Polychlorinated biphenyl congeners in sediments,plankton, molluscs,crustaceans, and eel in a freshwater lake: Implications of using reference chemicals and indicator organisms in bioaccumulation studies

The concentrations of six polychlorobiphenyl (PCB) congeners in sediments and four classes of biotic species of the aquatic food chain were investigated in a freshwater lake near Amsterdam. Despite the low concentrations of the contaminants in the sediment, significant amounts of PCBs were found in plankton, macro-invertebrates and fish. The composition of the PCB mixtures found in the various organisms cannot be explained in terms of simple partitioning of the PCB congeners between sediment, water, and organisms. In addition to bioconcentration, it is likely that biomagnification via consumption of contaminated food also contributed significantly to the total PCB concentrations. This is most pronounced for the higher trophic food-chain organisms. Studying bioaccumulation processes by monitoring just one type of organism is probably not very suitable, due to the pronounced differences in accumulation patterns demonstrated for the different organisms. In addition, significant differences were found in the accumulation of the six PCBs in the various biotic samples. This indicates that the fate of mixtures of PCBs is determined by the fate of the individual congeners and therefore cannot be monitored in terms of total PCBs concentrations.     

Toxic effects of polychlorinated biphenyl bioaccumulation in sea urchins exposed to contaminated sediments

The uptake patterns and toxicity of polychlorinated biphenyl (PCB) congeners in the white sea urchin, Lytechinus pictus, on exposure to contaminated sediments were investigated. First-order modeling of uptake of the 10 most abundant PCB congeners or domains (containing more than one coeluting congener) by L. pictus indicated that a 35-d exposure was insufficient to reach steady state. Bioaccumulation of PCBs in sea urchins exhibited substantial difference between field and amended sediments, suggesting that caution must be exercised in sample preparation. Some evidence was observed of dependence of measured biota-sediment accumulation factors (BSAFs) on K(ow), indicating that equilibrium partitioning of PCBs may not always be achieved between biota lipid, sediment organic carbon, and water. Survival of L. pictus was unaffected by exposure to field and amended sediments with PCB concentrations varying more than three orders of magnitude. The growth measures (diameter, wt, and gonad wt) were significantly reduced in L. pictus exposed to San Diego Bay ([SDB]; San Diego, CA, USA) sediment, whereas they were relatively unaffected after exposure to amended sediments (with much higher PCB concentrations than SDB sediment) prepared from a New Bedford Harbor (MA, USA) sediment. The toxic effects as measured by the growth rates in L. pictus were likely attributable to polycyclic aromatic hydrocarbons (PAHs), which were elevated in SDB sediment (7.3 microg/g), rather than PCBs.     

Population genetic structure of a nonmigratory estuarine fish (Fundulus heteroclitus) across a strong gradient of polychlorinated biphenyl contamination

Populations of the estuarine fish Fundulus heteroclitus indigenous to contaminated sites exhibit heritable resistance to some of the toxic effects of early life-stage exposure to polychlorinated biphenyls (PCBs). This evolved tolerance provides evidence of strong selection by PCBs, and it suggests other potential genetic effects of these stressors on resident populations. Environmental contaminants have the potential to affect the genetic structure of populations and to reduce genetic diversity, but species life-history traits, particularly patterns of migration and dispersal, also influence the distribution of genetic variation among populations. Therefore, the present was conducted to determine whether genetic diversity or genetic structure is altered in populations of F. heteroclitus indigenous to 18 sites in Massachusetts (USA) and Rhode Island (USA), representing a steep gradient of sediment PCB contamination and culminating in a Superfund site at New Bedford Harbor (NBH; MA, USA). Allele frequencies at enzymatic loci were used to assess genetic structure and diversity. Selection experiments using a highly toxic PCB congener (3,3',4,4',5-pentachlorobiphenyl) were conducted to determine if genetic patterns at field sites could be associated with contaminant exposures. Although allele frequencies clearly reflected a pattern of isolation by distance, the results indicated neither significant loss of genetic diversity nor alteration of allele frequencies for populations of F. heteroclitus in NBH.     

Adult tree swallow (Tachycineta bicolor) survival on the polychlorinated biphenyl-contaminated Housatonic River, Massachusetts, USA

Tree swallows (Tachycineta bicolor) were captured and banded at six sites that differed in polychlorinated biphenyl (PCB) contamination levels in the Housatonic River watershed, western Massachusetts, USA, from 2000 through 2004 to test the prediction that apparent survival rates of females in more contaminated areas were lower than those from less contaminated areas. We also tested whether plumage coloration affected over-winter survival and whether concentrations of PCBs in eggs differed between birds that did and that did not return the following year. Apparent survival rates were calculated using mark-recapture methods and compared using Akaike's Information Criterion. Model-adjusted survival rates ranged from 0.365 to 0.467 for PCB-contaminated females and between 0.404 and 0.476 for reference females. Models with either survival or capture probability modeled as functions of treatment (degree of PCB contamination), year, and age received some support. The model-averaged parameter estimate reflecting a treatment effect for high-PCB birds was negative (beta = -0.046, SE(beta) = 0.0939). Fifty-four percent of the total model weights involved models in which survival was a function of PCB treatment. Eggs were collected for contaminant analyses from a random sample of females that did and that did not return the following year. Concentrations of total PCBs were the same or higher in the eggs of females that returned compared to the eggs of those that did not return at both the highly and the moderately contaminated PCB sites. This may have resulted from higher-quality females with higher lipid reserves being more likely than lower-quality females to return the following year. Percentage lipid was positively correlated with total PCBs in eggs. Survival rates were similar among swallows with brown versus blue plumage.     

Accumulation of polychlorinated biphenyls from floodplain soils by passerine birds

Eggs, nestlings, and adults of the eastern bluebird (Sialia sialis) and house wren (Troglodytes aedon) were collected at a polychlorinated biphenyl (PCB)-contaminated site and a reference location on the Kalamazoo River (MI, USA). Eggs and nestlings of eastern bluebirds at the more contaminated location contained concentrations of 8.3 and 1.3 mg/kg, respectively, of total PCBs and 77 and 6.3 ng/kg, respectively, of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQs). Eggs, nestlings, and adults of house wrens from the contaminated location contained 6.3, 0.77, and 3.2 mg/kg, respectively, of PCBs and 400, 63, and 110 ng/kg, respectively, of TEQs. Concentrations of total PCBs and TEQs in tissues at the more contaminated location were significantly greater than concentrations in tissues at the reference site for all tissue types of both species. Exposures of the two species studied were different, which suggests that terrestrial-based insectivorous passerine species, foraging in the same area, may have differential exposure to PCBs depending on specific foraging techniques and the insect orders that are targeted. Despite the greater accumulation of PCBs at the more contaminated location, the risk of exposure to PCBs did not exceed the threshold for adverse effects at either location.     

Contaminant profiles in Southeast Asian immigrants consuming fish from polluted waters in northeastern Wisconsin

Recent immigrants to the USA from Southeast Asia may be at higher risk of exposure to fish-borne contaminants including polychlorinated biphenyls (PCBs), p, p′-dichlorodiphenyldichloroethene (DDE) and methylmercury (MeHg) because of their propensity to engage in subsistence fishing.Exposure to contaminants was assessed in men and women of Hmong descent living in Green Bay, Wisconsin, where the Fox River and lower Green Bay are contaminated with PCBs, and to a lesser extent with mercury. Serum samples from 142 people were analyzed for PCBs and p,p′-DDE by capillary column gas chromatography with electron capture detection (ECD). Whole blood was analyzed for total mercury by cold vapor atomic absorption spectrometry and atomic fluorescence spectroscopy. Lipid-adjusted total PCB concentrations ranged from 8.7 to 3,091 ng/g (full range of the data), with a geometric mean of 183.6 ng/g (estimated after eliminating one outlier). DDE ranged from 0.3 to 7,083 (full range of the data) with a geometric mean of 449.8 ng/g (estimated after eliminating two outliers). Men had higher PCB and DDE concentrations than women. Serum PCB concentrations were significantly correlated with fish consumption (r=0.43, p<0.0001), whereas DDE concentrations were not (r=0.09,p=0.29). Instead, serum DDE was strongly associated with the number of years spent in a Thai refugee camp before immigrating to the USA (r=0.60;p<0.0001). PCB congeners 138, 153, 118 and 180 accounted for a smaller percentage of the total PCBs than has been reported in other fish-eating populations, and several lightly chlorinated congeners were present in relatively large amounts. Mercury exposure was low in this population. In conclusion, Hmong immigrants in northeastern Wisconsin are at risk of elevated PCB exposure from consumption of locally caught fish. The pattern of exposure is somewhat different than patterns in other fish-eating populations, possibly due to use of Aroclor 1242 by the paper industry in this region.     

Corticosterone stress response in tree swallows nesting near polychlorinated biphenyl- and dioxin-contaminated rivers

We assayed baseline and stress-induced corticosterone concentrations from adult female and nestling tree swallows, Tachycineta bicolor, from New England, U.S.A., sites with different levels of contamination with polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Corticosterone was compared over 2 years from a highly contaminated PCB site along the Housatonic River (Berkshire County, MA, USA), a midrange contaminated site upstream, and a reference site. Adult females (n=29), sampled only in 2003, showed an inverted-U association with PCBs, with higher stress-induced corticosterone with midrange contamination than at the high-contamination site. In nestlings, stress-induced corticosterone was highest for the highly contaminated site compared with the other sites in 2003 (n=53, 29 nests), with no difference among sites in 2004 (n=93, 27 nests). In 2004, we began testing mechanisms underlying these changes in nestlings at the high- and low-PCB sites. Corticosterone response to dexamethasone injection (used to test negative feedback) was not different between sites, but stress-induced corticosterone was reduced at the contaminated site after adrenocorticotropin hormone injection (used to test adrenal responsiveness), suggesting an inhibited ability to mount a stress response. We also compared nestlings from a stretch of the Woonasquatucket River, Rhode Island, U.S.A., heavily contaminated with TCDD (n=80, 43 nests) with nestlings from an upstream site that had lower levels of TCDD and the Berkshire County reference site. Although there were no stress-induced differences, baseline corticosterone was lower at the higher TCDD site than at the reference site. Altogether these findings suggest that tree swallows chronically exposed to high PCB and TCDD levels exhibit altered baseline and stress-induced corticosterone responses, but the patterns of alteration might not be predictable.     

Tree swallow (Tachycineta bicolor) exposure to polychlorinated biphenyls at the Kalamazoo River superfund site, Michigan, USA

In 1990, a portion of the Kalamazoo River in Michigan, USA, was designated a Superfund site because of the presence of polychlorinated biphenyls (PCBs) in the sediment and floodplain soils. During a four-year period from 2000 to 2003, several avian species were monitored for reproductive effects and concentrations of PCBs in tissues attributed to food chain transfer from contaminated sediments. The tree swallow (Tachycineta bicolor) was chosen as a model receptor for contamination of passerine species. A top-down methodology was used to evaluate the bioaccumulation of PCBs, including non-ortho and mono-ortho congeners, in tree swallow eggs, nestlings, and adults at the Kalamazoo River area of concern (KRAOC) and at an upstream reference site. Generally, a sixfold difference in tissue concentrations of total PCBs was observed between the two sites with concentrations in eggs and nestlings at the KRAOC ranging from 0.95 to 15 microg PCB/g wet weight. Concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEQsWHO Avian) for PCBs, based on bird-specific World Health Organization toxic equivalence factors, were 10- to 30-fold greater in the KRAOC than at the reference location. Egg and nestling TEQsWHO-Avian ranged from 0.21 to 2.4 ng TEQ/g wet weight at the KRAOC. Hazard quotients calculated from literature-derived toxicity reference values were below 1.0 at both the target and the reference site based on the no-observed-adverse-effect level and the lowest-observed-adverse-effect level.     

Exposure and effects of chemical contaminants on tree swallows nesting along the Housatonic River,Berkshire County,Massachusetts, USA, 1998-2000

Hatching success of tree swallows (Tachycineta bicolor) was assessed for three years in relation to chemical contamination along the Housatonic River, Berkshire County (MA, USA), in 1998, 1999, and 2000. Nest boxes were erected at five sites along the Housatonic River and its tributaries and at one reference location. Concentrations of total polychlorinated biphenyls (PCBs) were some of the highest ever reported in bird eggs. Mean concentrations at sites along the Housatonic River ranged between 32 and 101 microg/g wet weight. A significant negative relationship was observed between concentrations of total PCBs in clutches and hatching success. A significant negative relationship was also observed between hatching success and the sum of the total dioxins and furans and the associated toxic equivalents (TEQs) for dioxins and furans. In a combined model with PCB TEQs and dioxin/furan TEQs, PCB TEQs were not significantly correlated to hatching success, whereas dioxin/furan TEQs were. Contamination of tree swallows was from local food sources. Accumulation rates of total PCBs in 12-d-old nestlings averaged between 34 and 76 microg/d at the sites along the main stem of the Housatonic River compared to <1 microg/d at the reference location.     

Resuspension of polychlorinated biphenyl-contaminated field sediment: release to the water column and determination of site-specific K DOC

Sediments from the New Bedford Harbor (NBH) U.S. Environmental Protection Agency (U.S. EPA) Superfund site (Massachusetts, USA), contaminated with polychlorinated biphenyls (PCBs), were resuspended under different water column redox conditions: untreated, oxidative, and reductive. The partitioning of PCBs to the overlying water column was measured with polyethylene samplers and compared to partitioning without resuspension. Greater concentrations of total aqueous (freely dissolved + dissolved organic carbon (DOC)-associated) PCBs were found in all resuspended treatments for PCBs with mid-range K(OW)s, but no difference was observed in total aqueous concentrations among different redox conditions. The magnitude of increased concentrations depended on resuspension time and congener K(OW), but ranged from approximately one to eight times those found without resuspension. In a parallel study, DOC was flocculated and removed from smaller-scale NBH sediment resuspensions. In situ K(DOC)s were determined and used to calculate freely dissolved and DOC-associated fractions of the increase in total aqueous PCB concentrations due to resuspension. The importance of DOC-associated PCBs increased with increasing K(OW). In situ K(DOC)s were approximately one to two orders of magnitude greater than those calculated with a commonly used linear free energy relationship (LFER). The present study demonstrates that resuspension of contaminated sediments releases PCBs to the water column, of which a significant fraction are DOC-associated (e.g., 28, 65, and 90% for PCBs 28, 66, and 110, respectively). Results also imply that site-specific PCB K(DOC)s are superior to those calculated with generic LFERs.     

Demography of short-tailed shrew populations living on polychlorinated biphenyl-contaminated sites

In ecological risk assessment, a key necessity is to understand how contaminants known to have negative impact on laboratory mammals affect the population demography of mammals living in their natural environment. We examined the demography of six local populations of the short-tailed shrew (Blarina brevicauda) living in eastern deciduous forest palustrine habitat along the Housatonic River (MA, USA) on soils contaminated with a range of polychlorinated biphenyl (PCB) concentrations (1.5-38.3 ppm). The objective of the study was to assess whether PCBs adversely affect the population demography of these small mammals living in their natural environment. Blarina were selected for study because they would be expected to readily bioaccumulate PCBs from the soil. Populations were intensively live trapped on 1-ha grids from spring to autumn 2001. There was no relationship between any demographic parameter and PCB soil concentrations. Densities were high (usually exceeding 20/ha, and on two grids exceeded 60/ha in summer); survival was good (typically 60-75% per 30 d); and sex ratio, reproduction rates, growth rates, and body mass were within the ranges reported in the literature. Thus, these shrew populations showed no detectable impact on their population demography from living on PCB-contaminated sites.     

Environmental exposure to polychlorinated biphenyls among raccoons (Procyon lotor) at the paducah gaseous diffusion plant,Western Kentucky,USA

An investigation involving raccoons (Procyon lotor) as a sentinel species at the Paducah Gaseous Diffusion Plant (PGDP) in Western Kentucky (USA) delineated the extent of exposure to polychlorinated biphenyls (PCBs) and PCB spatial distribution. Raccoon exposure to PCBs was demonstrated through analysis of subcutaneous fat, abdominal fat, liver, and brain tissues from raccoons collected at the PGDP but also was clearly evident in raccoons from a reference area situated along the Ohio River (USA). Raccoons with the highest tissue PCB concentrations appeared to be those inhabiting areas nearest the plant itself and most likely those that ventured into the plants interior. Male raccoons at the PGDP had similar concentrations of total PCBs in subcutaneous fat (1.86 +/- 0.64 microg/g) as males from the reference site (1.41 +/- 0.35 microg/g), but females had higher PCB body burdens than those at the reference site (9.90 +/- 6.13 microg/g vs 0.75 +/- 0.40 microg/g). Gross measurements of exposure to radiation-producing materials revealed that counts per minute exceeded background in 61% of PGDP raccoons compared with 27% at the reference site and five raccoons at the PGDP had beta counts that were more than twice the background. Differences among trapping success, growth rates, and serum chemistry parameters were noted but may have been related to habitat and other environmental and population density factors.     

Accumulation and maternal transfer of polychlorinated biphenyls in snapping turtles of the upper Hudson River, New York, USA

We conducted field studies over three years to assess body burdens and maternal transfer of polychlorinated biphenyls (PCBs) as well as indices of sexual dimorphism in snapping turtles (Chelydra serpentina) of the upper Hudson River (NY, USA.) We collected adult turtles in areas known to be contaminated with PCBs and in nearby reference areas for measurement of body size, precloacal length, and penis size. We analyzed PCB concentrations in eggs collected over three years and in whole blood from adults in one year. Total PCB concentrations (mean +/- standard error) in eggs were 2,800 +/- 520 and 59 +/- 5 ng/g wet weight in the contaminated area and the reference area, respectively. Eggs from the contaminated area were significantly enriched in tri-, penta-, and hepta-PCBs relative to the reference area. Blood from adults in the contaminated area averaged 475 +/- 200 and 125 +/- 34 ng/g wet weight for males and females, respectively. In the reference area, blood PCB concentrations were 7 +/- 3 and 4 +/- 1 ng/g wet weight for males and females, respectively. Significant positive relationships were found between carapace length and blood PCB concentration for both sexes in the contaminated area; however, only a marginal relationship was found between female carapace length and concentration of PCBs in their eggs. Our results suggest that PCB contamination of the upper Hudson River presents risks of establishing high body burdens and of maternal transfer of PCBs to eggs, although our measures of gross morphology revealed no discernable expression of abnormal sexual development or reproduction.     

PCB Congener Accumulation by Periphyton, Herbivores, and Omnivores

The concentrations of 20 polychlorinated biphenyl (PCB) congeners were measured in periphyton, herbivorous fish (stoneroller minnows, Campostoma anomalum), and omnivorous fish (striped shiners, Luxilus chrysocephalus) in an industrially contaminated stream and a reference stream in eastern Tennessee. The sum of the concentrations of the 20 congeners, normalized by dry mass, was one to two orders of magnitude higher in stonerollers and shiners than in periphyton. Normalizing PCB concentrations by lipid mass reduced concentration differences between periphyton and stonerollers, but PCBs per unit lipid in stonerollers were still 50–350% higher than those in periphyton. Shiners had significantly higher lipid-specific PCB concentrations than did stonerollers, so a trophic hierarchy of primary producer < herbivore < omnivore was evident in lipid-specific PCB concentrations. Differences in lipid type, exposure duration, and exposure sources may account for the trophic-level differences in total PCBs. Congener profiles were roughly similar in periphyton, stonerollers, and shiners: five congeners (IUPAC numbers 101, 110, 138, 153, and 180) constituted >60% of the total mass of PCBs analyzed in all three trophic levels. However, stoneroller and shiner tissue was enriched in congeners 153, 118, and 187 relative to periphyton; congeners 153 and 187 are resistant to metabolic breakdown by monooxygenases found in fish liver. Principal component analysis of congener percentages separated periphyton from fish and distinguished between sampling locations. Received: 16 August 1996/Revised: 3 November 1996     

Population genetic structure and tolerance to dioxin-like compounds of a migratory marine fish (Menidia menidia) at polychlorinated biphenyl-contaminated and reference sites

The present study was conducted to evaluate evidence of genetic adaptation to local contaminants in populations of the migratory marine fish Menidia menidia residing seasonally in reference sites or an industrial harbor contaminated with dioxin-like compounds (DLCs). For this purpose, we compared DLC sensitivity and genetic patterns of populations sampled from sites both inside and outside New Bedford Harbor (NBH; MA, USA), a U.S. Environmental Protection Agency Superfund site with extreme polychlorinated biphenyl (PCB) contamination. Offspring of M. menidia collected from NBH were significantly less sensitive regarding embryonic exposure to the dioxin-like PCB congener 3,3',4,4',5-pentachlorobiphenyl (PCB 126) than offspring of M. menidia from a reference site. Analysis of 10 polymorphic enzymatic loci indicated little genetic differentiation among populations in the study area. However, genotype frequencies of juveniles from both NBH and an adjacent site in Massachusetts exhibited significant deviations from Hardy-Weinberg equilibrium expectations at one locus, phosphoglucomutase (PGM*). Genetic analysis of survivors of embryonic laboratory exposure to PCB 126 indicated that genotypes at PGM* were related to survivorship. Although a relationship was identified between DLC tolerance and PGM* genotype, regional mixing of M. menidia populations during migration and absence of multigeneration exposure at contaminated sites may limit localized adaptation.     

Predicting the occurrence of genetic adaptation to dioxinlike compounds in populations of the estuarine fish Fundulus heteroclitus

A population of the nonmigratory estuarine fish species Fundulus heteroclitus (mummichog) indigenous to a polychlorinated biphenyl (PCB)-contaminated Superfund site (New Bedford Harbor, MA, USA) demonstrated an inherited tolerance to local, dioxinlike contaminants (DLCs). These findings suggest that DLCs have acted as selective agents, allowing the survival of only the most tolerant individuals, forming DLC-adapted populations. We hypothesized that DLC-tolerant mummichog populations would reside where local conditions are toxic to sensitive individuals, and that toxic environmental conditions could be predicted based on responses of sensitive early life stages to laboratory exposures of DLCs. As a measure of DLC tolerance, progeny of field-collected fish were tested in the laboratory with a dioxinlike PCB congener, 3,3',4,4',5-pentachlorobiphenyl (PCB 126). Mummichog populations were collected from sites with sediment PCB concentrations predicted to range from nontoxic to toxic. Consistent with predictions, tolerant populations were indigenous to sites with elevated sediment PCB concentrations. Also, as predicted, DLC-tolerant populations were resident to sites far less contaminated than the Superfund site. These results suggest that exposures to persistent, bioaccumulative, and toxic contaminants may produce evolutionary effects on a geographic scale larger than previously envisioned. This study presents an approach and describes a model system that may improve understanding of the scale of occurrence for these potentially irreversible ecological effects.     

Associations Between Female Reproductive Traits and Polychlorinated Biphenyl Sediment Concentrations in Wild Populations of Brown Bullhead (Ameiurus nebulosus)

Aquatic contaminants, specifically polychlorinated biphenyls (PCBs), a class of persistent organic contaminants, have been associated with sublethal effects on reproduction in fishes. Female brown bullhead (Ameiurus nebulosus) were used to assess variation in reproductive traits across eight populations differing in sediment sum PCB concentrations in the Lower Great Lakes region. Differences in maternal carotenoid allocation patterns among these populations were also examined. No significant associations were found between sediment sum PCB concentrations corrected for organic content (OC) and reproductive traits. However, egg diameter was negatively correlated with sediment PCB concentrations not corrected for OC, suggesting that observed relationships between sediment sum PCB concentrations and reproductive traits are driven by classes of environmental contaminants whose bioavailability are not predicted by OC, such as metals. An unexpected positive relationship was also found between egg carotenoid concentrations and sediment PCB concentrations. This positive relationship was explained by the maternal allocation of carotenoids based on a negative correlation between female muscle and egg carotenoid concentrations, where females from less contaminated locations had lower egg and greater muscle carotenoid concentrations than those from more contaminated locations. The results of this study identify sublethal effects of environmental contaminants on reproductive life-history traits in female brown bullhead, and investigations of adaptive mechanisms underlying this variation are warranted.     

Preferential biomagnification of aryl hydrocarbon hydroxylase-inducing polychlorinated biphenyl congeners in the Lake Michigan, USA, lower food web

Preferential biomagnification of 14 dioxin-like polychlorinated biphenyls (PCBs) was determined in lower-trophic-level organisms of the Lake Michigan, USA, food web. Bioaccumulation of these coplanar, aryl hydrocarbon hydroxylase (AHH)-inducing PCB congeners and total PCBs in phytoplankton, zooplankton, Mysis relicta, and Diporeia sp. were studied for two locations in Lake Michigan over time. The results indicate that both total PCB and AHH-inducing PCBs biomagnify with increasing food web trophic level, with biomagnification of the AHH-inducing PCBs occurring to a greater degree. The biomagnification factors (BMFs) of the AHH-inducing PCBs suggest that they are highly conserved relative to other PCB congeners. The concentrations expressed as dioxin toxic equivalencies (TEQ concentrations) indicate that the biomagnification of AHH PCBs causes greater concentrations, and thus greater toxicity risk, with increasing trophic level.     

Studies of transformer repair workers exposed to PCBs: I. Study design, PCB concentrations, questionnaire, and clinical examination results

A cross-sectional study compared 55 transformer repairmen, 38 currently, and 17 previously exposed to polychlorinated biphenyls (PCBs) with 56 non-exposed subjects. PCBs exposures occurred from air and contaminated surfaces, predominantly from Aroclor 1260 with some exposure to Aroclor 1242. Each worker underwent: a questionnaire; standardized medical examination; delayed hypersensitivity testing; and determination of serum and adipose tissue lipid total PCB concentrations. Adipose and serum [PCBs] were significantly higher in the currently exposed, but previously exposed workers did not differ significantly from comparison subjects. No subjects had a classical syndrome of PCB poisoning. A number of neurobehavioral and irritant symptoms were significantly more prevalent in the exposed group, but were probably not related to PCBs. Comedones were more frequent in the exposed group, but no evidence of classical chloracne was noted. Cutaneous delayed hypersensitivity responses to mumps and to trichophyton antigens did not differ between the groups. The association of PCBs with job functions were explored.     

Selective retention of polychlorinated biphenyl components in the mussel,Mytilus edulis

The retention properties of PCBs (polychlorinated biphenyls) were examined in the mussel (Mytilus edulis) over a period of 89 days. Mussels were transferred from a site of relatively high PCB contamination to a site of relatively low PCB concentration in Puget Sound, Washington. Retention of PCB components increased with increasing chlorine content. Concentrations of PCB decayed logarithmically with calculated half-lives ranging from 3 days for a PCB component with two and three chlorines to 50 days for a PCB component with six and seven chlorines. Components chosen to best represent the commercial PCB mixtures, Aroclor^® 1242, 1254, and 1260, were estimated to have half-lives of 8, 23, and 39 days, respectively. The selective retention of the higher chlorinated biphenyls appear to be the result of lower water solubility of these components.