Dioxins, PCBs and heavy metals in Chinese mitten crabs from Dutch rivers and lakes

Global trends of dioxin and dioxin-like PCBs in animal-origin foods: a systematic review and gap areas

Dioxins and dioxin-like polychlorinated biphenyls are a group of lipophilic compounds classified under persistent environmental pollutants (POPs). Significant sources of dioxin emissions include industrial effluents, open burning practices, and biomedical and municipal waste incinerators. These emissions will enter the food chain and accumulate in animal-origin foods (AOFs). A systematic review was conducted to analyze the global levels of dioxins and dioxin-like PCBs in AOFs using PRISMA guidelines 2020. The data on the dioxin contamination in AOFs were extracted from 53 publications based on their presence in eggs, meat and meat products, milk and dairy products, marine fish and fish products, and freshwater fish and crabs. A gap analysis was conducted based on the systematic review to understand the grey areas to be focused on the  future. No trend of dioxin contamination in AOFs was observed. A significant gap area was found in the need for nationwide data generation in countries without periodic monitoring of AOFs for dioxin contamination. Source apportionment studies need to be explored for the dioxin contamination of AOFs. Large-scale screening tests of AOFs using DR-CALUX based on market surveys are required for data generation. The outcomes of the study will be helpful for stakeholders and policyholders in framing new policies and guidelines for food safety in AOFs.

Are Chinese mitten crabs (Eriocheir sinensis) suitable as biomonitor or bioindicator of per- and polyfluoroalkyl substances (PFAS) pollution?

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in the environment. In Flanders, the bioaccumulation in aquatic organisms is currently being monitored using European perch and European eel. Since both are native species, there is an ethical need to search for other suitable biomonitors. This study aims to investigate whether the invasive Chinese mitten crab could be used in biomonitoring programs by assessing PFAS accumulation in hepatopancreas, muscle tissue, and carapace. Furthermore, we correlated accumulated concentrations to those in the local abiotic environment. Concentrations in the crabs (highest average ∑PFAS concentration of 688 ± 505 ng/g ww) were often higher than those in crab species from other regions across the globe, confirming that Flanders is highly polluted with PFAS. Concentrations in the crabs did not reflect those in the abiotic environment. This implies that biomonitoring is necessary to investigate the impact of PFAS pollution on organisms in aquatic ecosystems, as important data is missing when only the abiotic environment is monitored. The accumulation profiles differed between the invasive crab and the native European perch and European eel, potentially due to a different ecology and trophic position. Since all three species provide complementary information on the PFAS pollution, a multi-species approach in biomonitoring is recommended. Overall, our results show that the crabs can be used as biomonitor, but more information is necessary to confirm their suitability as bioindicator.

Total body burden of neurotoxicant Hg in Chinese mitten crab (Eriocheir sinensis) - Considerations of distribution and human risk assessment

The Chinese mitten crab (Eriocheir sinensis) is considered one of the 100 most invasive alien species in the world. Despite this, its role in ecosystems, among others, in the trophodynamics of pollutants including mercury, is still not fully understood. Becoming an increasingly important and widespread element of the trophic chain in new areas arouses interest from humans as consumers. Hence it is important to determine the level of contaminants (including Hg) in alien species. In the present study, great attention was paid separately to the soft tissues and hard tissues of the exoskeleton, which may play an important role in the detoxification of the crab's body from toxic Hg. The study was conducted on crabs collected in 2011-2021 in the Vistula Lagoon. Concentrations of total mercury and its forms were carried out using a Direct Mercury Analyzer, DMA-80 (Milestone, Italy). The present study showed that mercury accumulation of the crab's body largely occurred through the gills, followed by the oral route. The distribution of Hg in the crab's organs was related to the trophic origin of the mercury, while halide-bound mercury and semilabile forms from the respiration (filtration) process were redistributed into the crab's exoskeleton. Male crabs, compared to females, had a higher Hg burden on internal organs such as their hepatopancreas and gonads. Hg concentration in hard tissues was closely related to the type of mineralization of the carapace. The elimination of Hg from the muscles and from the hepatopancreas into the carapace was one of the important detoxification processes of the crab's body. Thus, moulting crabs effectively remove Hg protecting its body from the neurotoxin. As a result, a smaller Hg load is biomagnified, making the crab's muscle tissue fit for human consumption. The observed decrease in Hg concentrations from 2011 to 2021, as well as the spatial variability of Hg in the crab's muscles, testify that the crab can serve as a biomonitor for ecosystem changes.

Determination of 25 polybrominated diphenyl ethers in Chinese mitten crab ecosystems by gas chromatography-mass spectrometry

A sensitive and reliable method for determining 25 polybrominated diphenyl ethers (PBDEs) in Chinese mitten crabs and their ecosystems ranging from the growing environment to edible feed by gas chromatography coupled to triple quadrupole mass spectrometry with advanced electron ionization (GC-AEI-MS/MS) was developed and validated. Accelerated solvent extraction (ASE) and liquid-liquid extraction were used to extract solid and water samples, respectively. On the basis of a traditional acid-base silica column, deactivated silica was added and n-hexane elution was used to increase the effect of separation and purification. Two oven temperature programs were applied to achieve good separation of low brominated congeners and increase the sensitivity of high brominated congeners. The method provided good linearity (>0.9996). The recoveries of four matrices were in the range of 82-115% and the method quantification limits (MQLs) in crabs, feed, sediment and water ranged from 0.36-6 pg per g wet weight, 0.69-22.29 pg per g dry weight, 1.02-25.26 pg per g dry weight, and 2.43-40.14 pg L-1, respectively. The proposed method was used for ten samples from two aquatic sites and PBDEs were detected in Chinese mitten crabs, commercial feed and sediment, with the highest in crabs. This analytical technique can be used to monitor the content and the accumulation behavior of PBDEs in Chinese mitten crab ecosystems or other aquaculture systems.

High resolution mass spectrometric suspect screening, wide-scope target analysis of emerging contaminants and determination of legacy pollutants in adult black-tailed godwit Limosa limosa limosa in the Netherlands - A pilot study

The Dutch breeding population of the black-tailed godwit Limosa limosa limosa has declined substantially over recent decades; the role of contaminants is unknown. We analysed liver samples from 11 adult birds found dead on their breeding grounds in SW Friesland 2016-2020, six from extensive, herb-rich grasslands, five from intensive grasslands. We carried out LC and GC wide-scope target analysis of more than 2400 substances, LC suspect screening for more than 60,000 substances, target analysis for Cd, Hg, Ni and Pb, organo-phosphate flame retardants (OPFRs), dechlorane plus compounds and selected polybrominated diphenyl ether flame retardants (PBDEs), and bioassay for polybrominated dibenzo-p-dioxins and dibenzofurans (PBDDs/PDBFs) and dioxin-like polychlorinated biphenyls (dl-PCBs). Residues of 29 emerging contaminants (ECs) were determined through wide-scope target analysis. Another 20 were tentatively identified through suspect screening. These contaminants include industrial chemicals (personal care products, surfactants, PAHs and others), plant protection products (PPPs) and pharmaceuticals and their transformation products. Total contaminant load detected by wide-scope target analysis ranged from c. 155 to c. 1400 ng g^-1 and was generally lower in birds from extensive grasslands. Heatmaps suggest that birds from intensive grasslands have a greater mix and higher residue concentrations of PPPs, while birds from extensive grasslands have a greater mix and higher residue concentrations of per- and polyfluoroalkyl substances (PFAS). All four metals and two OPFRs were detected. All tested PBDEs were below the respective LODs. Bioassay revealed presence of PBDDs, PBDFs and dl-PCBs. Further research is required to elucidate potential health risks to godwits and contaminant sources.

Burden levels of polychlorinated dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls in typical edible meat animals

The concentrations and distributions of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) in the whole blood and meat of eight typical edible animals (chicken, donkey, horse, cattle, rabbit, sheep, duck, and pig) were illustrated. Total concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and PCBs (on a basis of liquid volume) in animal bloods were 142-484 pg/L and 46-62 ng/L, respectively. Total concentrations of PCDD/Fs and PCBs (on a basis of dry weight (dw) and lipid weight (lw)) in animal meat samples were 0.47-1090 pg/g dw (0.47-4513 pg/g lw) and 7.2-23 ng/g dw (10-776 ng/g lw), respectively. TEQs for both PCDD/Fs and PCBs in animal blood and meat samples were (67 ± 27) pg/L and (5.3 ± 14) pg/g dw (24 ± 56 pg/g lw), respectively. Besides, the dietary intakes of PCDD/Fs and PCBs were also estimated. Chicken and pig contributed more TEQs than other animals. Chicken contributed the most (95%) with high toxicity, followed by pig (3.4%) with high consumption. The dietary intake of chicken might pose risks to consumers who prefer to eat chicken products, who should comprehensively consider the essential nutrients and contaminants in food during dietary intake.

Cadmium: A Focus on the Brown Crab (Cancer pagurus) Industry and Potential Human Health Risks

Cadmium is a major health risk globally and is usually associated with pollution and anthropogenic activity. The presence of cadmium in food is monitored to ensure that the health and safety of consumers are maintained. Cadmium is ubiquitous in the Asian and Western diets, with the highest levels present in grains, leafy greens, and shellfish. As part of their natural lifecycle of moulting and shell renewal, all crustaceans-including the brown crab (Cancer pagurus)-bioaccumulate cadmium from their environment in their hepatopancreas. The brown crab is an important species to the crab-fishing industries of many European countries, including Ireland. However, the industry has come under scrutiny in Europe due to the presence of cadmium in the brown crab meat intended for live export to Asia. This review explores evidence regarding the effects of cadmium consumption on human health, with a focus on the brown crab. Differences in cadmium surveillance have given rise to issues in the crab industry, with economic consequences for multiple countries. Currently, evidence suggests that brown crab consumption is safe for humans in moderation, but individuals who consume diets characterised by high levels of cadmium from multiple food groups should be mindful of their dietary choices.

PCDD/Fs and DL-PCBs in Chinese Mitten Crab (Eriocheir sinensis) and Its Farming Environment in Shanghai, China

Most polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in the human body are acquired from dietary intake. The chronic exposure of humans to PCDD/Fs and DL-PCBs is a major health concern, and these compounds are strictly controlled in many areas. This study measured the levels of PCDD/Fs and DL-PCBs in Chinese mitten crab (Eriocheir sinensis) farms in Shanghai and determined potential sources. The mean concentrations of PCDD/Fs and DL-PCBs in the studied crab samples were 264.20 ± 260.14 and 506.25 ± 226.80 pg/g ww (wet weight), respectively. The range of the toxic equivalent (TEQ) for the total PCDD/Fs and DL-PCBs in the crab samples was 1.20–29.04 pg TEQ/g ww. Further analysis revealed that the TEQ input to crabs in aquacultural water was 1.6 times higher than the TEQ in edible crab parts. Aquatic plants, shore plants, and feed contributed about 0.05% of the total TEQ input to crabs. The TEQ contribution from sediment was 317 times that found in edible crab parts, and sediment may be the most prevalent source of PCDD/Fs and DL-PCBs in farm crabs. The evaluation of the Shanghai market crab revealed different levels of PCDD/Fs and DL-PCBs. The TEQs for the mean PCDD/F and DL-PCB levels were 1.55 ± 1.96 and 1.05 ± 0.55 pg TEQ/g ww, respectively. The tolerable daily intake (TDI) levels of adults and children were lower than the prescribed range (1–4 pg TEQ/kg (weight)·d), indicating no significant chronic or acute ingestion risk for adults and children.

New insights into the transfer and accumulation of dioxins and dioxin-like PCBs in the food web of farmed Chinese mitten crabs: A typical case from the Yangtze River area

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) transfer and accumulation behavior remains poorly understood in the farmed Chinese mitten crab (Eriocheir sinensis). In this study, dioxins and DL-PCBs concentration in 48 farming crabs in lower reaches of the Yangtze River was monitored and controlled field design was conducted in a typical farm to dissect the dioxins and DL-PCBs contamination in crab food web (crab, feeds, and environment). Results showed that dioxins and DL-PCBs were ubiquitous in farmed crabs with concentrations ranging from 0.390 to 37.2 pg toxic equivalents (TEQ) g^-1 ww and do not present a health risk to general consumers. Of the total dioxins TEQ found in crab in treated farms, 45.6% was attributed to direct transfer from the aquaculture environment and 46.5% to the consumption of snails. Consumption of feed material accounted for nearly all of the total DL-PCBs TEQ, divided as 58.2% from feed and 41.8% from snails. These results demonstrated that dominant routes of dioxins accumulation in crabs were transferred for the sediment-snail-crab and sediment-crab chains, whereas DL-PCBs is mainly transferred through consumption of feeds and snails. To our knowledge, this work is the first report of snails serving as a biomagnification medium that promotes accumulation of dioxins in mitten crabs. This observation provided crucial insight to prevent and reduce contamination of crab by dioxins and DL-PCBs.

Polychlorinated naphthalenes in farmed Chinese mitten crabs in China: Concentration, distribution and source analysis

Polychlorinated naphthalenes (PCNs) are both highly toxic and bioaccumulative environmental contaminates. Dietary intake is the primary pathway for human exposure to PCNs, and PCN concentrations in aquatic foodstuffs are relatively high. Chinese mitten crab (Eriocheir sinensis) is one kind of popular aquatic foodstuffs in Asian countries. Farmed crabs could exposure to PCNs both through feed and environment. However, information on the occurrence of PCNs in farmed crabs is scarce. The present study investigated 75 PCN congeners in farmed Chinese mitten crabs, crab compound feed and sediments collected from Anhui Province and Shanghai in China. The total PCN concentrations in farmed Chinese mitten crabs from Anhui Province and Shanghai were 11.2-42.2 and 5.46-43.8 pg/g wet weight (ww), respectively. The PCN homologue profiles in crabs from both areas were similar, and both were dominated by di-CNs and penta-CNs. In contrast, lower chlorinated PCNs (di-CNs, tri-CNs and tetra-CNs) were the most common homologues in specimens of crab compound feed and sediment samples, indicating that selective bioaccumulation and metabolism of PCNs might occur in farmed crabs. No regional differences were found in the PCN congener profiles of farmed crabs, feed and sediment samples taken from Anhui Province and Shanghai. An assessment found no significant health risk associated with Chinese exposure to PCNs through farmed Chinese mitten crab consumption.

Ecosystem impact and dietary exposure of polychlorinated biphenyls (PCBs) and heavy metals in Chinese mitten crabs (Eriocheir sinensis) and their farming areas in Jiangsu, China

This study investigated the presence of 18 dioxin-like and non-dioxin-like polychlorinated biphenyls (dl- and ndl-PCBs), heavy metals (Cd, Hg, Pb, and As) in Chinese mitten crabs (Eriocheir sinensis) and their distribution in Jiangsu, China. Risk assessment and source apportionment were employed for evaluating the eco-toxicological impact and human exposure. It was found that the compositions of PCBs varied spatially, suggesting different sources of pollutants, whilst PCB 28, 105, 114, and 126 were consistently found in all sample types, suggesting a common pollution source remained, and the bio-accumulation process was in effect. The total PCBs in sediment were found much higher than in water, and brown meat had the highest and most diverse PCB congeners among all tissues. The presence of heavy metals was found in all samples in descending order of As>Cd>Pb>Hg and in the order of shell>brown meat>white meat>gill for crabs. The results of risk assessment indicated that the potential carcinogenic and non-carcinogenic risks were within the acceptable range for long-term consumption of the crabs overall. However, the highest toxic equivalent (TEQ), carcinogenic, and non-carcinogenic risks were all recorded in Location C, where dl-PCB 126, 169, and As contributed to the majority of the risks. The ecological risk posed by all HMs was low, but cases of serious point source pollution have been found in the investigated regions, and risks caused by Cd individually should raise concerns. Source apportionment study revealed that the contaminants mostly originated from anthropogenic activities. Natural deposition and transportation played an important role as well.

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.

Freshwater crabs could act as vehicles of spreading avian influenza virus

Avian influenza virus (AIV) possessed significant risk to various animals and human health. Wild birds, especially waterfowls are considered to be the natural reservoir of AIVs. The ecology of AIV is still far from being fully understood. Freshwater crabs are nonnegligible biotic factor in AIV ecosystem. We analyzed the ability of freshwater crabs accumulate and spread AIV. We found that AIV remain infectious in water only for 36 h but persist in crabs for 48 h. Crabs could accumulate AIV in their gills and gastrointestinal tracts. The AIV titers in crabs were higher than the surrounding contaminated water. Crabs could accumulate AIV from contaminated water, carry the virus and spread to naïve crabs via surrounding water. Our study identified freshwater crab as a novel transmission vehicle in AIV ecosystem.

Polycyclic aromatic hydrocarbons (PAHs), arsenic, chromium and lead in warty crab (Eriphia verrucosa): occurrence and risk assessment

This study assesses the PAH and heavy metal levels in muscle of warty crabs (Eriphia verrucosa), from the northern coast of the Campania region improving the data on toxic contaminants in this crustacean. The results showed a minimal PAH contamination; the mean concentrations were as follows: 0.2, 1.6 and 1.7 μg kg-1 wet weight (ww) for BaP, PAH4 and PAH6, respectively. Regarding the levels of the two PAHs not included in the European regulations, the BkF mean concentration was 0.1 μg kg-1 ww, while DahA was detected only in 10.7% of samples. Pb and Cr were also detected at low levels with mean values of 0.068 and 0.468 mg kg-1 ww, respectively; instead, high As levels, with a mean value of 5.021 mg kg-1 ww, were found. Considering the EWIs and the ILCRs calculated in this study, the PAH, Pb and Cr contamination levels found in the edible part of the crabs resulted safe for human consumption. Contrariwise, the ILCR calculated for the As exceeded the acceptable level of cancer risk, although the calculation did not refer to the inorganic form which is the only one recognized as carcinogenic. Hence, this study shows that warty crabs can accumulate environmental contaminants in their muscle tissue representing an important route of exposure to these toxics for the local population that regularly consumes them. This finding highlights the importance of monitoring the presence of these pollutants in crabs and in general in all fish and seafood in order to ensure food safety for consumers.

Concentrations and sources of short- and medium-chain chlorinated paraffins in farmed Chinese mitten crabs in China

Aquatic foods are important sources of chlorinated paraffins (CPs) to humans. Farmed crabs are bottom-dwelling aquatic animals, and can accumulate CPs through food and aquatic environment. However, limited information is available on CPs concentrations in and sources to farmed crabs. In this study, short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) concentrations in 59 samples from the farmed crab food web (crab, crab feed, and aquaculture environment) were determined. The samples were from 17 crab farms in Anhui Province, Jiangxi Province, and Shanghai, in China. The SCCPs and MCCPs concentrations in the crab samples were 82-1760 and not detected-680 ng/g lipid weight, respectively. The dominant SCCPs and MCCPs in the crab samples were C₁₀Cl_6-7 and C₁₄Cl_7-8, respectively. The SCCPs concentrations in the crab food web samples were higher than the MCCPs concentrations. SCCPs contamination of the crab food web samples was not directly related to CPs product use. The main factors affecting SCCPs concentrations in the crab samples were different for different crab farms. Crab feed and the aquaculture environment could be sources of SCCPs to farmed crabs. No marked health risks are posed to humans through consuming CPs in Chinese mitten crabs farmed in China.

Heavy metal concentration levels and biometric analysis of Liocarcinus depurator from different locations on the western Black Sea coast of Turkey

The aim of the current work is to examine the concentrations of nine heavy metals such as chromium, nickel, copper, cadmium, zinc, cobalt, iron, lead, and metal (aluminium) in two body parts (carapace and walking legs) of Liocarcinus depurator from different stations (İlyas bey, Cide koyu, Anadolu feneri, igneada) in the western Black Sea coast of Turkey. And this study was carried out to examine morphological properties of Liocarcinus depurator in the region. The sex ratio (female/male) of 387 samples was calculated as F/M = 1:0.945. The mean carapace length and width were measured as 20.41 ± 2.41 mm and 25.10 ± 2.78 mm for female and 25.49 ± 3.33 mm and 32.32 ± 4.50 mm for male individually. The mean weight of crabs was measured as 4.09 ± 1.37 g for females and 8.33 ± 3.35 g for males. The samples were investigated trace metals by inductively coupled plasma-optical emission spectrometry (ICP-OES). Ranges over trace metals in all samples of L. depurator as follows: Cr 0.6-1.5, Mn 21-130, Cu 8-37, Zn 6-40, Cd 0.2-1.5, Pb 0.1-3.6, Co 0.1-1.1, Fe 22-160, and Ni 0.6-1 mg/kg wet wt. The walking legs and carapace/exoskeleton of female and male crabs were analyzed and contained various concentrations of Pb, Co, Ni, Cr, Cd, Fe, Cu, Zn, and Mn elements. The order of the heavy metal in all samples of L. depurator is shown as Fe > Cu > Mn > Zn > Cr > Cr > Ni > Cd > Pb > Co. In this research, metal levels of the crab samples compared between female and male and found highest mean metal concentrations in the station number 3 (Anadolu feneri) that the Al concentration in the carapace of female was 295.0 mg/kg wet wt and in the walking legs was 306.67 mg/kg wet wt, in the carapace of male was 264.4 mg/kg wet wt, and in the walking legs was 162.61 mg/kg wet wt in station number 3 (Anadolu feneri). The purpose of this work is to analyze the metal composition of this type of crab, which is abundant in the Black Sea region and is not planned to be attached to fisherman's nets, to evaluate whether it will be useful or not.

Application of gas chromatography coupled to triple quadrupole mass spectrometry (GC-(APCI)MS/MS) in determination of PCBs (mono-to deca-) and PCDD/Fs in Chinese mitten crab food webs

Polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins and furans (PCDD/Fs) are notorious persistent organic pollutants (POPs), which may bioaccumulate through food chain and play detrimental effects to organisms even at trace levels. Quantification of PCBs and PCDD/Fs in biotic samples is a great challenge. In the present study, gas chromatography coupled to triple quadrupole mass spectrometry with an atmospheric pressure chemical ionization source (GC-(APCI)MS/MS) was studied for the isotope-dilution analysis of PCBs (mono-to deca-) and PCDD/Fs in Chinese mitten crab food webs. High-resolution mass spectrometry (HRMS) was applied for comparison. Light PCBs are compared between the two instruments for the first time. After optimization of instrument parameters, the RSDs of relative response factors of calibration curves were between 3.4% and 15.5% for PCBs and 1.7%-7.9% for PCDD/Fs. The limits of detection were between 0.021 and 0.150 pg/mL for PCBs and 0.051-0.237 pg/mL for PCDD/Fs. PCB concentrations in crab food web samples detected by GC-(APCI)MS/MS were well correlated with those detected by HRGC/HRMS. A DiCB, 3,3'-dichlorobiphenyl (PCB11), was the dominant PCB congener in aquatic food webs. Other MoCB and DiCB congeners were also widely identified; hence, low-weight PCB congeners should arouse more concern in the future. GC-(APCI)MS/MS may become an alternative instrument satisfying the PCB and PCDD/F detection.

Risks and critical issues related to the discovery on the market of unauthorized live alien species on the Italian territory: Chinese crab (Eriocheir sinensis)

Eriocheir sinensis, Chinese Crab or Chinese Mitten Crab is a catadromous species belonging to the Varunidae family, native to river and estuarine areas of North and South East China and Korea. At European level, E. sinensis is widespread in the main water basins of Central and Northern Europe and, since 2016, it has been included in the list of invasive species important for the European Union and subjected to confinement and eradication measures which include the prohibition of collection, transit and placing on the market of live specimens (Regulation (EC) N° 1143/2014). The Chinese Crab can represent a significant danger for the local ecosystem and for the native biota as well as contributing to the appearance of hydrogeological instability phenomena resulting from the intense excavation and erosion of the riverbanks. The first finding of 5 kg of live specimens of Eriocheir sinensis was recorded in the official control by the UFS (Functional Simple Unit) veterinary public health and food safety of the ASL Toscana Centro at an ethnic catering establishment. The specimens were subjected to seizure, photographed, identified morphologically, and subjected to euthanasia and destruction in accordance with the European requirements for welfare and management of animal by-products. From the sanitary point of view, the dangers associated with the consumption of this crab are mainly biological and chemical therefore, risk communication is fundamental, not only at the level of the competent authorities in the sector, but also for the food business operators.

The use of non-adapted anaerobic consortium in batch reactors enable to couple polychlorinated biphenyl degradation and community adaptation

The removal of polychlorinated biphenyls (PCBs) and PCB biosorption was investigated in anaerobic batch reactors with non-adapted sludge fed with 1.5 mg L^-1 of six PCB congener (PCB 10, 28, 52, 153, 138 and 180), mineral medium and co-substrates. PCBs were analyzed by gas chromatography using headspace solid-phase microextraction (HS-SPME). In the methanogenic reactor the methane production, COD (Carbon Organic Demand) removal (90% of initial 2292.60 mg L^-1) and consumption of volatile organic acids were verified. Nevertheless, anaerobic activity was not observed in the reactor with inactivated biomass and biosorption range of 38% to 89% was measured for distinct PCB congeners in this reactor. The PCB removal was calculated from the PCB bioavailable (not biosorbed) and reached 76% of total PCBs. The selection of some representatives of the Thermotogaceae family, Sedimentibacter and Pseudomonas at 101 days of operation in the methanogenic reactor was correlated with PCB degradation. In addition, the various removal rates for each PCB congener indicate that the removal depends on bioavailability. The selection of the former non-adapted microbiota in the methanogenic reactor combined with PCB degradation occurred at 101 days. These results allow to assert that it is possible to simultaneously couple PCB degradation and community selection, without the previous adaptation step, which is a time-consuming stage.

Determination of polychlorinated biphenyls and organochlorine pesticides in Chinese mitten crabs (Eriocheir sinensis) using modified QuEChERS followed by GC-MS

Chinese mitten crabs (Eriocheir sinensis) are one of the most popular food items with a high nutritional value. The use of pesticides and environmental pollutants directly influenced improvements in productivity of mitten crabs. However, there is an increasing number of food safety issues raising consumer concerns. It is necessary to determine whether the pollutants that crabs contain are below the maximum residue limits to guarantee food safety. Moreover, there has been very little research on detecting pesticide residues and other pollutants in Chinese mitten crabs due to their complicated matrix effects. In the current study, a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method has been modified and validated for the simultaneous analysis of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in mitten crabs. By using acetonitrile extraction, low temperature (freezing) precipitation and clean-up by mixed sorbents of C18, PSA and Florisil (magnesium silicate), the method was proved to be valid with linearity, precision, recovery, limit of quantification (LOQ), and limit of detection (LOD) with recoveries ranging from 85.9-119.8% and LOQ within 0.1-3.6 μg kg-1. The method was also applied to detect PCBs and OCPs in 48 crab samples from Jiangxi Province, China. The results showed that most of the crab samples contained PCB 118, beta-HCH and p,p'-DDT, and the content of p,p'-DDD in mitten crabs of Jiangxi Province showed sex-specific differences, which might be connected with sex-differential regulation.

Activation of integrated stress response and disordered iron homeostasis upon combined exposure to cadmium and PCB77

Both cadmium and polychlorinated biphenyls (PCBs) can induce diverse detrimental effects on human health. Though these compounds co-exist in various environmental contexts and in the human body, studies on their joint toxicities are limited. Activation of the integrated stress response (ISR) and iron homeostasis are crucial for erythropoiesis. The impact of cadmium and PCBs on the ISR activation and iron homeostasis of erythroid progenitors is unknown. We investigated the adverse effects and mechanisms of CdCl₂ and PCB77 on HEL cells, a human cell model of erythroid progenitors. We found that at high concentrations of CdCl₂ and PCB77, cytotoxicity and apoptosis of HEL cells were mainly induced by CdCl₂. At low concentrations of CdCl₂ and PCB77, iron homeostasis inside HEL cells was disturbed by both of these two compounds. Both CdCl₂ and PCB77 activated ISR to combat stress, which at high concentration was mainly induced by ROS, leading to apoptosis, and at low concentration was partly induced by disordered iron homeostasis. The patterns of ISR activation and iron homeostasis disorder were different between CdCl₂ and PCB77. Their combined exposure exhibited synergetic effect on activating ISR but antagonistic effect on disturbing iron homeostasis. Our study demonstrates some previously unrecognized harmful characteristics and mechanisms of cadmium and PCB77.

Concentrations of total mercury and methylmercury in red snow crabs (Chionoecetes japonicus) caught off the coast of Japan

The total mercury (T-Hg) and methylmercury (MeHg) concentrations in red snow crabs (Chionoecetes japonicus) caught off the coast of Japan were analyzed. The T-Hg concentration ranged from 0.03 to 0.56 mg/kg (mean: 0.21 mg/kg) in the raw muscle, and 0.02 to 0.74 mg/kg (mean: 0.27 mg/kg) in the boiled muscle. The MeHg concentration ranged from 0.04 to 0.54 mg/kg (mean: 0.20 mg/kg) in the raw muscle. The mean ratio of MeHg to T-Hg was 0.88. The crab body weight was found to significantly correlate with the concentrations of T-Hg (r = 0.488) and MeHg (r = 0.490) (p ≤ 0.01). For the general population in Japan, the intake of MeHg from eating red snow crab was estimated to be lower than 0.013 mg/week, which was less than one-sixth of the tolerable MeHg intake (0.08 mg/week).

Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.

Sources of polychlorinated dibenzo-p-dioxins and dibenzofurans, and biphenyls in Chinese mitten crabs

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in Chinese mitten crabs from several areas were determined. The toxic equivalents (TEQs) for the mean PCDD/F and total PCDD/F and dioxin-like PCBs were 2.9 ± 2.7 and 5.7 ± 4.0 pg TEQ g^-1, respectively. The mean concentrations of PCBs and dl-PCBs were 282 and 59 times the concentrations of PCDD/Fs, respectively. PCDD/F and PCB sources in the crab food web were assessed. The total TEQ of PCDD/F and PCB supplied by crab compound feed was 2.1 times the TEQ in crab meat. Broken corn, aquatic biota, and water contributed around 12% of the total TEQ inputs for crab meat. The contribution from sediment was around 164 times that from crab meat, and sediment may be the most important source of PCDD/Fs and PCBs in cultured crabs. Principal component analysis (PCA) and stable isotope ratios for nitrogen (δ¹⁵N) and carbon (δ¹³C) supported the TEQ results. The mean total PCDD/F and dl-PCB TEQ exposure for humans consuming crabs was 3.4 pg TEQ per kilogram of body weight per day. The PCDD/Fs and PCBs in >80% of the crab samples would not cause the tolerable daily intake to be exceeded.

Indices of stress and immune function in Arctic barnacle goslings (Branta leucopsis) were impacted by social isolation but not a contaminated grazing environment

In many areas around the Arctic remains and spoil heaps of old mines can be found, which have been abandoned after their heydays. Runoff from tailings of these abandoned mines can directly contaminate the local environment with elevated concentrations of trace metals. Few studies have investigated the possible negative effects of contaminants on Arctic terrestrial animals that use these areas. Trace metals can accumulate in animals and this accumulation has been linked to negative effects on fitness. Both, the hypothalamus-pituitary-adrenal (HPA) axis and/or the immune system have been named as possible underlying causes for these observations. Free-living animals are often exposed to multiple stressors simultaneously, however, and this is often not considered in studies on the effects of contaminants on animal physiology. Here, we performed a study on Spitsbergen (Svalbard) taking both potential effects of trace metal contamination and social stress into account. We investigated experimentally effects of exposure to contaminants from a historic coal mine area on plasma corticosterone levels and on four innate immune parameters (haemolysis, haemagglutination, haptoglobin-like activity and nitric oxide) before and after social isolation in human-raised barnacle goslings (Branta leucopsis). Baseline corticosterone and immune parameters were not affected by mine-exposure. After social isolation, mine goslings tended to show decreased haemagglutination in comparison with control goslings, but we detected no difference in the other measures. Social isolation increased corticosterone and decreased haptoglobin-like activity in all goslings. Immunology and corticosterone levels of barnacle goslings thus seem unaffected, at least on the short term, by Arctic coal mining contamination.

Temporal trend of polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran and dioxin like-polychlorinated biphenyl concentrations in food from Taiwan markets during 2004-2012

The levels of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) or polychlorinated biphenyl (PCB) in foodstuffs have decreased over the past decade in many countries. However, the trend for the levels of these compounds in foodstuffs in Taiwan remains unknown. In this study, we compared the distribution of PCDD/F and PCB in nine foodstuff categories acquired from Taiwan markets from 2004 to 2012. The levels expressed as World Health Organization toxic equivalents (WHO-TEQs) in the different foodstuffs tested were as follows: fish, average 0.463 pg WHO₉₈-TEQ/g sample > seafood, 0.163 pg WHO₉₈-TEQ/g > eggs, 0.150 pg WHO₉₈-TEQ/g > oils, 0.126 pg WHO₉₈-TEQ/g > meats, 0.095 pg WHO₉₈-TEQ/g > dairy products, 0.054 pg WHO₉₈-TEQ/g > cereals, 0.017 pg WHO₉₈-TEQ/g > vegetables, 0.013 pg WHO₉₈-TEQ/g > fruits, 0.009 pg WHO₉₈-TEQ/g. Levels were particularly high in crab (average: 0.6 pg WHO₉₈-TEQ/g sample (1.243 pg WHO₉₈-TEQ/g sample) and large marine fish (0.6). In Taiwan, a decreasing trend of PCDD/Fs or dioxin-like PCBs (dl-PCBs) was observed in meat, dairy, eggs, and vegetables, whereas an elevated trend was observed in cereals or the levels were nearly equal in fruits and oils at alternative time shift. Dl-PCBs contributed to 60–65% toxicity equivalence levels in fish and seafood, but only to 13–40% in meat and cereal samples. The decreasing trend was consistent with the results in other countries; however, the trends in cereals, fruits, and oils were in contrast to previous results reported in other countries. Cereals and fruits are important crops in southern Taiwan, and the local pollution generated by industries or incinerators may seriously affect the distribution of PCDD/Fs and dl-PCBs. To ensure food safety, a risk assessment for residents living in different areas should be adopted for all food categories simultaneously in the future.