeOH/H2O. However, the C-AKIE and "Φ" of PCB77 (meta/para-dechlorinated congener) obviously deviated from the above correlations. Furthermore, significantly different product-related carbon isotope enrichment factors of PCB77 in Hex were found. These results demonstrated the existence of dechlorination position-specific and masking effects in carbon isotope fractionations.

In Situ Microbial Degradation of PBDEs in Sediments from an E-Waste Site as Revealed by Positive Matrix Factorization and Compound-Specific Stable Carbon Isotope Analysis.

In the present study, positive matrix factorization (PMF) and compound-specific isotope analysis were used to investigate the in situ biodegradation of polybrominated diphenyl ethers (PBDEs) in sediment cores collected from a pond at an e-waste recycling site in South China. The potential microorganisms relevant to the degradation of PBDEs were also assessed to aid in the understanding of in situ biodegradation. The PMF results suggested that reductive debromination took place in the sediments. The debromination signal (ratio of the concentration of factor 5 (PMF result) to the total PBDE content) was positively correlated with the relative abundance of Dehalococcoidetes at different core depths. The clear 13C enrichment of five PBDE congeners (BDE 28, 47, 49, 99, and 153) with increasing core depth indicated that a measurable change in isotope fractionation might have occurred during PBDE biodegradation. The in situ biodegradation was further validated by the widespread detection of mono-BDE congeners (BDE 2, BDE 3) and diphenyl ether in the sediments. This study provides new evidence to enhance our understanding of the in situ biodegradation of PBDEs and suggests that the extensive removal of bromine from PBDEs was mediated by indigenous microorganisms at the e-waste site.

Characterizing the Influence of Metabolism on the Halogenated Organic Contaminant Biomagnification in Two Artificial Food Chains Using Compound- and Enantiomer-Specific Stable Carbon Isotope Analysis.

Two artificial food chains, food tiger barb-oscar fish and food tiger barb-redtail catfish, were established in the laboratory. The species-specific biotransformation of ortho, para'-dichlorodiphenyltrichloroethane, 12 polychlorinated biphenyl, and five polybrominated diphenyl ether congeners were characterized by measuring the compound- and enantiomer-specific stable carbon isotope composition (δ13C), enantiomeric fraction of the chiral chemicals, and metabolites in the fish. Compound- and enantiomer-specific biotransformations were revealed by the alteration of δ13C and EF in both predator fish species. Significant correlations between the carbon stable isotope signatures and the depuration rates and biomagnification factors (BMF) were observed. Chemicals that exhibited changes in δ13C during the experiment have higher kd and lower BMF values than those with unchanged δ13C. Specifically, the difference between the predicted BMF based on the log Kow and the measured BMF, ΔBMF, was significantly positively and linearly correlated to the change in the δ13C (expressed by Δδ13C/δ13Cinitial, the percentage of Δδ13C: δ13Cending-δ13Cinitial to the initial δ13Cinitial) in both food chains. These results indicated that the impact of metabolism on the bioaccumulation potential of organic contaminants can be predicted by the stable carbon isotope fractionation of chemicals in the fish.

A rapid discrimination of authentic and unauthentic Radix Angelicae Sinensis growth regions by electronic nose coupled with multivariate statistical analyses.

Radix Angelicae Sinensis, known as Danggui in China, is an effective and wide applied material in Traditional Chinese Medicine (TCM) and it is used in more than 80 composite formulae. Danggui from Minxian County, Gansu Province is the best in quality. To rapidly and nondestructively discriminate Danggui from the authentic region of origin from that from an unauthentic region, an electronic nose coupled with multivariate statistical analyses was developed. Two different feature extraction methods were used to ensure the authentic region and unauthentic region of Danggui origin could be discriminated. One feature extraction method is to capture the average value of the maximum response of the electronic nose sensors (feature extraction method 1). The other one is to combine the maximum response of the sensors with their inter-ratios (feature extraction method 2). Multivariate statistical analyses, including principal component analysis (PCA), soft independent modeling of class analogy (SIMCA), and hierarchical clustering analysis (HCA) were employed. Nineteen samples were analyzed by PCA, SIMCA and HCA. Then the remaining samples (GZM1, SH) were projected onto the SIMCA model to validate the models. The results indicated that, in the use of feature extraction method 2, Danggui from Yunnan Province and Danggui from Gansu Province could be successfully discriminated using the electronic nose coupled with PCA, SIMCA and HCA, which suggested that the electronic-nose system could be used as a simple and rapid technique for the discrimination of Danggui between authentic and unauthentic region of origin.

Observable carbon isotope fractionation in the photodegradation of polybrominated diphenyl ethers by simulated sunlight.

In the present study, carbon isotope effects were investigated during the photodegradation of polybrominated diphenyl ethers (PBDEs) by compound-specific stable isotope analysis (CSIA). Five PBDE congeners (BDE 85, 99, 100, 153 and 154) in n-hexane were individually exposed to simulated sunlight for as long as 15 h, except for BDE 100 (24 h). Consecutive debromination of PBDE by photolysis in n-hexane was confirmed by the clear 13C enrichment of mother congeners and successive depletion of δ13C values for the photodegradation products with decreasing degree of bromination, which can be attributed to mass-dependent isotope fractionation. The observed variation in the isotope fractionation trends for the para-debrominated products might be linked to the different photocatalytic activities of the PBDE congeners. Higher fractionation was observed for penta-BDEs (εc=-2.2 ± 0.45‰ and -2.3 ± 0.26‰ for BDE 85 and BDE 99, respectively) compared to that for hexa-BDEs (εc=-1.7 ± 0.41‰, and -1.3 ± 0.12‰ for BDE 153 and BDE 154, respectively). Normal isotope effects (AKIE > 1) observed in our study supports the utility of CSIA for the evaluation of the photodegradation of PBDEs.

Comprehensive exploration of the ultraviolet degradation of polychlorinated biphenyls in different media.

As one of the most important natural transformation processes, photodegradation deserves more attention and research. In the current work, we comprehensively explored the photochemical behaviors of polychlorinated biphenyls (PCBs) in n-hexane (Hex), methanol/water, and silica gel under UV-irradiation. Photodegradation rates were found to be faster in methanol/water than in Hex. All of the three photochemical systems generated sigmatropic rearrangement products. The dominant photodegradation pathways were dechlorination, dechlorination/methoxylation/hydroxylation, and hydroxylation in Hex, methanol/water, and silica gel systems, respectively. Furthermore, some new photodegradation products, such as polychlorinated biphenyl ethers, polychlorinated dibenzofurans, polychlorinated biphenylenes, and methylated polychlorinated biphenyls, are reported for the first time. These findings would provide deeper insight into the phototransformation behaviors of PCBs.

Chlorine and Bromine Isotope Analysis of Polychlorinated Biphenyls and Polybrominated Diphenyl Ethers Using Gas Chromatography-Quadrupole Mass Spectrometry.

A compound-specific chlorine/bromine isotope analysis (Cl-/Br-CSIA) method was developed using gas chromatography-quadrupole mass spectrometry for polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), which are toxic to human health and are frequently detected in various abiotic and biotic media. For PCB congeners, the molecular ion method for a concentration of 0.5-10.0 ppm, a dwell time of 20-100 ms, a relative EM voltage of 200 V, an electric current of 34 µA, and an ionization energy of 70 eV was determined as the most suitable scheme, which obtained standard deviations (SDs) of chlorine isotope ratios ranging from 0.00008 to 0.00068. As for the PBDE congeners, the lowest SDs, ranging from 0.00050 to 0.00172, were determined using the top four ion method with a concentration of 5-10 ppm and a dwell time of 20-50 ms. Both the chlorine and bromine isotope ratios showed strong concentration dependencies. Therefore, external standardization or detecting chlorine and bromine isotope ratios at a uniform concentration level is necessary to eliminate the concentration effect. In addition, 13C-correction is critical to remove interference from carbon isotopes. This newly developed Cl-/Br-CSIA method successfully determined the chlorine/bromine isotope ratios of PCBs/PBDEs in technical mixtures and traced the chlorine/bromine isotope ratio variations of PCBs/PBDEs in photodegradation experiments, thereby suggesting that it is a promising tool for assessing the sources and transformation processes of PCBs and PDBEs in the environment.

Tracing the sources and microbial degradation of PCBs in field sediments by a multiple-line-of-evidence approach including compound-specific stable isotope analysis.

Comprehensive monitoring is crucial for tracing micropollutants in the natural environment. To better evaluate the sources and natural attenuation of polychlorinated biphenyls (PCBs), three composite sediment cores were sampled from a closed pond near e-waste recycling plants, and a multiple-line-of-evidence approach (MLEA) including quantification, enantiomer analysis, microbial community profiling, and compound-specific isotope analysis (CSIA) was used to investigate the fate of PCBs in sediment cores. The difference in the maximum PCB concentrations and associated depths between sites 1/2 and 3 and the corresponding significant (p < 0.01) difference in δ13C values strongly indicated two different PCB inputs at sites 1/2 and 3. A significant (p < 0.01) negative correlation between the variation in chlorine per biphenyl (CPB) and Log the abundance of Dehalococcoides/total molar concentration of PCBs (Log Dhc/TPCB) along the cores suggested that different degrees of PCB degradation occurred and that Dehalococcoides likely participated in PCB degradation in these sediments. Nonracemic compositions and pronounced stable carbon isotope fractionation (Δδ13C > 1‰) of PCB congeners were observed, confirming that in situ degradation occurred in the sediment cores. The progressive enrichment in 13C with increasing core depth suggested strengthened microbial degradation of the residual congener pools. The results of this study suggested that MLEA analysis of PCBs can provide reliable information to better monitor the sources and fate of these compounds in the environment.

Polychlorinated biphenyls and chlorinated paraffins in home-produced eggs from an e-waste polluted area in South China: Occurrence and human dietary exposure.

The levels of polychlorinated biphenyls (PCBs) and short/median-chain chlorinated paraffins (S/MCCPs) in 68 home-produced eggs collected in 2013 and 2016 from an electronic-waste (e-waste) site in South China were measured and the human dietary exposure to these two classes of contaminants via egg consumption was calculated. The levels of PCBs, SCCPs, and MCCPs varied from 236 to 8870 ng/g lipid weight (lw), 477 to 111,000 ng/g lw, and 125 to 91,100 ng/g lw, respectively. There are no significant differences in the levels of PCBs, SCCPs, and MCCPs between 2013 and 2016 (p > 0.05). The congener profiles of PCBs and MCCPs were similar to each other between 2013 and 2016; however, the homologue profiles of SCCPs were different. The Toxic Equivalent Quantities (TEQs) of ∑DL-PCBs and the levels of ∑ICES-6 PCBs strongly exceeded the limits set by EU Regulation 1259/2011 (2.5 pg World Health Organization-TEQ2005 g-1 lw for DL-∑PCBs and 40 ng/ g lw for ∑ICES-6 PCBs). The estimated daily intakes (EDI) of PCBs, SCCPs, and MCCPs by adults and children ranged between 5.57 and 1100, 11.8 and 11,900, and 3.62 and 11,400 ng/kg bw/d, respectively. PCBs pose serious health risks for local residents, especially for children, due to the high ratios of EDI (68% in 2013 and 70% in 2016 for adults and 100% for children) in excess of the exposure limits.

Level changes and human dietary exposure assessment of halogenated flame retardant levels in free-range chicken eggs: A case study of a former e-waste recycling site, South China.

To assess the impacts of e-waste regulations on environmental pollution, we built on a previous study from 2010 to investigate the levels and human dietary exposure of halogenated flame retardants (HFRs) in free-range chicken eggs from Baihe village in 2013 and 2016. The concentrations of PBDEs, PBBs, HBCDs, and DBDPE showed a significant decrease (p<0.05) from 2010 to 2013/2016, suggesting the efficacy of regulatory policies. The relative contribution of BDE209 were higher in 2013 and 2016 than in 2010, accounting for 67.8%, 61.4%, and 27.7%, respectively. The concentration ratios of PBB209:PBB153 were much lower in 2013 (1.51) and 2016 (1.32) than in 2010 (29.5). These observed different profiles likely due to the different environmental behaviors of HFRs (e.g. the different atmospheric migration abilities of PBDE congeners and degradation of PBB209). Our exposure estimates suggested high dietary intake of HFRs via home-produced eggs. As for PBDEs, considering the worst situation (highly polluted eggs were consumed), the margin of exposure (MOE) of BDE99 for both adults and children were 1.5 and 0.3 in 2013, and 1.1 and 0.2 in 2016, respectively, which were below 2.5. According to the CONTAM panel, an MOE larger than 2.5 indicates no health concern. Therefore, these MOE values represent a significant potential health concern due to the adverse impacts of PBDEs on human neurodevelopment and fertility.

Hepatic ethoxyresorufin-O-deethylase induction in the common kingfisher from an electronic waste recycling site.

The health effects of exposure to electronic waste (e-waste)-derived pollutants are an important issue. The authors explored the association between the hepatic levels of e-waste-derived halogenated contaminants (including polychlorinated biphenyls [PCBs], polybrominated diphenyl ethers [PBDEs], and polybrominated biphenyls [PBBs]) and hepatic ethoxyresorufin-O-deethylase (EROD) activity of the common kingfisher (Alcedo atthis) from an e-waste site and 2 reference sites in South China. The summed concentrations of PCBs, PBDEs, and PBBs ranged from 620 ng/g to 15 000 ng/g, 25 ng/g to 900 ng/g, and 14 ng/g to 49 ng/g wet weight, respectively, in the kingfishers from the e-waste site, and these values were significantly greater (2-3 orders of magnitude) than those obtained at the 2 reference sites. Correspondingly, significant hepatic EROD induction was observed in the kingfishers from the e-waste site compared with the reference sites. The EROD activity was significantly correlated to the levels of most of the PCB and PBDE congeners examined as well as PBB 153, suggesting that EROD induction may be evoked by these e-waste-derived pollutants. Environ Toxicol Chem 2016;35:1594-1599. © 2015 SETAC.

Aquatic bioaccumulation and trophic transfer of tetrabromobisphenol-A flame retardant introduced from a typical e-waste recycling site.

While the flame retardant chemical, tetrabromobisphenol-A (TBBP-A), has been frequently detected in the environment, knowledge regarding its species-specific bioaccumulation and trophic transfer is limited, especially in the highly contaminated sites. In this study, the components of an aquatic food web, including two invertebrates, two prey fish, and one predator fish, collected from a natural pond at an electronic waste (e-waste) recycling site in South China were analyzed for TBBP-A, using liquid chromatography-tandem mass spectrometry. The aquatic species had TBBP-A concentrations ranging from 350 to 1970 pg/g wet weight, with higher concentrations in the invertebrates relative to the fish species. Field-determined bioaccumulation factors of TBBP-A in the two aquatic invertebrates were nearly or greater than 5000, suggesting that TBBP-A is highly bioaccumulative in the two species. The lipid-normalized concentrations of TBBP-A in the aquatic species were negatively correlated with the trophic levels determined from stable nitrogen isotope (δ(15)N) (r = -0.82, p = 0.09), indicating that this compound experienced trophic dilution in the current food web.

[Identification of Pterocephalus hookeri].

OBJECTIVE: To study the identification method of Pterocephalus hookeri. METHOD: The microscopical, Physicochemical and TLC methods were used. RESULT AND CONCLUSION: The convenient and effective identification methods for P. hookeri were established, which provide basis for its quality standard and development.