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Toxic Equivalents (toxic + equivalent)
Selected Abstracts2,3,4,7,8-pentachlorodibenzofuran is a more potent cytochrome P4501A inducer than 2,3,7,8-tetrachlorodibenzo- p -dioxin in herring gull hepatocyte culturesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2010Jessica C. Hervé Abstract Concentration-dependent effects of 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), and 2,3,7,8-tetrachlorodibenzofuran (TCDF) on cytochrome P4501A (CYP1A) induction were determined in primary cultures of embryonic herring gull (Larus argentatus) hepatocytes exposed for 24,h. Based on the concentration that induced 50% of the maximal response (EC50), the relative potencies of TCDD and TCDF did not differ by more than 3.5-fold. However, also based on the EC50, PeCDF was 40-fold, 21-fold, and 9.8-fold more potent for inducing ethoxyresorufin- O -deethylase (EROD) activity, CYP1A4 mRNA expression, and CYP1A5 mRNA expression than TCDD, respectively. The relative CYP1A-inducing potencies of PeCDF and of other dioxin-like chemicals (DLCs) in herring gull hepatocytes (HEH RePs), along with data on concentrations of DLCs in Great Lakes herring gull eggs, were used to calculate World Health Organization toxic equivalent (WHO-TEQ) concentrations and herring gull embryonic hepatocyte toxic equivalent (HEH-TEQ) concentrations. The analysis indicated that, when using avian toxic equivalency factors (TEFs) recommended by the WHO, the relative contribution of TCDD (1.1,10.2%) to total WHO-TEQ concentration was higher than that of PeCDF (1.7,2.9%). These results differ from the relative contribution of TCDD and PeCDF when HEH RePs were used; PeCDF was a major contributor (36.5,52.9%) to total HEH-TEQ concentrations, whereas the contribution by TCDD (1.2,10.3%) was less than that of PeCDF. The WHO TEFs for avian species were largely derived from studies with the domestic chicken (Gallus gallus domesticus). The findings of the present study suggest that it is necessary to determine the relative potencies of DLCs in wild birds and to re-evaluate their relative contributions to the biochemical and toxic effects previously reported in herring gulls and other avian species. Environ. Toxicol. Chem. 2010;29:2088,2095. © 2010 SETAC [source] Optimization of activated carbon-based decontamination of fish oil by response surface methodologyEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2007Åge Oterhals Abstract The effect of activated carbon (AC) adsorption on the reduction of persistent organic pollutants (POP) in fish oil was studied based on response surface methodology at a 5-g/kg AC inclusion level. Pretreatment of the oil by alkali refining and bleaching increased the POP levels. The tested process variables (contact time and temperature) affected the AC adsorption rate and significant first- and second-order response models could be established. Polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/F) showed a very rapid adsorption behavior and the concentration and toxic equivalent (TEQ) level could be reduced by 99%. Adsorption of dioxin-like polychlorinated biphenyls (DL-PCB) was less effective and depended on ortho substitution, i.e. non- ortho PCB were adsorbed more effectively than mono- ortho PCB with a maximum of 87 and 21% reduction, respectively, corresponding to a DL-PCB-TEQ reduction of 73%. A common optimum for both PCDD/F and DL-PCB adsorption could not be identified. AC treatment had no effect on the level of polybrominated diphenyl ether flame retardants. The differences in adsorption patterns may be explained based on molecular conformation. No change in oil quality could be observed based on oxidation parameters. Compliance with present PCDD/F and DL-PCB legislation levels in fish oil can be achieved based on AC adsorption. [source] Patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the Hudson River, New York, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Christine M. Custer Abstract Belted kingfisher (Ceryle alcyon), spotted sandpiper (Actitus macularia), and tree swallow (Tachycineta bicolor) eggs were collected in 2004 from the upper Hudson River, New York, USA. This area is one of the most polychlorinated biphenyl (PCB)-contaminated locations in North America. Multivariate analyses indicated among species differences in the concentration and composition of PCB congeners, polychlorinated dibenzo- p -dioxin (PCDD), and dibenzofuran (PCDF, PCDD-F when combined with PCDDs) congeners, and chlorinated pesticides. Total PCB concentrations followed the typical food chain biomagnification paradigm of higher concentrations in piscivorous bird eggs and lower concentrations in eggs of species that feed at lower trophic levels. Concentrations in the insectivorous swallows (geometric mean,=,6.8,µg/g wet wt) were approximately half the concentrations present in the piscivorous kingfisher (11.7,µg/g) or omnivorous sandpiper (12.6,µg/g). In contrast, PCB toxic equivalents (TEQs) were higher in swallows (1,790,pg/g wet wt) than in either kingfishers (776,pg/g) or sandpipers (881,pg/g). This difference can be mainly attributed to higher PCB77 concentrations in swallows relative to the other two species. Also contrary to the accepted food-chain paradigm, the sum of PCDD-F concentrations and the sum of their TEQs were higher in swallows than in either sandpipers or kingfishers. Metabolic pathway differences in the respective food chains of the three species probably accounted for the differences observed in PCB TEQ, total PCDD-F, and PCDD-F TEQ concentrations among species. Environ. Toxicol. Chem. 2010;29:2286,2296. © 2010 SETAC [source] Predicting world health organization toxic equivalency factor dioxin and dioxin-like polychlorinated biphenyl levels in farmed atlantic salmon (Salmo salar) based on known levels in feedENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2007Marc H. G. Berntssen Abstract Assimilation and elimination rate constant of dietary polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DLPCBs) with a World Health Organization toxic equivalency factor (WHO-TEF) were estimated in market-size Atlantic salmon (Salmo salar) using fish that were previously fed vegetable oil,based (low in PCDD/Fs and DLPCBs) or fish oil,based (high in PCDD/Fs and PCBs) diets. At the start of the kinetic trial, half the fish that were fed fish oils were fed vegetable oil feeds and inverted (cross-over design) for five months. The assimilation efficiencies of the PCDD/F congeners were more variable (3,89%) and, generally, were lower than those of the DLPCBs (70,80%). Among the PCDD/F congeners, the assimilation efficiency of the most toxic tetra- and pentachlorinated PCDD/Fs was greater than that of higher-chlorinated PCDD/Fs. Elimination rates for DLPCBs were higher than those for PCDD/Fs. Lower-chlorinated PCDDs had a lower elimination rate than the higher-chlorinated PCDDs, but no differences were observed among PCDF congeners or DLPCB congeners. Kinetic parameters were used to predict the level of WHO-TEF dioxins and DLPCBs in Atlantic salmon reared in a large-scale facility under commercial conditions. Predictions were based on preanalyzed levels of these organochlorines in feeds with three different replacement levels (0, 30, and 60%) of vegetable oil. A simple one-compartmental, first-order kinetic model was used to predict the level of sum WHO toxic equivalents for PCDD/Fs and DL-PCBs. The predicted values varied by 0 to 11% from the measured values in the commercially reared salmon. [source] Congener-specific toxicokinetics of polychlorinated dibenzo- p -dioxins, polychlorinated dibenzofurans, and coplanar polychlorinated biphenyls in black-eared kites (Milvus migrans): Cytochrome P4501A,dependent hepatic sequestrationENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Akira Kubota Abstract Concentrations of dioxins and related compounds (DRCs), such as polychlorinated dibenzo- p -dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs), were determined in black-eared kites (BEKs; Milvus migrans) collected from the Kanto district in Japan. Total 2,3,7,8-tetra-CDD toxic equivalents (TEQs) were in the range of 99 to 3,800 pg/g lipid weight in the liver and 42 to 760 pg/g lipid weight in the pectoral muscle. Three congeners, including PCB 126, 2,3,4,7,8-penta-CDF, and 1,2,3,7,8-penta-CDD, made a greater contribution to total TEQs in both tissues. Levels of ethoxy-resorufin- O -deethylase activity and a cross-reactive protein with anti-rat cytochrome P4501A (CYP1A) polyclonal antibodies showed no significant correlation with hepatic TEQs. This may be attributed to low sensitivity and insufficient TEQ levels to cause CYP1A induction, high metabolic potential of a series of congeners, and influence of CYP1A inducers other than DRCs. Most of the PCDD/Fs and non- ortho Co-PCBs exhibited a total TEQ- and CYP1A-dependent increase in the liver to muscle concentration ratios, implying their concentration-dependent hepatic sequestration in which CYP1A was involved. Comparison of the toxicokinetics in avian species revealed that BEKs possibly have higher potentials than common cormorants for metabolizing and sequestering certain congeners in the liver in terms of hepatic concentration profiles and liver:muscle concentration ratios, respectively. These results clearly indicate that the toxicokinetics of DRCs is congener-, tissue-, and species-specific as well as concentration-dependent. Therefore, CYP1A expression is one of the critical factors that determine the toxicokinetics in wild avian species. [source] New organochlorine contaminants and metabolites in plasma and eggs of glaucous gulls (Larus hyperboreus) from the Norwegian ArcticENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2005Jonathan Verreault Abstract The present study investigated new or lesser-studied and legacy organochlorine (OC) contaminants and metabolites in plasma and eggs of glaucous gulls (Larus hyperboreus) collected from major breeding colonies on Bear Island in the Norwegian Arctic. Hexachlorobutadiene was below the method limit of detection (<0.07 ng/g lipid wt) in all samples. The sum (sum) of 20 chlorobornane congener concentrations ranged between 294 and 986 ng/g lipid weight and 104 and 1,121 ng/g lipid weight in plasma and eggs, respectively, whereas those of ,20polychlorinated naphthalene ranged between 1.34 and 126 ng/g lipid weight in plasma and 1.82 and 162 ng/g lipid weight in eggs. Bis(4-chlorophenyl) sulfone concentrations ranged between 5.24 and 143 ng/g lipid weight plasma, which is the first report of this contaminant in arctic biota north of Sweden. Based on 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalents (TEQs), partial dioxin-like toxicity varied between 3.04 and 20.8 ng TEQ/g lipid weight in plasma and 0.94 and 46.5 ng TEQ/g lipid weight in eggs, and largely was due to concentrations of non- ortho polychlorinated biphenyls (PCBs), with a very minor contribution from mono- ortho PCBs and polychlorinated naphthalenes. The major aryl sulfone metabolite in plasma was an unidentified hexachlorinated MeSO2 -PCB congener (range: 13.5,551 ng/g lipid wt), whereas the pentachlorinated congeners 3,- and 4,-MeSO2 -CB101 (range: 4.49,38.1 ng/g lipid wt) dominated in eggs. The predominant halogenated phenolic compound (HPC) in plasma was consistently the PCB metabolite 4-OH-CB187 (range: 0.29,17.5 ng/g wet wt), whereas in eggs, detectable HPCs were at very low and transient concentrations. As part of a complex profile of contaminant exposure, these chemical classes and metabolites may be contributing factors to enhance physiological stress in breeding glaucous gulls. [source] Harbor seals (Phoca vitulina) in British Columbia, Canada, and Washington State, USA, reveal a combination of local and global polychlorinated biphenyl, dioxin, and furan signalsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 1 2004Peter S. Ross Abstract The harbor seal (Phoca vitulina) can serve as a useful indicator of food web contamination by persistent organic pollutants (POPs) because of its high trophic level, wide distribution in temperate coastal waters of the Northern Hemisphere, and relative ease of capture. In 1996 through 1997, we live-captured 60 harbor seal pups from three regions, spanning remote (Queen Charlotte Strait, BC, Canada), moderately industrialized (Strait of Georgia, BC, Canada), and heavily industrialized (Puget Sound, WA, USA) marine basins straddling the Canada-United States border. Biopsy samples of blubber were taken and analyzed for congener-specific polychlorinated biphenyls (PCBs), polychlorinated dibenzo- p -dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) by using high-resolution gas chromatography-high-resolution mass spectrometry. Harbor seals in Puget Sound were heavily contaminated with PCBs, whereas seals from the Strait of Georgia had relatively high concentrations of PCDDs and PCDFs. Pattern evaluation and principal components analysis suggested that proximity to sources influenced the mixture to which seals were exposed, with those inhabiting more remote areas being exposed to lighter PCB congeners (those with lower Henry's law constant and KOW) that disperse more readily through atmospheric and other processes. Total toxic equivalents to 2,3,7,8-tetrachlorodibenzo- p -dioxin for the PCBs, PCDDs, and PCDFs suggest that Puget Sound seals are at greatest risk for adverse health effects, and that PCBs represent the class of dioxinlike contaminants of greatest concern at all sites. [source] Application of sewage sludge to arable land,soil concentrations of polybrominated diphenyl ethers and polychorinated dibenzo- p -dioxins, dibenzofurans, and biphenyls, and their accumulation in earthwormsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2002Nadja Matscheko Abstract Soils from five agricultural sites, three research sites, and two privately owned farms were analyzed for polychlorinated dibenzo- p -dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybronimated diphenylethers (PBDEs). In soils that had not been treated with sludge (reference soils), the international toxic equivalents (I-TEQs) were 0.6 to 1.5 pg/g dry matter (DM) for the PCDD/Fs, which are low compared to generally reported background soil levels in Europe. The concentrations of sum of six penta- and hexa-PCBs were 450 to 1,400 pg/g DM. The PBDEs 47 and 99 dominated among the tri- to hepta-PBDEs analyzed (8,80 pg/g DM). The impact of adding 1 to 3 tonnes of sludge (DM) per hectare per year on the concentrations was studied at the three research sites by calculating ratios of the compounds in sludge-treated soil to reference soil (S/R ratio). The concentrations of I-TEQs did not increase in the sludge-treated soil, whereas the S/R ratios for PBDEs were greater than one. Also, although the PCB contents were higher in the sludge-treated soils, the background sources were more important for the concentrations of PCBs than of PBDEs. The largest increase in the S/R ratios was found at a private farm where large amounts of sludge had been used in the past. Accumulation of the compounds in earthworms from the sites also was investigated. The biota-soil accumulation factors (BSAFs) of the tested compounds declined in the following order: ortho -PCBs , PBDEs > non-ortho -PCBs > 2,3,7,8-substituted PCDD/Fs. The average BSAF for ortho -PCBs was five (organic matter/lipids), and the lowest BSAFs (0.1,0.8) found were for octachlorodibenzo- p -dioxin. To our knowledge, accumulation of PBDEs in earthworms has not been published previously. [source] Polychlorinated biphenyls, organochlorine pesticides, tris(4-chlorophenyl)methane, and tris(4-chlorophenyl)methanol in livers of small cetaceans stranded along Florida coastal waters, USAENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2000Mafumi Watanabe Abstract Concentrations of polychlorinated biphenyl congeners (PCBs) and organochlorine pesticides were determined in the livers of bottlenose dolphins, Atlantic spotted dolphins, and pygmy sperm whales found stranded along the coastal waters of Florida, USA, during 1989 to 1994. The PCBs were the most predominant contaminants followed in order by DDTs, chlordanes, tris(4-chlorophenyl)methane (TCPMe), tris(4-chlorophenyl)methanol (TCPMOH), hexachlorobenzene, and hexachlorocyclohexane isomers. Among the cetaceans analyzed, organochlorine concentrations were greatest in bottlenose dolphins followed by Atlantic spotted dolphins and pygmy sperm whales. Hexa- and heptachlorobiphenyls were the predominant PCB congeners found in the livers of dolphins. Patterns of relative concentrations of PCB congeners varied among individual bottlenose dolphins. A few individuals contained predominant concentrations of octa- (CB-199, 196/201) and nonachlorobiphenyl (CB-206, 208) congeners, which suggested exposure to the highly chlorinated PCB formulation, Aroclor® 1268, a contaminant at a coastal site in Georgia bordering northern Florida. The estimated 2,3,7,8-tetrachlorodibenzo- p -dioxin toxic equivalents (TEQs) of coplanar PCBs in bottlenose dolphins were 170 to 18,000 pg/g, lipid weight (mean: 5,400 pg/g) with mono- ortho congeners 118, 105, and 156 contributing more than 80% of the TEQs. The ratios of CB-169 to CB-126 in cetacean livers were linearly related to total PCB concentrations, which suggested a strong induction of microsomal monooxygenase enzymes in the liver. The hepatic concentrations of TCPMe and TCPMOH in bottlenose dolphins and Atlantic spotted dolphins were greater than those in the blubber of marine mammals of various regions, which suggested the presence of sources for these chemicals along the Atlantic coast of Florida. [source] Role of dietary patterns for dioxin and PCB exposureMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 11 2009Helen E. Kvalem Abstract Dietary patterns were related to intake and blood concentrations of polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/PCDFs), dioxin-like polychlorinated biphenyls (dl-PCBs) and selected non-dioxin-like-PCBs (ndl-PCBs). Intake calculations were based on an extensive food frequency questionnaire and a congener-specific database on concentrations in Norwegian foods. The study (2003) applied a two-step inclusion strategy recruiting representative (n=73) and high consumers (n=111) of seafood and game. Estimated median intakes of sum PCDD/PCDFs and dl-PCBs of the representative and high consumers were 0.78 and 1.25 pg toxic equivalents (TEQ)/kg bw/day, respectively. Estimated median intakes of ndl-PCBs (sum chlorinated biphenyl (CB)-28, 52, 101, 138, 153, 180) were 4.26 and 6.40 ng/kg bw/day. The median blood concentrations of PCDD/PCDFs/dl-PCBs were 28.7 and 35.1 pg TEQ/g lipid, and ndl-PCBs (sum of CB-101, 138, 153 and 180) 252 and 299 ng/g lipid. The Spearman correlations between dietary intake and serum concentration were r=0.34 (p=0.017) for dl-compounds and r=0.37 (p<0.001) for ndl-PCBs. Oily fish was the major source of dl-compounds and ndl-PCBs in high and representative consumers. Four dietary patterns were identified by principal component analysis. Two were related to high intakes, one dominated by oily fish ((,-3)), the other by fish liver and seagull eggs ("northern coastal"). Only the latter was closely associated with high blood concentrations of dioxins and PCBs. [source] | ||||||||||