Potentially hazardous residues of non-ortho chlorine substituted coplanar PCBs in human adipose tissue

The non-ortho chlorine substituted coplanar polychlorinated biphenyls (PCBs), namely, 3,3',4,4'-tetra-(T4CB), 3,3'4,4',5-penta-(P5CB), and 3,3',4,4',5,5', hexachlorobiphenyl (H6CB) are found to be the most toxic congeners of PCBs eliciting toxic and biological responses typical of 2,3,7,8-tetrachloro dibenzo-p-dioxin (T4CDD). Analyses of human adipose tissues for these congeners revealed 94-860 pg/g of T4CB, 120-730 pg/g of P5CB, and 36-200 pg/g of H6CB on wet weight basis. These were significantly higher than 2,3,7,8-T4CDD detected in the same samples (less than 1-18 pg/g). On the basis of in vitro and in vivo induction of hepatic microsomal benzo(a)pyrene hydroxylase (AHH) and ethoxyresorufin O-deethylase (EROD), "T4CDD toxic equivalents" were calculated for coplanar PCBs in humans. "T4CDD toxic equivalent" for 3,3',4,4',5-P5CB was one order of magnitude higher than 2,3,7,8-T4CDD. Considering the extreme toxic potential and persistence of coplanar PCBs, their presence in the human body may pose a greater toxic threat than dioxins and dibenzofurans.     

Promotion of endometriosis in mice by polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls.

Previous studies showed exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) enhances the development of endometriotic lesions. In this study we examined the effects of other polyhalogenated aromatic hydrocarbons on endometriotic proliferation. B6C3F1 female mice were treated via oral gavage a total of five times, with 3 weeks between each dosing, with 0, 1, 3, or 10 micrograms 2,3,7,8,-TCDD/kg body weight (bw); 3 or 30 mg 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153)/kg bw; 100, 300, or 1000 micrograms 3,3',4,4',5-pentachlorobiphenyl (PCB 126)/kg bw; 10, 30, or 100 micrograms 2,3,4,7,8-pentachlorodibenzofuran (4-PeCDF)/kg bw; or 2 or 20 mg 1,3,6,8-TCDD/kg at 10 ml/kg bw. Endometriosis was surgically induced during the week of the second dosing. Three weeks following the final dose, the mice were euthanized and endometriotic lesions, whole body, liver, ovaries, uterine horn, and thymus were weighted, and lesion diameters were measured. Lesions, uterine horns, and ovaries were fixed for histopathology and livers were processed for measurement of ethoxyresorufin O-deethylase (EROD) activity. Both 2,3,7,8-TCDD (1 and 3 micrograms/kg bw) and 4-PeCDF (100 micrograms/kg bw) significantly enhanced the growth of endometrial lesions. No statistically significant increase in endometriotic lesion size was detected in animals treated with either PCB 126 or with the highest dose of 2,3,7,8-TCDD, possibly due to the effects of histologically observed ovarian toxicity. The nondioxin-like compounds, PCB 153 and 1,3,6,8-TCDD, produced no observable effects on endometriosis. Hepatic EROD activity was significantly induced by 2,3,7,8-TCDD, 4-PeCDF, and PCB 126, but not by PCB 153 or 1,3,6,8-TCDD. The results of this study provide preliminary support for the hypothesis that halogenated aromatic hydrocarbon-promoted endometriosis may be Ah receptor mediated.     

Interactive effects of environmentally relevant polychlorinated biphenyls and dioxins on [3H]phorbol ester binding in rat cerebellar granule cells.

Polychlorinated biphenyls (PCBs) are persistent contaminants that exist as complex mixtures in the environment. One problem faced by risk assessors is that the possible interactive effects of specific PCB congeners and related chemicals found in environmental and biological samples have not been systematically investigated. Some PCBs perturb Ca2+ homeostasis and cause protein kinase C (PKC) translocation in neuronal cell cultures and in brain homogenate preparations at concentrations where no cytotoxicity is observed, and these systems are necessary for the growth and normal functioning of neurons. The changes in second messenger systems appear to be associated with the extent of noncoplanarity of the PCB molecule. We studied the interactive effects of selected PCB congeners, a PCB metabolite, and a dioxin on PKC translocation, as determined by [3H]phorbol ester binding in cerebellar granule cells. The binary combinations included coplanar and noncoplanar PCB congeners or PCB congeners with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)/PCB metabolite. In addition, we tested the interactive effects of several PCB congeners (three or more) found in environmental samples such as human milk and blood, contaminated fish, and brain samples from PCB-treated animals. The results indicated that 1) the coplanar congener [3,3',4, 4'-tetrachlorobiphenyl (TeCB)] did not alter the in vitro activity of the noncoplanar (2,2',5,5'-TeCB) or coplanar [4, 4'-dichlorobiphenyl (DCB)] congeners; 2) binary mixtures of active PCB congeners (2,2',4,4'-TeCB and 2,2'-DCB; 2,2'-DCB and 3,5-DCB; 2,2',3,5',6-PeCB and 2,2',4,4',5-PeCB) interact in a dose-additive manner; 3) TCDD did not alter the activity of either coplanar (3,3', 4,4'-TeCB) or noncoplanar (2,2',5,5'-TeCB) congeners; 4) the interaction between the parent PCB congener and hydroxy metabolite of PCB is additive; 5) PCB congener mixtures at the ratios found in environmental samples are biologically active; and 6) there was no indication of synergism in any of the combinations studied. These results suggest that the biological effects of binary mixtures of PCB congeners fit a dose-additive model, indicating that there is a specific site of action for these PCB congeners which is independent of the aryl hydrocarbon receptor. Environmental mixtures contain mostly noncoplanar PCB congeners, and because they appear to be biologically active, the potential human health risk by this group of chemicals should be considered in the risk assessment of PCBs.     

Synergistic effect of 2,2',4,4',5,5'-hexachlorobiphenyl and 2,3,7,8-tetrachlorodibenzo-p-dioxin on hepatic porphyrin levels in the rat.

We studied the effect of polychlorinated biphenyls (PCBs) on hepatic porphyrin accumulation in female Sprague-Dawley rats by feeding them diets containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153), 2,3,3',4,4',5-hexachlorobiphenyl (PCB 156), 3,3',4,4',5-pentachlorobiphenyl (PCB 126), or combinations of the single PCB congeners with TCDD for 13 weeks. A dose-dependent increase in hepatic porphyrin accumulation occurred after TCDD, PCB 126, or PCB 156 administration, reaching maximal levels of about twice control values. The lowest dose levels for which a significant increase in hepatic porphyrin accumulation was found were 0.7 microgram TCDD/kg diet, 50 micrograms PCB 126/kg diet, or 6 mg PCB 156/kg diet. These doses are equivalent to 47 ng TCDD/kg/day, 3.2 micrograms PCB 126/kg/day, and 365 micrograms PCB 156/kg/day. Relative potencies for hepatic porphyrin accumulation, using TCDD as a reference, ranged from 0.015 to 0.06 for PCB 126 and from 0.0001 to 0.0003 for PCB 156. CYP1A2 activities significantly correlated with hepatic porphyrin levels, with coefficients of 0.629, 0.483, or 0.808 for TCDD, PCB 126, or PCB 156, respectively. Administration of PCB 153 alone did not result in hepatic porphyrin accumulation. Co-administration of PCB 153 and TCDD revealed a strong synergistic effect on porphyrin accumulation (about 800 times control levels). This synergistic effect was significant in rats fed diets containing any combination of PCB 153 with TCDD. Uroporphyrin III and heptacarboxylic porphyrin were accumulated in porphyrinogenic livers. These results suggest that TCDD induction of CYP1A2 may be involved, leading to oxidation of uroporphyrinogen III to uroporphyrin III, in combination with an increase in delta-aminolevulinic acid synthetase induced by PCB 153. Under porphyrinogenic conditions, an inhibitor of CYP1A2 activity may also be formed. The interactive effects on porphyrin accumulation after co-administration of dioxinlike and non-dioxinlike compounds may have significant implications for the risk assessment of these chemicals.     

Accumulation patterns of polychlorinated biphenyl congeners and organochlorine pesticides in Steller's sea eagles and white-tailed sea eagles, threatened species, in Hokkaido, Japan

Polychlorinated biphenyls (PCBs), including coplanar congeners, hexachlorocyclohexane isomers, chlordane-related compounds, and hexachlorobenzene, were found in the breast muscle of Steller's sea eagles (SSE) and white-tailed sea eagles (WSE) threatened species, collected in Hokkaido, Japan, during the two years from 1998 to 1999. Both PCBs and DDTs were the most notable compounds, with concentrations one to two orders of magnitude higher than the other compounds, that is, from 120 to 39,000 and from 68 to 15,000 ng/g wet weight, respectively. Non-ortho (International Union of Pure and Applied Chemistry [IUPAC] 77, 126, and 169) and mono-ortho (IUPAC 105, 118, and 156)-substituted coplanar PCB congeners amounted to 9.2 to 740 pg/g of 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents derived from the World Health Organization, Paris, France (WHO), toxic equivalent factors. The atmospheric PCBs and DDTs in eastern Siberian cities, such as Khabarovsk and Magadan, have been reported to be much higher than Hokkaido and the North Pacific. Thus, we speculated that the eagles might have been contaminated in these areas, where they spend most of the year except winter, which they spend in eastern Siberia. Adult eagles accumulated more PCBs and DDTs than younger ones. The patterns of PCB congeners were also found to change, depending on the age of the eagle examined; adult eagles showed relatively higher proportions of highly chlorinated PCBs thanjuvenile eagles did. This difference would be related to the efficiency of the excretion and the metabolism of each PCB congener in the eagles.     

Isomer-specific analysis and toxic evaluation of polychlorinated biphenyls in striped dolphins affected by an epizootic in the western Mediterranean sea

Isomer-specific concentrations of polychlorinated biphenyls (PCBs) including planar, mono- and di-ortho congeners and concentrations of DDT were determined in striped dolphins affected by a morbillivirus epizootic in the western Mediterranean in 1990. Extremely high concentrations of PCBs ranging from 94 to 670 g/g (wet wt) were detected in the blubber. Similarly, DDT concentrations were high, between 22 and 230 g/g (wet wt). The concentrations of three non-ortho coplanar PCBs were 43 (3,3,4,4-T₄CB), 6.8 (3,3,4,4,5-P₅CB), and 7.8 (3,3,4,4,5,5-H₆CB) ng/g (wet wt), respectively, the highest residue levels reported to date. The estimated 2,3,7,8-TCDD toxic equivalents of non-, mono- and di-ortho PCB congeners in striped dolphins were several times higher than those observed for other marine mammals and humans. Mono-ortho congeners contributed greater 2,3,7,8-TCDD toxic equivalents than non-ortho members. The higher ratio of 3,3,4,4,5,5-H₆CB/3,3,4,4,5-P₅CB (IUPAC 169/126) suggested a strong induction of mixed function oxidase enzymes and highlighted the possibility of using this ratio as an index for risk assessment of PCB contamination in marine mammals. Elevated concentrations of PCBs may have played a role in the immune depression in striped dolphins, ultimately leading to the development of morbillivirus disease.     

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.     

Contamination Levels and Specific Accumulation of Persistent Organochlorines in Caspian Seal (Phoca caspica) from the Caspian Sea, Russia

Persistent organochlorines, such as polychlorinated biphenyls (PCBs) including coplanar congeners, DDTs, HCHs, chlordanes (CHLs), and HCB, were determined in the blubber of Caspian seals (Phoca caspica) and their fish diet (Rutilus sp.) collected in 1993 from the northern Caspian Sea, Russia. Notable concentrations of DDTs and HCHs were found at mean values of 19 and 1.3 μg/g on wet-weight basis in adult male seals, respectively. PCB pollution in Caspian seals was not so considerable compared with those of seals that suffered mass mortality. Less gender difference of organochlorine residue levels in adult animals implies less excretion of organochlorines from the body of adult females through lactation and gestation, probably due to the higher rate of pregnancy failure. Immature seals had a wide range of organochlorine concentrations, which decreased as body length increased, suggesting dilution. Caspian seals can be considered to have higher degradation capacity for coplanar PCBs. Mean TEQs (2,3,7,8-TCDD toxic equivalents) for non-, mono- and di-ortho coplanar PCBs was 51 pg/g on wet-weight basis, which was lower than those in seals that have suffered mass mortality, but comparable to those found in Arctic seals. Received: 21 October 1998/Accepted: 19 April 1999     

Isomer-Specific Accumulation and Toxic Assessment of Polychlorinated Biphenyls, Including Coplanar Congeners, in Cetaceans from the North Pacific and Asian Coastal Waters

To elucidate the global distribution and toxicological impacts of polychlorinated biphenyls (PCBs) on cetaceans, the present study determined the concentrations of individual PCB congeners, including toxic non-ortho (IUPAC Nos. 77, 126, 169) and mono-ortho (IUPAC Nos. 105, 118, 156) coplanar congeners, in the blubber of 10 species of adult male odontocetes collected from several locations in the North Pacific Ocean and along coastal waters of Japan, Hong Kong, the Philippines, and India during 1985–1997. Total PCB concentrations in cetaceans from temperate and cold waters were higher than those in cetaceans from tropical regions. Residue levels were found to be the highest in Fraser's dolphins collected off Kii Peninsula, Japan, and hump-backed dolphins from Hong Kong, reflecting serious marine pollution by PCBs in industrialized Asian countries. Penta- and hexa-chlorobiphenyls were the predominant PCB congeners, accounting for about 70% of the total PCBs. 2,3,7,8-Tetrachlorodibenzo-p-dioxin equivalents (TEQs) of non- and mono-ortho coplanar PCBs in the blubber of cetaceans ranged from 36 (in spinner dolphins from the Philippines) to 510 pg/g wet weight (in hump-backed dolphins from Hong Kong). Toxic evaluation of coplanar PCBs using the TEQ concept indicates an greater impact on cetaceans from mid-latitudes. Toxicity contribution of mono-ortho congener IUPAC 118 was prominent in species from high latitude oceans, such as the Bering Sea and the North Pacific, whereas non-ortho congener IUPAC 126 accounted for the highest contribution in cetaceans from lower latitude regions, such as the Philippines and India. The estimated TEQ concentrations in the blubber of some cetacean species, such as northern right whale dolphin and Pacific white-sided dolphin from the northern North Pacific, Dall's porpoise from the Japan Sea, striped dolphin off Sanriku and Fraser's dolphin off Kii Peninsula, Japan, hump-backed dolphin and finless porpoise from Hong Kong, exceeded the levels associated with immunosuppression in harbour seals. Received: 7 September 1999/Accepted: 3 May 2000     

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.     

Hepatic microsomal cytochrome p450s and chlorinated hydrocarbons in largha and ribbon seals from Hokkaido, Japan: differential response of seal species to Ah receptor agonist exposure

From 16 largha seals (Phoca largha) and 15 ribbon seals (Phoca fasciata) in the coastal waters of Hokkaido, Japan, blubber chlorinated hydrocarbon (CHC) levels and hepatic cytochrome P450 (CYP) catalytic activities and their immunochemically detected protein content levels were measured. Concentrations of DDTs (2,2-bis(4-chlorophenyl)-1,1-dichloroethylene,p,p'-DDE; 2,2-bis(4-chlorophenyl)-1,1-dichloroethane, p,p'-DDD; dichlorodiphenyltrichloroethane, p,p'-DDT), polychlorinated biphenyl congeners (PCBs), and chlordane compounds (oxychlordane, chlordanes, and nonachlors) in both species were in the range of 290 to 5,300, 420 to 4,000, and 130 to 1,500 ng/g lipid weight, respectively. Aryl hydrocarbon receptor (AhR) agonists, non-ortho (IUPAC 77 and 126) and mono-ortho (IUPAC 105, 118, and 156) coplanar PCB congeners, were also detected, and the 2,3,7,8-tetrachlordibenzo-p-dioxin (TCDD) toxic equivalents (TEQs) were 4.9 to 120 pg TEQ/g lipid weight. Cross-reactive proteins with polyclonal antibodies against rat CYP1A1 and CYP3A2 were notably detected in seal liver microsomes. Interestingly, a polyclonal antibody against rat CYP2B1 recognized proteins only at trace levels. In largha seals, both levels of alkoxyresorufin- (methoxy-, ethoxy-, pentoxy-, and benzyloxyresorufin) O-dealkylase (AROD) activities and proteins detected by polyclonal antibodies against rat CYP1A1 were significantly correlated with the concentrations of individual coplanar PCB congeners, total TEQs, and total PCBs. Threshold concentrations for TEQs in blubber of the largha seal to induce hepatic CYP1A protein and EROD activity were estimated to be 8.5 and 19 pg TEQ/g fat weight, respectively. In ribbon seals, similar correlations were not detected, although the TEQ levels were not significantly lower than those in largha seals. These results suggest that AROD activity and CYP1A1 protein in the liver of the largha seal could be a biomarker for the exposure to AhR agonists such as coplanar PCB congeners. This study also indicates differences in AhR-mediated responses to the CHC exposures between largha and ribbon seals.     

Polychlorinated Dibenzo-<Emphasis Type="Italic">p</Emphasis>-Dioxins,Dibenzofurans, and Dioxin-Like Polychlorinated Biphenyls in Livers of Birds from Japan

Concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and non- and mono-ortho-chlorine-substituted polychlorinated biphenyls (dioxin-like PCBs) were measured in livers of 17 species of birds collected from Japan. Birds were grouped according to their feeding habits as granivores, piscivores, omnivores, and predators for discussions. Livers of granivores contained relatively low concentrations of PCDD/DFs (80–660 pg/g) followed in increasing order by omnivores (2,300–8,000 pg/g), piscivores (61–12,000 pg/g) and predators (480–490,000 pg/g on a fat weight basis). Especially, one species of predatory bird (mountain hawk eagle) contained elevated concentrations of PCDDs, PCDFs, and dioxin-like PCBs, and the measured concentration is one of the highest reported to date. Homolog and congener patterns of PCDDs and PCDFs varied among species; hence, the results suggested that feeding habits, specific elimination, and metabolism influence contamination pattern. Concentrations of dioxin-like PCBs were in the order of granivores (32–83 ng/g) < predators [excluding mountain hawk eagle] (32–2,500 ng/g) < piscivore (61–12,000 ng/g) < omnivores (1,800–67,000 ng/g on a fat weight basis). Mountain hawk eagle contained the highest concentration of dioxin-like PCBs (55,000 ng/g fat weight). 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) toxic equivalents (TEQs) ranged from 53–450,000 pg/g fat weight. 23478-PeCDF, 2378-TCDD/TCDF, and PCB congeners IUPAC 126 and 77 were major contributors to TEQs in birds. To our knowledge, this is the first study of PCDD/DFs and dioxin-like PCBs in livers of several species of Japanese birds. Received: 11 March 2001/Accepted: 5 August 2001     

Mono-ortho- and non-ortho-substituted polychlorinated biphenyls in human milk from Mohawk and control women: Effects of maternal factors and previous lactation

Fifty-four individual human milk samples from 50 mothers (20 Mohawks and 30 controls) were analyzed for four non-ortho- and eight mono-ortho-substituted polychlorinated biphenyls (PCBs). Mean total coplanar PCBs concentrations were 49 ng/g and 55 ng/g lipid for Mohawk and control women, respectively. A statistical evaluation of all analytical data reveals no significant difference of total coplanar PCB level between Mohawk and control women. The level of these contaminants is influenced by the age of the mother, number of breastfed children, and length of nursing period. Older women, primiparae, and cigarette smokers had higher levels of coplanar PCBs. In general, women had higher levels of coplanar PCBs in the first lactation and in the earlier samples of a given lactation, while levels declined both with duration of breast-feeding and with number of children nursed.The contribution of individual non-ortho- and mono-ortho-substituted PCB congeners to the total calculated toxic equivalent values (TEQ) was assessed for the breast milk samples. The levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in human milk of pooled specimens from Los Angeles, California and Binghamton, New York, widely separate cities in the United States (Schecter et al. 1989), were presented for reference purpose. The main contributions to the TEQ were PCB congeners #118 (25.8 pg/g lipid), #126 (25 pg/g lipid), #105 (10.8 pg/g lipid), and #156 (7.4 pg/g lipid). Collectively, these compounds accounted for 70% of the TEQ values. Based on the TEFs proposed by Safe (1990), the overall TEQs calculated for the monitored PCBs, were about five times those due to total PCDD/Fs.     

PCDDs/PCDFs, PCBs, and Organochlorine Pesticides in Eggs of Eurasian Sparrowhawks (Accipiter nisus), Hobbies (Falco subbuteo), and Northern Goshawks (Accipiter gentilis) Collected in the Area of Berlin-Brandenburg, Germany

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine (OC) pesticides were measured in unsuccessfully hatched eggs of three different kinds of predatory birds: 3 eggs of sparrowhawks, 7 eggs of hobbies, and 16 eggs of goshawks collected in the German region of Berlin-Brandenburg.Using toxic equivalency factors for birds, eggs of hobbies contained mean concentrations of 478 pg TEQ/g fat and 551 pg TEQ/g fat contributed by PCDD/Fs and coplanar PCBs, respectively. For sparrowhawks the respective TCDD equivalents were 424 and 1278 pg/g fat; those for goshawks were 211 and 935 pg/g fat. The mean value of the summed concentrations of the PCB congeners 28, 52, 101, 138, 153, and 180 amounted to 11 μg/g fat in eggs of hobbies, 9.5 μg/g fat for sparrowhawks, and 16.1 μg/g fat for goshawks.Of the analyzed organochlorine pesticides the concentration of p,p′-DDE was highest (up to 273 μg/g); the concentration of the other OCs, with the exception of methoxychlor in eggs of goshawks (highest level of 10.6 μg/g fat), were negligible. In all cases the calculated toxicity of the coplanar PCBs surpassed the toxicity of the PCDD/Fs, at least by a factor of two. Due to the higher concentration of the coplanar PCB 77 compared to PCB 126 in eggs of hobbies, it is concluded that its metabolic excretion in this species is much lower than in sparrowhawks and goshawks. Received: 25 May 2001/Accepted: 10 December 2001     

Squamous epithelial lesion of the mandibles and maxillae of wild mink (Mustela vison) naturally exposed to polychlorinated biphenyls

Approximately 125 km of the Kalamazoo River, located in southwestern Michigan (USA), are designated as a Superfund site, with polychlorinated biphenyls (PCBs) as the contaminant of concern. Mink (Mustela vison) are a naturally occurring predator in this area and also a species of concern because of their known sensitivity to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and structurally similar compounds, such as PCBs. Four of nine mink trapped from the Kalamazoo River area of concern (KRAOC) exhibited histological evidence of a jaw lesion previously identified in ranch mink. The jaw lesion, hyperplasia of squamous epithelium in the mandible and maxilla, is known to be caused by 3,3',4,4',5-pentachlorobiphenyl (PCB 126) and TCDD. Mink trapped from an upstream reference area (Fort Custer Recreation Area [FCRA]) did not exhibit the lesion. Mean concentrations of total PCBs were 2.8 and 2.3 mg/kg wet weight in the livers of mink from the KRAOC and FCRA, respectively, and TCDD toxic equivalent (TEQ) concentrations were 0.30 and 0.11 microg/kg wet weight, respectively. Significant correlations were found between the severity of the lesion and the hepatic concentrations of total PCBs and TEQs. To our knowledge, this is the first published report of the lesion occurring in wild mink.     

A mass spectroscopic method for analysis of AHH-inducing and other polychlorinated biphenyl congeners and selected pesticides in fish

The 209 polychlorinated biphenyl (PCB) congeners exhibit a wide range in toxicity to fish, birds, and mammals. This paper discusses the use of gas chromatography/mass spectrometry negative chemical ionization (GC/MS-NCI) to quantify congeners of highly suspected toxicity such as IUPAC #77 (3,3,4,4-tetrachlorobiphenyl) and #126 (3,3,4,4,5-pentachlorobiphenyl). GC/MS analysis time needed to produce the necessary resolution was reduced to 1 h per sample or standard, allowing an autosampler to inject 12 samples in 24 hours, plus 12 standards/QC samples. Identification and quantification of some 60+ congeners and several selected pesticides and estimation of total PCBs are also possible within the 1 h analysis. For congeners of high chlorination (penta through octa), the method exhibited excellent sensitivity, such that we could not locate a fish which exhibited PCB levels below our calibrated quantitation range. NCI was not as sensitive for mono through tri and for some tetrachlorinated PCB congeners, an exception being PCB #77, for which sensitivity was of the same order as for the more highly chlorinated biphenyls. Long term stability was excellent. Over a 6-mo period, results of replicate analyses for PCB congeners and pesticides in a composited sample of lake trout (Salvelinus namaycush) from Lake Michigan had a relative standard deviation of 12% of the mean. Over the same time period, mean recoveries for samples spiked at concentrations similar to those in Lake Michigan lake trout were 90–102%. Response was linear over a wide range of concentrations for each of the analyzed compounds. This method is now being used for routine analysis of PCB congeners and selected pesticides in our laboratory.Contribution 799 of the National Fisheries Research Center-Great Lakes, U.S. Fish and Wildlife Service, 1451 Green Road, Ann Arbor, MI 48105.     

Egg incubation position affects toxicity of air cell administered polychlorinated biphenyl 126 (3,3',4,4',5-pentachlorobiphenyl) in chicken (Gallus gallus) embryos

The avian egg is used extensively for chemical screening and determining the relative sensitivity of species to environmental contaminants (e.g., metals, pesticides, polyhalogenated compounds). The effect of egg incubation position on embryonic survival, pipping, and hatching success was examined following air cell administration of polychlorinated biphenyl (PCB) congener 126 (3,3',4,4',5-pentachlorobiphenyl [PCB 126]; 500-2,000 pg/g egg) on day 4 of development in fertile chicken (Gallus gallus) eggs. Depending on dose, toxicity was found to be up to nine times greater in vertically versus horizontally incubated eggs. This may be due to enhanced embryonic exposure to the injection bolus in vertically incubated eggs compared to more gradual uptake in horizontally incubated eggs. Following air cell administration of PCB 126, horizontal incubation of eggs may more closely approximate uptake and toxicity that has been observed with naturally incorporated contaminants. These data have implications for chemical screening and use of laboratory data for ecological risk assessments.     

Toxic potential of non-ortho and mono-ortho coplanar polychlorinated biphenyls in Aroclors®, seals,and humans

Mono-ortho and non-ortho coplanar polychlorinated biphenyls (PCBs) were analyzed in Aroclors^®, seals, and humans by graphitized carbon, a recently developed HPLC method (Hong et al. 1992b) and high-resolution gas chromatography with electron capture detection (HRGC/ECD). The concentration data were multiplied by potency factors derived from aryl hydrocarbon hydroxylase (AHH) induction to give 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents. The ability to separate coplanar PCBs from the majority of PCBs has allowed the use of TCDD toxicity equivalence to compare the relative dioxin-like potency of PCB residues in the complex mixtures. The most active mixtures, Aroclors^® 1254, 1248, and 1242, contained 42–54% by weight of chlorine. The results demonstrate that the apparent dioxin-like potency of PCB residues in Aroclors^®, seals, and humans is dominated by three congeners, 3,3,4,4-tetra-, 2,3,3,4,4-, and 3,3,4,4,5-pen-tachlorobiphenyl (IUPAC nos. 77, 105, 126).     

The Effects of 3,3′,4,4′,5-Pentachlorobiphenyl (PCB 126) on Mink (<Emphasis Type="Italic">Mustela vison</Emphasis>) Reproduction and Kit Survivability and Growth

This study was conducted to determine if dietary exposure to 3,3′4,4′,5-pentachlorobiphenyl (PCB 126) would have an adverse effect on the reproductive performance of female mink (Mustela vison) and survivability and growth of their kits. Standard dark, female mink were fed diets containing PCB 126 at concentrations of 0, 0.24, 2.4, and 24 μg PCB 126/kg feed (0, 24, 240 and 2,400 ng 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD] toxic equivalents [TEQs]/kg, respectively) from 21 days prior to breeding until weaning of their kits at six weeks of age. There were no significant differences in the number of females that whelped or the average litter size between the control group and the 0.24 μg PCB 126/kg feed group. In addition, kit body weights at birth and at three, six and 28 weeks of age as well as kit survivability through weaning were similar between the two groups. In contrast, female mink fed diets containing 2.4 and 24 μg PCB 126/kg feed that had confirmed matings, failed to whelp. Histological examination of their uterine horns verified fetal implantation sites or placental scars, which indicated partial fetal development. Based on the impaired reproductive performance reported in this study, a no observable adverse effect level (NOAEL) of 0.24 μg PCB 126/kg feed (24 ng TEQs/kg) and a lowest observable adverse effect level (LOAEL) of 2.4 μg PCB 126/kg feed (240 ng TEQs /kg) were determined.     

Relationship of serum levels of individual PCB, dioxin, and furan congeners and DDE with Great Lakes sport-caught fish consumption

Great Lakes (GL) sport fish consumption is a potential route of exposure for environmentally persistent organochlorine contaminants, which may have human health effects. In this report, relationships are explored among individual congeners in a large cohort of frequent and infrequent GL sport fish consumers. Blood samples were obtained in 1993-1995 and analyzed for 1,1-bis(4-chlorophenyl)-2,2-dichloroethene (DDE) and for 62 noncoplanar polychlorinated biphenyls (PCBs), 4 coplanar PCBs, 8 polychlorinated dibenzo-p-dioxin (dioxin), and10 dibenzofuran (furan) congeners. All GL fish eaters and referents had detectable levels of DDE, total noncoplanar PCBs, total coplanar PCBs, total dioxins, and total furans. Noncoplanar PCBs were higher in GL sport fish consumers than in a referent population from the same geographic area, were associated with GL sport-caught fish (GLSCF) consumption, and varied significantly by Great Lake. DDE, lower chlorinated dioxin and furan toxic equivalents (TEQs), and coplanar PCB TEQs were positively associated with noncoplanar PCBs but were not associated with GL sport fish consumption independent of PCB level. Highly chlorinated dioxin and furan congener TEQs were not significantly associated with noncoplanar PCBs or GL sport fish consumption, suggesting that participants were acquiring some of these TEQs from a source other than GLSCF. In epidemiologic studies, it may be important to include populations with higher organochlorine exposures as well as background exposures and to consider the effects of individual congeners or mixtures of congeners on health outcomes.