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At least 631 records · Page 35Linked to original sources
USGS1998

Induction of cytochrome P450-associated monooxygenases in northern leopard frogs, Rana pipiens, by 3,3′,4,4′,5-Pentachlorobiphenyl

Northern leopard frogs ( Rana pipiens ) were injected intraperitoneally either with a solution of polychlorinated biphenyl (PCB) 126 in corn oil at a concentration of 0.2, 0.7, 2.3, or 7.8 mg/kg body weight or with corn oil alone. Appropriate assay conditions with hepatic microsomes were determined for four cytochrome P450-associated monooxygenases: ethoxyresorufin- O -dealkylase (EROD), methoxy-ROD (MROD), benzyloxy-ROD (BROD), and pentoxy-ROD (PROD). One week after PCB administration, the specific activities of EROD, MROD, BROD, and PROD were not elevated at doses ≤0.7 mg/kg ( p > 0.05) but were significantly increased at doses ≥2.3 mg/kg compared to the control groups ( p < 0.05). The increased activities of these four enzymes were 3 to 6.4 times those in the control groups. The increased activities were maintained for at least 4 weeks. Because of a lack of induction at low doses of PCB 126, which were still relatively high compared to currently known environmental concentrations, we suspect that EROD, MROD, BROD, and PROD activities are not sensitive biomarkers for coplanar PCB exposure in leopard frogs.

Environmental Toxicology and Chemistry↗
USGS1998

Reproduction and environmental contamination in tree swallows nesting in the Fox River drainage and Green Bay, Wisconsin, USA

Concentration, accumulation, and effects of polychlorinated biphenyls (PCBs) o nreproduction in tree swallows ( Tachycineta bicolor ) were studied at four sites in the Fox River drainage and in Green Bay, Lake Michigan, Wisconsin, USA, in 1994 and 1995. Total PCBs in eggs and newly hatched young (mean = 3.01 μg/g wet weight, years and sites combined) and 12-d-old nestlings (mean = 2.34 μg/g wet weight) at two contaminated sites (Kidney Island and Arrowhead) were higher than concentrations at two reference sites (Lake Poygan and High Cliff State Park, years and sites combined, pippers mean = 0.26 μg/g, nestlings mean = 0.01 μg/g). Concentrations of 11 PCB congeners were also higher at contaminated compared to reference sites. Polychlorinated biphenyls (PCBs) accumulated in nestlings at a higher rate (1.34–6.69 μg/d) at contaminated sites compared to reference locations (0.06–0.42 μg/d). Dichlorodiphenyldichloroethylene (DDE) was the only other organochlorine found in all samples; concentrations for all samples averaged ≤0.20 μg/g wet weight. Total PCBs and p,p ′-DDE concentrations did not differ among clutches where all eggs hatched, some eggs hatched, and no eggs hatched.

Wisconsin↗
USGS1998

Effects of 3,3′,4,4′,5-pentachlorobiphenyl and 2,3,7,8-tetrachlorodibenzo-p-dioxin injected into the yolks of double-crested cormorant (Phalacrocorax auritus) eggs prior to incubation

Double-crested cormorant ( Phalacrocorax auritus ) eggs were injected with either 3,3′,4,4′,5-pentachlorobiphenyl (polychlorinated biphenyl [PCB] 126; 70-698 μg/kg egg) or 2,3,7,8-tetrachlorodibenzo- p -dioxin (TCDD; 1.3-11.7 μg/kg egg) prior to incubation. These compounds were injected into the yolks of cormorant eggs collected from incomplete clutches at isolated colonies on Lake Winnipegosis, Manitoba, Canada. Eggs were incubated for approximately 26 to 28 d. After hatching the brain, bursa, heart, liver, and spleen were dissected and weighed. Torsos were preserved in formalin for examination of the gonads. Median lethal doses (LD50s) calculated from mortality data at hatching were 177 and 4.0 μg/kg egg for PCB 126 and TCDD, respectively. No significant differences were found in the incidence of developmental abnormalities in any of the treatment groups. Bursa weights were significantly less in the greatest (11.7 μg/kg egg) TCDD group compared to the vehicle control group. Spleen weights were significantly less in the 349 μg PCB 126/kg egg and the 5.4 and 11.7 μg TCDD/kg egg groups when compared to the vehicle control group. No histological alterations of the gonads were found. Hepatic ethoxyresorufin- O -deethylase activity in all PCB 126 and TCDD dose groups was significantly greater compared to the control activity. The toxic equivalency factor for PCB 126 was 0.02.

Environmental Toxicology and Chemistry↗
USGS1998

Relation of lead exposure to sediment ingestion in mute swans on the Chesapeake Bay, USA

Although wildlife risk assessments are generally based on the accumulation of environmental contaminants through food chains, wildlife may also ingest contaminants incidentally with sediment. Forty-two mute swans ( Cygnus olor ) were collected from unpolluted portions of central Chesapeake Bay, Maryland, USA, in spring 1995, and their intestinal digesta were analyzed for 13 metals (aluminum [Al], boron, barium, cadmium, copper [Cu], iron, magnesium, manganese, nickel, lead [Pb], strontium, vanadium, and zinc) and for acid-insoluble ash, a marker of sediment. Swan livers and sediment samples also were analyzed for the same metals. Group method of data handling demonstrated that the digesta Al, which is associated with clays, was the best predictor of digesta Pb. Adding concentrations of other metals as predictors did not improve the accuracy of the estimates of Pb concentrations from Al concentrations. The r 2 of the equation relating the log of digesta Pb to the log of digesta Al was 0.86, whereas the r 2 of the equation relating the log of digesta Pb to the log of digesta acid-insoluble ash was 0.50. Accounting for the sediment ingested was critical to determining the exposure of mute swans to Pb, as well as to some of the other metals, and sediment ingestion should be considered in ecotoxicological risk assessments of waterfowl. The mean of 7.4% acid-insoluble ash in the digesta corresponded to an estimated 3.2% sediment in the diet. The Pb concentrations in the digesta were two to three times the concentration that would have been predicted from sediment Pb concentrations; presumably, the swans had ingested clays high in Pb that had settled on the vegetation. The swans were probably not exposed to high Cu concentrations but nevertheless had hepatic Cu concentrations that would be considered very high if found in other species.

Environmental Toxicology and Chemistry↗
USGS1998

Blood changes in mallards exposed to white phosphorus

White phosphorus (P 4 ) has been extensively used by the military for various purposes, including marking artillery impacts and as an obscurant. Target practice in an Alaskan tidal marsh during the last 4 decades has deposited large amounts of P 4 particles in sediments and water, which have resulted in die-offs of several waterfowl species. Because the toxicity of P 4 in birds has not been well documented and because it is quickly excreted or metabolized in living animals, we sought to determine the effects of experimental dosing on blood characteristics in game farm mallards ( Anas platyrhynchos ). In two experiments, one employing single doses of 5.4 mg P 4 per kilogram body weight in corn oil and the other using daily repeated doses of pelletized P 4 at either 0.5 or 1.0 mg/kg, there were significant changes in aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase (LDH), inorganic P, hematocrit, and hemoglobin. Other indications of exposure included changes in uric acid, creatinine, and total protein, which were consistent with reported liver and kidney damage due to this contaminant. Changes in white blood cells included a greater frequency of thrombocytes and fewer lymphocytes in dosed birds compared to controls. A biomarker of exposure based on LDH activity and hemoglobin is proposed.

Environmental Toxicology and Chemistry↗
USGS1998

Photoenhanced toxicity of a carbamate insecticide to early life stage anuran amphibians

Aican clawed frog ( Xenopus laevis ) and gray tree frog ( Hyla versicolor ) embryos and tadpoles were exposed to sublethal levels of carbaryl, a broad-spectrum insecticide, and ultraviolet radiation to determine interactive and sublethal effects. Ultraviolet intensity (UV-B [285–320 nm] plus UV-A [321–400 nm]) was controlled with various types of plastic filters and quantified with a scanning spectroradiometer. Significant differences in swimming activity and mortality of both species were evident during the 96-h experiments. Ultraviolet-B radiation alone and carbaryl in the presence of UV-B significantly decreased swimming activity of both species. As little as 1.5% intensity of ambient solar UV-B radiation photoactivated carbaryl. Toxicity of 7.5 mg/L carbaryl increased by 10-fold in the presence of UV-B in all species and life stages tested. Our results indicate that photoenhancement by solar UV-B radiation should be considered when evaluating the toxicity of contaminants to amphibians and other organisms.

Environmental Toxicology and Chemistry↗
USGS1999

Tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity tests

A method is described for preparing formulated sediments for use intoxicity testing. Ingredients used to prepare formulated sediments included commercially available silt, clay, sand, humic acid, dolomite, and α-cellulose (as a source of organic carbon). α-Cellulose was selected as the source of organic carbon because it is commercially available, consistent from batch to batch, and low in contaminant concentrations. The tolerance of freshwater test organisms to formulated sediments for use as control materials in whole-sediment toxicity testing was evaluated. Sediment exposures were conducted for 10 d with the amphipod Hyalella azteca , the midges Chironomus riparius and C. tentans , and the oligochaete Lumbriculus variegatus and for 28 d with H. azteca . Responses of organisms in formulated sediments was compared with a field-collected control sediment that has routinely been used to determine test acceptability. Tolerance of organisms to formulated sediments was evaluated by determining responses to varying levels of α-cellulose, to varying levels of grain size, to evaluation of different food types, or to evaluation of different sources of overlying water. In the 10-d exposures, survival of organisms exposed to the formulated sediments routinely met or exceeded the responses of test organisms exposed to the control sediment and routinely met test acceptability criteria required in standard methods. Growth of amphipods and oligochaetes in 10-d exposures with formulated sediment was often less than growth of organisms in the field-collected control sediment. Additional research is needed, using the method employed to prepare formulated sediment, to determine if conditioning formulated sediments before starting 10-d tests would improve the growth of amphipods. In the 28-d exposures, survival of H. azteca was low when reconstituted water was used as the source of overlying water. However, when well water was used as the source of overlying water in 28-d exposures, consistent responses of amphipods were observed in both formulated and control sediments.

Environmental Toxicology and Chemistry↗
USGS1999

Behavioral avoidance: Possible mechanism for explaining abundanc and distribution of trout species in a metal-impacted river

Behavioral avoidance of metal mixtures by rainbow trout ( Oncorhynchus mykiss ) was determined in the laboratory under water quality conditions that simulated the upper Clark Fork River, Montana, USA. A metal mixture with a fixed ratio of observed ambient metal concentrations (12 μg/L Cu:1.1 μg/L Cd:3.2 μg/L Pb:50 μg/L Zn) was used to determine avoidance in a countercurrent avoidance chamber. Rainbow trout avoided all metal concentrations tested from 10 to 1,000% of the simulated ambient metal mixture. The behavioral response of rainbow trout to the metal mixture was more sensitive than the response of brown trout ( Salmo trutta ) previously reported from the same laboratory under the same experimental conditions. Additionally, rainbow trout that were acclimated to the simulated ambient metal mixture for 45 d preferred clean water and avoided higher metal concentrations. Therefore, our laboratory experiments on the behavioral avoidance responses of rainbow trout, as well as previously reported experiments on brown trout, show that both species will avoid typical metal concentrations observed on the Clark Fork River. And the greater sensitivity of rainbow trout to the metal mixture may explain, in part, why rainbow trout populations appear to be more severely affected, compared to brown trout populations, in the upper Clark Fork River.

Environmental Toxicology and Chemistry↗
USGS1999

Comparison of organochlorine contaminants among sea otter (Enhydra lutris) populations in California and Alaska

Organochlorine pesticides, polychlorinated biphenyls (PCBs) including non- ortho PCBs, polychlorinated dibenzo- p -dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) were measured in sea otter liver tissue from California, southeast Alaska, and the western Aleutian archipelago collected between 1988 and 1992. Average total dichlorodiphenyltrichloroethane concentrations for California otters (850 μg/kg wet weight) were over 20 times higher than in Aleutian otters (40 μg/kg) and over 800 times higher than otters from southeast Alaska (1 μg/kg). Levels for total PCBs in Aleutian otters (310 μg/kg) were 1.7 times higher than levels in California otters (190 μg/kg) and 38 times higher than otters from southeast Alaska (8 μg/kg). Levels for PCDD and PCDF were extremely low in all otter populations. Levels of PCBs in Aleutian and Californian otters are abnormally high when compared with southeast Alaskan otters. The source of PCBs to the Aleutian Islands remains unclear and vital to understanding the potential impacts to sea otters.

Environmental Toxicology and Chemistry↗
USGS1999

Cytochrome P4501A induction, benzo[a]pyrene metabolism, and nucleotide adduct formation in fish hepatoma cells: Effect of preexposure to 3,3',4,4',5-pentachlorobiphenyl

In PLHC-1 hepatoma cells, benzo[a]pyrene (B[a]P) caused a maximum induction of cytochrome P4501A (CYP1A) activity, measured as ethoxyresorufin O-deethylation (EROD), after 4 to 8 h of exposure, depending on the B[a]P concentration. The decline of EROD activity at longer exposure times was probably caused by the rapid metabolism of B[a]P in this system (57% metabolism within 4 h incubation). In subsequent experiments, PLHC-1 cells were preinduced with PCB 126 for 24 h and then received a dose of 10, 100, or 1,000 nM 3H-B[a]P. A 1-nM concentration of PCB 126 caused an 80-fold induction of CYP1A activity, resulting in an increase in B[a]P metabolism of less than 10%, except at the highest concentration of B[a]P (1,000 nM), where a 50% increase was observed. In another experiment, an 80-fold induction of CYP1A activity caused a 20% increase in the metabolism of B[a]P (100 nM), and RNA adduct formation was increased approximately twofold. These results indicate that, at exposure concentrations up to 100 nM B[a]P, CYP1A activity is not rate limiting for B[a]P metabolism. Furthermore, CYP1A seems to also he specifically involved in B[a]P activation in PLHC-1 cells. However, CYP1A induction causes only a relatively small increase in activation, probably because of the action of other enzymes involved in B[a]P activation and deactivation.

Environmental Toxicology and Chemistry↗
USGS1999

Concentrations of selenium, mercury, and lead in blood of emperor geese in western Alaska

We found up to 10 ppm wet weight of selenium in blood samples collected from emperor geese ( Chen canagica ) on their breeding grounds on the Yukon‐Kuskokwim Delta in western Alaska, USA. Incubating adult females captured in late May through mid‐June 1997 had significantly higher concentrations of selenium in their blood (mean = 5.60 ppm) than adult females captured during wing molt in late July 1996 (mean = 2.78 ppm). Females that nested early or were in good body condition had higher concentrations of selenium in their blood than did other nesting females. Blood samples from 4 of 29 goslings had detectable levels of selenium (mean = 0.14 ppm). Our findings suggest that emperor geese are exposed to more selenium in the marine environment of their wintering and staging areas on the Alaska Peninsula than on the breeding grounds. The highest concentration of mercury found in the blood of emperor geese was 0.24 ppm. One bird had a blood lead concentration of 0.67 ppm, but 82% had no detectable lead in their blood, suggesting that lead exposure from the ingestion of lead shot poses little threat for emperor geese in western Alaska, contrary to findings reported for sympatric spectacled eiders ( Somateria fischeri ).

Alaska↗
USGS1999

Effect of high aluminum consumption on mechanics and composition of furculae of free-ranging coots

High levels of ingested Al can affect mechanical properties of bones. Because of the spring action of the furcula during the wingbeat, small changes in the mechanical properties of this bone may have measurable impacts on long-distance flight. We examined the furculae and ingesta of free-ranging American coots (Fulica americana) in San Francisco Bay (California, USA), where they consume a diet high in Al. We measured the spring stiffness and phase angle (δ) of the furculae and the concentrations of Al, Ca, F, Mg, and P in both the furculae and ingesta. The ingesta had mean Al concentrations (2,384 μg/g, dry weight) and Al:P molar ratios (6.4:1) predicted to affect bone integrity but the bone concentrations of Al were near the normal range and the furcula stiffness did not change with Al concentration. The tan δ of the furculae changed with Al concentration but the relationship was weak. The chemical speciation of the ingested Al may have affected its physiologic role and the high mean levels of ingested calcium (71,283 μg/g, dry weight) very likely neutralized the activity of the Al. Controlled feeding studies have shown that F strengthens avian bones. The bones in our study had molar concentrations of F more than two orders of magnitude greater than Al (170:1) but F appears to have insignificant influence on bone mechanics. The coots in San Francisco Bay apparently are not suffering furcula impairment despite a diet high in Al.

Environmental Toxicology and Chemistry↗
USGS1999

Lead exposure in passerines inhabiting lead-contaminated floodplains in the Coeur d'Alene River Basin, Idaho, USA

Blood collected from song sparrows ( Melospiza melodia ) and American robins ( Turdus migratorius ) captured with mist nets in a lead-contaminated (assessment) area and nearby uncontaminated (reference) areas within the Coeur d'Alene Basin in northern Idaho was analyzed for δ-aminolevulinic acid dehydratase activity (ALAD) and hematocrit levels, and livers were analyzed for lead. Mean ALAD inhibition in the assessment area was 51% in song sparrows and 75% in American robins. The proportion of the sampled population with ALAD inhibition >50% was calculated to be 43% for song sparrows and 83% for American robins. Assessment area hematocrit values for song sparrows ( x = 39.9) and American robins ( x = 39.5) were lower than in reference areas ( x = 42.4 for song sparrows and 40.2 for American robins); however, differences were not statistically significant ( p > 0.05). Significantly higher levels of lead (wet weight) were found in livers from song sparrows captured on the assessment area ( x = 1.93 ppm) than on reference areas ( x = 0.10 ppm) ( p = 0.0079). Study results indicate that 43% (95% confidence interval [CI] = 12.9-77.5%) of the song sparrows and 83% (95% CI = 41.8-99.2%) of the American robins inhabiting the floodplain along the Coeur d'Alene River in the assessment area are being exposed to lead at levels sufficient to inhibit ALAD by > 50%. Variability in lead exposure indicators was attributed to high variability in environmental lead concentrations in the Coeur d'Alene River Basin.

Environmental Toxicology and Chemistry↗
USGS1999

Organochlorine contaminants and reproductive success of double-crested cormorants from Green Bay, Wisconsin, USA

In 1994 and 1995, nesting success of double-crested cormorants ( Phalacrocorax auritus ) was measured at Cat Island, in southern Green Bay, Lake Michigan, Wisconsin, USA. Sample eggs at pipping and unhatched eggs were collected and analyzed for organochlorines (including total polychlorinated biphenyls [PCBs] and DDE), hepatic microsomal ethoxyresorufin-O-dealkylase (EROD) activity in embryos, and eggshell thickness. Of 1,570 eggs laid, 32% did not hatch and 0.4% had deformed embryos. Of 632 chicks monitored from hatching to 12 d of age, 9% were missing or found dead; no deformities were observed. The PCB concentrations in sample eggs from clutches with deformed embryos (mean = 10.2 μg/g wet weight) and dead embryos (11.4 μg/g) were not significantly higher than concentrations in sample eggs from nests where all eggs hatched (12.1 μg/g). A logistic regression of hatching success versus DDE, dieldrin, and PCB concentrations in sibling eggs identified DDE and not dieldrin or PCBs as a significant risk factor. A logistic regression of hatching success versus DDE and eggshell thickness implicated DDE and not eggshell thickness as a significant risk factor. Even though the insecticide DDT was banned in the early 1970s, we suggest that DDE concentrations in double-crested cormorant eggs in Green Bay are still having an effect on reproduction in this species.

Wisconsin↗
USGS1999

Exposure of great egret ( Ardea albus ) nestlings to mercury through diet in the Everglades ecosystem

We estimated exposure of great egret ( Ardea albus ) nestlings to mercury in food in the Florida Everglades, USA, by collecting regurgitated food samples during the 1993 to 1996 breeding seasons and during 1995 measured concentrations of mercury in individual prey items from those samples. Great egret nestlings had a diet composed predominantly of fish (>95% of biomass), though the species composition of fish in the diet fluctuated considerably among years. Great egrets concentrated on the larger fish available in the marsh, especially members of the Centrarchidae. The importance of all nonnative fish fluctuated from 0 to 32% of the diet by biomass and was dominated by pike killifish ( Belonesox belizanus ) and cichlids (Cichlidae). Total mercury concentrations in prey fish ranged from 0.04 to 1.40 mg/kg wet weight, and we found a significant relationship between mass of individual fish and mercury concentration. We estimated the concentration of total mercury in the diet as a whole by weighting the mercury concentration in a given fish species by the proportion of that species in the diet. We estimate that total mercury concentrations in the diets ranged among years from 0.37 to 0.47 mg/kg fish (4-year mean = 0.41 mg/kg). We estimated total mercury exposure in great egret nestlings by combining these mercury concentrations with measurements of food intake rate, as measured over the course of the nestling period in both lab and field situations. We estimate that, at the 0.41 mg/kg level, nestlings would ingest 4.32 mg total mercury during an 80-day nestling period. Captive feeding studies reported elsewhere suggest that this level of exposure in the wild could be associated with reduced fledging mass, increased lethargy, decreased appetite, and, possibly, poor health and juvenile survival.

Environmental Toxicology and Chemistry↗
USGS1999

Productivity, diets, and environmental contaminants in nesting bald eagles from the Aleutian Archipelago

We studied productivity, diets, and environmental contaminants in nesting bald eagles from the western Aleutian Islands, Alaska, USA, during the summers of 1993 and 1994. Productivity on Adak, Tanaga, and Amchitka Islands ranged from 0.88 to 1.24 young produced per occupied site and was comparable to that of healthy populations in the lower 48 United States. However, productivity on Kiska Island was depressed, averaging 0.67 young per occupied site. The lower reproductive success on Kiska was associated with elevated levels of dichlorodiphenyldichloroethylene and other organochlorine pesticides. Many of the organochlorine pesticides were elevated in bald eagle eggs from the four islands, but concentrations of these contaminants and Hg were significantly higher in eggs from Kiska Island than in eggs from the other islands. In contrast, polychlorinated biphenyl concentrations were higher in eggs from Adak, Amchitka, and Kiska (where military facilities have been installed) than in those from Tanaga (which has had little military activity). The most likely source of these contaminants in bald eagles was from their diets, which were variable spatially and temporally. Fish made up most (56%) of the eagles' diet on Adak and Tanaga Islands, followed by birds (25%) and mammals (19%). In contrast, birds comprised the majority (60%) of bald eagle diets on Amchitka and Kiska Islands, followed by mammals (30%) and fish (10%). The high proportion of seabirds in the diet of eagles from Kiska Island could be the major source of organochlorine and Hg contamination. Elevated concentrations of organochlorines in bald eagle eggs from the Aleutian Archipelago was surprising, because of the distance to agricultural areas. The results indicate that these contaminants can be transported long distances and affect wildlife populations in remote and pristine areas. We also discuss potential sources and transport mechanisms of these contaminants to the Aleutian Islands.

Environmental Toxicology and Chemistry↗
USGS1999

Hydroxyatrazine in soils and sediments

Hydroxyatrazine (HA) is the major metabolite of atrazine in most surface soils. Knowledge of HA sorption to soils, and its pattern of stream water contamination suggest that it is persistent in the environment. Soils with different atrazine use histories were collected from four sites, and sediments were collected from an agricultural watershed. Samples were exhaustively extracted with a mixed—mode extractant, and HA was quantitated using high performance liquid chromatography with UV detection. Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were also measured in all samples. Concentrations of HA were considerably greater than concentrations of atrazine, DEA, and DIA in all soils and sediments studied. Soil concentrations of HA ranged from 14 to 640 μg/kg with a median concentration of 84 μg/kg. Sediment concentrations of HA ranged from 11 to 96 μg/kg, with a median concentration of 14 μg/kg. Correlations of HA and atrazine concentrations to soil properties indicated that HA levels in soils were controlled by sorption of atrazine. Because atrazine hydrolysis is known to be enhanced by sorption and pH extremes, soils with high organic matter (OM) and clay content and low pH will result in greater atrazine sorption and subsequent hydrolysis. Significant correlation of HA concentrations to OM, pH, and cation exchange capacity of sediments indicated that mixed—mode sorption (i.e., binding by cation exchange and hydrophobic interactions) was the mechanism controlling HA levels in sediment. The presence of HA in soils and stream sediments at the levels observed support existing hypotheses regarding its transport in surface runoff. These results also indicated that persistence of HA in terrestrial and aquatic ecosystems is an additional risk factor associated with atrazine usage.

Environmental Toxicology and Chemistry↗
USGS1999

Polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in tree swallows from the upper Hudson River, New York State, USA

The upper Hudson River of New York State, USA, is contaminated with polychlorinated biphenyls (PCBs) as a result of industrial discharges throughout the latter half of this century. In 1994 and 1995, we monitored the transfer of PCBs from aquatic sediments to a terrestrial wildlife community using the tree swallow ( Tachycineta bicolor ) as a model organism. Tree swallow eggs and nestlings were collected at four colonies established along a 40-km stretch of the upper Hudson River watershed. Samples were analyzed for total PCBs and PCB congeners, including non- ortho - and mono-ortho-substituted PCBs. Mean concentrations of PCBs in tree swallow eggs and nestlings ranged from 721 to 62,200 ng/g and were as much as 15 times greater than PCB concentrations in tree swallow eggs and nestlings collected from PCB-contaminated areas within the Great Lakes ecosystem. The corresponding 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs) calculated using avian toxic equivalency factors ranged from 410 to 25,400 pg/g. Concentrations of PCB congener 77 (3,39,4,49-tetrachlorobiphenyl) were extremely elevated and were major contributors to the calculated TEQs. Homologue pattern comparisons between Hudson River and Saginaw River (Michigan, USA) ecosystems supported the hypothesis that a consistent Hudson River PCB source was the major contributor to PCBs in Hudson River tree swallows. The high concentrations of PCBs in Hudson River sediments and resultant concentrations observed in tree swallows were indicative of a potential elevated risk to these and other wildlife linked to the aquatic food web of the Hudson River ecosystem.

New York↗