PCB concentrations in shrimp from major import markets and the United States.

Currently, environmental studies describing levels of polychlorinated biphenyls (PCBs) in imported shrimp are limited, particularly studies of aquaculture shrimp. In the present study, we measured concentrations of the 209 PCB congeners in 84 uncooked, warm-water shrimp samples from the United States and 14 other countries in three continents. Total PCB and dioxin-like PCB (DL-PCB) levels were not significantly different between wild-caught and farm-raised shrimp, and the distribution of total PCB levels did not vary considerably by country of origin although significant differences were observed in some cases. Regional trends in both total PCB and DL-PCB concentrations were observed, with the highest concentrations measured in shrimp from North America followed by Asia and then South America. The lower chlorinated homologues (i.e., mono-, di-, and tri-PCBs) generally comprised a greater fraction of the total levels measured in farm-raised shrimp and shrimp from Asia and South America whereas higher chlorinated homologues (i.e., hepta-, octa-, nona-, and deca-PCBs) contributed more to levels in wild-caught shrimp and shrimp from North America. Estimated daily intake of PCBs associated with shrimp consumption ranged from 2 pg/kg/d (shrimp from South America) to 15 pg/kg/d (shrimp from North America). Results from the present study were comparable to other studies conducted recently and demonstrate that exposure to PCBs from consumption of farm-raised and wild-caught shrimp imported from different regions are not likely to pose any health risks.

Levels of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls in southern Mississippi catfish and estimation of potential health risks.

Fish consumption has been classified as one of the primary pathways of exposure to polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and biphenyls (PCBs). In this study, we evaluated tissue levels of the 17 laterally substituted PCDD/Fs, 12 dioxin-like PCBs, and 97 non-dioxin-like PCBs in a number of wild-caught and farm-raised catfish collected throughout southern Mississippi. Total lipid-adjusted TEQ and non-dioxin-like PCB concentrations in wild-caught catfish fillets were significantly higher than concentrations in farm-raised fillet samples. The percent contribution of PCDDs, PCDFs, and dioxin-like PCBs to mean total TEQ varied between wild-caught and farm-raised samples as well as by collection site for wild-caught catfish. The non-dioxin-like PCBs that contributed the most to total PCB concentrations also differed between wild-caught and farm-raised samples. Regardless of whether samples were farm-raised or wild-caught, estimated cancer risks associated with consumption of these catfish were less than 27.0E-06. Overall, results of this study indicate that levels of dioxin-like compounds and PCBs in Mississippi catfish are similar to those measured in more recent studies in the US and that levels of these compounds appear to be decreasing in this food source.

Assessment of polybrominated diphenyl ether exposures and health risks associated with consumption of southern Mississippi catfish.

Despite the growing public interest in polybrominated diphenyl ethers (PBDEs), there are relatively few studies in the published literature which characterize and quantify human intake of these compounds. In this study, PBDE concentrations were measured in southern Mississippi catfish to determine background levels, daily intake, and risk associated with the consumption of these chemicals from a primary food source for residents in this region of the United States. A total of 33 wild catfish samples were collected from five sites, and 28 farm-raised catfish samples were purchased, all of which were from locations in southern Mississippi. All samples were analyzed for 43 PBDEs (mono- through deca-congeners) using high-resolution gas chromatography-mass spectrometry. Both PBDE concentrations (sigmaPBDE ranged from 0.3 to 23.3 ng/g wet weight) and congener profiles varied by fish type and location; however, BDE congeners 47, 99, 100, 153, and 154 were the dominant contributors in all samples. The estimated daily intake of PBDEs associated with consumption of the catfish ranged from 0.03 to 1.80 ng/kg-day. Evaluation of the cancer risk for BDE 209 and the noncancer hazard for BDE congeners 47, 99, 153, and 209 indicated that health risks/hazards due to fish consumption in adults are substantially lower than risk levels generally considered to be at the U.S. EPA minimum concern level.

Spatial distribution of polybrominated diphenyl ethers and polychlorinated dibenzo-p-dioxins and dibenzofurans in soil and combusted residue at Guiyu, an electronic waste recycling site in southeast China.

Surface soils and combusted residue from a village located in southeast China, which has been intensely involved in the dismantling and "recycling" of computer parts (e-waste) for the past decade, were analyzed for polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Total PBDE concentrations were highest in combusted residue of plastic chips and cables collected from a residential area (33,000-97,400 ng/g, dry wt), in soils from an acid leaching site (2720-4250 ng/g, dry wt), and a printer roller dump site (593-2890 ng/g, dry wt). BDE-209 was the most dominant congener (35-82%) among the study sites indicating the prevalence of commercial Deca-BDE, however signature congeners from commercial Penta- and Octa-BDE were also found. PCDD/F concentrations were also highest in soil from the acid leaching site (12,500-89,800 pg/g, 203-1100 pg WHO-TEQ/g, dry wt) and in combusted residue (13,500-25,300 pg/g, 84.3-174 pg WHO-TEQ/g, dry wt) and were comparable to PCDD/F levels of some open dumping sites in Asian developing countries. Of the e-waste activities, acid leaching and open burning emitted the highest concentrations of PBDEs and PCDD/Fs. This study is among the very few studies dealing with the important issue of pollution generated from crude e-waste recycling. Our results showthatthe crude processing of e-waste has become one of the major contributors of PBDEs and PCDD/Fs to the terrestrial environment.

Complete mass balance of dietary polychlorinated dibenzo-p-dioxins and dibenzofurans in dairy cattle and characterization of the apparent synthesis of hepta- and octachlorodioxins.

Mass balances of 2,3,7,8-substituted dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were measured in cows following administration of pentachlorophenol (PCP)-treated wood. Fecal excretion accounted for the major fraction of all congeners. Recovery in feces increased with increasing chlorination, while storage in body fat and excretion in milk decreased with increasing chlorination. The PCDFs with no chlorines in the 4- and 6-positions were apparently metabolized because residues were not detected in milk and body fat. Storage and excretion of 1,2,3,4,6,7,8-HpCDD and 1,2,3,4,6,7,8,9-OCDD exceeded intake by factors of 1.7 and 3.4, but recovery of other PCDD/Fs did not exceed intake significantly. Excess excretion of OCDD, but not HpCDD, was confirmed in a follow-up study. Synthesis of HpCDD and OCDD did not occur when PCP-treated wood was fermented with rumen microorganisms, and enhanced concentrations of HpCDD and OCDD were not found in gastrointestinal tract contents of dosed animals. Formation of OCDD during incubation of feces spiked with PCP-treated wood led to the conclusion that synthesis was postexcretion during sample preparation.