PCB Burdens Research Articles

Organochlorine contaminants in wild mink from the lower Great Lakes basin, Canada, 1998-2006.

Organochlorine contaminants were measured in livers of wild mink (Neovison vison) trapped in the lower Great Lakes basin from 1998 to 2006. To assess exposure and potential risk in mink feeding on Great Lakes biota, concentrations of contaminants were compared in mink trapped within 7.8km of the shoreline as well as at inland sites (i.e., 8-40km). Overall, significant spatial variation in mean hepatic concentrations of sum PCBs and seven other organochlorines was found in mink from 13 Great Lakes sites, many of which are within the Great Lakes Areas of Concern. Mean sum PCB concentrations, on a lipid weight basis, ranged from 2μg/g in mink from inland Lake Ontario sites to 44μg/g in mink from western Lake Erie. Concentrations of other organochlorines in mink were generally low. Mink from western Lake Erie had the highest mean cumulative organochlorine burdens dominated largely by PCBs. A significant age effect was found with 1-year-old mink having significantly higher PCB burdens than mink less than 1year in age. With respect to published PCB threshold effect concentrations, some mink exceeded those associated with effects on reproduction and survival as well as the presence of jaw lesions. This was most consistently found in western Lake Erie where the health of populations of wild mink may be adversely affected and where no mink 2years of age or older were collected.

A multitracer approach to assess the spatial contamination pattern of hake (Merluccius merluccius) in the French Mediterranean

Chemical contamination levels and stable isotope ratios provide integrated information about contaminant exposure, trophic position and also biological and environmental influences on marine organisms. By combining these approaches with otolith shape analyses, the aim of the present study was to document the spatial variability of Hg and PCB contamination of the European hake (Merluccius merluccius) in the French Mediterranean, hypothesizing that local contaminant sources, environmental conditions and biological specificities lead to site-specific contamination patterns. High Hg concentrations discriminated Corsica (average: 1.36±0.80μgg−1dm) from the Gulf of Lions (average values<0.5μgg−1dm), where Rhône River input caused high PCB burdens. CB 153 average concentrations ranged between 4.00±0.64 and 18.39±12.38ngg−1dm in the Gulf of Lions, whatever the sex of the individuals, whereas the highest values in Corsica were 6.75±4.22ngg−1dm. Otolith shape discriminated juveniles and adults, due to their different habitats. The use of combined ecotracers was revealed as a powerful tool to discriminate between fish populations at large and small spatial scale, and to enable understanding of the environmental and biological influences on contamination patterns.

The effects of repeated planting, planting density, and specific transfer pathways on PCB uptake by Cucurbita pepo grown in field conditions

An in situ field investigation into the potential of PCB phytoextraction by Cucurbita pepo ssp. pepo (pumpkin) plants was continued for a second year at a field site known to be contaminated with a mixture of Aroclors 1254 and 1260 (average soil [PCB] = 21 μg/g). Plant stem and leaf PCB concentrations in this second field season (11 and 8.9 μg/g, respectively) were observed to increase significantly from the stem and leaf PCB concentrations reported in the previous year (5.7 and 3.9 μg/g, respectively) while the total biomass produced as well as soil and plant root PCB concentrations did not change. Furthermore, the lower stems of some plants exhibited PCB concentrations as high as 43 μg/g, resulting in bioaccumulation factors (where BAF plant part = [PCB] plant part / [PCB] soil) for parts of the plant shoot as high as 2. Increased planting density was observed to significantly decrease both plant biomass and plant stem PCB concentrations (to 7.7 μg/g), but did not change plant root PCB concentrations. Finally, the results from this study provided further evidence that that under realistic field conditions, PCB transfer to pumpkin plants was primarily via root uptake and translocation. Other contaminant transfer pathways such as direct soil contamination, atmospheric deposition and volatilization from soil and subsequent redeposition on shoots appeared to have negligible contributions to overall pumpkin plant PCB burdens.

Evolution rates and PCB content of surface films that develop on impervious urban surfaces

Surface films on impervious surfaces mediate the fate of organic contaminants in urban areas. Using sheltered 3-mm diameter glass beads as a surrogate impervious urban surface, studies in downtown Toronto showed that surface films developed at a consistent rate of ∼1.6–2.6 nm day −1. Linear film growth was observed up to and including the last day of three studies of 89-, 273-, and 84-day duration. Total PCB content (sum of 15 PCB congeners) also increased linearly, at a similar rate as the surface film. A complementary study using unsheltered beads showed that up to 80% of film mass and PCB content were removed by film wash-off during rain events. The film growth rate on beads exposed at a rural site, 200 km northeast of Toronto, was ∼12–20 times lower with PCB burdens that were ∼7–22 times lower compared to Toronto. Based on these findings, it is estimated that approximately 56–226 g of PCBs are captured by a 70 nm thick film covering just the horizontal surface area of Toronto. This is a substantial quantity of PCB that is available for rapid surface–air exchange and wash-off.

Subtle sabotage: endocrine disruption in wild populations

How important is endocrine disruption as a threat to wildlife populations? This review applies causal criteria to existing studies of wild populations of fish, amphibians, reptiles, birds, and mammals to answer three questions: (1) Have endocrine-mediated effects of contaminant exposure been documented? (2) Have individual adverse effects that could lead to population effects been documented? (3) Have population level effects been documented? In fish, the possibility of population level effects is inferred from impaired individual fertility. Substantial evidence directly links fertility impairment to endocrine disruption. In amphibians, population declines are occurring worldwide and causes may vary among regions, with contaminant-induced sexual disruption being one of many insults that stymie population growth. In reptiles, local populations of alligators have been dramatically reduced by direct toxicity and recovery has probably been slowed by sexual disruption, particularly feminization induced by chronic contaminant exposure. In contrast, heavily contaminated snapping turtles display feminized secondary sex characteristics, evidence of disrupted sexual development, but populations are densest at the most heavily contaminated site. In birds, population decline and recovery have been directly linked to p,p’-DDE-mediated eggshell thinning and subsequent banning of the parent compound DDT in the US and Europe. Regional populations of predatory birds still suffer chick mortality related to PCB and DDT burdens, but no causal link with endocrine-mediated processes has been demonstrated. In mammals, contaminant- induced hormonal derangements in seals and polar bears have been documented, but no clear evidence links endocrine effects to population declines. Although endocrine disruption will rarely be the sole cause of failing recruitment or decreased abundance, it may subtly sabotage sexual development, sex ratio, and metabolic compensation for environmental stress. Endocrine disruption is unlikely to extirpate a species over its entire range, but in combination with other stressors such as habitat loss, over-harvesting, and global climate change, may contribute to local extinctions. Rev. Biol. Trop. 54(Suppl. 1): 1-19. Epub 2006 Sept. 30.

Seasonal Dynamics of PCB and Toxaphene Bioaccumulation within a Lake Michigan Food Web

Seasonal variations in PCB and toxaphene concentrations were measured in bulk zooplankton, mysid shrimp, benthic amphipods, alewife, and bloater chub collected from Grand Traverse Bay, Lake Michigan between April and September of 1997 and 1998. Concentrations of PCBs in the dissolved phase of the water column were consistent over time; however, seasonal changes in contaminant concentrations within the biota were significant. Seasonal changes were most pronounced in zooplankton, which displayed highest PCB burdens in April and decreased by as much as 75% through September, coincident with changes in phytoplankton biomass, species composition, and changes in the particulate pools of PCBs within the water column. Mysis sp. display a similar PCB trend as zooplankton, while Diporeia sp. displayed maximal PCB concentrations in late summer during 1997. PCB trends in the primary forage fish alewife ( Alosa pseudoharengus) and bloater ( Coregonus hoyi) were correlated more to shifts in lipid content and seasonal diet preferences. PCB concentrations were higher (p < 0.01) in bloater (310 ± 98 ng/g wet weight) than alewife (233 ± 70 ng/g wet weight), however alewife possessed higher toxaphene burdens (198 ± 72 ng/g wet weight) than bloater (88 ± 36 ng/g wet weight). Alewife contaminant burdens were high in spring and fall of both years, decreasing by as much as 60% in midsummer, and were reflective of changes measured in their lipid content associated with gamete production and spawning. These results suggest that despite invariant concentrations of the dissolved pool of PCBs within the lake, accumulation of PCBs by the biota on seasonal scales is controlled appreciably by growth and lipid dynamics, and foraging behavior.

The relative importance of species invasions and sediment disturbance in regulating chemical dynamics in western Lake Erie

PCB congener concentrations were measured in aquatic biota and sediment from the western basin of Lake Erie during 1993–1994 and 1996–1997. Between these time periods the round goby ( Neogobius melanostomus) invaded and proliferated in the basin and mean annual particulate organic carbon (POC), dissolved organic carbon (DOC) and PCB congener concentrations in sediment changed. The objectives of this study were to use a food web bioaccumulation model and field data to quantify the relative importance of the round goby, POC, DOC and chemical concentration in sediment, to PCB congener levels in aquatic biota prior to (1993–1994) and since (1996–1997) the invasion of the basin by round gobies. The predicted effects of round gobies on PCB congener transfer, mediated through alterations in food web structure, were small increases (range 2–6%) in PCB burdens of pelagic fish species such as alewife and walleye. Larger increases (range 8–19%) in PCB burdens were predicted for benthic feeding sport fish species such as yellow perch and largemouth bass. Small decreases (range 1–5%) in PCB congener concentrations in fish were predicted to result from decreases in bioavailable concentrations of PCBs in water. Bioavailable concentrations of PCBs in water were predicted to decrease as a result of observed changes in POC and DOC concentrations. However, in all cases predicted changes in PCB concentrations in fish, resulting from changes in food web structure and POC and DOC, were smaller than those predicted from measured increases in PCB congener concentrations in sediment between 1993 and 1994 and 1996–1997. Increased concentrations of PCBs in sediment were attributed to exposure of older and more heavily contaminanted sediments from turbulence caused by higher wind speeds in 1996–1997 compared to 1993–1994.

Bioaccumulation of 2,4,6‐trinitrotoluene and polychlorinated biphenyls through two routes of exposure in a terrestrial amphibian: Is the dermal route significant?

AbstractTiger salamanders (Ambystoma tigrinum) were exposed via soil and/or food (earthworms) to 2,4,6‐trinitrotoluene (TNT) and a PCB mixture (Aroclor 1260) at environmentally relevant concentrations. Four exposures were considered: (1) uncontaminated food + uncontaminated soil (control group); (2) contaminated soil + uncontaminated food (dermal group); (3) contaminated food + uncontaminated soil (oral group); and, (4) contaminated soil + contaminated food (dual‐exposure group). The chemical exposure was estimated for each group by analysis of both soil and earthworms. Body burdens of TNT and its primary metabolites were highest in the dermal groups while PCB burdens were highest in the oral groups. Concentrations of the primary TNT metabolites evaluated, 2‐amino‐dinitrotoluene (DNT) and 4‐amino‐DNT, exceeded that of unmetabolized TNT and accumulated to 116 and 670 ng/g, respectively. These results provide evidence that dermal exposures to nitroaromatics in terrestrial salamanders may make an important contribution to total body burden and thus may be important when considering the health consequences of such exposures. Further, the demonstration of the accumulation of TNT and TNT metabolites in a primitive vertebrate may have food web modeling implications.

Bioavailability of PCBs to male laboratory rats maintained on litters of contaminated soils: PCB burden and induction of alkoxyresorufin O-dealkylase activities in liver and lung.

Male rats from the Sprague-Dawley laboratory strain were maintained in the laboratory during 3 days and 1 night on litters containing a reference soil and different amounts of a soil, mainly polluted by PCBs (207 ppm expressed in Aroclor(R) 1254; SIII soil). Two categories of biomarkers of exposure were measured in both liver and lung of these rats: PCB burdens and activities of microsomal liver and lung cytochrome P450-dependent mono-oxygenases, namely ethoxy-, pentoxy-, and benzoxy-resorufin O-dealkylase activities (EROD, PROD, and BROD, respectively). PCB burdens in liver and lung of rats exposed to SIII soil were 1,845 and 241 ppb, respectively (expressed in Aroclor(R) 1254 equivalents). EROD, PROD, and BROD were significantly induced in the liver of rats exposed to SIII soil, while only EROD activity was induced in the lung. Induction of hepatic EROD activity was approximately 3- to 5.4-fold; pulmonary EROD activity was induced by 9- to 12-fold. In the lung, PROD and BROD activities were inhibited. When rats were exposed to SIII soil diluted with various amounts of standard ISO soil, a nearly linear dose-response relationship was found between the level of PCBs in the litter and EROD activity in both liver and lung. A nonlinear dose-response relationship exists with hepatic BROD activity; no dose-response relationship was observed with hepatic PROD and pulmonary PROD and BROD activities. EROD activity measurement in both liver and lung of rats maintained on a litter of PCB polluted soil was used to assess the bioavailability to mammals of PCBs.

A microcosm experiment to assess the outgassing potential of PCBs from sediment-water systems

A laboratory microcosm study was performed to assess the outgassing potential of PCBs from sediment-water systems. PCBs collected in the headspace of the sampler units were adsorbed onto polyurethane foam plugs, which were intermittently sampled over a total period of 56 days. The sediment composition, the level of PCB contamination in the sediment, and incubation temperature were all found to influence the rate of outgassing. Total outgassing losses over the 56 days ranged between 0.04 and 2.5% of the initial sediment PCB burdens.

Polychlorinated biphenyls and organochlorine pesticides in EELS ( Anguilla anguilla L.) from Welsh rivers

Organochlorine concentrations in the muscle tissues of eels at 41 freshwater sites across Wales were surveyed in 1993. Positive but weak relationships were detected between eel age or length and the concentration of some organochlorines. Isomers of HCH were below detection at most sites. Dieldrin was widespread at 10–100 μg kt −1 wet weight, despite its ban in sheep dip in 1989. Total DDT residue concentrations averaged 73 μg kg −1. Total PCB burdens expressed as Arochlor 1260, were > 50 μg kg −1 at 76% of sites and > 100 μg kg −1 at 46% of sites. The range of concentrations was comparable with other UK data. Rural sites had relatively low levels of PCBs, highest contamination occurring in the lower reaches of industrialised catchments. The inferences for environmental effects are discussed.

Biomonitoring environmental contamination with pipping black-crowned night heron embryos: Induction of cytochrome P450

Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins were measured in pipping black-crowned night heron (Nycticorax nycticorax) embryos collected from a reference site (next to the Chincoteague National Wildlife Refuge, VA) and three polluted sites (Cat Island, Green Bay, Lake Michigan, WI; Bair Island, San Francisco Bay, CA; West Marin Island, San Francisco Bay, CA). In a laboratory study, artificially incubated night heron embryos from the reference site were treated with 3-methylcholanthrene (200 μg administered into the air cell 2 d before pipping) or phenobarbital (2 mg daily for 2 d before pipping). Compared to controls (untreated + vehicle-treated embryos), 3-methylcholanthrene induced a greater than fivefold increase in activities of several monooxygenases (arylhydrocarbon hydroxylase, AHH; benzyloxyresorufin-O-dealkylase, BROD; ethoxyresorufin-O-dealkylase, EROD; pentoxyresorufin-O-dealkylase, PROD) and a greater than 100-fold increase in the concentration of immunodetected cytochrome P450 1A (CYP1A). Phenobarbital treatment resulted in only a slight increase in BROD activity but induced proteins recognized by antibodies to cytochrome P450 2B (CYP2B) by 2,000-fold. In a field study, activities of AHH, BROD, EROD, and ethoxycoumarin-O-dealkylase (ECOD) were up to 85-fold higher in pipping black-crowned night herons collected from Cat Island compared to other sites. Hepatic CYP1A and CYP2B cross-reactive proteins were detected in significantly more individuals from Cat Island than from the reference site. Greatest burdens of total PCBs and p,p′-DDE were detected in embryos from Cat Island. Cytochrome P450-associated monooxygenase activities and cytochrome P450 proteins (AHH, BROD, EROD, ECOD, CYP1A, CYP2B) were significantly associated with total PCB burdens (r = 0.50-0.72). These data indicate that cytochrome P450 may be a useful biomarker of exposure to some PCB mixtures in black-crowned night heron embryos.

Organochlorine contamination in shorebirds from Washington state and the significance for their falcon predators

Arctic-breeding shorebirds collected in western Washington state during winter and spring, and a comparative sample collected in coastal California during the winter were analyzed for organochlorine contaminants to determine the potential impact of these residues on populations of peregrine falcons (Falco peregrinus) and merlins (F. columbarius) which prey upon shorebirds in western Washington. Dunlins (Calidris alpina), an important winter prey for falcons in western Washington, were collected between 1975 and 1981. During winter 1980-81, dunlins carried low organochlorine residues; DDE levels ranged from 0.01 to 1.2 ppm, and PCB levels ranged from 0.02 to 0.82 ppm (wet weight). Levels of other organochlorine contaminants (HCB, Chlordane compounds, Dieldrin, and Heptachlor Epoxide), analyzed in a subsample of dunlins, were consistently lower than DDE and PCB levels, and ranged from 0.001 to 0.22 ppm (wet weight). Dunlins in western Washington did not significantly increase their DDE or PCB burdens over the 1980-81 winter. A decline in DDE residues between 1978 and 1981 was noted, and declines in PCB residues from both 1975 and 1978 to 1980-81 were noted. Residues in other wintering shorebirds from western Washington were similar. Wintering sanderlings (Calidris alba) from California, revealed much higher DDE contamination than in Washington (up to 32 ppm, wet weight). Spring migrant shorebirds in western Washington contained both low and very high DDE residues (up to 417 ppm, wet weight). There is evidence suggesting these high DDE concentrations are accumulated along the Pacific coast of North America.

Dynamics of Polychlorinated Biphenyls in Striped Bass from the Hudson River. III. Tissue Disposition and Routes for Elimination

Striped bass were exposed to14C-polychlorinated biphenyls (PCB) in single-dose and multiple-dose experiments. Samples were analyzed to determine rate constants for PCB elimination from individual tissues, PCB concentration in tissues, the proportion of the PCB burden retained and the proportion of the cumulative dose retained by each tissue at various times after exposure. An experiment was also conducted to determine both the potential for secondary PCB uptake in dietary exposure studies and the relative tissue disposition of PCBs assimilated from dietary sources as compared to direct water uptake. PCBs were present in the tissues of striped bass within 6 h after administration of a single dose. Certain tissue compartments, such as the liver/gall bladder, accumulated PCBs over a period of 48 h even though the whole-body burden had decreased between 24 and 48 h. Except for the gills, elimination rate constants for all tissues were similar and were similar to the whole body elimination rate constant. Elimination during the first few hours following exposure to PCBs may be due to equilibrium partitioning from the gill to the environment. The multiple-dose study showed that PCB burdens in striped bass continued to increase with dosing. However, tissue-specific rate constants for PCB elimination led to an increased flux of PCB out of tissues, and an overall decline in the percent of the cumulative dose remaining in the body 48 h after administration of each dose. The most likely route for PCB elimination from striped bass was from tissues to the liver and thence to the intestine via the bile. There were no differences in the tissue disposition of PCB related to route of exposure.