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

Bush, Brian; Tumasonis, Casimir F.; Baker, Frederick D.

doi:10.1007/bf01956169

Cited by 68 publications

(26 citation statements)

References 27 publications

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“…While each of peaks 1, 2, and 5 has two adjacent unsubstituted carbons, only peak 1 (of the structurally identified congeners) is metabolized by the microsomal monooxygenase system. These results seem to agree with the persistence in human tissue (21) of 2,4,5,2',4',5'-and 2,3,4,2',4',5'-hexachlorobiphenyls (the two equivalents of peaks 4 and 5 in PBBs, respectively) and the apparent resistance to in vivo metabolism of all those PCBs with a 4,4'-substitution in avians (22,23). Therefore, it appears that the presence of two adjacent unsubstituted carbons is not sufficient by itself to render the brominated biphenyl molecules vulnerable to microsomal oxidation.…”

Section: Discussionsupporting

confidence: 83%

“…Peak 2, the second pentabrominated component of PBBs, with bromines at the 2,4,5,3', and 4' positions was found to be resistant to metabolism. The same pentachlorinated biphenyl homologe was found to be persistent in tissues from humans (21) as well as chickens (22). Peaks 3 through 6 are all hexabrominated biphenyls, but only peak 3 is metabolized.…”

Section: Discussionmentioning

confidence: 95%

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Studies on the Microsomal Metabolism and Binding of Polybrominated Biphenyls (PBBs)

Dannan¹,

Moore²,

Aust³

1978

Environmental Health Perspectives

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The metabolism of polybrominated biphenyls (PBBs) was studied in vitro by using rat liver microsomes in the presence of NADPH and atmospheric 02. Quantitative recoveries of all PBBs were obtained after incubations with control or 3-methylcholanthrene (MC) induced microsomes. Of the twelve major components, losses of only peaks I (2,4,5,2',5'-pentabromobiphenyl) and 3 (a hexabromobiphenyl) were observed following incubations with microsomes from phenobarbital (PB)-or PBBs-pretreated rats. Of seven structurally identified PBB components, only peak 1 has a bromine-free para position. Peaks 1, 2, and 5 all have two adjacent unsubstituted carbons, yet only peak I is metabolized. Of two dibromobiphenyl model compounds studied, the 2,2'-congener was very rapidly metabolized by PB-induced microsomes whereas its 4,4'-isomer was not. These results suggest that the presence of a free para position is required for the metabolism of brominated biphenyls. Of lesser importance appears to be the number of bromines or the availability of two adjacent unsubstituted carbons. In vivo evidence for the metabolism of peaks 1 and 3 was also provided by their drastically diminished levels in liver and milk extracts. When a '4C-PBB mixture consisting almost exclusively of peaks 4 (2,4,5,2',4',5'-hexabromobiphenyl) and 8 (2,3,4,5,2'4',5'-heptabromobiphenyl) was incubated with PB-or PBBs-induced microsomes and NADPH, only traces of radioactivity remained with the microsomes after extensive extraction. However, less radioactivity was bound to microsomes from MC pretreated or especially control rats. No radioactivity was bound to exogenous DNA included in similar microsomal incubations, regardless of the type of microsomes used. Under the same conditions, [3H]-benzo[a]pyrene metabolites were bound to DNA, and PBB-induced microsomes enhanced this binding more than six-fold.

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Section: Discussionsupporting

confidence: 83%

Section: Discussionmentioning

confidence: 95%

Studies on the Microsomal Metabolism and Binding of Polybrominated Biphenyls (PBBs)

Dannan¹,

Moore²,

Aust³

1978

Environmental Health Perspectives

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“…The distribution and metabolism of PCBs in mammals and treated animals have appeared in many reports, and it was recognized that highly-chlorinated biphenyls accumulated in adipose tissues; however, low-chlorinated biphenyls were rapidly excreted from the body (Bush et al 1974, Jensen and Sundstrrm 1974a,b, Gage and Holm 1976. From their data, this tendency has been considered to be a common one.…”

Section: Pattern Analysismentioning

confidence: 99%

Long-term studies of the excretion of polychlorinated biphenyls (PCBs) through the mother's milk of an occupationally exposed worker

Yakushiji

Watanabe

Kuwabara

et al. 1978

Arch. Environ. Contam. Toxicol.

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Abstract.Long-term studies of the excretion of polychlorinated biphenyls (PCBs) through the mother's milk were conducted on an occupationally exposed worker, who worked with PCBs in a capacitor factory.PCBs level in the mother's blood was 57 ppb, a level 10 to 20 times higher than that of non-exposed persons. The other tissues and fluids obtained at time of delivery were also assayed. PCB contents in umbilicus tissues, umbilicus blood and amnion fluid were l/s, 1/4 and 1/8, respectively, the amount found in the mother's blood.An approximate 76% decrease in PCB levels in the milk were noted 16 months after delivery; 200 mg of PCBs were excreted in about 818 liters of milk for this 16-month period.A detailed analysis of the individual components in PCB residues clarified the remarkable changes of the PCB pattern in the blood.Since PCBs in mother's milk were detected in the high concentration range of 0.01 to 0.7 ppm on the whole milk basis in Japan in 1972 (Isono 1972), many research institutes have been investigating the environmental behavior of PCBs. Therefore, the residue levels to be expected and related new information became available from these studies (Takeshita et al. 1974, Hashimoto et al. 1976, Shimada 1976, Nakayama and Aoki 1977, Nishimura et al. 1977).In our investigation of PCBs in blood and mother's milk of non-exposed women for 6 years, we have been studying the problem of breast-feeding through the su-vey of PCBs. The levels of PCB in mother's milk and blood were almost stable from 1972 to 1977; in the range os 0.03 to 0.04 ppm on the whole milk basis (Yakushiji et al. 1977a, b). An average intake of 150 ml/kg of milk per day per baby would mean that each baby would consume approximately 4.5 to 6/zg/kg of PCB's per day. Then one-half the number of Japanese babies would ingest larger

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“…Although it is difficult to assess the role of metabolism here, the data would suggest a more rapid accumulation of the 2,4,5,3',4'-isomer in the egg. Other workers (30) have already observed a correlation between PCB content of eggs and embryo mortality and teratogenicity.…”

Section: Nonmetabolic Alteration Of Chlorinated Biphenylsmentioning

confidence: 99%