RESUMO
Nests of three passerine birds, house wren (HOWR), tree swallow (TRES), and eastern bluebird (EABL) were monitored daily (2005-2007) at study areas (SAs) downstream of Midland, Michigan where soil and sediment concentrations of polychlorinated dibenzofurans (PCDFs) were significantly greater than the regional background concentrations and upstream reference areas (RAs). Similarly, TRES research conducted at sites contaminated with dioxin-like compounds indicated that concentrations of polychlorinated dibenzo-p-dioxins and PCDFs, expressed as ΣPCDD/DFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents observed in the diet and eggs of these three species would be predicted to cause significant effects on reproduction. However, site-specific reproductive parameters including hatching success and fledging success at downstream SAs were similar to or greater than those at upstream RAs. Specifically, hatching success was not significantly different among years, species, locations, or between early and late nesting attempts. Of all initiated clutches, 66% (n = 427), 73% (n = 245), and 64% (n = 122) successfully fledged at least one nestling for HOWR, TRES, and EABL, respectively. Overall reproductive performance was similar between SAs and RAs. The reason for these unexpected results is consistent with the fact that there are species-specific and congener-specific differences in sensitivities to the effects of aryl hydrocarbon receptor agonists.
Assuntos
Dioxinas/toxicidade , Monitoramento Ambiental/métodos , Reprodução/efeitos dos fármacos , Aves Canoras/crescimento & desenvolvimento , Andorinhas/crescimento & desenvolvimento , Animais , Benzofuranos/análise , Benzofuranos/toxicidade , Dibenzofuranos Policlorados , Sedimentos Geológicos/análise , Sedimentos Geológicos/química , Michigan , Dibenzodioxinas Policloradas/análise , Dibenzodioxinas Policloradas/toxicidade , Receptores de Hidrocarboneto Arílico/agonistas , Medição de Risco , Rios/química , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Poluentes Químicos da Água/toxicidadeRESUMO
Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs), in soils and sediments of the Tittabawassee River (TR) and associated floodplains downstream of Midland, Michigan (USA) were greater than upstream sites and prompted a site-specific risk assessment of great blue herons (GBH). Dietary exposure of GBH to PCDFs and polychlorinated dibenzo-p-dioxins (PCDDs) was evaluated based on site-specific concentrations of residues in prey items. Concentrations of ∑PCDD/DFs and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO-Avian)) in prey items collected from the TR were consistently greater than those collected from associated reference areas (RAs) and further downstream in the Saginaw River (SR). The average daily dose (ADD(pot)) of ∑PCDD/DFs to GBH was 45- to 54-fold greater along the TR and 12-fold greater along the SR when compared to the RA. ∑PCDD/DFs were normalized to TEQ(WHO-Avian), and fold differences in the ADD(pot) increased, being 150- to 190-fold greater along the TR and 36-fold greater along the SR than they were in the RA. Greater fold changes in the ADD(pot) based on TEQ(WHO-Avian) between the RA and the TR and SR was due to prey items from the latter reaches having a greater relative toxic potency of ∑PCDD/DFs, primarily from greater amounts of 2,3,7,8-tetrachlorodibenzofuran but also 2,3,4,7,8-pentachlorodibenzofuran. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated via comparison to selected toxicity reference values. The prediction of minimal to no risk of adverse population-level effects resultant from the assessment of site-specific dietary exposure of GBH to ∑PCDD/DFs along the TR and SR is consistent with site-specific assessments of tissue-based exposures as well as population condition.
Assuntos
Benzofuranos/metabolismo , Aves/metabolismo , Dieta/estatística & dados numéricos , Exposição Ambiental/análise , Poluentes Ambientais/metabolismo , Dibenzodioxinas Policloradas/análogos & derivados , Animais , Anuros/metabolismo , Astacoidea/metabolismo , Benzofuranos/análise , Dibenzofuranos Policlorados , Exposição Ambiental/estatística & dados numéricos , Poluentes Ambientais/análise , Poluição Ambiental/estatística & dados numéricos , Peixes/metabolismo , Cadeia Alimentar , Sedimentos Geológicos/química , Michigan , Bifenilos Policlorados/análise , Bifenilos Policlorados/metabolismo , Dibenzodioxinas Policloradas/análise , Dibenzodioxinas Policloradas/metabolismo , Rios/química , Solo/químicaRESUMO
Dietary exposure of house wrens (Troglodytes aedon), tree swallows (Tachycineta bicolor), and eastern bluebirds (Sialia sialis) to polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) near Midland, Michigan (USA) was evaluated based on site-specific data, including concentrations of residues in bolus samples and individual invertebrate orders and dietary compositions by study species. Site-specific dietary compositions for the three species were similar to those reported in the literature, but differed in their relative proportions of some dietary items. Oligocheata (non-depurated) and Brachycera (Diptera) contained the greatest average concentrations of ΣPCDD/DFs of the major site-specific dietary items collected via food web-based sampling. Average ingestion values of ΣPCDD/DFs from site-specific bolus-based and food web-based dietary concentrations for nestlings at study areas (SAs) were 6- to 20-fold and 2- to 9-fold greater than at proximally located reference areas (RAs), respectively. Average ingestion values of total 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO - Avian)) from site-specific bolus-based and food web-based dietary concentrations for nestlings at SAs were 31- to 121-fold and 9- to 64-fold greater than at proximally located RAs, respectively. Estimates of ΣPCDD/DFs and TEQ(WHO - Avian) tissue concentrations based on nestling dietary exposures were greater than those measured. Plausible explanations include nestling metabolism of 2,3,7,8-tetrachlorodibenzofuran and assimilation rates of less than the 70% assumed to occur over the nestling growth period. Profiles of the relative concentrations of individual PCDD/DF congeners in samples of invertebrates and bolus at SAs on the Tittabawassee River downstream of the source of contamination were dominated by 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin (22% to 44%) and 2,3,7,8-tetrachlorodibenzofuran (18% to 50%).
Assuntos
Benzofuranos/análise , Dibenzodioxinas Policloradas/análogos & derivados , Poluentes Químicos da Água/análise , Animais , Dibenzofuranos Policlorados , Monitoramento Ambiental , Cadeia Alimentar , Contaminação de Alimentos/análise , Michigan , Dibenzodioxinas Policloradas/análise , Aves Canoras , AndorinhasRESUMO
House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (SigmaPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of SigmaPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (SigmaTEQs(WHO-Avian)), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of SigmaPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of SigmaPCDD/DFs and SigmaTEQs(WHO-Avian) ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of SigmaTEQs(WHO-Avian) were positively correlated with SigmaPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69-84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs.
Assuntos
Benzofuranos/toxicidade , Exposição Ambiental/análise , Poluentes Ambientais/toxicidade , Passeriformes/crescimento & desenvolvimento , Dibenzodioxinas Policloradas/análogos & derivados , Rios/química , Áreas Alagadas , Animais , Benzofuranos/análise , Benzofuranos/farmacocinética , Dibenzofuranos Policlorados , Poluentes Ambientais/análise , Poluentes Ambientais/farmacocinética , Feminino , Michigan , Óvulo/química , Dibenzodioxinas Policloradas/análise , Dibenzodioxinas Policloradas/farmacocinética , Dibenzodioxinas Policloradas/toxicidadeRESUMO
White-winged dove (Zenaida asiatica L.) exposure to environmentally accessible lead is a management concern. Detectable concentrations of lead were found in 142 (66%) of 214 white-winged doves collected in 2002 and 2003 at two wildlife management units in South Texas. Mean +/- SD lead concentration was 0.70 +/- 1.10 microg/g dry weight and ranged from ND to 11.01 microg/g dw. Lead concentrations were significantly lower in the 2002 samples, but similar between management units, age, and gender. White-winged doves in South Texas are being exposed to lead in the environment with some reaching subclinical to toxic levels.
Assuntos
Columbiformes/metabolismo , Monitoramento Ambiental , Poluentes Ambientais/metabolismo , Chumbo/metabolismo , Animais , Feminino , Fígado/metabolismo , Masculino , TexasRESUMO
Our study determined if white-winged doves (WWDs; Zenaida asiatica asiatica) breeding in locations where environmentally persistent contaminants occur in the Lower Rio Grande Valley of Texas have levels of contaminants that can hinder reproduction. During summer 2003, 70 (32 males, 38 females) adult WWDs were collected from 8 at-risk sites. Liver tissues were analyzed for ten major and trace elements and muscle tissues were analyzed for 20 organochlorine compounds, 21 polychlorinated biphenyl congeners, and toxaphene. Samples were compared to ten (five male, five female) captive-raised control WWDs. Arsenic, chromium, and lead were not detected or were below the detection limit, whereas copper, zinc, selenium, mercury, nickel, cadmium, and silver were detected in 70 (100%), 70 (100%), 52 (74%), 21 (30%), 4 (6%), 1 (1%), and 1 (1%) WWDs, respectively. None of the detected elements had significant sampling site, bird gender, or Site x Gender interactions, and each occurred at background levels. Toxaphene and polychlorinated biphenyls were not detected, whereas DDE, dieldrin, gamma-BHC, and chlordane were detected in 13 (19%), 5 (7%), 2 (3%), and 1 (1%) field-collected WWDs, respectively, but all concentrations occurred at background levels. Concentrations of elements and compounds in field-collected WWDs did not significantly differ from those of the controls. Correlations between leukocyte counts and detectable contaminants generally indicated no correlation between each percentage of leukocyte type present and levels of selenium, copper, zinc, mercury, or DDE detected. One sample that had 0.072 mug/g dieldrin exhibited a low lymphocyte percentage (66%) out of only five samples. Comparisons could not be made with gamma-BHC, chlordane, or the other elements that had a low number of samples with detectable levels. Overall, concentrations of elements and organochlorines found in WWDs were below levels known to impair reproduction and survival in birds.
Assuntos
Columbidae/metabolismo , Poluentes Ambientais/análise , Animais , Animais Selvagens , Columbidae/fisiologia , Monitoramento Ambiental , Poluentes Ambientais/toxicidade , Feminino , Imunidade/efeitos dos fármacos , Contagem de Leucócitos , Fígado/química , Masculino , Metais/análise , Metais/toxicidade , Praguicidas/análise , Praguicidas/toxicidade , Bifenilos Policlorados/análise , Reprodução/efeitos dos fármacos , TexasRESUMO
The registration of pesticides follows guidance published by the European Food Safety Authority (EFSA). As a default, the EFSA guidance document on risk assessment for birds and mammals assumes that animals feed exclusively on pesticide-treated fields. However, the guidance document suggests refining the risk via the proportion of food animals obtain from a treated field or specific crop (expressed via the portion of diet obtained from a treated area [PT value]). The EFSA guidance equalizes the portion of food taken from a treated area per day with the portion of time spent potentially foraging over the course of a day within this area. Therefore, radiotracking is commonly used to gather species-, crop-, and season-specific PT data, and radio telemetry of continuously tracked farmland species can deliver individual PT values for a given day, crop, and species. In the present study the authors introduce a way of calculating long-term PT values based on empirically recorded data via telemetry field studies for the most appropriate use in wildlife risk assessment of pesticides. The novel aspect of the proposal is that the authors follow the prerequisite given by EFSA to cover the long-term risk by introducing 21-d PT values that aim to cover both intra- and inter-individual variability of foraging focal farmland species in cropped habitats. Currently, the intra-individual variability is not taken into account for PT calculations. The authors demonstrate this approach and discuss EFSA guidance input requirements for PT values recorded in field studies, based on a PT field study conducted with woodpigeons (Columba palumbus) radiotracked in an agricultural landscape in the United Kingdom. The results indicate that a 21-d PT value considering intra-individual variability gives a more appropriate PT value for long-term risk assessments. Environ Toxicol Chem 2017;36:1270-1277. © 2016 SETAC.
Assuntos
Columbidae/metabolismo , Exposição Ambiental/análise , Praguicidas/análise , Animais , Animais Selvagens , Ecossistema , Inocuidade dos Alimentos , Método de Monte Carlo , Radiometria , Medição de Risco , Estações do Ano , TelemetriaRESUMO
Concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in Tittabawassee River floodplain soils and biota downstream of Midland, Michigan, USA, are greater than regional background concentrations. From 2005 to 2008, a multiple lines of evidence approach was utilized to evaluate the potential for effects of PCDD/DFs on American robins (Turdus migratorius) breeding in the floodplains. A dietary-based assessment indicated there was potential for adverse effects for American robins predicted to have the greatest exposures. Conversely, a tissue-based risk assessment based on site-specific PCDD/DF concentrations in American robin eggs indicated minimal potential for adverse effects. An assessment based on reproductive endpoints indicated that measures of hatch success in study areas were significantly less than those of reference areas. However, there was no dose-response relationship between that endpoint and concentrations of PCDD/DF. Although dietary-based exposure and reproductive endpoint assessments predicted potential for adverse effects to resident American robins, the tissue-based assessment indicates minimal to no potential for adverse effects, which is reinforced by the fact the response was not dose related. It is likely that the dietary assessment is overly conservative given the inherent uncertainties of estimating dietary exposure relative to direct tissue-based assessment measures. Based on the available data, it can be concluded that exposure to PCDD/DFs in the Tittabawassee River floodplain would not likely result in adverse population-level effects to American robins.
Assuntos
Benzofuranos/análise , Monitoramento Ambiental , Dibenzodioxinas Policloradas/análogos & derivados , Aves Canoras/fisiologia , Animais , Benzofuranos/metabolismo , Dibenzofuranos Policlorados , Michigan , Dibenzodioxinas Policloradas/análise , Dibenzodioxinas Policloradas/metabolismo , Reprodução/efeitos dos fármacos , Medição de Risco , Rios/química , Solo/químicaRESUMO
The sensitivity of avian species to the toxic effects of dioxin-like compounds (DLCs) varies up to 1000-fold among species, and this variability has been associated with interspecies differences in aryl hydrocarbon receptor 1 ligand-binding domain (AHR1 LBD) sequence. We previously showed that LD(50) values, based on in ovo exposures to DLCs, were significantly correlated with in vitro EC(50) values obtained with a luciferase reporter gene (LRG) assay that measures AHR1-mediated induction of cytochrome P4501A in COS-7 cells transfected with avian AHR1 constructs. Those findings suggest that the AHR1 LBD sequence and the LRG assay can be used to predict avian species sensitivity to DLCs. In the present study, the AHR1 LBD sequences of 86 avian species were studied, and differences at amino acid sites 256, 257, 297, 324, 337, and 380 were identified. Site-directed mutagenesis, the LRG assay, and homology modeling highlighted the importance of each amino acid site in AHR1 sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin and other DLCs. The results of the study revealed that (1) only amino acids at sites 324 and 380 affect the sensitivity of AHR1 expression constructs of the 86 avian species to DLCs and (2) in vitro luciferase activity of AHR1 constructs containing only the LBD of the species of interest is significantly correlated (r (2) = 0.93, p < 0.0001) with in ovo toxicity data for those species. These results indicate promise for the use of AHR1 LBD amino acid sequences independently, or combined with the LRG assay, to predict avian species sensitivity to DLCs.
Assuntos
Dioxinas/toxicidade , Receptores de Hidrocarboneto Arílico/metabolismo , Sequência de Aminoácidos , Animais , Hidrocarboneto de Aril Hidroxilases/genética , Sítios de Ligação , Aves , Western Blotting , Células COS , Técnicas de Cultura de Células , Chlorocebus aethiops , Dioxinas/química , Relação Dose-Resposta a Droga , Dose Letal Mediana , Ligantes , Fígado/efeitos dos fármacos , Fígado/metabolismo , Luciferases/genética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Valor Preditivo dos Testes , Ligação Proteica , Receptores de Hidrocarboneto Arílico/química , Receptores de Hidrocarboneto Arílico/genética , Alinhamento de Sequência , Especificidade da Espécie , TransfecçãoRESUMO
Concentrations of polychlorinated dibenzofurans (PCDFs) and other dioxin-like compounds in soils and sediments of the Tittabawassee River and associated floodplains downstream of Midland, Michigan, USA, are greater than upstream sites. As a result of these concentrations, which are some of the greatest ever reported, a site-specific exposure assessment of belted kingfisher breeding in the assessment area was conducted. To reduce the uncertainty associated with predicting exposure from abiotic matrices, concentrations of residues were quantified in site-specific prey items and in eggs and nestlings of belted kingfisher. Dietary exposure, expressed as the potential average daily dose, based on site-specific concentrations of PCDFs, polychlorinated dibenzo-p-dioxins (PCDDs), and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQ(WHO-Avian)) in prey items was consistently greater along the Tittabawassee River than in associated reference areas and further downstream sites in the Saginaw River. Concentrations of PCDD/DFs in eggs and nestlings of belted kingfisher varied among sampling areas, being greater in both eggs and nestlings nesting along the Tittabawassee River compared to those of belted kingfisher from upstream reference areas. Geometric mean concentrations of PCDD/DFs were 130 and 200 ng/kg wet weight in eggs and nestlings of belted kingfisher, respectively. These concentrations are the equivalent of 84 and 95 ng TEQ(WHO-Avian)/kg. Site-specific biomagnification factors for select PCDD/DF congeners ranged from <1.0 to 1.8 in belted kingfisher.
Assuntos
Benzofuranos/farmacocinética , Aves , Dieta/veterinária , Dibenzodioxinas Policloradas/farmacocinética , Poluentes do Solo/farmacocinética , Animais , Dibenzofuranos Policlorados , Dioxinas/farmacocinética , Cadeia Alimentar , Michigan , Óvulo/química , Rios/química , Solo/químicaRESUMO
A site-specific multiple lines of evidence risk assessment was conducted for house wrens (Troglodytes aedon) and eastern bluebirds (Sialia sialis) along the Tittabawassee River downstream of Midland, Michigan, where concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) in flood-plain soils and sediments are greater compared to upstream areas and some of the greatest anywhere in the world. Lines of evidence supporting the population-level assessment endpoints included site-specific dietary- and tissue-based exposure assessments and population productivity measurements during breeding seasons 2005-2007. While a hazard assessment based on site-specific diets suggested that populations residing in the downstream floodplain had the potential to be affected, concentrations in eggs compared to appropriate toxicity reference values (TRVs) did not predict a potential for population-level effects. There were no significant effects on reproductive success of either species. The most probable cause of the apparent difference between the dietary- and tissue-based exposure assessments was that the dietary-based TRVs were overly conservative based on intraperitoneal injections in the ring-necked pheasant. Agreement between the risk assessment based on concentrations of PCDFs and PCDDs in eggs and reproductive performance in both species supports the conclusion of a small potential for population-level effects at this site.
RESUMO
Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs), in soils and sediments downstream of Midland, Michigan (USA) were greater than upstream sites and prompted a site-specific hazard assessment of tree swallows breeding in the associated floodplains. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated at study areas (SAs) along the Tittabawassee and Saginaw rivers downstream of Midland. The site-specific multiple lines of evidence approach to hazard assessment included endpoints for dietary- and tissue-based exposures, and population productivity measurements for tree swallows ([TS]; Tachycineta bicolor) measured during the 2005, 2006, and 2007 breeding seasons. Exposure to dioxin-like compounds in TS eggs were some of the greatest recorded and were similar among all upstream and downstream study sites. Conversely, concentrations in nestlings from SAs were significantly greater compared to reference areas (RAs). The pattern of relative concentrations of PCDD/DFs in eggs and nestlings at RAs was dominated by dioxin congeners, whereas at SAs it was dominated by furan congeners. No statistically significant differences were noted in exposure to PCDD/DFs or in population-level responses when compared among locations, and total clutch failures were rare. Hatching success and fledging success were weakly negatively correlated with concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) in individual eggs and nestlings, respectively. On-site concentrations of TEQs in floodplain soils were some of the greatest ever reported in the environment, and several lines of evidence indicate potential population-level effects on TS overall reproductive productivity.
Assuntos
Dioxinas/toxicidade , Poluentes do Solo/toxicidade , Andorinhas/fisiologia , Poluentes Químicos da Água/toxicidade , Animais , Benzofuranos/metabolismo , Benzofuranos/toxicidade , Dibenzofuranos Policlorados , Dioxinas/metabolismo , Monitoramento Ambiental , Sedimentos Geológicos/química , Michigan , Óvulo/metabolismo , Dibenzodioxinas Policloradas/análogos & derivados , Dibenzodioxinas Policloradas/metabolismo , Dibenzodioxinas Policloradas/toxicidade , Reprodução , Medição de Risco , Rios/química , Solo/química , Andorinhas/metabolismo , Poluentes Químicos da Água/metabolismoRESUMO
Soils and sediments downstream of Midland, Michigan, USA have elevated polychlorinated dibenzofuran (PCDF) and polychlorinated dibenzo-p-dioxin (PCDD) concentrations. To determine if the PCDD/DF concentrations have the potential to adversely affect terrestrial avian predators, a site-specific, multiple lines of evidence risk assessment was conducted for the great horned owl (Bubo virginianus; GHO). As long-lived resident top predators, the GHO has the potential to be exposed to relatively great concentrations of bioaccumulative compounds such as PCDD/DF. From 2005 to 2008, concentrations of PCDD/DF were measured in blood plasma of adult and nestling GHOs and addled eggs. Indicators of the condition of the population, including abundance and reproductive success, were collected along 115 km of river corridor. Fifty-five active 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) equivalents (TEQ(WHO-Avian)) nests were monitored in 21 breeding territories from 2005 to 2008. The geometric mean concentration in blood plasma of GHOs was greater in the study area (SA) than in the reference area (RA) for both adults (RA: 3.1; SA: 9.4 ng TEQ(WHO-Avian)/kg) and nestlings (RA: 0.82 ng TEQ(WHO-Avian)/kg, SA: 2.1 ng TEQ(WHO-Avian)/kg) GHOs, but less than concentrations expected to cause adverse effects based on laboratory studies. Concentrations of TEQ(WHO-Avian) in addled GHO eggs were also greater in the SA than the RA (50 and 7.3 ng/kg, wet weight, respectively), but were less than concentrations expected to cause adverse effects. The GHO population condition and productivity were both greater in the study area than in the reference area and were similar to other GHO populations. This result suggests the GHO population in the Tittabawassee River floodplain is consistent with what would be expected for this area.
Assuntos
Benzofuranos/toxicidade , Dibenzodioxinas Policloradas/análogos & derivados , Estrigiformes , Poluentes Químicos da Água/toxicidade , Animais , Dibenzofuranos Policlorados , Ecologia , Dibenzodioxinas Policloradas/toxicidade , Medição de RiscoRESUMO
Concentrations of dioxin-like compounds, primarily polychlorinated dibenzofurans (PCDFs), in soils and sediments of the Tittabawassee River (TR) and associated floodplains downstream of Midland, Michigan, USA, were greater than upstream sites and prompted a site-specific risk assessment of great blue herons (GBH). Tissue exposure of PCDF and polychlorinated dibenzo-p-dioxins (PCDDs) was assessed in multiple GBH tissue types, including blood plasma of adults and eggs, as well as blood plasma, adipose, liver, and muscle of nestlings. Adult GBH exposure was associated with foraging area and age class, with concentrations of PCDD/DF being greater in blood plasma of adult GBH foraging in the TR compared with those foraging in upstream reference areas and in older birds as compared with their younger cohorts. Concentrations of PCDD/DFs and dioxin-like polychlorinated biphenyls (PCBs) in eggs and nestling tissues of GBH collected from rookeries within the TR floodplain were generally similar among rookeries. Mean concentrations of PCDD/DFs in eggs of GBH ranged from 45 to 67 ng/kg, wet weight for the rookeries studied, with a maximum concentration of 210 ng/kg, wet weight observed. Adipose consistently had the greatest concentration of PCDD/DFs of all tissues collected from nestlings of GBH, ranging from 98 to 430 ng/kg, wet weight. Potential for adverse population-level effects from site-specific contaminant exposures were evaluated by comparison with selected toxicity reference values (TRVs). Minimal risk of adverse population-level effects were predicted when exposures measured in tissues of GBH collected from rookeries within the TR were compared with appropriate TRVs. This prediction is consistent with site-specific measures of population condition, which included clutch size and number of nestlings per successful nest.
Assuntos
Tecido Adiposo/metabolismo , Aves , Fígado/metabolismo , Músculo Esquelético/metabolismo , Dibenzodioxinas Policloradas/análogos & derivados , Rios/química , Poluentes Químicos da Água/análise , Tecido Adiposo/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Fígado/efeitos dos fármacos , Michigan , Músculo Esquelético/efeitos dos fármacos , Óvulo/metabolismo , Dibenzodioxinas Policloradas/análise , Dibenzodioxinas Policloradas/toxicidade , Medição de Risco , Poluentes Químicos da Água/toxicidadeRESUMO
Soils and sediments in the floodplain of the Tittabawassee River downstream of Midland, Michigan, USA contain elevated concentrations of polychlorinated dibenzofurans (PCDF) and polychlorinated dibenzo-p-dioxins (PCDD). As a long-lived, resident top predator, the great horned owl (Bubo virginianus; GHO) has the potential to be exposed to bioaccumulative compounds such as PCDD/DF. Site-specific components of the GHO diet were collected along 115 km of the Tittabawassee, Pine, Chippewa, and Saginaw Rivers during 2005 and 2006. The site-specific GHO biomass-based diet was dominated by cottontail rabbits (Sylvilagus floridanus) and muskrats (Ondatra zibethicus). Incidental soil ingestion and cottontail rabbits were the primary contributors of PCDD/DF to the GHO diet. The great horned owl daily dietary exposure estimates were greater in the study area (SA) (3.3 to 5.0 ng 2,3,7,8-TCDD equivalents (TEQ(WHO-avian))/kg body wt/d) than the reference area (RA) (0.07 ng TEQ(WHO-Avian)/kg body wt/d). Hazard quotients (HQs) based on central tendency estimates of the average daily dose and no-observable-adverse effect level (NOAEL) for the screech owl and uncertainty factors were <1.0 for both the RA and the SA. Hazard quotients based on upper end estimates of the average daily dose and NOAEL were <1.0 in the RA and up to 3.4 in the SA.