Response to stress of mussels (Mytilus edulis) exposed in dutch tidal waters

• 1.1.Mussels were exposed in the Dutch coastal zone and the Western Scheldt estuary. After six weeks of exposure, trace metals, PCBs and PAHs were measured in the soft tissue.
• 2.2. Tissue concentrations of contaminants are high in the Western Scheldt and intermediate near the Rhine outflow, except for the lower PCB congeners.
• 3.3. Results show that the survival in air is significantly lower at higher tissue concentrations, in particular of the lower PCB congeners.
• 4.4. The clearance rate is reduced at the highest tissue concentrations.

     

Behaviour of selected PCBs,PAHs and γ-HCH in the Scheldt estuary,S.W. Netherlands

The behaviour of some organic micropollutants in the abiotic compartments water, particulate matter and bottom sediments of the Scheldt estuary, S.W. Netherlands, was studied between 1986 and 1989. Special attention was given to two individual PolyChlorinated Biphenyl congeners (PCB 52 and PCB 153), two Polycyclic Aromatic Hydrocarbons (PAHs) fluoranthene and benzo(a)pyrene and γ-HCH. Dissolved PCBs and γ-HCH behave conservatively during estuarine mixing. The concentration of γ-HCH in the fresh-water is extremely high in spring compared to the other seasons. Dissolved fluoranthene does not behave conservatively. The concentration of dissolved fluoranthene in the freshwater endmember shows a seasonal dependence with highest concentrations in winter and lowest in summer. Benzo(a)pyrene could hardly be detected in the dissolved phase with the methods used. PCBs and PAHs in particulate matter and sediments behave essentially conservatively as a result of the mixing of riverine particulates with high, and marine particulates with low organic micropollutant contents. Particulate fluoranthene is removed at low salinities under (nearly) anoxic conditions probably by microbial degradation. The rivers Scheldt and Rupel appear to be the major sources for the compounds studied. However, in particular the organic micropollutant contents of the sediments indicate that important emissions along the estuary were or are still present. Measurements of individual PCBs and PAHs in the <63 μm fraction of a dated sediment core from a salt marsh in the eastern part of the Scheldt estuary show that the recent input of PCBs and PAHs into the estuaryis probably 2–3 times lower than the maximum input in the mid-1960s. The PCB profile shows postdepositional congener-selective mobilization caused by advective transport. The PAH assemblage is remarkably uniform in the sediment core. The PAH ratios indicate that combustion of coal is the main source of PAHs in the Scheldt estuary.     

Reductive dechlorination of low concentration polychlorinated biphenyls as affected by a rhamnolipid biosurfactant

We investigated whether the threshold concentration for polychlorinated biphenyl (PCB) dechlorination may be lower in biosurfactant-amended sediments compared with biosurfactant-free samples. At PCB concentrations of 40, 60, and 120 ppm, the surfactant amendment enhanced the PCB dechlorination rate at all concentrations and the rate was also faster at higher concentrations. On a congener group basis, dechlorination proceeded largely with group A (congeners with low threshold) in both surfactant-free and -amended sediments, accumulating mainly group C (residual products of dechlorination) congeners, and surfactant enhanced the dechlorination rate of group A congeners. Since the PCB threshold concentration for the inoculum in the experiment was lower than 40 ppm, we carried out another experiment using sediments with lower PCB concentrations, 10, 20, and 30 ppm. Sediments with 100 ppm were also performed to measure dechlorination at a PCB saturation concentration. Comparison between the plateaus exhibited that the extent of dechlorination below 40 ppm PCBs was much lower than that at a saturation concentration of 100 ppm. There was no significant difference in the extent of dechlorination between surfactant-free and -amended sediments. Moreover, surfactant did not change the congener specificity or broaden the congener spectrum for dechlorination at PCB concentrations below 40 ppm. Taken together, it seems that at a given PCB concentration, dechlorination characteristics of dechlorinating populations may be determined by not only the congener specificity of the microorganisms but also the affinity of dechlorinating enzyme(s) to individual PCB congeners.     

PCBs in Passaic River Sediments: Some Analytical Considerations

Analytical results for Aroclor may contain a great deal of uncertainty if the relative ratios of certain PCB congeners are substantially altered following differential environmental degradation. Selective degradation of PCB congeners has been shown to occur in biological tissues, and recent studies have shown that Aroclor analyses may significantly underestimate PCB concentrations in fish. The purpose of this study is to assess whether a similar phenomenon can occur with PCB-impacted sediments. Five hundred and thirty-seven sediment samples from the Passaic River were analyzed for Aroclors and selected non-ortho (PCB #77, 126, and 169) and mono-ortho (PCB #105, 114, 118, 123, 156, 157, 167, and 189) coplanar PCB congeners. Aroclors 1248 and 1254 were detected in 67 and 53% of the samples, respectively; 54 samples (approximately 10%) did not contain detectable levels of any Aroclors. In these 54 samples, the sum of the detected PCB congener concentrations was significantly greater, on average, than the Aroclor limit of detection by approximately threefold. In individual samples the sum of the PCB congeners exceeded the Aroclor limit of detection by up to 36-fold. In those samples in which Aroclors were detected, the summed PCB congener concentrations exceeded the Aroclor 1248 and 1254 concentrations, on average, by 41 and 33%, respectively. Given the fact that only a fraction of the 209 PCB congeners were quan-titated, these findings indicate that Arocolor data may significantly underestimate total PCB concentrations in Passaic River sediments. Total PCB data obtained from total homologue analysis indicated that Aroclor results underestimated total PCB mass by up to 43-fold. These findings suggest that caution is required when comparing Aroclor sediment data from the Passaic River to total PCB sediment criteria.     

Congener Level PCB Desorption Kinetics of Field-Contaminated Sediments

The purpose of this research was to study congener level PCB desorption kinetics of field-contaminated sediments and develop a simple methodology to analyze the desorption behavior. Batch desorption kinetic studies were conducted using XAD-4 resin. Two-phase desorption kinetics were observed for most PCB congeners, consisting of an initial fast rate followed by an extended period of slow rate. A dual first-order rate model was fitted to the PCB desorption data to estimate PCB concentrations in the fast and slow desorbing pools. The fast and slow desorption rates were found to decrease with increasing chlorina-tion of PCB congeners, decreasing ortho chlorination, and decreasing temperature. Estimated first-order desorption rate constants for the fast pools were found to be two orders of magnitude higher than those for the corresponding slow pools. The log of first-order rate constants for the different PCB congeners were found to be linearly related to the log of octanol-water partition coefficients. Therefore, desorption rate constants of higher chlorinated PCB congeners, which typically require long-term desorption tests, could be extrapolated using measured rate constants of lower-chlorinated PCB congeners from short-term desorption tests. This finding may provide a process to significantly reduce the duration of experiments required for estimating desorption kinetics.     

Effects of polychlorinated biphenyls on cytochrome P450 induction in the chick embryo hepatocyte culture

The effects of pure synthetic polychlorinated biphenyl (PCB) congeners on the induction of cytochrome P450 and associated activities were examined in cultured chick embryo hepatocytes. Dose-response effects for the induction of total cytochrome P450 ethoxyresorufin-O-deethylase (EROD) activity, and benzphetamine demethylase (BPDM) activity were studied using 10 selected tetra- to hexachlorinated PCB congeners. These studies revealed that PCBs caused effects in the chick hepatocyte culture different from previously observed effects in rat liver. Based on their effects in chick hepatocytes, the PCBs could be categorized into two groups. The first group (consisting of 3,3',4,4'-PCB, 3,3',4,4',5-PCB, 3,3',4,4',5,5'-PCB, 2',3,3',4,5-PCB, 2,3,3',4,4',5'-PCB, and 2,3,4,4',5-PCB) induced total cytochrome P450 2.4- to 2.9-fold and EROD activity from 1-2 pmol/min/mg protein to 162-247. There was marked variation in potency, but all these congeners had a maximal inducing dose above which cytochrome P450 concentrations and EROD activities declined. BPDM activities were increased only slightly (1.2- to 1.6-fold) at the maximal cytochrome P450 inducing dose. The second group of congeners (consisting of 2,2',4,5,5'-PCB. 2,2',4,4',5,5'-PCB, and 2,2',3,4,4',6-PCB) induced total cytochrome P450 concentrations 4.0-fold and BPDM activities 2.2- to 2.6-fold with greatest activity occurring at the highest doses which could be added (10-50 microM). However, EROD activities were also increased by these congeners to 60-112 pmol/min/mg protein with declining activities seen at the highest PCB doses (i.e., resembling EROD induction patterns of the first group). The EROD induction patterns with these latter PCB congeners are noteworthy since these PCBs do not induce EROD activity in the rat. For both groups of PCB congeners, EROD induction was associated with increased accumulation of uroporphyrin in cultures exposed to exogenous 5-aminolevulinate. Studies investigating the reason for the depression of cytochrome P450 concentrations and/or EROD activities by high doses of the PCBs revealed that with the first group there was slightly decreased total protein synthesis, decreased total cell heme concentrations, and decreased accumulation of radiolabeled heme synthesized from 5-[14C]aminolevulinate. These changes might represent nonspecific toxic effects of the first group of PCBs. However, since these changes were not seen with the second group of PCBs, it is unlikely that either inhibition of heme synthesis or toxicity cause the depression of EROD activity with high PCB doses.     

PCB contamination in marine sediments from Golfo Dulce, Pacific coast of Costa Rica

Twenty-nine marine sediment samples collected from 1996 through 2002 from the Golfo Dulce embayment of Costa Rica were analyzed for PCB concentrations. The Esquinas River and Rincon Bay in the northern and western part of the gulf had relatively low overall concentrations of PCBs, with no samples having greater than 2.1 microg/g dw sediment. The Port of Golfito had the highest overall concentrations, ranging up to 15.7 microg/g dw sediment. These samples were also dominated by higher chlorinated congeners. Samples from the deeper (> 100 m) waters in the northern part of the gulf, as well as within the sediment plume from the Rio Coto Colorado had intermediate values. Within the Rio Coto Colorado sediment plume the concentrations did decrease with increasing depth and the congeners showed a shift towards less chlorinated congeners with depth. However, the deep northern basin had some of the highest PCB concentrations and the shift towards less chlorinated congeners was not apparent or significant. Whether the anoxic conditions that exist in the deep waters are capable of initiating dechlorination is still unknown. Overall, the data from Golfo Dulce show moderate PCB contamination, despite the pristine nature of the gulf and surrounding lands.     

Effect of surfactant solubilization on biodegradation of polychlorinated biphenyl congeners by Pseudomonas LB400

A variety of commercial surfactants were tested to determine their effect on polychlorinated biphenyl (PCB) transformation by Pseudomonas LB400. Initial tests determined that most surfactants were fully or partially able to solubilize the PCB congeners 2,5,2′-chlorobiphenyl (CBP), 2,4,2′,4′-CBP, 2,3,5,2′,5′-CBP and 2,4,5,2′,4′,5′-CBP, at concentrations above the surfactants' critical micelle concentration (CMC). Surfactants were also found to have no negative effect on bacterial survival, as cell numbers were the same or higher after incubation in the presence of surfactants than after incubation without surfactants. A comparison of the extent of biotransformation of single PCB congeners by the bacterium revealed that, at surfactant concentrations above the CMC, the presence of an anionic surfactant promoted while nonionic surfactants inhibited PCB transformation, compared to a control with no surfactant. The rates of transformation of PCB congeners were also higher in the presence of the anionic surfactant compared to the control. The inhibitory effects of a nonionic surfactant, Igepal CO-630 at a concentration above its CMC, on transformation of 2,4,5,2′,5′-CBP could be eliminated by diluting the surfactant/PCB solution to a concentration close to the surfactant CMC. Received: 26 October 1998 / Received revision: 5 March 1999 / Accepted: 14 March 1999     

Relationship between Measures of Exposure to PCBs/Dioxins and Behavioral Effects in Recent Developmental Studies

This paper does not reflect official EPA policy. Epidemiological studies on the neurodevelopmental effects of exposure to PCBs initiated in the last decade have had the opportunity to take advantage of modern methodologies for the analysis of congeners of PCBs, dioxins, and related orga-nochlorine compounds. Each of these studies is a longitudinal prospective study, in which women were recruited during pregnancy and the children are being followed for at least several years after birth. The study from which the largest body of data has been published to date is being performed in the Netherlands, in which exposure to PCBs and related compounds is through the general food supply. Mother-infant pairs were recruited in two cities. Half of the infants were bottle-fed and half breast-fed in each city. Four PCB congeners (118, 138, 153, 180) were assessed in maternal and cord plasma, breast milk, and plasma of the child at 3.5 years. TEQ in breast milk was calculated based on PCDDs/PCDFs and dioxin-like PCBs. Various measures of in utero exposure were associated with suboptimal neurological status during infancy, whereas maternal plasma PCB concentration was associated with cognitive deficits (Kaufman scores) at 3.5 years of age. The child's concurrent plasma PCB levels and maternal PCB plasma levels independently predicted performance on various aspects of a vigilance task, and maternal and cord plasma levels predicted impairment of complex play behavior. Poor scores on behavioral ratings were associated with concurrent blood PCB concentrations in the child. A study in Oswego in Lake Ontario fish eaters includes mothers who never ate Great Lakes fish and mothers who consumed greater than 40 PCB-equivalent pounds of Lake Ontario fish over their lifetime. Sixty-eight PCB congeners were measured in cord blood. Suboptimal neurological status during infancy was associated with maternal fish consumption and highly chlorinated cord PCB levels, whereas deficits in short-term memory at 6 months and 1 year of age were associated with total chlorinated cord PCB levels. In a study in Germany of 171 mother-infant pairs, PCB congeners 138, 153, and 180 were measured in cord plasma and milk 2 weeks after birth; both measures are considered markers of in utero exposure. Suboptimal neurological status during infancy, decrements in Bayley scores at 30 months and Kaufman scores at 42 months were associated with PCBs in milk but not cord plasma. These studies, combined with data from previous studies, reveal a consistent relationship between PCB exposure and suboptimal neurological status during infancy, and cognitive deficits associated with in utero exposure. Data from the Dutch study revealed effects on other behavioral domains associated with concurrent (postnatal) exposure. Although it is not possible to identify specific congeners or groups of congeners that may be responsible for the neurotoxic effects observed in these studies, the TEQ approach was not particularly predictive for neurotoxic outcomes.     

Thyroid hormone status of Atlantic croaker exposed to Aroclor 1254 and selected PCB congeners

Atlantic croaker (Micropogonias undulatus) were exposed to the polychlorinated biphenyl (PCB) mixture (Aroclor 1254) or one of three individual congeners (planar PCB 77 or ortho-substituted PCB 47 and PCB 153) in the diet for 30 days to investigate the effects of PCBs on circulating thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Aroclor 1254 (0.2 and 1.0 mg/kg body mass/day) decreased plasma T3 levels consistently, but the effects on T4 levels were inconsistent from year to year. Exposure to PCB 153 (0.1 and 1.0 mg/kg body mass/day) significantly lowered both T4 and T3, while PCB 47 at the same doses had no effect on thyroid hormone levels. The lower doses of PCB 77 (0.004, 0.01 and 0.02 mg/kg body mass/day) had no effect on T4 or T3, whereas the highest dose (0.1 mg/kg body mass/day) increased T4 levels significantly. The results of the present study demonstrate that exposure to PCBs at environmentally realistic concentrations can have profound effects on the thyroid status of Atlantic croaker. The ortho-substituted PCB 153 appears to contribute at least partially to the deleterious effects of Aroclor 1254 on thyroid status, whereas the planar PCB 77 at concentrations present in the mixture is unlikely to alter thyroid hormone levels.     

Input of organochlorine compounds by snow to European high mountain lakes

1.  Persistent organic pollutants (POPs) can be trapped by and accumulate in cold regions. To understand POP accumulation in temperate high mountain lakes, we collected samples of snow from the catchments of several high mountain lakes in Europe.
2.  Organochlorine compounds (OCs) are regularly found in snow collected in European high mountain sites. Polychlorobiphenyls (PCBs) were found in all samples examined. Hexachlorocyclohexanes (HCHs) are also common whereas DDTs and hexachlorobenzene were found less frequently.
3.  Comparison of the concentrations of these pollutants in snow with OC levels in the waters of these lakes or atmospheric deposition during cold periods shows that the snowpack constitutes a significant seasonal PCB reservoir in all catchments and that snow trapping is a major mechanism for the incorporation of HCHs in the lakes situated in the coldest sites, e.g. Gossenköllesee in the Alps.
4.  Correlation of the concentrations of the PCB congeners in snow versus mean annual winter temperature shows higher accumulation at lower temperatures. The less volatile PCBs exhibit higher temperature dependences than the more volatile congeners. This trend differs from altitudinal dependences observed in other sites such as Canada and may be related to the specific range of winter temperature in each area of study.     

Site-specific microbial communities in three PCB-impacted sediments are associated with different in situ dechlorinating activities

Competitive PCR and denaturing HPLC analyses together with an assay detecting potential polychlorinated biphenyl (PCB) dechlorinating activities were combined with physical-chemical site characterizations to identify factors affecting the reductive dechlorination of PCBs in the three historically impacted sediments: Grasse and Buffalo Rivers, NY and Anacostia River, DC. In Grasse River sediment an in situ enriched population of Dehalococcoides phylotypes was abundant in high numbers together with a relatively high dechlorination activity and a high concentration of congeners containing unflanked chlorine substitutions. In contrast microbial communities in Anacostia and Buffalo Rivers sediments consisted of similar total numbers of putative dechlorinating bacteria, but the populations consisted of more diverse putative dechlorinating phylotypes and were associated with lower dechlorination activities and higher concentrations of flanked congeners. Differences observed in the PCB dechlorination activity were not influenced by the chemical PCB availability in spiked sediment or physical sediment characteristics, but were consistent with the concentration of PCBs and total organic carbon in the native sediment. Application of molecular methods for selective detection of indigenous microbial dechlorinating communities combined with assessment of the dechlorinating activity and analysis of the in situ congener profiles provided a comprehensive approach for characterization and identification of sites that are amenable to bioremediation, which is essential for the development of in situ treatment strategies.     

Three Stages of a Biofilm Community Developing at the Liquid-Liquid Interface between Polychlorinated Biphenyls and Water

Soil contaminated with polychlorinated biphenyls (PCB) was used as an inoculum to grow a complex biofilm community on PCB oil (Aroclor 1242) on a substratum (Permanox). The biofilm was monitored for 31 days by confocal laser scanning microscopy, community fingerprinting using single-strand conformational polymorphism (SSCP), amplicons of the 16S rRNA genes, and chemical analyses of the PCB congeners. SSCP analysis of the young biofilm revealed a rather diverse microbial community with species of the genera Herbaspirillum and Bradyrhizobium as dominant members. The biofilm developing on the PCB droplets displayed pronounced stages of PCB degradation and biofilm development not described before from pure-culture experiments. The first step was the colonization of the substratum while the PCB oil was hardly populated. When a certain density of bacteria was reached on the Permanox, the PCB was colonized, but soon the degradation of the congeners was markedly reduced and many cells were damaged, as seen by LIVE/DEAD staining. Finally, the biofilm formed aggregates and invaded the PCB oil, showing lower numbers of damaged cells than before and a dramatic increase in PCB degradation. This sequence of biofilm formation is understood as a maturation process prior to PCB oil colonization. This is followed by a thin biofilm on the PCB droplet, an aggregation process forming pockets in the PCB, and finally an invasion of the biofilm into the PCB oil. Only the mature biofilm showed degradation of pentachlorinated PCB congeners, which may be reductively dechlorinated and the resulting trichlorobiphenyls then aerobically metabolized.     

Polychlorinated biphenyls (pcbs) in fish-eating sea birds—III. Molecular features and metabolic interpretations of PCB isomers and congeners in adipose tissues

1. Enrichment factors have been calculated for several persistent PCB congeners in the adipose tissue for five species of fish-eating sea birds (female razorbills, puffins, guillemots, shags and cormorants) obtained from the same sites during 1978–1984 (see preceding papers).2. The enrichment factor of an individual PCB is expressed as its concentration in the tissue compared with its abundance in commerical mixtures of PCBs or compared with the concentration in the tissue of the abundant congener 2,2',4,4',5,5'-hexachlorobiphenyl (congener 153, IUPAC system of numbering).3. There were no significant differences between the five species in the enrichment factor of individual persistent PCBs compared with congener 153, indicating similar levels of diminished metabolism of this group of congeners.4. Of the 47 individual PCBs identified, ten congeners had enrichment factors of > 1 in all of the species and these accounted for up to 70% of the concentration of total PCBs present. Some of these persistent congeners had approximately coplanar configurations (i.e. non-ortho -substituted congeners). Five congeners, which accounted for about 35% of the total concentration of PCBs in the tissues, shared the molecular feature of chlorine substituents at adjacent meta-para carbon atoms.5. A number of congeners were identified with enrichment factors of <1 compared with their abundance in Aroclor 1260, and very striking differences were observed between the five species in the ratio of non-persistent congeners to the persistent congener 153. These non-persistent congeners share the molecular feature of at least one pair of adjacent unsubstituted meta-para carbon atoms in the rings. This agrees with our molecular “rule” (see preceding papers) that congeners with this structural feature are subjected to metabolism by the cytochrome P-450 component of hepatic microsomal monooxygenases.6. Evidence is presented that this molecular rule applies to the persistence or non-persistence of classes of PCBs in other biological systems and that the complete absence of H atoms at adjacent carbon atoms is an essential structural requirement for the accumulation of PCBs in tissues.7. The persistence or non-persistence of individual PCBs is compared with their ability to induce specific isoforms of the cytochrome P-450 components of hepatic microsomal monooxygenases, and the toxic effects of individual PCBs that accumulate is discussed in terms of the potential environmental hazard that they represent.     

Accumulation and toxicity assessment of polychlorinated biphenyls in black-footed albatross (Diomedea nigripes) from Midway Atoll,North Pacific Ocean

Polychlorinated biphenyls (PCBs) are ubiquitous chemicals that were used as additives in capacitors and transformers; and heavy contamination in the past of Midway Atoll, a national wildlife refuge, puts the wildlife, including the black-footed albatross (BFAL), at risk. In this study, we assess the profiles and toxicity of the individual PCB congeners at a natural equilibrium state in various tissues of 1-month old and 4–5-month old BFAL chicks and black-footed and Laysan albatross eggs found on the atoll. In the 1-month old chicks from Midway Atoll, the major seven congeners PCBs 99, 118, 138, 153, 170, 180 and 183 accounted for 36–78% of the total PCBs in the various body parts, and the total PCB concentrations in the bird samples are inversely related to the total body weights. In the 4–5-month old chicks, these same congeners accounted for much lower percentages (7–26%) than in the 1-month-old chicks, with higher amounts of the less chlorinated congeners. The total toxic equivalents (TEQs) for all of the tissues in the 1-month old chicks ranged from 130 to 11,000 pg g⁻¹ (lipid weight, lw), and the total TEQs for the 4–5-month old chicks ranged from 18,000 to 100,000 pg g⁻¹. The average total concentration was 7.9 and 4.6 μg g⁻¹ lw in the BFAL eggs and Laysan albatross eggs, respectively. The high concentrations could be accounted for by the age and PCB accumulation of the female producing the egg. The average TEQs were 70 and 90 pg g⁻¹ in the Laysan albatross eggs and BFAL eggs, respectively. This PCB concentration and toxicity information can be used to determine the toxicological risk of the BFAL chicks while nesting at Midway Atoll, and the analysis of the albatross eggs is an indication of the contamination of the female albatross at the time of egg formation, with the levels acting as an indicator of the total PCB body burdens that the females are experiencing. The information from this study is indicative of the toxicological risk to the seabirds that nest and feed near Midway and of the overall PCB contamination in the North Pacific Ocean.     

Occurrence of organochlorine contaminants in tissues of the coelacanth Latimeria chalumnae

Synopsis Gas chromatography coupled with electrolytic conductivity detection and electron capture negative chemical ionization mass spectrometry have been used to identify and quantify organochlorine xenobiotics in tissues from two specimens of the living coelacanth Latimeria chalumnae. Compounds identified include polychlorinated biphenyls (PCB), 4,4-DDT and its metabolites 4,4-DDD and 4,4-DDE. Levels of these compounds in the specimens were observed to be generally related to tissue lipid content. Highest concentrations of the xenobiotics were present in the lipid-rich swim bladder, followed by adipose tissue and liver. Levels ranged from 89 to 510 g kg^–1 for PCB and 210 to 840 g kg^–1 for -DDT (including DDD and DDE) on a wet-weight basis. Organochlorine concentrations in relatively lipid-poor tissues, i.e. muscle and kidney, were lower. Parent DDT contributed significantly to the -DDT burden. PCB congeners containing five to seven chlorines were most prevalent. Component distributions did not match those present in common commercial PCB formulations. However, major congeners observed were similar to those reported for other fishes.     

Effects of Age,Adipose Percent,and Reproduction on PCB Concentrations and Profiles in an Extreme Fasting North Pacific Marine Mammal

Persistent organic pollutants, including polychlorinated biphenyls (PCBs), are widely distributed and detectable far from anthropogenic sources. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometers to forage in coastal and open-ocean regions of the northeast Pacific Ocean and then return to land where they fast while breeding and molting. Our study examined potential effects of age, adipose percent, and the difference between the breeding and molting fasts on PCB concentrations and congener profiles in blubber and serum of northern elephant seal females. Between 2005 and 2007, we sampled blubber and blood from 58 seals before and after a foraging trip, which were then analyzed for PCBs. Age did not significantly affect total PCB concentrations; however, the proportion of PCB congeners with different numbers of chlorine atoms was significantly affected by age, especially in the outer blubber. Younger adult females had a significantly greater proportion of low-chlorinated PCBs (tri-, tetra-, and penta-CBs) than older females, with the opposite trend observed for hepta-CBs, indicating that an age-associated process such as parity (birth) may significantly affect congener profiles. The percent of adipose tissue had a significant relationship with inner blubber PCB concentrations, with the highest mean concentrations observed at the end of the molting fast. These results highlight the importance of sampling across the entire blubber layer when assessing contaminant levels in phocid seals and taking into account the adipose stores and reproductive status of an animal when conducting contaminant research.     

Laboratory Estimation of Net Trophic Transfer Efficiencies of PCB Congeners to Lake Trout (Salvelinus namaycush) from Its Prey

A technique for laboratory estimation of net trophic transfer efficiency (γ) of polychlorinated biphenyl (PCB) congeners to piscivorous fish from their prey is described herein. During a 135-day laboratory experiment, we fed bloater (Coregonus hoyi) that had been caught in Lake Michigan to lake trout (Salvelinus namaycush) kept in eight laboratory tanks. Bloater is a natural prey for lake trout. In four of the tanks, a relatively high flow rate was used to ensure relatively high activity by the lake trout, whereas a low flow rate was used in the other four tanks, allowing for low lake trout activity. On a tank-by-tank basis, the amount of food eaten by the lake trout on each day of the experiment was recorded. Each lake trout was weighed at the start and end of the experiment. Four to nine lake trout from each of the eight tanks were sacrificed at the start of the experiment, and all 10 lake trout remaining in each of the tanks were euthanized at the end of the experiment. We determined concentrations of 75 PCB congeners in the lake trout at the start of the experiment, in the lake trout at the end of the experiment, and in bloaters fed to the lake trout during the experiment. Based on these measurements, γ was calculated for each of 75 PCB congeners in each of the eight tanks. Mean γ was calculated for each of the 75 PCB congeners for both active and inactive lake trout. Because the experiment was replicated in eight tanks, the standard error about mean γ could be estimated. Results from this type of experiment are useful in risk assessment models to predict future risk to humans and wildlife eating contaminated fish under various scenarios of environmental contamination.     

The importance of runoff to DDT and PCB inputs to the Sado estuary and Ria Formosa

PCB congeners, DDT and metabolites were determined in suspended sediments and in the oysterCrassostrea angulata from the upper Sado estuary over two years (1987/88 and 1990) and from Ria Formosa during 1990. Levels of DDT concentrations in suspended sediments collected in both estuarine areas, either in 1988 or 1990, increased in winter. Otherwise, PCB concentrations varied in an erratic way. A DDT enrichment was also recorded inC. angulata in winter and an increase of only PCB concentration levels in oysters of the upper Sado estuary was registered at the same period. These results suggest that, in the absence of important direct sources of PCB and DDT, runoff appears to be the major source of those compounds in both the study areas. Levels of concentrations of these pollutants in oysters reflect either their increase in the environment or changes in particle dynamics in the two estuarine areas.     

In vitro chromosome damage due to PCB interactions

In order to study the possible mutagenic properties of polychlorinated biphenyls (PCBs), human lymphocyte cultures were examined for chromosome breakage, rearrangements, sister-chromatid exchange, and mitotic delay. The present study, which used cyclophosphamide as a positive control, shows that one planar PCB congener, 3,4,3',4'-tetrachlorobiphenyl, caused dose-related chromosome breakage in human lymphocytes exposed in vitro to 0.1-10(-4) micrograms/ml. In contrast, the non-planar PCB, 2,5,2',5', did not cause chromosome damage in comparable tests even at concentrations as high as 1 microgram/ml. However, when 3,4,3',4' at a concentration lower than that which causes chromosome breakage (10(-5) micrograms/ml) was combined with a non-clastogenic concentration of 2,5,2',5', the chromosomal damage observed was far in excess of what one would expect from higher doses of 3,4,3',4' alone. These results suggest that some PCB congeners may interact to cause synergistic genotoxic effects.