Identification of chlorinated dibenzofurans in American polychlorinated biphenyls

Photodegradation of polychlorinated biphenyls in water/nitrogen-doped silica and air/nitrogen-doped silica systems: Kinetics, mechanism and quantitative structure activity relationship (QSAR) analysis

Developing efficient and low-cost photocatalytic materials is essential for removing polychlorinated biphenyls (PCBs). In this work, the photodegradation process of fourteen representative polychlorinated biphenyls (PCBs) in both water/nitrogen-doped SiO2 (N-SiO2) and air/N-SiO2 systems was studied. The photodegradation kinetics of PCBs is consistent with the pseudo-first-order kinetic equation. The variation in the degradation effects of different PCBs in the two systems is primarily related to the position of the Cl substituent and the effective absorption wavelength range of PCBs. A total of fourteen intermediates for 4'-Dichlorobiphenyl (PCB-15), 2,2',4,4',6,6'-Hexachlorobiphenyl (PCB-155), and 2,2',3,3',4,4',5,5',6,6'-Decachlorobiphenyl (PCB-209) generated from four reaction pathways were identified based on both mass spectrometry analysis and theoretical calculations. Using the values of lnk (k denotes pseudo-first-order kinetic constants) for the 11 PCBs in the training set and the calculated molecular and structural parameters, quantitative structure-activity relationship (QSAR) models for the two systems were constructed by using multiple linear regression (MLR) method to better understand the factors affecting the photodegradation rate of PCBs. The QSAR equations were obtained with Cl atom substitution at position 3 (N3) as the main parameter, which were lnk = -1.98 - 0.19 N3 for the water/N-SiO2 system and lnk = -1.56 - 0.34 N3 for the air/N-SiO2 system, with the correlation coefficient (R2) of 0.66 and 0.73, leave-one-out cross-validation (Q2LOO) of 0.51 and 0.59, respectively, and bootstrapping validation coefficients (Q2BOOT) values of both 0.74, confirming that the models were well fitted and showed high robustness and prediction ability. This study provides valuable insights into photocatalytic degradation studies of PCBs.

Discovery of hydroxylated polychlorinated biphenyls (OH-PCBs) in sediment from a lake Michigan waterway and original commercial aroclors

Hydroxylated polychlorinated biphenyls (OH-PCBs) were measured in surficial sediment from Indiana Harbor and Ship Canal (IHSC), East Chicago, IN and five original Monsanto Aroclors. These compounds were measured using gas chromatography with tandem mass spectrometry (GC-MS/MS) and certified standards that allowed us to identify 65 individual or coeluting congeners. Concentrations in the sediment ranged from 0.20 to 26 ng/g dry weight. Profiles of most samples were similar and were dominated by mono- to penta-chlorinated OH-PCBs. Interestingly, most of the samples strongly resembled the OH-PCB profiles of Aroclors 1221, 1242, 1248, and 1254, yet 25% of OH-PCBs measured in the sediment were not detected in Aroclors. A strong positive correlation was found between ΣOH-PCB and ΣPCB (p < 0.0001) and also between many individual OH-PCB:PCB pairs (p < 0.05). Analysis of OH-PCB:PCB pairs suggest PCB degradation is unlikely as a source of OH-PCBs in IHSC sediment. We are the first to report levels of OH-PCBs in sediment and Aroclors, and our discovery is significant because it is likely that OH-PCB contamination exists in sediment anywhere that PCB contamination from Aroclors is present.

Determination of PCBs, PCDDs and PCDFs in insulating oil samples from stored Chinese electrical capacitors by HRGC/HRMS

Homologue and congener profiles of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in commercial PCBs formulations are key information for the source identification of PCBs contamination as well as for the risk assessment caused by potential exposure. The isotope dilution technology in combination with high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) has made the accurate determination of such profiles possible. So far, various commercial PCB formulations except Chinese products have been successfully determined. Two PCBs containing insulating oil samples from stored Chinese electrical capacitors have been determined with the same methodology for comparability. The total concentration PCBs in two oil samples were 790,000 μg g(-1) and 720,000 μg g(-1), respectively. TriCBs, TetraCBs, and DiCBs were found to be most abundant. Concentration of dioxins contamination in two samples is 650-670 ng TEQ g(-1), of which 69-71ngTEQg(-1) from PCDD/Fs with the predominant congeners of 1,2,7,8-TeCDF; 2,3,7,8-TeCDF; 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDF. The contributions of DL-PCBs in total TEQ in both samples were more than 85%. The dioxin-like toxicity in insulating oils contained in electrical capacitors could be considered receive attention as an important dioxins source if such wastes are not managed in an environmentally sound manner.

Patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the Hudson River, New York, USA

Belted kingfisher (Ceryle alcyon), spotted sandpiper (Actitus macularia), and tree swallow (Tachycineta bicolor) eggs were collected in 2004 from the upper Hudson River, New York, USA. This area is one of the most polychlorinated biphenyl (PCB)-contaminated locations in North America. Multivariate analyses indicated among species differences in the concentration and composition of PCB congeners, polychlorinated dibenzo-p-dioxin (PCDD), and dibenzofuran (PCDF, PCDD-F when combined with PCDDs) congeners, and chlorinated pesticides. Total PCB concentrations followed the typical food chain biomagnification paradigm of higher concentrations in piscivorous bird eggs and lower concentrations in eggs of species that feed at lower trophic levels. Concentrations in the insectivorous swallows (geometric mean = 6.8 µg/g wet wt) were approximately half the concentrations present in the piscivorous kingfisher (11.7 µg/g) or omnivorous sandpiper (12.6 µg/g). In contrast, PCB toxic equivalents (TEQs) were higher in swallows (1,790 pg/g wet wt) than in either kingfishers (776 pg/g) or sandpipers (881 pg/g). This difference can be mainly attributed to higher PCB77 concentrations in swallows relative to the other two species. Also contrary to the accepted food-chain paradigm, the sum of PCDD-F concentrations and the sum of their TEQs were higher in swallows than in either sandpipers or kingfishers. Metabolic pathway differences in the respective food chains of the three species probably accounted for the differences observed in PCB TEQ, total PCDD-F, and PCDD-F TEQ concentrations among species.

In utero effects of chemicals on reproductive tissues in females

Chemicals found in the environment as industrial byproducts or pollutants as well as those that are prescribed or part of our daily lives can have multiple effects on the human body. The manner in which we are exposed, and the levels we are exposed to are significant contributing factors. Adults have the bodily defense mechanisms in place to combat exposures to adverse toxicants and general pollution at a variety of levels. However, developing organisms may not have adequate defense mechanisms, and toxicants can have a significant effect on their health and development. In this review, we take particular note of the toxicities of chemicals on the developing female reproductive system as a result of in utero exposure. Environmental and prescribed chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), diethylstilbestrol, and genistein, as well as others, will be reviewed for their in utero toxicity in the neuroendocrine system, the ovary, oviduct, placenta, uterus, vagina, cervix, and mammary gland.

Comparison of seven indicator PCBs and three coplanar PCBs in beef, pork, and chicken fat

The risk assessment of polychlorinated biphenyls (PCBs) is difficult since complex congeners were used in many industrial applications for a long period of time and the residue monitoring in foods of animal origin and the environment were not established in comparable systems. The relationships of determined concentrations in indicator PCB congeners (mono- and di-ortho PCBs) and coplanar PCB congeners (non-ortho PCBs) in livestock products are presented in this study. The concentrations of seven indicator PCBs were compared with three coplanar PCBs in beef, pork, and chicken fat. Distributions of concentration for the indicator PCBs in three different animal species were similar except for that of PCB-118 (2,3',4,4',5-pentachlorobiphenyl) in pork fat. The congeners with the highest concentration were PCB-138 (2,2',3,4,4',5'-hexachlorobiphenyl) in beef and pork fat and PCB-28 (2,4,4'-trichlorobiphenyl) in chicken fat. The bioaccumulation and metabolism of PCBs in animal species represent different congener profiles in livestock products. The percentage of the total concentration of three coplanar PCBs was about 2% of the total concentration of the seven indicator PCBs. Relatively high concentration of mono-ortho and di-ortho PCBs in fat samples of livestock products may be calculated with the concentration of coplanar PCBs that can be usually determined on a sequential procedure with dioxin analysis. Therefore, the relationship of the amounts between seven indicator PCBs and three coplanar PCBs may be useful to derive the composition and level of contaminants in beef, pork, and chicken.

Bioanalytical screening methods for dioxins and dioxin-like compounds a review of bioassay/biomarker technology

Determination of environmental pollutants utilizing biodetectors such as bioassays, biomarkers, enzyme immunoassays (EIAs), or other bioanalytical tools is a continuously growing area. The present literature review describes the principles and advantages/limitations of several bioanalytical detection methods (BDMs) for the screening and diagnosis of dioxin and dioxin-like compounds. This study characterizes briefly the family of dioxin and dioxin-like compounds, discusses potential Ah receptor (AhR) ligands and cytochrome P-450 (CYP) 1A1-enzyme-inducing compounds. 'Milestones' in the development of BDMs are summarized and explained in detail for a number of bioanalytical tools that can be used to detect these classes of dioxin-like persistent bioaccumulative toxicants (PBTs). The design of a screening profile with a battery of bioassays/biomarkers coupled with the chemical analysis is evaluated. The relative potencies (REPs) to 2,3,7,8-TCDD for dioxin-like compounds are reviewed for various BDMs and the differences are noted.

Biochemical and toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin in immature male and female chickens

It has been reported that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced body wasting in mammals is associated with decreased adipose tissue lipoprotein lipase (LPL) and glucose transporting (GT) activity with differential sensitivity between genders. This study extends those findings to chickens as an avian model. A significant decrease in body weight gain was demonstrated in immature male and female chickens 10 days after treatment with a single intraperitoneal (i.p.) dose of 10 and 100 microg TCDD/kg. Body weight gain decrease was associated with hepatomegaly and induction of hepatic CYP1A enzymes in both genders. The increase in liver/body weight ratio (48%) and the decreased LPL activity (28%) were significant only in females at 10 microg TCDD/kg. However, the increase in liver/body weight ratio (31%) and the decrease in LPL activity (26%) were significantly demonstrated in males at 100 microg TCDD/kg. Levels of GT were significantly decreased in females (46%) and in males (48%) following treatment with 10 microg TCDD/kg and 100 microg TCDD/kg, respectively. Therefore, in chickens, as in mammals, the TCDD-induced body wasting is accompanied with decreased LPL activity and decreased GT activity and the magnitude of these changes is gender dependent. In contrast to mammals, this study suggests that female chickens are equally, if not more responsive to TCDD toxicity than males.

Polychlorinated naphthalenes in groundwater samples from the Llobregat aquifer (Spain)

Polychlorinated naphthalenes (PCNs) have characteristics fairly similar to those of polychlorinated biphenyls and terphenyls (PCBs and PCTs) and although they have been used in numerous applications, very few reports on the occurrence of PCNs in water have been published. Both automated solid-phase extraction (SPE) and liquid-liquid extraction (LLE) procedures were evaluated to concentrate PCNs. High-resolution gas chromatography with electron-capture detection (HRGC-ECD) and mass spectrometric detection in the selected ion monitoring mode (SIM) were used to analyze PCNs in groundwater samples from the aquifer of the Llobregat river near Barcelona (NE Spain). The homologue distribution profiles of PCNs found in groundwater samples and the standard mixtures of Halowax (1099, 1013 and 1014) were compared. Quantification was achieved by HRGC-ECD. Total PCN concentrations expressed as Halowax 1099 equivalents ranged from < 0.5 ng/l to 79.1 micrograms/l in the water samples, with tetrachloronaphthalenes (TetraPCN) as the major group of congeners.

Comparative toxicity of polychlorinated biphenyls to Japanese quail (Coturnix c. japonica) and American kestrels (Falco sparverius)

Polychlorinated biphenyls (PCBs) and related halogenated hydrocarbons bioaccumulate to high concentrations in top predators, such as raptorial birds, yet little is known of PCB toxicity to such species. This study explored several aspects of both the acute and chronic response of American kestrels (Falco sparverius) to three purified PCB congeners and a commercial mixture, Aroclor 1254, and compared the response to that of the Japanese quail (Coturnix c. japonica), a more studied species known to be PCB sensitive. In one experiment, adult female birds were given single oral doses of either Aroclor 1254, 3,3',4,4'-TCB (PCB 77, IUPAC nomenclature), 3,3',4,4',5-PCB (PCB 126) or 2,2',4,4',5,5'-HCB (PCB 153) and sacrificed after 5 d. In kestrels, neither the pure compounds nor the mixture affected hepatic or renal porphyrin levels. There was slight but significant hepatic and renal ethoxyresorufin O-deethylase (EROD) induction in birds dosed with PCBs 77 and 126. A cytochrome P-4501A (CYP1A) cross-reactive protein was detected in liver and kidney of kestrels given PCBs 77 and 126, but not in Aroclor 1254-dosed birds. In quail, an acute dose of Aroclor 1254 caused significant liver weight increases, hepatic and renal EROD and aminopyrine n-demethylase (APND) induction, and dose-related hepatic and renal porphyria. Quail treated with PCB 126 developed hepatic and renal porphyria; EROD and APND were also induced. Administration of PCB 77 caused only slight induction of hepatic EROD activity. PCB 153 caused some hepatic and renal porphyria and induced EROD to the same degree as PCB 126. A hepatic CYP1A cross-reactive protein was induced about 200-fold in all individual quail that exhibited significant EROD induction and was also induced in kidney of 1 quail given Aroclor 1254. A second experiment examined chronic exposure to Aroclor 1254 by feeding adult females of both species a daily dose of 7 mg/kg/d for 4-, 8-, and 12-wk periods. There were no effects on hepatic porphyrins in kestrels. APND and aldrin epoxidase (AE) were induced; EROD was not induced, although a hepatic CYP1A-like protein was detected in 1 kestrel dosed for 12 wk. Chronic exposure of quail to Aroclor 1254 caused highly significant increases in mean hepatic porphyrin levels and in activity of EROD, APND, and 4-chlorobiphenyl hydroxylase; a CYP1A-like protein was also induced about 200-fold. In both studies, Aroclor 1254 residues accumulated in tissues of both species, but there was no significant relationship between residue levels and effects. In conclusion, adult American kestrels were relatively insensitive to the effects of PCBs, from both acute and chronic exposure, on hepatic and renal porphyrin levels. Although concentrations of a CYP1A-like protein were increased in some kestrels given PCBs, EROD activity was only marginally increased, suggesting that catalytic activity of this protein differed among the two species.

Histopathology of postpartum placental sites in mink (Mustela vison) exposed to polychlorinated biphenyls or fractions thereof

Polychlorinated biphenyls (PCB) cause reproductive failure in mink. Ovulation and nidation occur, but the fetuses die during gestation. The toxicity of different chlorinated biphenyl (CB) congeners differs markedly. Dioxin-like congeners with no (0-ortho CBs) chlorine in the ortho position to the biphenyl bond are considered to be highly toxic. Altogether, 13 groups of 10 female mink (Mustela vison) were exposed to PCB or CB fractions thereof during the reproductive season of 1988 and 1989. In 1988, one group of mink received 2 mg/day of Clophen A50 and five groups received single fractions thereof or synthetic 0-ortho CB in their diet. In 1989, one group received 1.64 mg/day of Aroclor 1254 and six groups received combinations of fractions thereof. The daily amounts of the fractions administered per animal were equivalent to those present in 2 mg of Clophen A50 or 1.64 mg of Aroclor 1254. After administration for 3 months in both experiments, the animals were killed 5 days after parturition. Histological examination focused on the placental sites. The most involuted placental sites were those of early fetal death in primiparous, non-whelping animals in the 1989 experiment. The least involuted placental sites, displaying a hyperplastic and pleomorphic uterine luminal epithelium, in which proliferating cell nuclear antigen (PCNA) was present, were those of late fetal death in biparous, non-whelping animals in the 1988 experiment. The survival of the fetoplacental unit was related to PCB exposure. The histology of the placental sites seemed only to be related to the survival time of the fetuses and to the number of former reproductive seasons.

Modulation of gene expression and endocrine response pathways by 2,3,7,8-tetrachlorodibenzo-p-dioxin and related compounds

The aryl hydrocarbon (Ah) receptor binds several different structural classes of chemicals, including halogenated aromatics, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polynuclear aromatic and heteropolynuclear aromatic hydrocarbons. TCDD induces expression of several genes including CYP1A1, and molecular biology studies show that the Ah receptor acts as a nuclear ligand-induced transcription factor that interacts with xenobiotic or dioxin responsive elements located in 5'-flanking regions of responsive genes. TCDD also elicits diverse toxic effects, modulates endocrine pathways and inhibits a broad spectrum of estrogen (17 beta-estradiol)-induced responses in rodents and human breast cancer cell lines. Molecular biology studies show that TCDD inhibited 17 beta-estradiol-induced cathepsin D gene expression by targeted interaction of the nuclear Ah receptor with imperfect dioxin responsive elements strategically located within the estrogen receptor-Sp1 enhancer sequence of this gene.

Polychlorinated biphenyls (PCBs): environmental impact, biochemical and toxic responses, and implications for risk assessment

Commercial polychlorinated biphenyls (PCBs) and environmental extracts contain complex mixtures of congeners that can be unequivocally identified and quantitated. Some PCB mixtures elicit a spectrum of biochemical and toxic responses in humans and laboratory animals and many of these effects resemble those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons, which act through the aryl hydrocarbon (Ah)-receptor signal transduction pathway. Structure-activity relationships developed for PCB congeners and metabolites have demonstrated that several structural classes of compounds exhibit diverse biochemical and toxic responses. Structure-toxicity studies suggest that the coplanar PCBs, namely, 3,3',4,4'-tetrachlorobiphenyl (tetraCB), 3,3',4,4',5-pentaCB, 3,3',4,4',5,5'-hexaCB, and their monoortho analogs are Ah-receptor agonists and contribute significantly to the toxicity of the PCB mixtures. Previous studies with TCDD and structurally related compounds have utilized a toxic equivalency factor (TEF) approach for the hazard and risk assessment of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) congeners in which the TCDD or toxic TEQ = sigma([PCDFi x TEFi]n)+sigma([PCDDi x TEFi]n) equivalent (TEQ) of a mixture is related to the TEFs and concentrations of the individual (i) congeners as indicated in the equation (note: n = the number of congeners). Based on the results of quantitative structure-activity studies, the following TEF values have been estimated by making use of the data available for the coplanar and monoortho coplanar PCBs: 3,3',4,4',5-pentaCB, 0.1; 3,3',4,4',5,5'-hexaCB, 0.05; 3,3',4,4'-tetraCB, 0.01; 2,3,3',4,4'-pentaCB, 0.001; 2,3',4,4',5-pentaCB, 0.0001; 2,3,3',4,4',5-hexaCB, 0.0003; 2,3,3',4,4',5'-hexaCB, 0.0003; 2',3,4,4',5-pentaCB, 0.00005; and 2,3,4,4',5-pentaCB, 0.0002. Application of the TEF approach for the risk assessment of PCBs must be used with considerable caution. Analysis of the results of laboratory animal and wildlife studies suggests that the predictive value of TEQs for PCBs may be both species- and response-dependent because both additive and nonadditive (antagonistic) interactions have been observed with PCB mixtures. In the latter case, the TEF approach would significantly overestimate the toxicity of a PCB mixture. Analysis of the rodent carcinogenicity data for Aroclor 1260 using the TEF approach suggests that this response is primarily Ah-receptor-independent. Thus, risk assessment of PCB mixtures that uses cancer as the endpoint cannot solely utilize a TEF approach and requires more quantitative information on the individual congeners contributing to the tumor-promoter activity of PCB mixtures.

Metabolism of benzo(a)pyrene by lung microsomes from rabbits pretreated with polychlorinated biphenyls and 2,3,4,7,8-pentachlorodibenzofuran

The polychlorinated biphenyls (PCBs) mixture, Aroclor 1254, is a weak inducer of aryl hydrocarbon hydroxylase (AHH) activity in rabbit lung. In contrast, 2,3,4,7,8-pentachlorodibenzofuran (PCDF), like 3-methylcholanthrene (3-MC), caused a 3-fold increase in pulmonary AHH activity. An important finding of the present studies was that AHH activity, whether assayed by the flourometric or HPLC methods, was dependent on the buffer used in the incubation mixture. The metabolism of benzo(a)pyrene (BP) to its oxidative metabolites, as assayed by HPLC, revealed that PCBs, PCDF and 3-MC pretreatments caused greater than 15-fold and about 3- to 4-fold increase in the formation of the tumorigenic metabolites 9,10- and 7,8-dihydrodiols, respectively. In contrast to 3-MC and PCDF, PCBs caused a 75% decrease in the formation of the K-region metabolite, BP-4,5-dihydrodiol. These studies strongly suggest that the catalysis of BP metabolism is mediated by more than one isoform of cytochrome P450 (P450).

Great Lakes embryo mortality, edema, and deformities syndrome (GLEMEDS) in colonial fish-eating birds: similarity to chick-edema disease

Several species of colonial fish-eating birds nesting in the Great Lakes basin, including herring gulls, common terns and double-crested cormorants, have exhibited chronic impairment of reproduction. In addition to eggshell thinning caused by high levels of DDT and metabolites, the reproductive impairment is characterized by high embryonic and chick mortality, edema, growth retardation, and deformities, hence the name Great Lakes embryo mortality, edema, and deformities syndrome (GLEMEDS). The hypothesis has been advanced that GLEMEDS in colonial fish-eating birds resembles chick-edema disease of poultry and has been caused by exposure to chick-edema active compounds that have a common mode of action through the cytochrome P-448 system. Detailed evidence has been collected from the following three groups of studies on herring gulls in the lower Great Lakes during the early 1970s; Forster's terns in Green Bay, Wisconsin in 1983; and double-crested cormorants and Caspian terns in various locations in the upper Great Lakes from 1986 onwards. It has proved difficult to establish not only the onset of the disease in the various species at various locations but also the period in which chick-edema active compounds were released. Anecdotal evidence suggested that serious egg mortality in Lake Ontario herring gulls first occurred in 1966, through the signs of chick-edema disease were not looked for until 1974. Only indirect evidence is available on the date of the release of one of the presumed causal agents, 2,3,7,8-tetrachlorodibenzo-p-dioxin, but highest levels may have occurred in the early to mid 1960s. More reliable data show that the onset of the improvement of reproduction of Lake Ontario herring gulls coincided with the declines in organochlorine compounds and particularly 2,3,7,8-TCDD and PCB. Similarly, information on the onset of the disease and exposures in the Forster's tern and double-crested cormorants in Green Bay is uncertain but bird banders did not observe deformities until the 1970s, which corresponds with the onset of high levels of PCB. If the disappearance of the Caspian tern from Saginaw Bay in the mid 1960s corresponds with the onset of GLEMEDS at that location, then there is a close temporal relationship to the onset of high PCB levels. Chick-edema disease is difficult to diagnose because there is no specific lesion, but rather there is a suite of lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Development and validation of in vitro induction assays for toxic halogenated aromatic mixtures: a review

Halogenated aromatic industrial compounds, typified by the polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) have been identified as residues in almost every component of the global ecosystem. Risk assessment of the complex mixtures of halogenated aromatics found in environmental samples is complicated by analytical problems and the lack of toxicological information on individual compounds and mixtures. Research in our laboratory has focused on the development and vadidation of the in vitro aryl hydrocarbon hydroxylase (AHH) induction assay in rat hepatoma H-4-II E cells in culture for quantitating individual toxic halogenated aryl hydrocarbons and their mixtures. For several PCB, PCDD, PCDF congeners, their mixed bromo/chloro analogs and reconstituted mixtures there was an excellent linear correlation between their -log ED50 values for AHH induction in rat hepatoma cells and their -log ED50 values for in vivo hepatic microsomal AHH induction, inhibition of body weight gain and thymic atrophy in the rat. It has also been shown for selected compounds that there was a good correlation between their in vitro AHH induction potencies and their effects in guinea pigs (AHH induction, inhibition of body weight gain) and mice (immunotoxicity). This assay system has been utilized to quantitative the "2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents" present in extracts from diverse sources including fly ash from a municipal incinerator and pyrolyzed brominated flame retardants which contain a complex mixture of halogenated dibenzo-p-dioxins and dibenzofurans.

Gas chromatographic/mass spectrometric analysis of specific isomers of polychlorodibenzofurans

The gas chromatographic/mass spectrometric characteristics of 26 congeners of polychlorinated dibenzofurans, previously characterized by specific synthetic routes and by standard spectroscopic techniques, have been evaluated. The electron impact mass spectra are not particularly isomer-specific, though 2,3,7,8-tetrachlorodibenzofuran is distinguishable on this basis from the three other tetrachloro isomers investigated in this work. Positive ion methane chemical ionization mass spectra do show a greater degree of isomer distinction, and are reasonably reproducible. Electron attachment negative ion spectral characteristics are also presented. Preliminary results on negative ion chemical ionization mass spectra, obtained using methane plus small amounts of oxygen as reagent gas, are reported.

Toxicological manifestations of 2,4,5,2',4',5'-, 2,3,6,2',3',6'-, and 3,4,5,3',4',5'-hexachlorobiphenyl and Aroclor 1254 in mink

Adult female mink were fed diets that contained 2.5 ppm Aroclor 1254, 0.1 or 0.5 ppm 3,4,5,3',4',5'-hexachlorobiphenyl (345 HCB), 2.5 or 5.0 ppm 2,4,5,2',4',5'-hexachlorobiphenyl (245 HCB) or 2,3,6,2',3',6'-hexachlorobiphenyl (236 HCB), or a control diet from 1 mo prior to breeding through parturition. All mink fed 0.5 ppm 345 HCB died within 60 d, while those fed 0.1 ppm showed 50% mortality after 3 mo exposure. Only one stillborn kit was whelped in the Aroclor 1254 group. No adverse reproductive effects were observed in the animals fed 236 HCB or 245 HCB. Plasma progesterone concentrations were significantly depressed by Aroclor 1254 and significantly elevated by 0.1 ppm 345 HCB. 17 beta-Estradiol concentrations were not significantly altered by any of the dietary treatments. Hepatic microsomal cytochrome P-450 concentrations were significantly elevated by all treatments except 236 HCB, with the largest increases occurring in mink exposed to Aroclor 1254 and 345 HCB. Aminopyrine N-demethylase activity was elevated by 5.0 ppm 245 HCB. Aroclor 1254 caused significant elevations in both benzo[a]pyrene hydroxylase and ethoxyresorufin O-deethylase activities. Benzo[a]pyrene hydroxylase activities were also significantly elevated in mink fed 245 HCB and 345 HCB. Aroclor 1254 caused a significant elevation in cerebellar and hypothalamic norepinephrine concentrations and a significant elevation in hypothalamic dopamine concentrations. Cerebral dopamine was elevated by 0.1 ppm 345 HCB, while midbrain dopamine levels were depressed. Norepinephrine concentrations were significantly elevated by 5.0 ppm 236 HCB in the midbrain and by 5.0 ppm 245 HCB in the medulla.

Accumulation of a commercial polychlorinated biphenyl mixture (Aroclor 1016) in adult rhesus monkeys and their nursing infants

Female rhesus monkeys (24) were divided into 3 groups and fed diets calculated to contain 1.0, 0.25 or 0 parts per million (ppm) of a commercial mixture of polychlorinated biphenyls (PCBs), Aroclor 1016. The animals consumed a calculated total of 18.1 +/- 3.1, 4.5 +/- 0.6 and 0 mg Aroclor 1016/kg of body weight over the 87 +/- 9 week experimental period. All animals were bred, conceived and experienced uncomplicated pregnancies. The birth weights of the infants born to females receiving the 1.0 ppm PCB diets were significantly less than those of the control infants. There was a positive relationship between the levels of Aroclor 1016 in the tissues and the dose administered in the diets. Aroclor 1016 content of infant tissues was consistent with maternal adipose tissue PCB levels. The content of Aroclor 1016 in the milk fat of the animals more closely approximated that in the individual's adipose tissue than in the serum. At weaning, the mesenteric fat of the experimental infants contained concentrations of Aroclor 1016 which were 4-7 times that found in the mothers. Analyses of the tissues and fluids of the experimental animals demonstrated accumulation of PCB isomerides. The number of isomerides present and the ratio of those detected differed between adult and infants as well as between milk and serum. After weaning, the pattern of Aroclor 1016 isomerides present in the infants' adipose was similar to that observed at weaning although the concentrations had decreased.

A comparative study of polychlorinated dibenzofurans, polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin on aryl hydrocarbon hydroxylase inducing potency in rats

The aryl hydrocarbon hydroxylase (AHH) inducing potency of toxic chlorinated aromatic hydrocarbons such as polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was studied in the young male Wistar rats. Alternatively, a technical PCDF mixture, 15 individual PCDF isomers or TCDD were administered i.p. in doses of 5 micrograms/kg; a PCB mixture was given in a dose of 50 mg/kg. The order of AHH inducing ability was TCDD greater than PCDFs much greater than PCBs in kidney, lung, and liver. In the prostate, thymus, and spleen, only TCDD enhanced the AHH activity. The AHH inducibility in the lung and liver, induced by 15 pure PCDF isomers with varying chlorine substitutions was also examined. Only 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-tetra-CDF) and 2,3,4,7,8-pentachlorodibenzofurans (2,3,4,7,8-penta-CDF) significantly induced the hepatic AHH activity (4- and 2-fold, respectively), while eight PCDF isomers, including these two, significantly enhanced the pulmonary AHH activity (6- to 30-fold). Taking into account both the potent AHH inducibility and the high bioaccumulation of these compounds, 2,3,7,8-tetra- and 2,3,4,7,8-penta-CDF should be given due attention with regard to environmental-related factors and the possibility of involvement in the etiology of "yusho" disease.

Liver morphology in guinea pigs administered either pyrolysis products of a polychlorinated biphenyl transformer fluid or 2,3,7,8-tetrachlorodibenzo-p-dioxin

A transformer cooled and insulated with a mixture of 65% Aroclor 1254 and 35% chlorinated benzenes located in the Binghamton State Office Building in Binghamton, New York, was involved in a fire, which produced soot containing polychlorinated biphenyls, biphenylenes, dioxins, and dibenzofurans. A single dose of either soot or 2,3,7,8-tetrachlorodibenzo-p-dioxin in aqueous methyl cellulose was administered by gavage to Hartley guinea pigs of both sexes. The liver tissue was examined 42 days after administration. By light microscopy hypertrophy of hepatocytes, steatosis, focal necrosis, and cytoplasmic hyalin-like bodies were observed as a result of both treatments. Bile duct proliferation (adenofibrosis) was observed only in the guinea pig groups administered soot. These animals also showed proliferation of the smooth endoplasmic reticulum, concentric membrane arrays (CMA), mitochondrial alterations, decreased rough endoplasmic reticulum, and autophagolysosomes by electron microscopy. The CMAs, which corresponded to the hyalin-like bodies, surrounded lipid droplets and cytoplasmic matrix containing mitochondria and degenerating organelles.

Mutagenicity testing of chlorinated biphenyls and chlorinated dibenzofurans

4 chlorinated biphenyl and 5 chlorinated dibenzofuran compounds have been evaluated in the reversion assay developed by B.N Ames using Salmonella typhimurium histidine auxotrophs. All these compounds (2,4,2'-4'-tetrachlorobiphenyl, 3,4,3',4'-tetrachlorobiphenyl, 4-chlorobiphenyl, 2,4,,6,2',4',6'-hexachlorobiphenyl, dibenzofuran, 2,9-dichlorodibenzofuran, 3,6-dichlorodibenzofuran, 2,3,7,8-tetrachlorodibenzofuran and octachlorodibenzofuran) were nonmutagenic for strains TA98 and TA100 when tested over a 3-log dose range. They were also not mutagenic whether or not varying concentrations of microsomal extracts (S9) from uninduced rats or from rats induced by several methods were included in the experimental protocol.

General approach to the fractionation and class determination of complex mixtures of chlorinated aromatic compounds

Among the "inadvertent" environmental pollutants are polychlorinated biphenyls, terphenyls, quadphenyls, naphthalenes, diphenyl ethers, dibenzofurans, dibenzo-p-dioxins and benzenes. Mixtures of these classes of compounds also occur in commercial products such as transformer fluids. To analyze such mixtures, gas chromatography--mass spectrometry may be combined with pre-fractionation on basic and acidic alumina columns and semi-quantitative perchlorination techniques. These procedures are illustrated for synthetic mixtures as well as for two samples of stored transformer fluid. Although the described procedure is mainly intended to be applied to the characterization of the major class components of such mixtures, it is also applicable to the determination of trace components such as the dibenzofurans in commercial polychlorinated biphenyls. The mass spectral techniques permit the simultaneous patterning, or "fingerprinting", of the compounds comprising each major class of chlorinated aromatics present.

Polychlorinated biphenyls (Aroclors 1016 and 1242): effects on survival and reproduction in mink and ferrets

Diets that contained various levels of supplemental Aroclor 1242 or Aroclor 1016 were fed to mink and ferrets to investigate the chronic toxicity of these PCBs in two closely related species. In mink, Aroclor 1242 was found to be more toxic than comparable or higher levels of Aroclor 1016. The Aroclor 1242 diets caused complete reproductive failure at levels as low as five ppm of the diet. Aroclor 1016 impaired reproduction less than Aroclor 1242. Although fewer females whelped and the four-week kit weights were less than the control animals, no outward signs of abnormalities beyond their smaller size were found in the kits whelped and nursed by dams fed Aroclor 1016. Ferrets were more resistant to the effects of either PCB mixture than were the mink, as noted by the lower mortality rate on the Aroclor 1242 diet and the almost normal level of reproduction on the Aroclor 1016 diet. Feeding Aroclor 1242 at 20 ppm resulted in complete reproductive failure, but was not fatal to adult ferrets. This finding is in sharp contrast to the 100% mortality of adult mink fed the same level. Although the chlorine content is similar in both compounds, Aroclor 1242 has a higher percentage of molecules with five or more chlorines per biphenyl. This difference in higher substituted biphenyl isomer content and/or the reduced levels of contaminants in the Aroclor 1016 mixture may be of major importance in evaluating the toxicity of these compounds.