The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Susan L Schantz - One of the best experts on this subject based on the ideXlab platform.
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formulation and characterization of an experimental pcb mixture designed to mimic human exposure from contaminated fish
Toxicological Sciences, 2005Co-Authors: Paul J Kostyniak, Larry G Hansen, Richard F. Seegal, James R Olson, John J Widholm, Rich D Fitzpatrick, Jennifer L Helferich, Helen J K Sable, Isaac N Pessah, Susan L SchantzAbstract:Each environmental exposure matrix contains a unique mixture of PCB Congeners. Since several Congener types have multiple and distinct biological actions, it is important to characterize Congener profiles in exposure sources. The Fox River Environment and Diet Study (FRIENDS) is assessing the human health effects of consumption of PCB-contaminated fish from the Fox River in northeastern Wisconsin. Concurrent laboratory studies required the formulation of a dosing solution which closely mimicked the human PCB exposure from fish. PCB Congener profiles from Fox River walleye were compared to profiles for various theoretical mixtures having different relative percentages of Aroclors by weight. The theoretical mixture which provided the best approximation of the Fox River fish PCB profile contained 35% 1242, 35% 1248, 15% 1254, and 15% 1260. A PCB mixture was formulated to match this theoretical construct, and the Congener profile for the mixture of Aroclors was determined by capillary column gas chromatography with electron capture detection (GC/ECD). The relative percent of each Congener was compared to the PCB Congener profile of the theoretical Aroclor mixture and that for Fox River walleye. The specific Congeners differed on average by 17% from the theoretical Aroclor mixture predicted values, and the specific Congeners measured in the mixture were on average within 71% of those reported for Fox River fish. The mixture was found to have relatively low AhR activity but high RyR activity. Indirect comparisons suggest that in vivo toxicity was slightly greater than that for Aroclor 1254. This illustrates that Aroclor mixtures are useful for formulating dosing solutions which closely approximate actual environmental exposures.
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effects of pcb exposure on neuropsychological function in children
Environmental Health Perspectives, 2003Co-Authors: Susan L Schantz, John J Widholm, Deborah C RiceAbstract:In the last decade advances in the analytic methods for quantification of polychlorinated biphenyls (PCBs) have resulted in widespread availability of Congener-specific analysis procedures, and large amounts of data on PCB Congener profiles in soil, air, water, sediments, foodstuffs, and human tissues have become available. These data have revealed that the PCB residues in environmental media and human tissues may not closely resemble any of the commercial PCB mixtures, depending on source of exposure, bioaccumulation through the food chain, and weathering of PCBs in the environment. At the same time, toxicological research has led to a growing awareness that different classes of PCB Congeners have different profiles of toxicity. These advances in analytic techniques and toxicological knowledge are beginning to influence the risk assessment process. As the data from ongoing PCB studies assessing the mediators of neurobehavioral outcomes in children are published, the weight of evidence for PCB effects on neurodevelopment is growing. Studies in Taiwan, Michigan (USA), New York (USA), Holland, Germany, and the Faroe Islands have all reported negative associations between prenatal PCB exposure and measures of cognitive functioning in infancy or childhood. The German study also reported a negative association between postnatal PCB exposure and cognitive function in early childhood--a result that had not been found in previous studies. Only one published study in North Carolina (USA) has failed to find an association between PCB exposure and cognitive outcomes. Despite the fact that several more recent studies have used Congener-specific analytic techniques, there have been only limited attempts to assess the role of specific PCB Congeners or classes of Congeners in mediating neurodevelopmental outcomes. From a statistical standpoint, attempts to determine the role of individual Congeners in mediating outcomes are hampered by the fact that concentrations of most individual Congeners are highly correlated with each other and with total PCBs. From a toxicological standpoint, these efforts are hampered by the fact that many of the PCB Congeners present in human tissues have never been studied in the laboratory, and their relative potency to produce nervous system effects is unknown. More complete information on the health effects of various Congeners or Congener classes would allow more informed scientific and risk assessment decisions.
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PCB Congener profile in the serum of humans consuming Great Lakes fish.
Environmental health perspectives, 2000Co-Authors: Harold E. B. Humphrey, Joseph C. Gardiner, Jasma R. Pandya, Anne M. Sweeney, Donna M. Gasior, Robert J. Mccaffrey, Susan L SchantzAbstract:Abstract The State of Michigan has a long history of research into human exposure to environmental contaminants through consumption of recreationally caught fish. A large cohort of Lake Michigan residents who eat fish (fish-eaters) and those who do not eat fish (nonfish-eaters) established in 1980 served as the basis for the Congener-specific polychlorinated biphenyl (PCB) exposure evaluation reported here. In this paper we present the serum PCB Congener profile for a subset of this cohort who were over 50 years of age. Serum samples were collected in 1993-1995 and were evaluated by a dual column capillary column gas chromatography procedure capable of detecting over 90 PCB Congeners. This evaluation demonstrated significant PCB exposure in the fish-eaters (mean serum PCB of 14.26 ppb; n = 101). This elevated exposure allowed the establishment of a detailed profile of the PCB Congeners found in humans exposed by this route. Twenty-two Congeners of varying concentrations were the most prevalent and constituted over 95% of the total PCB present in most subjects. Four Congeners, 138/163 (2,2',3,4,4',5-PCB/2,3,3',4', 5,6-PCB), 180 (2,2',3,4,4',5,5'-PCB), and 153 (2,2',4,4',5,5'-PCB), accounted for 55-64% of the total PCB load. Other Congeners, some of toxicologic significance, were also detected by this analytical protocol. Nonfish-eaters had lower total serum PCB levels (mean = 4. 56; n = 78), but the same general pattern of PCB Congeners was present. It was demonstrated that careful selection of a subset of prevalent PCB Congeners could provide a cost-effective assessment of exposure without losing critical scientific information.
Judit E. G. Smits - One of the best experts on this subject based on the ideXlab platform.
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PCB Congener profiles in nestling tree swallows and their insect prey. Archives of Environmental Contamination and Toxicology
2007Co-Authors: Gary R. Bortolotti, Mary Sebastian, Judit E. G. SmitsAbstract:Abstract. Tree swallows (Tachycineta bicolor) are widely used as indicators of local polychlorinated biphenyl (PCB) contamination in North America. Although determining total PCB residues in tissues is useful in environmental monitoring, analysis of PCB Congener profiles may reveal sources of contamination and thus prove to be a more refined tool to track contaminants through the food web. To show how differences in PCB Congener patterns in birds can be linked to the PCB patterns in their prey, we evaluated PCB Congeners in tissues of tree swallow nestlings and their insect prey using principal component analysis and Euclidean similarities. The PC1 scores for PCB residues in nestlings fell between those of the Hexagenia (Ephemeroptera, mayflies) and Chironomidae (Diptera, midges), the two major prey groups of the nestlings. The Congener pattern was not related to the location of nest boxes within the study area. However, Hexagenia insects and the nestlings that consumed them were richer in less chlori-nated Congeners and had higher PC1 scores than Chironomidae insect. In concordance, Congener pattern of nestlings that hatched earlier and consumed more mayflies was more similar than that of other nestling to the pattern of nestings texagenia as calculated by Euclidean similarities. We point to the importance of understanding the seasonal availability of spe-cific types of insect prey and their PCB Congener pattern be-fore these data are applied in models of trophic transfer of individual PCB Congeners within a food web. Tree swallows (Tachycineta bicolor) are migratory aerial-feeding insectivorous birds widely used as a sentinel species of contaminant exposure across North America (Bishop et al
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PCB Congener Profiles in Nestling Tree Swallows and Their Insect Prey
Archives of environmental contamination and toxicology, 2006Co-Authors: Zsuzsanna Papp, Gary R. Bortolotti, Mary Sebastian, Judit E. G. SmitsAbstract:Tree swallows (Tachycineta bicolor) are widely used as indicators of local polychlorinated biphenyl (PCB) contamination in North America. Although determining total PCB residues in tissues is useful in environmental monitoring, analysis of PCB Congener profiles may reveal sources of contamination and thus prove to be a more refined tool to track contaminants through the food web. To show how differences in PCB Congener patterns in birds can be linked to the PCB patterns in their prey, we evaluated PCB Congeners in tissues of tree swallow nestlings and their insect prey using principal component analysis and Euclidean similarities. The PC1 scores for PCB residues in nestlings fell between those of the Hexagenia (Ephemeroptera, mayflies) and Chironomidae (Diptera, midges), the two major prey groups of the nestlings. The Congener pattern was not related to the location of nest boxes within the study area. However, Hexagenia insects and the nestlings that consumed them were richer in less chlorinated Congeners and had higher PC1 scores than Chironomidae insect. In concordance, Congener pattern of nestlings that hatched earlier and consumed more mayflies was more similar than that of other nestling to the pattern of nestings texagenia as calculated by Euclidean similarities. We point to the importance of understanding the seasonal availability of specific types of insect prey and their PCB Congener pattern before these data are applied in models of trophic transfer of individual PCB Congeners within a food web.
Geneva M. Omann - One of the best experts on this subject based on the ideXlab platform.
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effects of selected polybrominated diphenyl ether flame retardants on lake trout salvelinus namaycush thymocyte viability apoptosis and necrosis
Environmental Toxicology and Chemistry, 2005Co-Authors: Kelly L. Birchmeier, Kimberly A. Smith, Leonard I. Sweet, Sergei M. Chernyak, Jean V. Adams, Dora R Passinoreader, Geneva M. OmannAbstract:Polybrominated diphenyl ether (PBDE) flame-retardants have been identified as an emergent contaminants issue in many parts of the world. In vitro analyses were conducted to test the hypothesis that selected PBDEs Congeners affect viability, apoptosis, and necrosis of thymocytes from laboratory-reared lake trout (Salvelinus namaycush). At current environmental levels (<1 mg/L), effects of the tested PBDEs on thymocytes were negligible. However, at 100 mg/L, major effects were seen for Congener brominated diphenyl ether 47 (BDE-47) and minor effects were seen for Congener BDE-99.
Sergei M. Chernyak - One of the best experts on this subject based on the ideXlab platform.
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effects of selected polybrominated diphenyl ether flame retardants on lake trout salvelinus namaycush thymocyte viability apoptosis and necrosis
Environmental Toxicology and Chemistry, 2005Co-Authors: Kelly L. Birchmeier, Kimberly A. Smith, Leonard I. Sweet, Sergei M. Chernyak, Jean V. Adams, Dora R Passinoreader, Geneva M. OmannAbstract:Polybrominated diphenyl ether (PBDE) flame-retardants have been identified as an emergent contaminants issue in many parts of the world. In vitro analyses were conducted to test the hypothesis that selected PBDEs Congeners affect viability, apoptosis, and necrosis of thymocytes from laboratory-reared lake trout (Salvelinus namaycush). At current environmental levels (<1 mg/L), effects of the tested PBDEs on thymocytes were negligible. However, at 100 mg/L, major effects were seen for Congener brominated diphenyl ether 47 (BDE-47) and minor effects were seen for Congener BDE-99.
Dora R Passinoreader - One of the best experts on this subject based on the ideXlab platform.
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effects of selected polybrominated diphenyl ether flame retardants on lake trout salvelinus namaycush thymocyte viability apoptosis and necrosis
Environmental Toxicology and Chemistry, 2005Co-Authors: Kelly L. Birchmeier, Kimberly A. Smith, Leonard I. Sweet, Sergei M. Chernyak, Jean V. Adams, Dora R Passinoreader, Geneva M. OmannAbstract:Polybrominated diphenyl ether (PBDE) flame-retardants have been identified as an emergent contaminants issue in many parts of the world. In vitro analyses were conducted to test the hypothesis that selected PBDEs Congeners affect viability, apoptosis, and necrosis of thymocytes from laboratory-reared lake trout (Salvelinus namaycush). At current environmental levels (<1 mg/L), effects of the tested PBDEs on thymocytes were negligible. However, at 100 mg/L, major effects were seen for Congener brominated diphenyl ether 47 (BDE-47) and minor effects were seen for Congener BDE-99.
