Polychlorinated dibenzo-P-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBS) in bivalve mollusk from Galician Rías (N. W., SPAIN)

Polychlorinated dibenzo-p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls in bivalve molluscs. Risk to Polish consumers?

Introduction

Concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were investigated in six species of bivalve mollusc purchased on the Polish retail market. The risk to consumers was calculated as a percentage of the tolerable weekly intake (TWI) (2 pg World Health Organization toxic equivalent (WHO-TEQ) kg-1 body weight (b.w.)).

Material and Methods

Altogether 32 samples were analysed using an isotope dilution technique with high resolution gas chromatography coupled with high resolution mass spectrometry.

Results

Low levels of all analysed compounds were found. The range of PCDD/Fs was 0.08-0.37 pg WHO-TEQ g-1 of wet weight (w.w.) and 0.04-0.41 pg WHO-TEQ g-1 w.w. for DL-PCBs. The highest concentrations of all analysed compounds were found in Pacific oysters, at 0.30 pg WHO-TEQ g-1 w.w. for the sum of PCDD/Fs and 0.19 pg WHO-TEQ g-1 for the sum of DL-PCBs. These concentrations were 2-4 times higher than those detected in the other analysed mollusc species. Different species-dependent congener profiles were observed for PCDD/F concentrations, while PCB congener concentration profiles were species independent. The risk to consumers was assessed relating theoretical intakes of PCDD/Fs and DL-PCBs per 25, 50 and 100 g of consumption of molluscs per week to the TWI.

Conclusion

Taking into account the low consumption of molluscs in Poland and low concentrations of analysed compounds, neither adults nor children are likely to exceed the TWI by ingestion of food in this category.

Assessment of PCDD/F and dioxin-like PCB levels in environmental and food samples in the vicinity of IZAYDAS waste incinerator plant (WIP): from past to present

The study includes the determination of the general background PCDD/F and dl-PCB levels in environmental (ambient air and soil) and food (meat, milk, egg, leafy vegetable, root vegetable and fruit samples) samples collected in four sampling sites in the vicinity of IZAYDAS WIP and its possible health risks. The local and meteorological conditions (prevailing wind direction, season, raining, and soil structure) were taken into account in the selection of sampling sites. The concentrations of PCDD/F and dl-PCB in ambient air ranged from 0.00841 to 0.05881 pg I-TEQ/m³. These results are quite low and it showed that there is no significant PCDD/F pollution in the vicinity of the plant. The results of PCDD/F and dl-PCB in eight soil samples (four in the range of 0-1.2 km, four in the range of 1.2-5 km) taken from the vicinity of IZAYDAS varied between 0.12681 and 0.4353 pg TEQ/g. The levels of PCDD/F and dl-PCBs measured in food samples were found to be significantly lower than both the limit values given by the Turkish Food Codex and the levels measured in the previous studies (between 2008 and 2009). In the health risk assessment, carcinogenic risk was calculated for PCDD/F and dl-PCBs made according to the exposure scenarios established for the study. The total intake values for the sum of PCDD/F and dl-PCB were found between 0.08 and 0.37 pg TEQ/kg.day for adults. These values are well below the limit value, which is considered as 2 pg WHO-TEQ/kg body weight.day. In this context, it was concluded that carcinogenic risk due to PCDD/F and dl-PCB intake is significantly low in the vicinity of the plant.

Spatial and temporal trends of PCDD/Fs in sediment and bivalves along the Korean coasts during 2001-2012

Concentrations of polychlorinated dibenzo-para-dioxins and dibenzofurans (PCDD/Fs) were measured in sediment and bivalves at 25 locations along the Korean coasts during 2001-2012. Concentrations of PCDD/Fs in sediment and bivalves ranged from 0.15 to 18.9 pg TEQ/g dry weight and from 0.06 to 7.70 pg TEQ/g wet weight, respectively. Elevated PCDD/F concentrations were found at locations close to largest industrial complexes and commercial harbors. A significant decreasing trend of PCDD/Fs in sediment was associated with strong regulation of PCDD/Fs, whereas levels in bivalves did not show a decreasing trend. Octachlorinated dibenzo-p-dioxin (OCDD) was predominant in sediment, while tetrachlorinated dibenzofuran and OCDD were predominant in bivalves. Almost half (46%) of sediment samples exceeded the threshold effect level suggested by the US National Oceanic and Atmospheric Administration, implying ecotoxicological risks to benthic organisms. Our findings support the effectiveness of legislative action on PCDD/Fs for coastal environments of Korea.

Bioassay system for the detection of aryl hydrocarbon receptor agonists in waterborne pesticides using zebrafish cyp1a1 promoter-luciferase recombinant hepatic cells

Currently used pesticides are widely distributed in surface water. Most of them are harmful to aquatic animals. In the present study, a novel recombinant hepatic cell line was developed for detecting the activity of aryl hydrocarbon receptor (AhR) agonists, and their potential bio-toxicity to aquatic animals was evaluated. First, HepG2 cells were stably transfected with a luciferase reporter plasmid containing a zebrafish (Danio rerio) cyp1a1 promoter with twelve copies of dioxin-responsive elements. The minimal detection limit was a 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentration of 0.3 ng/L (equivalent to 0.93 pM). The AhR agonist activity of thirty-seven pesticides was screened by measuring luciferase expression in the recombinant cells. Four pesticides (ipconazole, mepanipyrim, quinoxyfen and pencycuron) significantly induced luciferase expression. Additionally, cells treated with these four pesticides increased the cyp1a1 mRNA expression level, which further confirmed that they are AhR agonists. In conclusion, for the first time, we developed recombinant hepatic cells with a luciferase reporter plasmid containing a modified zebrafish cyp1a1 promoter. The cyp1a1 promoter luciferase reporter cells can be used as a sensitive and specific model to screen AhR agonists among currently used pesticides in water, which could be beneficial for risk assessment in aquatic environments.

Occurrence, sources and ecotoxicological risks of polychlorinated biphenyls (PCBs) in sediment cores from urban, rural and reclamation-affected rivers of the Pearl River Delta, China

Sediment cores were collected to a depth of 40 cm (50 cm for urban river sediments) in the Pearl River Delta of China from rural river sediments and river sediments undergoing the process of urbanization and reclamation. Polychlorinated biphenyls (PCBs) in sediment cores were determined to evaluate their levels, distribution, possible sources and potential risks aimed at providing effective information of management practices for local governments. Our results showed that the total concentrations of PCBs (∑16PCBs) in urban, rural and reclamation-affected river sediments ranged from 16.15 to 477.85 μg kg^-1 (dry weight), with mean values of 121.94, 150.49 and 124.20 μg kg^-1 (dry weight), respectively. The most abundant PCB congeners among the study area were light PCBs. Generally, PCBs showed a decreasing trend with depth along sediment cores at most sampling sites. Source analysis indicated that PCBs in the three types of river sediments mainly originated from Aroclor 1242, 1248, 1254 and 1016. Risks evaluation based on sediment quality guideline quotient (SQGQ) showed PCBs at most sampling sites would cause no or moderate adverse biological effects on benthic organisms except surface sediments of U4 and R5 (high adverse biological effects). However, threshold effects level (TEL) is ignored when calculating SQGQ, which might underestimate the risks of PCBs. Thus, a new SQGQ (NSQGQ) taken TEL into consideration was established. Results showed that NSQGQ could evaluate ecotoxicological risks of PCBs better. Redundancy analysis (RDA) showed that PCBs in sediments were positively correlated with sand content and microbial biomass carbon (MBC) (p < 0.05).