Developmental toxicity of in ovo exposure to polychlorinated biphenyls: I. Immediate and subsequent effects on first-generation nestling American kestrels (Falco sparverius)

We determined that in ovo exposure to polychlorinated biphenyls (PCBs) alters growth of first-generation nestlings during and one year after parental exposure. Captive American kestrels (Falco sparverius) laid eggs with environmentally relevant total PCB levels (34.1 microg/g whole-egg wet wt) when fed PCB-spiked (Aroclor 1248, 1254, and 1260) food (7 mg/kg body wt/ d) for 100 d in 1998. In 1999, the same adults laid eggs with estimated total PCBs of 29.0 microg/g. Nonsurviving PCB-exposed chicks were small (mass, bones) in 1998. Survivors showed a strong sex-specific growth response (mass, bones) compared to respective sex controls: Only female hatchlings were larger, and only male nestlings had longer feathers (1998); maximal growth and bone growth rates also differed (males were advanced, faster; females delayed, slower) (1999); and male nestlings fledged earlier and were smaller, while females were larger (1998, 1999). However, regardless of sex, PCB-exposed nestlings generally grew at faster rates in both years. In 1998, greater contaminant burdens and toxic equivalent concentrations in sibling eggs were associated with nestlings being lighter, having longer bones and feathers, and growing at faster rates (mass, bone) for females but slower rates (mass) for males. Both physiological-biochemical and behavioral changes are likely mechanisms. This study supports and expands on the Great Lakes embryo mortality, edema, and deformities syndrome: While PCB exposure alters nestling size, maximal growth and growth rates also change immediately, are sustained, and are sex specific.     

Developmental toxicity of in ovo exposure to polychlorinated biphenyls: II. Effects of maternal or paternal exposure on second-generation nestling american kestrels

The development of second-generation nestling American kestrels (Falco sparverius) was altered by in ovo exposure of only one parent to polychlorinated biphenyls (PCBs). Polychlorinated biphenyls appear to alter nestling development through both maternally and paternally mediated effects. In 1998, F0 parent kestrels consumed approximately 5 to 7 microg total PCBs/g bird/d (Aroclors 1248:1254: 1260) for approximately 100 d prior to eggs hatching; these eggs, containing total PCB concentrations of 34.1 microg/g, produced 13 F1 offspring, which were then paired in 1999 with unexposed kestrels to examine developmental effects of maternal or paternal in ovo PCB exposure. Using a toxicokinetics model, eggs from the maternally exposed group had predicted PCB levels of 0.03 to 0.34 microg/g, with enriched higher chlorinated congeners. Polychlorinated biphenyl concentrations in eggs of all generations have recently been found in eggs and nestlings of free-ranging eagles. Consistent with the first generation, maternally exposed F2 females generally were larger, had altered growth rates, and delayed maximal growth and fledging compared with control females. Maternally exposed F2 males were heavier but had shorter bones, grew more quickly and earlier, and fledged 2 d later than control males. In the maternally exposed group, concentrations of plasma triiodothyronine were elevated in F2 females but suppressed in F2 males. Paternally exposed F2 hatchlings of both sexes were comparable in size to controls with the exception of having longer tarsi bones, but subsequently showed slower, delayed growth (both sexes) and fledging (females) and lower thyroxine concentrations (males). The alterations in thyroid hormones in the F2 generation are discussed in light of the enrichment of higher chlorinated PCB congeners and hydroxylated PCB congeners. The developmental changes in the kestrel nestlings are likely a function of several possible mechanisms involving maternal PCB deposition, parental behavior, and neurobehavioral and endocrine-thyroid function in nestlings.     

In ovo exposure to polychlorinated biphenyls: reproductive effects on second-generation American kestrels

The reproductive success of wild birds has been affected by exposure to multiple contaminants. Reproduction of captive American kestrels (Falco sparverius) was suppressed when adult birds were exposed to dietary polychlorinated biphenyls (PCBs). In this study, the reproductive effects of in ovo exposure to PCBs is explored, along with determining effects on reproduction in second-generation birds indirectly exposed to PCBs. Reproductive changes in this subsequent generation are examined separately in male and female birds. Captive American kestrels (F. sparverius) were hatched from clutches with eggs containing environmentally relevant levels of total PCBs (34.0 μg/g whole egg WW versus 0 μg/g controls); parent birds had been fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg BW day⁻¹) for 100 days until their eggs hatched. In 1999, the second-generation PCB birds were paired with unexposed kestrels having reproductive experience. In ovo PCB exposure suppressed egg laying completely in 25% of PCB females and resulted in delays in clutch initiation and smaller clutch sizes for PCB male and female pairs. There was no evidence in this study of in ovo PCB treatment effects on fertility or hatching success. The decline in reproductive success was also reflected in the reduced fledging success and higher incidence of complete brood mortality of PCB nestlings. Differences between in ovo–exposed PCB males and females but not between controls were evident in reproductive success. In ovo PCB exposure appears to have had greater effects on female kestrels until clutch completion, with a greater time lag between pairing and egg laying, reduced numbers of pairs laying eggs, and smaller clutches being laid. In ovo PCB exposure has greater effects later in the breeding season on male kestrels, which had poorer hatching and fledging success relative to the PCB females. Possible behavioral and physiological mechanisms involved in these reproductive changes are discussed. Received: 25 July 2000/Accepted: 8 December 2000     

Reproductive impairment in zebra finches (Taeniopygia guttata)

The effects of polychlorinated biphenyls (PCBs) as compounds that may disrupt endocrine activity and, consequently, alter reproductive performance were investigated in altricial zebra finches (Taeniopygia guttata). The breeding performance and breeding cycle of zebra finches differed significantly between nonexposed birds and those experimentally pulse-exposed to Aroclor 1248, a PCB compound (40 microg/bird). Aroclor-exposed birds showed significantly increased numbers of clutches laid, nests constructed per pair, incubation time per pair, and percentage of hatchling mortality compared to controls. Not all reproductive parameters were affected. Those traditionally regarded as indicators of reproductive capacity (number of eggs laid per clutch, number of eggs laid per pair, hatchlings per clutch, and fledglings per clutch) did not differ statistically between exposed and control birds. Findings support the hypothesis that very low PCB doses may be associated with endocrine disruption. It is suggested that evaluation of reproductive parameters related to parental care is more adequate to assess endocrine disruption than is evaluation of reproductive success parameters. Given its short breeding cycle, altricial breeding behavior, and other advantages not possessed by precocial birds, we propose using the zebra finch for evaluations of chemicals with endocrine-disruptive activity.     

Effects of contaminant exposure on reproductive success of ospreys (Pandion haliaetus) nesting in Delaware River and Bay, USA

Despite serious water-quality problems and pollutant loading and retention, Delaware River and Bay (USA) provide important wildlife habitat. In 2002, we conducted a comprehensive evaluation of contaminant exposure and reproduction of ospreys (Pandion haliaetus) breeding in Delaware River and Bay. Sample eggs were collected from 39 nests and analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), and mercury; a subset of 15 eggs was analyzed for perfluorinated compounds and polybrominated diphenyl ethers (PBDEs). The fate of each nest was monitored weekly. Concentrations of 10 organochlorine pesticides or metabolites, total PCBs, and several toxic PCB congeners were greater (p < 0.05) in eggs collected between the Chesapeake and Delaware Canal (C and D Canal) and Trenton (Delaware River and northern Bay) compared to other sites. Concentrations of p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE; 0.785-3.84 microg/g wet wt) and total PCBs (5.50-14.5 microg/g wet wt) in eggs collected between the C and D Canal and Trenton were similar to levels recently found in the Chesapeake Bay. In all study segments, at least one young fledged from 66 to 75% of nests. Productivity for Delaware Inland Bays (reference area) and southern Delaware Bay was 1.17 and 1.42 fledglings/active nest, respectively; north of the C and D Canal, productivity was 1.00 fledgling/active nest, which is marginally adequate to maintain the population. Using these data, a logistic regression model found that contaminant concentrations (p,p'-DDE, heptachlor epoxide, chlordane and metabolites, and total PCBs) were predictive of hatching success. Several perfluorinated compounds and PBDEs were detected in eggs at concentrations approaching 1 microg/g wet weight. These findings provide evidence that contaminants continue to be a significant stressor on osprey productivity in the northern Delaware River and Bay.     

Courtship Behavior of Captive American Kestrels (Falco sparverius) Exposed to Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) adversely affect reproduction in birds. Captive adult male and female American kestrels (Falco sparverius) were studied to investigate the potential behavioral and hormonal alterations during the courtship period resulting from clinical exposure to PCBs. American kestrels ingested 7 mg/kg/body weight/bird/day of a 1:1:1 mixture of Aroclors 1248, 1254, and 1260 through their diet of day-old cockerels. The dietary dosage of Aroclors resulted in environmentally relevant total PCB residues in the eggs, averaging 34.1 μg/g wet weight (geometric mean). There was no difference between treatment and control birds in the circulating levels of total androgens (p = 0.44) or in 17β-estradiol (p = 0.29), one week following pairing. Male kestrels exposed to dietary PCBs exhibited significantly more sexual behaviors (p = 0.034) and flight behaviors (p = 0.026) than the control males. Sexual behaviors of male kestrels included; nest-box inspections, solicitation of copulation, the offer of food to the female, and giving the female food. The flight behaviors of the male included; flying from one perch to another and aerial display. In addition, the frequency of male sexual behaviors were correlated (r = 0.605, p = 0.001) with total PCB residues in the eggs of their mates. A concurrent study found that these same PCB-exposed kestrels experienced a delay in clutch initiation as well as a greater number of completely infertile clutches. Received: 22 September 2000/Accepted: 19 March 2001     

Influence of contamination by organochlorine pesticides and polychlorinated biphenyls on the breeding of the spanish imperial eagle (Aquila adalberti)

We evaluated temporal and regional trends of organochlorine (OC) pesticide (including polychlorinated biphenyl [PCB]) levels in eggs of the Spanish Imperial Eagle (Aquila adalberti) collected in Spain between 1972 and 2003. Levels of p,p'-dichlorodiphenyldichloroethylene (DDE) and PCBs varied significantly (p = 0.022) among regions (central, western, and Do?ana), being higher in Do?ana than in the central and western populations (DDE: 1.64 +/- 5.56, 0.816 +/- 1.70, and 1.1 +/- 2.66 microg/g, respectively; PCBs: 1.189 +/- 5.0, 0.517 +/- 1.55, and 0.578 +/- 1.75 microg/g, respectively). Levels of DDE decreased with time, but a significant interaction was observed between region and time. In Do?ana, egg volume and breadth as well as Ratcliffe Index were significantly lower after DDT use (p = 0.0018) than during the pre-DDT period (p = 0.0018); eggs were significantly smaller overall than in the other two regions (p = 0.04) and were smaller when DDE levels increased, even when controlling for regional differences (p = 0.04). Productivity in Do?ana was significantly lower than in the other regions (p < 0.001). Clutch size in Do?ana varied according to DDE concentrations (p = 0.01), with the highest DDE concentrations found in clutches consisting of one egg. When considering eggs with DDE levels greater than 3.5 microg/g, a significant effect of DDE on fertility was found (p = 0.03). Clutches with DDE levels greater than 4.0 microg/g had a higher probability of hatching failure (p = 0.07) and produced fewer fledglings (p = 0.03). If we consider 3.5 microg/g as the lowest-observable-adverse-effect level, the proportion of sampled clutches that exceeded that level in Do?ana (29%) was significantly higher than in other regions (p < 0.001). These eggs showed a mean percentage of thinning of 16.72%. Contamination by OCs, mainly DDE, could explain, at least in part, the low productivity of the Spanish Imperial Eagles in Do?ana.     

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.     

Polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents in eggs of red-breasted mergansers near Green Bay,Wisconsin, USA,in 1977–78 and 1990

The hypothesis that the concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEqs) contributed by non-ortho- and mono-ortho-substituted (coplanar) PCB congeners have changed relative to total concentrations of PCBs over time was tested by analyzing eggs of red-breasted mergansers collected from the same locality in 1977–78 and in 1990. Twelve eggs from each time period were analyzed for coplanar PCBs, using a porous graphitic carbon HPLC column and GCECD. TEqs were calculated from coplanar PCB concentrations and bioassay-derived toxic equivalency factors. Median total PCB concentrations decreased from 25 to 13 g/g, fresh weight (fw), and TEqs decreased from 320 pg/g to 160 pg/g, fw. The relative potency of the PCB mixtures, expressed as the ratio of TEqs contributed by the coplanar PCB congeners to total PCBs, did not change, nor did the ratio of concentrations of coplanar congeners to total PCBs. Thus, the relative potency of the mixture of PCBs in the eggs has not changed even as the concentrations declined significantly. The greater relative potency of TEqs relative to that which would be expected from the Aroclor^® mixtures released into the environment is due to selective bioaccumulation, biomagnification, and metabolism, rather than as a result of differential weathering as a function of time.     

Organochlorine Pesticides, PCBs, Dibenzodioxin, and Furan Concentrations in Common Snapping Turtle Eggs (Chelydra serpentina serpentina) in Akwesasne, Mohawk Territory, Ontario, Canada

Subsamples of eight clutches of common snapping turtle eggs (Chelydra serpentina serpentina) were collected from four sites from the territory of the Mohawk Nation, Akwesasne, on the shore of the St. Lawrence River. Egg contents were analyzed for organochlorine pesticides, polychlorinated biphenyls (PCBs), dibenzodioxins, and furans. The sites were 2 to 13 km downstream from PCB-contaminated landfill sites. Maximum concentrations of total PCBs in snapping turtle clutches were extremely high, and ranged from 2 378.2 ng/g to 737 683 ng/g (wet weight) and are among the highest recorded in any tissue of a free-ranging animal. Similarly, in a pooled sample of eggs from all four sites, the summed concentrations of non-ortho PCBs (n = 6 congeners) was also very high at 54.54 ng/g and the summed dioxin and furan concentrations (n = 11 congeners) was 85.8 ng/g. Sum organochlorine pesticide levels varied from 28 to 2,264 ng/g among the four sites. The levels of PCBs found in turtle eggs exceed concentrations associated with developmental problems and reduced hatching success in snapping turtles and other species and also exceed the Canadian tissue residue guidelines for toxic equivalency concentrations. The extremely high levels of organochlorine contaminants demonstrate the high degree of contamination in the environment in the Akwesasne area. Received: 27 March 2000/Accepted: 15 November 2000     

Microcontaminants and reproductive impairment of the Forster's tern on Green Bay,Lake Michigan-1983

For the 1983 nesting season, Forster's tern (Sterna forsteri) reproductive success was significantly impaired on organochlorine contaminated Green Bay, Lake Michigan compared to a relatively uncontaminated inland location at Lake Poygan, Wisconsin. Compared with tern eggs from Lake Poygan, eggs from Green Bay had significantly higher median concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), other polychlorinated dibenzo-p-dioxins (PCDDs), total polychlorinated biphenyls (PCBs), total (three congeners) non-ortho, ortho' PCBs, five individual PCB congeners known to induce aryl hydrocarbon hydroxylase (AHH) and several other organochlorine contaminants. Conversions of analytical concentrations of TCDD and PCB congeners based on relative AHH induction potencies allowed for estimation of total 2,3,7,8-TCDD equivalents. Two PCB congeners, 2,3,3,4,4- and 3,3,4,4,5-pentachlorobiphenyl (PeCB) accounted for more than 90% of the median estimated TCDD equivalents at both Green Bay and Lake Poygan. The median estimated TCDD equivalents were almost 11-fold higher in tern eggs from Green Bay than in eggs from Lake Poygan (2175 and 201 pg/g). The hatching success of Green Bay sibling eggs from nests where eggs were collected for contaminant analyses was 75% lower at Green Bay than at Lake Poygan. Hatchability of eggs taken from other nests and artificially incubated was about 50% lower for Green Bay than for Lake Poygan. Among hatchlings from laboratory incubation, those from Green Bay weighed approximately 20% less and had a mean liver weight to body weight ratio 26% greater than those from Lake Poygan. In both field and laboratory, mean minimum incubation periods were significantly longer for eggs from Green Bay compared to Lake Poygan (8.25 and 4.58 days, respectively). Mean minimum incubation time for Green Bay eggs in the field was 4.37 days longer than in the laboratory. Hatchability was greatly improved when Green Bay eggs were incubated by Lake Poygan adults in an egg-exchange experiment, but was sharply decreased in Lake Poygan eggs incubated in Green Bay nests. Nest abandonment and egg disappearance were substantial at Green Bay but nil at Lake Poygan. Thus, not only factors intrinsic to the egg, but also extrinsic factors (parental attentiveness), impaired reproductive outcome at Green Bay. The epidemiological evidence from this study strongly suggested that contaminants were a causal factor. AHH-active PCB congeners (intrinsic effects) and PCBs in general (extrinsic effects) appeared to be the only contaminants at the concentrations measured in eggs, capable of producing the effects that were observed at Green Bay.     

Worker exposure to polychlorinated biphenyls in elastic polysulphide sealant renovation

Worker exposure to polychlorinated biphenyls (PCBs) in renovation of prefabricated houses was assessed by biological monitoring of 24 PCB congeners including the 10 most abundant PCBs in elastic polysulphide sealants. Serum samples from 22 exposed and 21 non-exposed men were analysed using gas chromatography-mass spectrometry with negative chemical ionization. Total PCB concentration of 24 PCB congeners in workers' serum varied between 0.6 and 17.8 microg/l (mean 3.9 microg/l, median 1.9 microg/l). The Finnish upper reference limit for occupationally non-exposed persons (3 microg/l) was exceeded in the serum samples of 10 workers. Concentrations for non-exposed persons were 0.3-3.0 microg/l (mean 1.7 microg/l, median 1.5 microg/l). The concentration for the sum of the 10 most abundant PCB congeners in elastic polysulphide sealants in serum samples taken in autumn after the renovation season was 2-10 times higher than in samples from the same workers (n=5) taken in the previous spring. The concentrations of PCB congeners PCB 28, 52, 77, 101, 138, 153 and 180 in hygienic samples taken from the breathing zone of the workers were low, ranging from not detected to 3.1 microg/m3. The concentrations of PCB 28 and 52 in sera were positively correlated with the concentrations in air samples taken from the breathing zone of six workers (r=0.70 and 0.80).     

Levels of chlorinated insecticides,total PCBs and PCB congeners in Spanish Gull eggs

Eggs from Herring Gulls, Audouin Gulls and Gull Billed Terns were collected at three different locations in Spain during the breeding season of 1988. Organochlorine pesticides, total polychlorinated biphenyls (PCBs) and seven selected individual chlorobiphenyl congeners were determined in each of the thirty infertile eggs.The levels of DDE and total PCBs in eggs from the Delta Ebro River are greater than those gathered at Chafarinas Island and Cuenca. Among the species investigated, the Gull Billed Tern eggs showed the lowest level followed by the Herring Gull and the Audouin Gull eggs.The levels of the seven congeners of PCBs showed that 138 was the most prominent, followed by, in decreasing order, 153, 180, 170, 101, 151, and 194. Congener 138 constituted 10.5% ± 2.7 (S.D) of the total PCBs concentration, the 153 8.7% ± 4.2, the 180 7.5% ± 1.9, the 170 3.2% ±1.0, the 101 1.9% ± 3.06, the 151 1.1% ± 1.5 and the 194 0.9% ± 0.5.Polychlorinated biphenyl (PCB) residues (48 congeners) from gull eggs gathered at Ebro Delta and Chafarinas Islands were analyzed with SIMCA (Soft Independent Modeling of Class Analogy), a principal components analysis technique. A series of technical Aroclors^® were also analyzed to provide a reference data set for pattern recognition. Environmental PCB residue profiles differed according to the sample's origin. This analysis discriminated between the two regions sampled.     

Applicability of spraints for monitoring organic contaminants in free-ranging otters (Lutra lutra)

In the current study, the use of spraints for monitoring levels of polychlorinated biphenyls (PCBs) in individual otters was experimentally validated. On the basis of a detailed pattern analysis, it is concluded that in the current study, PCB concentrations in spraints that contain relatively high concentrations of nonmetabolizable PCB congeners (PCB 138 and 153 > 42.5% of total PCB concentrations) reflect the internal PCB concentrations of the otter that produced the spraint. In general, however, spraints should be selected that contain relative concentrations of PCB138 and PCB153 > 95th percentile of these congeners in samples from local food items of otters. On the basis of relationships between levels in spraints and internal levels and on earlier reported effect concentrations, a threshold level range of 1.0 to 2.3 microg/g (lipid normalized) in such spraints is proposed. The validated methods to monitor PCBs in otters may be combined with genetic marker techniques that can assess the identity of the otter that produced the spraints. In such a design, it is feasible to monitor PCB levels in individual free-ranging otters in a truly animal friendly way.     

Enantiomeric composition of chiral polychlorinated biphenyl atropisomers in dated sediment cores

Enantiomer fractions (EFs) of seven chiral polychlorinated biphenyls (PCBs) were measured in dated sediment cores of Lake Hartwell (SC, USA) and Lake Ontario (USA) to detect, quantify, and gain insight regarding microbial reductive dechlorination of PCBs in lake sediments with high and low concentrations, respectively. Lake Hartwell sediments had high total PCBs (5-60 microg/g), with significantly nonracemic EFs that generally were consistent with those from previous laboratory microcosm reductive dechlorination experiments using sediments from these sites. Thus, stereoselective reductive dechlorination had occurred in situ, including at total PCB concentrations of less than the threshold of approximately 30 to 80 microg/g suggested as being necessary for reductive dechlorination. Enantiomer fractions of PCBs 91, 95, 132, and 136 in Lake Hartwell cores were significantly correlated both with concentrations of those individual congeners and with total PCB concentration for some sites. This result indicates that enantioselective microbial dechlorination activity increases with higher concentrations within sediments for these congeners. Enantiomer composition reversed with depth for PCBs 91, 132, and 176, suggesting that multiple microbial populations may be present within the same core that are enantioselectively dechlorinating PCBs. Such observations indicate that concentration and time are not the only factors affecting biotransformation, complicating prediction of enantioselectivity. Comparison of EFs with dates suggested biotransformation half-lives of approximately 30 years, which is on the same time scale as sequestration by burial. In contrast, Lake Ontario sediments (maximum total PCBs, 400 ng/g) had racemic or near-racemic amounts of most congeners throughout the core profile, which is consistent with achiral indicators suggesting no microbial biotransformation within Lake Ontario sediments. Thresholds for reductive dechlorination may exist, but they would be at concentrations of less than 30 to 80 microg/g.     

Behavioral variation and its consequences during incubation for American kestrels exposed to polychlorinated biphenyls

We investigated whether polychlorinated biphenyl (PCB) exposure in American kestrels (Falco sparverius) influenced incubation behavior and whether altered behavior could lead to poor reproductive success. Captive kestrels were fed a mixture of PCBs (Aroclors 1248:1254:1260) at an approximate daily dose of 7 mg/kg body weight, 1 month prior to pairing and throughout incubation. Behaviors of 23 control and 23 PCB-exposed pairs were monitored throughout incubation using an electronic balance in the nest box. PCB exposure resulted in longer incubation periods and in altered incubation behaviors. Seven of 14 behavioral variables showed some association with treatment, with sex-specific effects largely biased toward disrupted male behavior. For most behaviors, the treatment effect was explained by the delayed clutch initiation induced by PCBs rather than by a direct physiological impact of the contaminants. PCB-exposed pairs with greater attendance to their eggs and better coordination of incubation duties had improved hatching success.     

Metabolites of polychlorinated biphenyls in human liver and adipose tissue

A method for analysis of hydroxylated metabolites of polychlorinated biphenyls (OH-PCBs) was developed and adopted to the previously described method for determination of PCBs and methylsulfonyl-PCBs (MeSO2-PCBs) in human liver and adipose tissue. The concentrations of OH-PCBs (14 congeners), MeSO2-PCBs (24 congeners), and PCBs (17 congeners) in five paired samples of human liver and adipose tissue are reported. The sum of OH-PCB congeners was higher in liver (7-175 ng/g lipids) than in adipose tissue (0.3-9 ng/g lipids). In both liver and adipose tissue, 2,2',3,4,4',5'-hexachloro-3'-biphenylol (3'-OH-CB138) and 2,2',3,3',4,5'-hexachloro-4'-biphenylol (4'-OH-CB130) were the predominant hydroxylated PCB metabolites. The sum of OH-PCB congeners were of the same order of magnitude as those of methylsulfonyl metabolites of PCB in the same samples, 12 to 358 ng/g lipids and 2 to 9 ng/g lipids in liver and adipose tissue, respectively. The levels of PCBs were similar in liver and adipose tissue, 459 to 2,085 ng/g lipids and 561 to 2,343 ng/g lipids, respectively. The sum of OH-PCBs and the sum of MeSO2-PCBs correlated to the sum of PCBs. The determined PCB metabolites constituted 3 to 26% of total PCB concentration in the liver and 0.3 to 0.8% of total PCBs in the adipose tissue samples.     

The Belgian PCB/dioxin incident: analysis of the food chain contamination and health risk evaluation

The Belgian PCB incident occurred at the end of January 1999 when a mixture of polychlorinated biphenyls (PCBs) contaminated with dioxins was accidentally added to a stock of recycled fat used in the production of animal feeds. Although signs of poultry poisoning were noticed by February, 1999, the source and the extent of the contamination were discovered only in May 1999, when it appeared that more than 2500 farms could have been supplied with contaminated feeds. This resulted in a major food crisis, which rapidly extended to the whole country and could be resolved only by the implementation of a large PCB/dioxin food monitoring program. Screening for PCB contamination was based on the determination of the seven PCB markers. When PCB concentrations exceeded the tolerance levels of 0.1 (milk), 0.2 (poultry, bovine, and pig meat), or 1 (animal feed) microg/g fat, dioxins (17 PCDD/Fs congeners) were also determined. At the end of December 1999, the database contained the results of more than 55,000 PCB and 500 dioxin analyses. The study of PCB levels and profiles in contaminated feeds delivered to poultry or pig farms confirmed that the Belgian PCB incident was due to a single source of PCB oil introduced into the food chain at the end of January 1999. This PCB oil had a congeners pattern closely matched to a mixture of Aroclor 1260/1254 in the proportion 75/25. The total amount of PCBs added to recycled fats was estimated at 50 kg (sum of the seven markers) or approximately 150 kg total PCBs, which corresponds to about 100 liters of PCB oil. This PCB mixture contained about 1g TEQ dioxins (more than 90- contributed by PCDFs) and about 2g TEQ dioxin-like PCBs. The proportions of PCB 52 and 101 congeners were fairly constant in animal feeds, excluding the possibility of secondary contamination due to fat recycling from contaminated animals. The highest concentrations of PCBs and dioxins were found in poultry and especially in the reproduction animals (hens and chicks), which showed the classical manifestations of chick edema disease. The pigs were also affected but to a lesser extent and no sign of intoxication was observed. The study of PCB/dioxin patterns and of the PCB:dioxin ratios revealed major differences in the metabolism of these compounds by farm animals. Whereas the PCBs:dioxins ratio was fairly constant in all poultry products with a mean value similar to that found in contaminated feeds (50,000), in pigs this ratio was both much higher and more variable (values up to 10,000,000), reflecting a faster elimination of dioxins than PCBs in these animals. These metabolic differences also emerged from the PCB and dioxin patterns which were altered much more in pigs than in poultry. Although the most contaminated food products (chicken meat) had PCB and dioxin levels more than 100 times above maximal recommended values, it is unlikely that this incident could have caused adverse effects in the general population of Belgium. A doubling of the PCB and dioxin burden of the young adult population would require the consumption of, respectively, 10 and 20 highly contaminated meals. In view of the very limited proportion of the poultry chain effectively contaminated during the incident (around 2%), such an extreme scenario was quite improbable for the general population except perhaps for farmers consuming their own products. But even in that case, it would have meant going back to the levels in the 1980s or attaining the body burden of subjects regularly eating contaminated seafood.     

Effects of polychlorinated biphenyls on the schooling behavior of Japanese medaka (Oryzias latipes)

The effects of polychlorinated biphenyls (PCBs; Kanechlor 400) on the schooling behavior of Japanese medaka (Oryzias latipes) were tested after feeding with various concentrations of PCBs (0, 1, 5, 25, and 125 microg/g). To test schooling, three PCB-exposed medaka and three untreated fish were placed in one chamber, and their swimming trajectories were recorded. Swimming velocity, turning angle, and nearest-neighbor distance (NND) were analyzed individually, and the polarization and expanse of each schooling group were analyzed. Fractal dimension analysis was performed for trajectory, swimming velocity, and turning angle. Six behaviors (school formed by six swimming medaka, school formed by six stationary medaka, school formed by three to five swimming medaka, school formed by three to five stationary medaka, swimming without schooling, and stationary without schooling) were quantified with time. Behavioral parameters were the same for PCB-exposed and unexposed medaka in the same schooling group. Swimming velocity decreased in a dose-dependent manner, and NND in the group exposed to 25 microg/g of PCBs was significantly longer (126%) than that in the controls. The fractal dimensions of trajectory and turning angle increased significantly in the highest PCB-exposure group, indicating that schools containing PCB-exposed individuals frequently changed direction. The PCBs shortened the time of school formed by six swimming fish, which was 23.7% of the control value in the group exposed to 25 microg/g of PCBs. The frequency of collisions between individuals was significantly greater in the highest-exposure group (31.3) than in the controls (13.3). Thus, PCB exposure influences the behavior of unexposed fish in the same school, consequently affecting schooling behavior.     

PCB Levels and Accumulation Patterns in Waterbird Eggs and in Their Prey at Lake Kerkini,a North-Eastern Mediterranean Wetland of International Importance

Seven “target” PCB levels were determined and compared in waterbird eggs, in their prey, and in water at Lake Kerkini, northern Greece, to investigate PCB bioaccumulation patterns and to define the best bioindicator of target PCBs for this area. PCBs were analysed from eggs of Phalacrocorax carbo, Podiceps cristatus, Ardea cinerea, Egretta garzetta, and Nycticorax nycticorax and from prey types Alburnus alburnus, Rutilus rutilus, Lepomis gibbosus. Carassius auratus, and Rana sp. PCBs analysed were detected in all bird eggs, prey, and water but contamination patterns differed among these sample types. The lipid-corrected geometric means of the congeners analysed were significantly different among most bird species and among some prey species. PCB congeners 118, 138, 153, and 180 accounted for around 80% of the total PCB contamination in bird egg samples. Percent congener concentrations of high-chlorinated PCBs tended to increase from water through prey to most bird egg samples whereas the low chlorinated PCBs (28 and 52) decreased. Bioaccumulation factors (BAFs) also exhibited an increasing trend for higher chlorinated PCBs from prey types to bird eggs. The greatest BAFs of six of the congeners were shared between Phalacrocorax carbo and Ardea cinerea. Among prey, the BAFs of four PCBs were highest in Lepomis gibbosus. Biomagnification factors varied between 1.01 and 39.57. In contrast to low chlorinated PCBs, high chlorinated congeners biomagnified considerably through fish prey. The highest biomagnification took place in Phalacrocorax carbo. No relationship was found between the lipid content of samples and BAFs of PCBs probably due to biotransformation differences of the congeners in the biota sampled. Due to the greatest PCB concentrations especially of the higher chlorinated PCBs in the eggs of Phalacrocorax carbo and its considerable bioaccumulation tendencies, it is proposed as the best PCB biomonitor of target PCBs at Lake Kerkini. Lepomis gibbosus had the highest concentrations of most congeners and exhibited the greatest bioaccumulative properties among prey and can be used as an alternative biomonitor.