Residual characteristics and potential health risk assessment of polychlorinated biphenyls (PCBs) in seafood and surface sediments from Xiangshan Bay, China (2011–2016)

Reducing baseline toxicity in fishery product-related sediments from land to sea: Region-specific solutions are required

Eastern China is a major producer of fishery products (including inland aquaculture, coastal mariculture, and coastal fishing products). The quality of the products is affected by hydrophobic organic contaminants (HOCs) in the sediments. Based on in-vitro luminescent bacterial assay, the baseline toxicity (BEQBio) of 56 common HOCs were assessed in the present study. Specifically, the BEQBio of sediments declined from land (31-400 mg/kg) to sea (9.1-270 mg/kg). However, the toxicity contribution explained by the HOCs increased gradually from land (0.70 %) to sea (10 %) using Iceberg Modeling. In the inland pond, current use HOCs (pyrethroid pesticide (PEs), organic tin (OTCs), and antibiotic) exhibited considerable concentrations, although their toxicity contribution was very small (0.076 %), thus more regulations on the use of HOCs should be proposed and further screening is needed to confirm the major toxicants. In coastal mariculture area, the toxicity contribution of current use HOCs further declined (0.010 %), whereas environmental background HOCs, such as polycyclic aromatic hydrocarbons (PAHs), became increasingly significant, with the contribution ratio increasing from 0.37 % to 2.4 %. To minimize the negative impacts of PAHs, optimization of energy structure in transportation and coastal industry is required. In the coastal fishing area, the phased-out persistent organic pollutants (POPs) remained a major concern, in terms of both concentration and toxicity contribution. The phased-out POPs explained 7.0 % of the toxic effects of the sediments from the coastal fishing area, due to historical residue, industrial emissions, and their high toxicities. For this reason, it is critical to improve the relevant emission regulations and standards, so as to eventually reduce the unintentional discharges of POPs.

Kelp as a biomonitor of persistent organic pollutants in coastal areas of China: Contamination levels and human health risk

Kelp, the brown alga distributed in coastal areas all over the world, is also an important medicine food homology product in China. However, the levels and profiles of persistent organic pollutants (POPs) in kelp have not been thoroughly investigated to date. Polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and emerging bromine flame retardants (eBFRs) were evaluated in 41 kelp samples from the main kelp producing areas in China. The concentrations of total PCBs, PBDEs and eBFRs were in the range of 0.321-4.24 ng/g dry weight (dw), 0.255-25.5 ng/g dw and 3.00 × 10-3-47.2 ng/g dw in kelp, respectively. The pollutant pattern was dominated by decabromodiphenyl ethane (DBDPE, 13.0 ± 11.7 ng/g dw) followed in decreasing order by BDE-209 (2.74 ± 4.09 ng/g dw), CB-11 (1.32 ± 1.06 ng/g dw). The tested results showed that kelp could reflect the pollution status of PCBs, PBDEs and eBFRs, indicating the suitability of kelp as a biomonitor of these harmful substances. Finally, the data obtained was used to evaluate human non-cancer and cancer risks of PCBs and PBDEs via kelp consumption for Chinese. Though the calculated risk indices were considered acceptable according to the international standards even in the worst scenarios, the POPs levels in kelp should be monitored continuously as a good environmental indicator.

Neonicotinoids Persisting in the Sea Pose a Potential Chronic Risk to Marine Organisms: A Case from Xiangshan Bay, China (2015-2019)

Neonicotinoid insecticides (neonics) are extensively employed in agriculture and pervade various environmental matrices. However, few studies have documented the occurrence and potential chronic ecological risks of these chemicals in the marine environment. We collected 720 seawater samples from Xiangshan Bay during 2015-2019 and the integrated concentrations of seven neonics were determined using the relative potency factor method. Trend analyses using the Mann-Kendall test in time series, along with the estimation of the flux of neonics into the sea, were conducted. At last, the ecological risk of neonics was evaluated by water quality criteria derivation based on species sensitivity distribution. Our findings revealed that 47.6% of samples contained at least one neonic, with the integrated concentration of neonics ranging from 63.30 to 1684.14 ng/L. Imidacloprid and dinotefuran exhibited the highest frequency of detection in the analysis. The significance level of the Mann-Kendall test ranged from 2.16 × 10-10 to 1.21 × 10-5 (S > 0), indicating all neonics behaved with sharply increasing trends. Approximately 8.47 × 10-2 tons of neonics were discharged into Xiangshan Bay. Notably, the integrated concentrations of neonics represented a potential chronic ecological risk to marine organisms. This study provided novel insights into the spatial distribution, source, and migration of neonic species and their impacts on marine ecosystems.

Magnetic solid phase extraction and determination of polychlorinated biphenyls in beverages utilizing C60 modified magnetic polyamido-amine dendrimers in combination with gas chromatography-tandem mass spectrometry

Polychlorinated biphenyls (PCBs) are persistent organic pollutants which are widely present in environment and harmful to human health. In this study, an efficient and convenient magnetic solid phase extraction method with C₆₀ modified magnetic polyamido-amine (PAMAM) dendrimers as sorbents was established for enriching trace amounts of PCBs in beverage samples. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized for analysis of PCBs. Parameters affecting extraction efficiency were optimized. Under optimal parameters, good linearity can be achieved in concentration range of 0.001-20 μg L^-1 and 0.002-20 μg L^-1 for nine selected PCBs. The limits of detection for PCBs were in the range of 0.1-0.2 ng L^-1. The spiked recoveries were in the range of 87.0 %-115.1 % (n = 3). The results proved that this established method was reliable for monitoring trace PCBs in beverage samples.

Environmental contamination and human exposure of polychlorinated biphenyls (PCBs) in China: A review

Polychlorinated biphenyls (PCBs), together with 11 other organic compounds, were initially listed as persistent organic pollutants (POPs) by the Stockholm Convention because of their potential threat to ecosystems and humans. In China, many monitoring studies have been undertaken to reveal the level of PCBs in environment since 2005 due to the introduced stricter environmental regulations. However, there are still significant gaps in understanding the overall spatial and temporal distributions of PCBs in China. This review systematically discusses the occurrence and distribution of PCBs in environmental matrices, organisms, and humans in China. Results showed that PCB contamination in northern and southern China was not significantly different, but the PCB levels in East China were commonly higher than those in West China, which might have been due to the widespread consumption of PCBs and intensive human activities in East China. Serious PCB contamination was found in e-waste disassembling areas (e.g., Taizhou of Zhejiang Province and Qingyuan and Guiyu of Guangdong Province). Higher PCB concentrations were also chronicled in megalopolises and industrial clusters. The unintentionally produced PCBs (UP-PCBs) formed during industrial thermal processes may play an increasingly significant role in PCB pollution in China. Low PCB levels were recorded in rural and underdeveloped districts, particularly in remote and high-altitude localities such as the Tibetan Plateau and the South China Sea. However, these data are limited. Human exposure to PCBs is closely related to the characteristics of environmental pollution. This review also discusses existing issues and future research prospects on PCBs in China. For instance, the accumulation characteristics and migration regularities of PCBs in food webs should be further studied. More investigations should be undertaken to assess the quantitative relationship between external and internal exposure to PCBs. For example, bioaccessibility and bioavailability studies should be supplemented to evaluate human health risks more accurately.

Immunotoxicity of polychlorinated biphenyls (PCBs) to the marine crustacean species, Scylla paramamosain

Polychlorinated biphenyls (PCBs) are persistent organic pollutants in environments, and they can negatively affect aquatic animal health. After 7 days of PCBs exposure, the activities of catalase, phenoloxidase, and superoxide dismutase and the total hemocyte count in the haemolymph were significantly decreased and the reactive oxygen species (ROS) content and phagocytic rate of hemocytes were significantly increased in mud crab Scylla paramamosain. Additionally, serum lysozyme, glutathione, glutathione-S-transferase, and glutathione peroxidase activities were significantly down-regulated in mud crab after PCBs exposure. The survival rate of crab hemocytes significantly declined as the PCBs concentration increased, indicating that PCBs had a cytotoxic effect on hemocytes. Exposure to increasing concentrations of PCBs also increased the degree of DNA damage in crab hemocytes. After PCBs exposure, the expression levels of P53 and caspase-3 in hemocytes were significantly up-regulated, which suggests that apoptosis was occurring. The apoptosis rate of hemocytes was up-regulated as the PCBs concentration increased, indicating that apoptosis was induced by the PCBs-activated caspase-3 pathway. These data suggest that exposure to PCBs hampered the immune response of mud crabs, most likely by (1) inducing ROS, causing DNA damage, and reducing the viability of hemocytes, (2) reducing the activities of antioxidant enzymes, and (3) inducing phagocytosis and apoptosis of hemocytes. And the final result of PCBs-induced immunotoxicity to mud crabs is the reduced bacterial disease resistance and survival rate of crabs under Vibrio alginolyticus challenge.

Polyethylene-water partition coefficients for polychlorinated biphenyls: Application of QSPR predictions models with experimental validation

The water environmental recalcitrance and ecotoxicity caused by polychlorinated biphenyls (PCBs) are international issues of common concern. The partition coefficients with PCBs between low-density polyethylene (LDPE) and water (K_PE-w) are significant to assess their environmental transport and/or fate in aquatic environment. Even moderately hydrophobic PCBs, however, possess large K_PE-w values, which makes directly experimental measurement labored. Here, based on the combination of quantitative structure-property relationships (QSPRs) and machine-learning algorithms, 10 in-silico models are developed to provide a quick estimate of K_PE-w. These models exhibit good goodness-of-fit (R²_adj: 0.919-0.975), robustness (Q²_LOO: 0.870-0.954) and external prediction performances (Q²_ext: 0.880-0.971), providing a speedy feasibility to close data gaps for limited or absent experimental information, especially the RF-2 model. Particularly, an additional experimental verification is performed for models by a rapid and accurate three-phase system (aqueous phase, surfactant micelles and LDPE). The results of the experiments for 16 PCBs show the modeling results agree well with experimental values, within or approaching the residuals of ± 0.3 log unit. Mechanism interpretations imply that the number of chlorine atoms and ortho-substituted chlorines are the great effect parameters for K_PE-w. This result also heightens interest in measuring and predicting the K_PE-w values of chemicals containing halogen atoms in water.

Spatiotemporal occurrence, sources and risk assessment of polycyclic aromatic hydrocarbons in a typical mariculture ecosystem

The spatiotemporal variations, influencing factors and potential sources, as well as the ecological/health risks of polycyclic aromatic hydrocarbons (PAHs) were systematically investigated in seawater, sediment, and fish from Xiangshan Bay, China, one of the most important and oldest domestic marine aquaculture bases. The average concentrations of Σ_PAHs in seawater, sediment and fish were 150 ± 70.0 ng/L, 276 ± 271 μg/kg (dry weight, dw), and 434 ± 151 μg/kg (dw), respectively. Naphthalene, phenanthrene, fluoranthene, benzo(b)fluoranthene and pyrene were the dominant contaminants in all samples. The highest PAH concentrations in the seawater and sediment samples occurred in the inner bay where the mariculture and industry are clustered. Seasonal differences were observed in the seawater samples but not in the sediment samples. Among all 15 fish species, large yellow croaker (Larimichthys crocea) (775 μg/kg (dw)), red drum (Sciaenops ocellatus) (749 μg/kg (dw)), and flathead grey mullet (Mugil cephalus) (637 μg/kg (dw)) had relatively high PAH accumulation concentrations in muscle tissue. According to the molecular diagnostic ratio method, the PAHs in seawater mainly originated from a mixed source of petroleum and combustion, whereas biomass/coal combustion sources were identified for sediment. The results obtained from the risk quotient (for seawater), sediment quality guidelines and toxic equivalence quotients (for seawater and sediment) methods showed that the ecological risks posed by PAHs were generally at a low to moderate level. Potentially toxic effects existed from PAH-contaminated fish consumption, and the resulting potential carcinogenic risk was also slightly higher than the recommended guidelines (10^-6).

Probing the contamination characteristics, mobility, and risk assessments of typical plastic additive-phthalate esters from a typical coastal aquaculture area, China

Contamination characteristics, equilibrium partitioning and risk assessment of phthalate esters (PAEs) were investigated in seawater, sediment and biological samples collected from the Xiangshan Bay area during an annual investigation between January and November 2019. PAE concentrations detected in the mariculture environment in surface seawater, sediment, and biological samples were 172-3365 ng/L, 190-2430 μg/kg (dry weight [dw]), and 820-4926 μg/kg (dw), respectively. The dominant congeners in different media included di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), and di(2-ethylhexyl) phthalate (DEHP). The inner bay and the bay mouth were the gathering area of PAEs and heavily influenced by the mariculture activities, river inputs, and anthropogenic activities. The bioaccumulation of PAEs demonstrated benthic feeding fishes with relatively high trophic levels concentrated high levels of phthalates. The mobility of PAEs in sediment-seawater showed that the transfer tendency of low-molecular weight species was from the sediment to the water, which was in contrast with those of high-molecular weight PAEs. DEHP, DiBP and DnBP had various degrees of ecological risks in the aquatic environment, whereas only the DiBP posed potential risks in sediments. The current assessment of carcinogenic and noncarcinogenic risks posed by fish consumption were within acceptable limits for humans.

The level of selected organochlorine compounds residues in popular edible mushrooms from north-eastern Poland

Although DDT, γ-HCH and PCBs have been almost completely withdrawn from world production and use, they are still present in the environment. Mushrooms are eagerly collected and consumed local raw material in north-eastern part of Poland. The aim of the study was to determine the content of DDT, γ-HCH and PCB residues in popular species (Boletus badius, Boletus edulis, Cantharellus cibarius) and to estimate the human exposure of uptaking of these compounds with mushrooms. The content of γ-HCH, DDT and PCB was determined using gas chromatography. The presence of analyzed compounds was observed in all the species under study. The highest content of γ-HCH and ΣDDT was determined in C. cibarius - 7.19 and 180.37 µg/kg of lipids, respectively, whereas the highest amount of ΣPCB was observed in B. edulis - 20.89 µg/kg of lipids. The contents were low and did not pose a threat to human health.

Bioaccessibility-corrected health risk of heavy metal exposure via shellfish consumption in coastal region of China

A systematic investigation into bioaccessible heavy metals in shellfish Crassostrea ariakensis, Chlamys farreri, and Sinonovacula constricta from coastal cities Shenzhen, Zhoushan, Qingdao, and Dandong was carried out to assess the potential health risk to residents in coastal regions in China. The bioaccessible fractions of heavy metals were (μg‧g-1): Zn (0.63-15.01), Cu (0.10-12.91), Cd (0.01-0.64), As (0.11-0.33), Cr (0.07-0.12), Pb (0.01-0.03). The bioaccessibilities of heavy metals were Cr 61.86%, inorganic As (iAs) 60.44%, Pb 55.74%, Cu 46.83%, Zn 28.16%, and Cd 24.99%. As for child and adult, the bioaccessibility-corrected estimated daily intakes were acceptable and the non-carcinogenic risks posed by heavy metals were not obvious. The carcinogenic risks posed by bioaccessible heavy metals at the fifth percentile were 10-fold higher than the acceptable level (10-4), with iAs and Cd to be the major contributors, regardless of child or adult. The probabilistic estimation showed the low risk of shellfish consumption, which was verified by higher values of maximum allowable consumption rate and monthly meals at the 95 percentile; while some control of consumption rate and monthly meals was necessary for reducing heavy metal exposure of most shellfish samples, except for the safe consumption of S. constricta for both child and adult in Qingdao and Shenzhen, China.

Ecological risk assessment of persistent organic pollutants (POPs) in surface sediments from aquaculture system

Organochlorinated pesticides (OCPs) and Polychlorinated biphenyls (PCBs) in the surface sediments from shrimp ponds in four regions of the northern part of the Central Java coast (namely Brebes, Tegal, Pemalang, and Pekalongan) were investigated. The highest concentration of ∑ OCPs was found in Brebes Regency, ranging from 68.1 ± 3.4 to 168.1 ± 9.8 μg kg^-1 dw. As indicated by the DDT ratio and chlordane ratio, the value suggested that those compounds may mainly originate from historical inputs rather than a recent application. The concentrations of Ʃ 7 indicator PCBs were determined, with the concentration ranged from 1.2 ± 0.7 μg kg^-1 dw (Pekalongan) to 2.2 ± 0.4 μg kg^-1 dw (Tegal). The most toxic PCB congener, PCB 118, was detected in all studied regions, with the highest proportion found in Tegal. Source analysis indicated that PCBs in the sediments mainly originated from Aroclor 1254 and Aroclor 1248. Compared to sediment quality guidelines (SQGs), some OCPs were found with concentrations which potentially posed an adverse effect. Our findings suggested that more attention should be paid to ensure sustainable shrimp culture facing such a risk of the OCPs and PCBs.