Critical evaluation of polychlorinated biphenyl toxicity in terrestrial and marine mammals: Increasing impact of non-ortho and mono-ortho coplanar polychlorinated biphenyls from land to ocean

Residues of potentially toxic non-ortho chlorine substituted coplanar 3,3,4,4-tetra-,3,3,4,4,5-penta-, 3,3,4,4,5,5-hexachlorobiphenyl and their mono- and di-ortho analogs (2,3,4,4,5-penta-, 2,3,3,4,4-penta-, 2,3,3,4,4,5-hexa-and 2,2,3,3,4,4-hexa-, 2,2,3,4,4,5-hexa-chlorobiphenyl) were determined in humans, dogs, cats (terrestrial), a finless porpoise (Neophocoena phocoenoides-coastal), Dall's porpoises (Phocoenoides dalli,dalli), Baird's beaked whales (Berardius bairdii) and killer whales (Orcinus orca-open ocean). Among the coplanar polychlorinated biphenyl (PCB) congeners, the concentration of the di-ortho congeners was the highest and the non-ortho congeners was the lowest. However, all three coplanar PCBs occurred at significantly higher levels than toxic polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). The relative bioconcentration and metabolic capacity of terrestrial and marine mammals to these chemicals, suggest that the toxic threat of coplanar PCBs increases from land to ocean, but the reverse is true for PCDDs and PCDFs. The toxic threat of coplanar PCBs to higher aquatic predators such as cetaceans was principally assessed by 2,3,7,8-T₄CDD Toxic Equivalent Analysis which is based on the induction of arylhydrocarbon hydroxylase (AHH) and ethoxyresorufinO-deethylase (EROD). Analysis indicates, in particular, that the bioaccumulation of toxic 3,3,4,4,5-penta- and 2,3,3,4,4-pentachlorobiphenyls in carnivorous marine mammals is a cause for considerable concern.     

Congener-specific data on polychlorinated biphenyls in tissues of common porpoise from Puck Bay,Baltic Sea

Individual congeners of polychlorinated biphenyls (PCBs), including the highly toxic non-ortho coplanar 3,3,4,4-tetrachlorobiphenyl (IUPAC No. 77), 3,3,4,4,5-pentachlorobiphenyl (IUPAC No. 126), and 3,3,4,4,5,5-hexachlorobiphenyl (IUPAC No. 169), and their mono- and di-ortho analogs, have been identified and quantified in the blubber, liver, and muscles of three female common porpoise Phocoena phocoena collected from the Puck Bay (inner Gulf of Gdask, Poland) in 1989–1990, to elucidate actual concentrations and toxic potential. The total 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalent for 13 coplanar PCBs in blubber was 1,500±470 pg/g wet wt. 2,3,4,4,5-Pentachlorobiphenyl (IUPAC No. 118) was the most contributing individual and occupied between 57 and 67% in total toxic equivalent of coplanar PCBs in blubber, while 2,2,4,4,5,5-hexachlorobiphenyl (IUPAC No. 153), 2,3,3,4,4-pentachlorobiphenyl (IUPAC No. 105) and 2,2,3,4,4,5-hexachlorobiphenyl (IUPAC No. 138) comprised between 9.5–14, 7.6–11.5, and 7.2–11.0%, respectively (totally 82–95%), and 2,3,3,4,4,5-hexachlorobiphenyl (IUPAC No. 156) was absent. A potentially most toxic non-ortho PCB members such as 3,3,4,4,5-pentachlorobiphenyl, 3,3,4,4,5,5-hexachlorobiphenyl and 3,3,4,4-tetrachlorobiphenyl were only minor contributors, altogether occupying between 1.0 and 14.5% in total TEQ of coplanar PCBs. Concentrations of total PCBs in lipids of the blubber ranged from 26 to 47 g/g and were comparable or lower than reported earlier for common porpoises from the Baltic Sea, North Sea, and North Atlantic by other authors.     

Levels of organochlorine pesticides and polychlorinated biphenyls (PCBs) in mothers' milk collected in Osaka prefecture from 1969 to 1976

Long-term investigations of polychlorinated hydrocarbon levels in mothers' milk were made from 1969 to 1976. The levels ofp,p-DDE, p,p DDT, dieldrin and PCB in mothers' milk were within the range reported by others. However, -BHC(Hexachlorocyclohexane) levels in the milk were 10 times that found in non-Japanese. A gradual decrease in the -BHC level in the milk was observed during this period. In contrast, the levelsof p,p-DDE,p,p-DDT, dieldrin and PCB were consistent for the 7-year period. A significant correlation between the levels of PCB andp,p-DDE in mothers' milk and blood was observed in the 1974–1976 samples. However, after prohibition of the use of chlorinated hydrocarbons, this relationship was less apparent in the 1972–1973 samples.     

DDT Residues in samples of human milk,and in mothers' and cord blood serum,in a continental town in Croatia (Yugoslavia)*

Summary Concentrations of p,p'-DDE, p,p-DDD, and p,p-DDT were determined in 34 samples of human milk obtained 3–5 days after delivery and in 37 samples obtained at later times of lactation (up to 55 weeks). All samples contained p,p-DDE, but only several contained p,p-DDD and p,p-DDT. The concentrations of p,p-DDE were 31 g/l in the beginning of lactation and 53 g/l at later time intervals. The concentration ranges in both groups overlap almost completely and the difference in the mean values is not significant.Serum samples from 35 mothers and cord blood were also analyzed. All samples contained p,p-DDE, the concentrations being 18 g/l and 6.8 g/l in the mothers' and cord blood serum, respectively. Serum samples of 24 nonpregnant women contained the same amount of p,p-DDE (20 pg/1) as mothers' sera.All samples were collected in a continental town of Croatia (Yugoslavia) between 1977 and 1979. The concentrations of DDT residues were determined by gas chromatography, and two methods for extraction from milk were used and compared.This work was supported in part by the Environmental Protection Agency (USA) and the World Health Organization (Geneva)     

Polychlorobiphenyls, ΣDDT,and hexachlorocyclohexane isomers in the western North Pacific ecosystem

Polychlorobiphenyls (PCBs), DDT (p,p-DDT,p,p-DDD, andp,p-DDE and HCH isomers (hexachlorocyclohexanes including , , and isomers) were determined in a marine food chain, including seawater, zooplankton, myctophid, squid and striped dolphin collected from the western North Pacific waters. The concentrations of these pollutants increased in higher trophic levels, where the highest bioconcentration factors (concentration ratio in organisms to water), as much as 10⁷, were obtained from both PCBs and DDT in striped dolphin. The proportions of highly chlorinated biphenyls,p,p-DDE and -HCH increased in higher-ranking predators. These observations suggest that the bioaccumulation mechanisms in lower trophic levels depend primarily on the physicochemical properties of pollutants, whereas those in higher trophic levels are affected by the biodegradability of the pollutants and the metabolic capacity and life-span of the organisms.     

Polychlorobiphenyl congeners,p,p′-DDE,and sperm function in humans

170 seminal samples from fertile men, men with idiopathic oligospermia or azoospermia and men status post vasectomy were analyzed for 74 polychlorobiphenyl (PCB) congeners,p,p-DDE, mirex, and hexachlorobenzene using the technique of glass capillary gas chromatography with electron capture detection. Low concentrations of 32 PCB congeners were measured (mean total PCB residue of 5.8 ng/g wet weight). The application of multiple linear regression analysis to the data is described and the result is critically evaluated. There is a correlation between sperm motility and count. There are indications that the concentrations of three PCB congeners (2,4,5,245- and 2,4,5,234-hexachlorobiphenyl and 2,4,5,34-pentachlorobiphenyl) are inversely correlated with sperm motility index in samples with a sperm count less than 20 million cells/ml. The implications of the discerned associations are discussed.     

Polychlorinated biphenyls: Photolysis of 3,4,3′,4′-tetrachlorobiphenyl and 4,4′-dichlorobiphenyl in solution

Summary The large difference in retention times for the photoproducts of 3,4,34-tetrachlorobiphenyl can be explained on the basis of their chlorine content and the effect of vicinal chlorosubstitution as observed by V. Zitko and coworkers (4).The absence of biphenyl among the photoproducts of 4,4-dichlorobiphenyl was not surprising since 4-chlorobiphenyl (max 203, 253) does not absorb at the wavelength of irradiation (>286), 4,4-dichlorobiphenyl exhibits only marginal absorption at this wavelength (max 201, 259, 286) this explains the low yield of 4-chlorobiphenyl obtained (appx. .1%). The greater reactivity at the meta position may be the result of bond weakening due to steric interactions with the chlorine atom at the para position. Rate studies may provide an answer to this problem.     

Accumulation and persistence of individual polychlorinated biphenyl congeners in liver,blood, and adipose tissue of rats following dietary exposure to Aroclor® 1254

Female F344/NCr rats were exposed continuously to Aroclor^® 1254 (1, 3.3, 10, 33, or 100 ppm in the diet) for 7, 28, or 84 days in order to assess the accumulation of polychlorinated biphenyls (PCBs) in liver, blood, and adipose tissue. The persistence of the individual PCB congeners which are detected in liver was examined in the three tissues of additional groups of rats exposed for 7 days followed by 21 days on control diet, or for 28 days followed by 56 days on control diet. Limited accumulation of PCB congeners with low chlorine substitution (tri- and tetrachlorobiphenyls) in the liver and blood, and preferential retention of highly substituted PCB congeners (penta-and hexachlorobiphenyls) were observed in rats continuously exposed to Aroclor. In these rats, time- and dose-dependent increases in the relative levels of two congeners which cause profound phenobarbital-type induction [2,2,3,4,4,5-hexachlorobiphenyl (BZ# 138) and 2,2,4,4,5,5-hexachlorobiphenyl (BZ# 153)] were detected in the liver and adipose tissue. Rats receiving control diet following Aroclor treatment displayed a time- and dose-dependent decrease in the relative levels in blood, adipose and hepatic tissue of 2,3,34,4-pentachlorobiphenyl (BZ# 105) and 2,3,4,4,5-pentachlorobiphenyl (BZ# 118), two of the major congeners showing both TCDD- and phenobarbital-type induction. These rats also displayed increases in the relative adipose levels of another relatively potent mixed-type inducer, 2,3,3,4,4,5-hexachlorobiphenyl (BZ# 156), and increases in adipose and hepatic levels of the pure phenobarbital-type inducer, 2,2,4,4,5-pentachlorobiphenyl (BZ# 99).     

Chromatographic determination of dicofol and metabolites in egg yolks

Egg yolk was spiked withp,p-dicofol (p,p-DCF) (0.1–2.0 g/gm),p,p-dichlorobenzophenone (p,p-DCBP) (0.1–2.0 (g/gm), and 1,1-bis(4-chlorophenyl)-2,2-dichloroethylene (p,p- DDE) (0.05–1.0 g/gm). The fortified egg yolk (2–5 g) was mixed with acetonitrile to extract non-fat organic materials. After removal of acetonitrile, the spiked chemicals were separated with a column chromatograph packed with acid alumina. Recovery efficiencies forp,p-DCBP andp,p-DDE were determined by gas chromatography, and forp,p-dicofol by high performance liquid chromatography. The recovery efficiencies forp,p-dicofol,p,p-DCBP andp,p-DDE were 77.2–93.8%, 84.1–101.1%, and 88.5–96.0%, respectively.     

Effects of thyroidectomy on the storage of organochlorine insectisides

Summary Rats submitted to p,p-DDT at 200 ppm in drinking water showed increased p, p-DDT storage which was not statistically different from that of thyroidectomized rats receiving p, p-DDT. Rats receiving p, p-DDT also showed increased fat storage of total o, p-DDT and Dieldrin and decreased total BHC storage.Thyroidectomy decreased the amount of p, p-DDT naturally occurring in the animal body and raised the metabolization of this compound.In thyroidectomized rats submitted to the same dosage of p, p-DDT, increased storage of p, p-DDT, o, p-DDT and Dieldrin was found. A statistically significant increase in BHC was also observed.It is concluded that p, p-DDT in the diet may affect the storage level of other organochlorine insecticides depending on its concentration, and that the physiopathological state of the body, e. g. thyroidectomy has a definite influence on the storage of organochlorine insecticides in the animal body and on their biological effect.     

Levels of β-HCH,HCB, p,p′-DDE,p,p′-DDT and PCBs in human milk from a continental town in Croatia,Yugoslavia

Summary Concentrations of -HCH, HCB, p,p-DDE, p,p-DDT and PCBs were determined by gas chromatography in 50 human milk samples collected from the general population during 1981/1982 in a continental town in Croatia (Yugoslavia). The samples were collected between one and 22 weeks after delivery from mothers breast-feeding one child only. The mothers' age was 18 to 31 years, and they were nursing their first or second child. All 50 samples contained -HCH, HCB, p,p-DDE and PCBs, whereas p,p-DDT was present in 37 samples. The concentrations of -HCH, HCB, p,p-DDE, p,p-DDT and PCBs expressed on a whole milk basis were (median in g/kg): 11, 7.1, 67, 7.3 and 22 respectively, and expressed on a fat basis (median in mg/kg): 0.28, 0.21, 1.9, 0.18 and 0.62 respectively. The fat content was 3.7% (median). PCBs were present in a mixture containing penta-, hexa- and heptachlorobiphenyls.     

Residual organochlorine pesticides in the fat of mutton birds of New Zealand

Summary The organochlorine insecticides pp-DDT, its metabolites pp-DDE and pp-DDD, -HCCH, HEOD and PCBs were identified in the fat of mutton birds of New Zealand. The mean levels for six adult birds were: total DDT 17.30 ppm (78% pp-DDE), pp-DDT 1.54 ppm, pp-DDE 13.50 ppm, pp-DDD 0,64 ppm, -HCCH 5.17 ppm, HEOD 0.93 ppm, PCBs 1.83 ppm. All the compounds found in the adult birds except -HCCH, were also present in a chick bird but in considerably smaller amounts.     

Polychlorobiphenyis (PCBs) in sediments of Tokyo Bay,Japan

Sediment cores were collected from five sites in Tokyo Bay. The sediment age was estimated by the²¹⁰Pb method and the polychlorobiphenyls (PCBs)(2,5,2,4,5 — pentachlorobiphenyl,3,4,2,4, 5-pentachlorobiphenyl, 3,4,2,3,4-pentachlorobiphenyl, 2,3,6,2,3,6-hexachlorobiphenyl, 2,4, 5,2,4,5-hexachlorobiphenyl, and 2,4,5,2,3,4, 5-heptachlorobiphenyl) profiles in the sediments were determined quantitatively by gas chromatography. With respect to the horizontal distribution of PCBs, the levels were highest off Tokyo and Kawasaki, the inner western part of the bay off the mouths of the Tama and Arakawa Rivers, and declined in the direction of the eastern and southern parts of the bay. It was assumed that most of the PCBs supplied to the bay from the adjacent rivers and the industrial zones along the western coast were coprecipitated with suspended particles near the river mouths and the western coast, while PCBs adsorbed by fine particles are carried throughout the bay by the current. The accumulation rate of PCBs in Tokyo Bay sediments gradually increased, starting about 1936, and reached a maximum value in 1972 and declined moderately thereafter. The time-dependent changes in the quantity released into the environment were estimated from the amount of PCBs manufactured and used. The accumulation rate of PCBs in Tokyo Bay sediments was then compared with the estimated rate of release into the environment.     

Polychlorinated biphenyl congeners (PCBs),p,p′-DDE and hexachlorobenzene in human milk in three areas of upstate New York

Forty human milk samples from women in an urban and a rural vicinity on Lake Ontario (Rochester and Oswego) and a mixed urban and rural location on the Hudson River (Albany), New York, were analyzed for 74 PCB congeners,p,p-DDE, hexachlorobenzene, and mirex in order to determine the intake of breast-fed infants. All of the compounds were detected in the samples, but only eight PCB congeners andp,p-DDE accounted for 88% of the chlorinated hydrocarbons detected.p,p-DDE was the predominant pollutant (mean 78 ng/g wet weight), but the levels detected were low compared with the results from other parts of North America. Eight individual PCB congeners comprise 52% of the total PCB residue (mean 26.5 ng/g of whole milk); they ranged in mean concentration from 3.2 ng/g (2,4,5,2,4,5-hexachlorobiphenyl) to 1 ng/g (2,3,4,3,4-pentachlorobiphenyl). Statistical correlation analysis among PCB congeners indicates a possible higher exposure to less chlorinated congeners at Oswego than at Albany.     

The ultraviolet absorption spectra of some chlorinated biphenyls

The UV spectra of 29 chlorobiphenyls have been examined. With increasing chloro substitution in which there are less than two chlorine groupsortho to the Ph-Ph bond the _max values for the band (attributed to conjugation between the two phenyl rings) are shifted to longer wavelengths and for the more highly substituted chlorobiphenyls there is also a bathochromic shift of the main band (due to the benzenoid skeleton). Introduction of two or more chlorine atoms ortho to the Ph-Ph bond results in a hipsochromic shift of band and diminished value due to steric inhibition of resonance between the two phenyl rings. The sterically hindered chlorobiphenyls and the more highly chlorinated Aroclors also exhibit a series of low-intensity finestructured absorption maxima between 268–302 nm. The UV spectra of chlorobiphenyls are particularly diagnostic with respect to the degree of substitution at the 2, 2, 6 and 6 positions and can be used in the structural analysis of separated chlorobiphenyls. The data may also aid in correlating the photochemical reactivities.     

Presence of PCB,DDE and DDT in human milk in the provinces of New Brunswick and Nova Scotia,Canada

Summary PCB, p,p-DDE and p,p-DDT residue levels were measured in human milk from New Brunswick and Nova Scotia. Preliminary results indicate that the levels of p,p-DDT and p,p-DDE are higher in the former area, possibly because of the wider use of insecticide sprays in the past. It should be emphasized that because of the limited number of samples analyzed, further work must be done before a significant difference in these areas can be established.     

Chronic toxicity and bioaccumulation of 2,5,2′,5′- and 3,4,3′,4′-tetrachlorobiphenyl and Aroclor® 1242 in the amphipodHyalella azteca

The addition of 100 (g/L of Aroclor^® 1242 (A1242) or 2,5,2,5-tetrachlorobiphenyl (TeCB) during 10 week chronic toxicity tests withHyalella azteca resulted in complete mortality. There were no effects on survival, growth, or reproduction after addition of 30 g/L. Toxic effects were observed at tissue levels of between 30 and 180 g/g on a wet weight basis, and tissue levels appear to be a better indicator of toxicity than levels in water. No toxic effects were observed after additions of up to 2,700 g/L of the coplanar congener 3,4,3,4-TeCB.H. azteca has the ability to avoid accumulating in excess of 140 g/g 3,4,3,4-TeCB. The amount taken up was proportional to the amount added in water up to 100 g/L, but was constant at higher additions, possibly accounting for its relatively low toxicity. The low toxicity of the coplanar congener, as compared to the non-coplanar 2,5,2,5-TeCB, is in direct contrast to the high toxicity of coplanar PCB congeners to mammals and may be associated with slower rates of aromatic hydrocarbon metabolism in amphipods. Polychlorinated biphenyl levels measured in amphipods from Lake Ontario are approximately 100-fold below levels associated with toxicity inH. azteca, but are above levels which, through biomagnification up the food chain, lead to salmonid residues in excess of 2 g/g, a tolerance limit for human consumption.     

Toxicity and persistence of PCB homologs and isomers in the avian system

This study reports the biotransformation and persistence of PCBs in the hen, her eggs, and chicks hatched from these eggs. Twelve White Leghorn hens and one rooster were given 50 µg/ml of the PCB mixture Aroclor 1254 in their drinking water (6.3 mg/kg body weight) for six weeks. The resultant concentration in the yolk of eggs laid during the following 20 weeks and in the tissues of surviving embryos and chicks was determined by thin-layer chromatography and gas chromatography. Mortality of embryos and deformity of chicks were found to be correlated with PCB content of the eggs. Moreover, after storage of the PCB mixture in the hen's body, the toxic potency of the PCB mixture deposited in the eggs more than doubled. It was shown that 3,4,2,3,6-pentachlorobiphenyl (peak 9) was cleared faster from the hen than 3,4,2,4,5-pentachlorobiphenyl (peak 12) and 2,3,4,2,4,5-hexachlorobiphenyl (peak 14) and that 4,4-chlorination is more important than degree of chlorination in determining persistence of chlorinated biphenyls in the hen, embryo, and chick.     

DDT,DDD, and DDE contamination of sediment in the Newark Bay estuary,New Jersey

Two hundred and forty-six surface and buried sediment samples from Newark Bay, New Jersey, and its major tributaries (Passaic River, Hackensack River, Newark Bay, Arthur Kill, Elizabeth River, and Kill Van Kull) were assayed for p,p-dichlorodiphenyltrichloroethane (p,p-DDT), p,p-dichlorodiphenyldichloroethane (p,p-DDD), and p,p-dichlorodiphenylchloroethylene (p,p-DDE) between February 1990 and March 1993. Chronological profiles in sediments from pre-1940 to the present were determined by radioisotope activities of ²¹⁰Pb and ¹³⁷Cs. The concentrations of these chemicals were compared to National Oceanic and Atmospheric Administration (NOAA) benchmark sediment values (Long and Morgan 1991). The objectives were to (a) determine the spatial and temporal distributions of DDT compounds in sediments, (b) identify possible sources, and (c) assess the potential for sediment toxicity within the estuary. Mean concentrations in surface sediments in individual waterways ranged from 5 to 473 g/kg for p,p-DDT, 18 to 429 g/kg for p,p-DDD, and 5 to 111 g/kg for p,p-DDE. A regional background mean concentration of approximately 100–300 g/kg p,p-DDT (sum of p,p-DDT, p,p-DDD, and p,p-DDE) was measured in surface sediments throughout the estuary, with the exception of the Arthur Kill, where mean concentrations exceeded 700 g/kg. The elevated concentrations found in recently deposited surface sediments in the Arthur Kill may be due to the presence of ongoing sources. The highest concentrations in buried sediments occurred in the lower Passaic River at depths corresponding to historical deposits from 1940 to 1970, the peak time period for production and usage of DDT in the United States. Comparisons to NOAA benchmark sediment toxicity values indicate that p,p-DDT, p,p-DDD, and p,p-DDE concentrations in surface sediments may pose a potential hazard to fish, shellfish, and other benthic and demersal organisms in some portions of the estuary, particularly in the upper and lower Arthur Kill.     

Ethyl m-aminobenzoate methanesulfonate dependent and carrier dependent pharmacokinetics of extremely lipophilic compounds in rainbow trout

Significant differences were found in both uptake and pharmacokinetics in fish when six lipophilic compounds were dosed by gavage in either an oil or an gelatin carrier. Pharmacokinetics were also different when fish were anaesthetized with ethyl m-aminobenzoate methanesulfonate (MS-222) before dosing. The highest uptake percentages, uptake rates and concentrations of the compounds were found in the fish which were given the gelatin carrier only. MS-222 decreased the uptake of the compounds. Absorption of the compounds from oil was lower than from gelatin. In addition, absorption from oil continued for 21 d, which lasted longer than from gelatin. In the fish which were given the gelatin, the concentrations of the compounds in both muscle and liver showed a compound dependent decrease in the course of the experiment. In general, in all treatments higher concentrations were found in liver than in muscle. For each treatment, the absorption rates of pentachlorobenzene, hexachlorobenzene, 2,2,5,5-tetrachlorobiphenyl and 2,2,4,4,5,5-hexachlorobiphenyl were similar, but different from the other treatments. It can be concluded that the experimental methodology significantly affects the pharmacokinetic parameters that are used to model the bioconcentration of hydrophobic chemicals in the environment.