Comparative fates of three structurally distinct PCB congeners in rats and house flies

Saghir, Shakil Ahmed

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Description

Title

Comparative fates of three structurally distinct PCB congeners in rats and house flies

Author(s)

Saghir, Shakil Ahmed

Issue Date

1994

Doctoral Committee Chair(s)

Hansen, Larry G.

Department of Study

Comparative Biosciences

Discipline

Veterinary Medicine

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Health Sciences, Toxicology
• Health Sciences, Pharmacology
• Environmental Sciences

Language

eng

Abstract

• The toxicity, biotransformation and biological activities of polychlorinated biphenyls (PCBs) are influenced by the number and position of chlorine atoms on the biphenyl rings. The excretion and tissue retention of three $\sp{14}$C-labeled structurally distinct lower chlorinated PCBs (2,2$\sp\prime$,5-tri-, 2,2$\sp\prime$,4,4$\sp\prime$-tetra- and 3,3$\sp\prime$,4,4$\sp\prime$-tetrachlorobiphenyls) were examined in prepubertal (24-day old) rats following iv injection into the tail vein. Toxicokinetics and enzyme-related toxicities of these PCBs were also examined in female house flies following topical application.
• The total excretion of 2,2$\sp\prime$,5-triCB within 72 hours was 62% and 51%, whereas excretion of 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB was 22% and 25% and 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB was only 6.7% and 10% in male and female rats, respectively. Elimination half-lives of 37.5, 672, and 186 hours for males and 49.2, 351, and 152 hours for females were determined for 2,2$\sp\prime$,5-triCB, 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB and 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB, respectively. At 72 hours following dosing, the highest concentrations were generally found in serum, adrenals, fat and ovaries. Much of the 2,2$\sp\prime$,5-triCB and 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB was tightly bound to the tissues and serum; serum-bound CB was associated with serum albumin in vitro, whereas in vivo binding was predominantly to proteins other than serum albumin.
• In house flies, the rapidly absorbed and excreted 2,2$\sp\prime$,5-triCB was more toxic to 5-day old flies when the microsomal enzyme levels were highest. Although 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB was very acutely toxic, it was slightly less toxic to 5-day old flies. Low absorption of 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB probably contributed to its low toxicity at all ages (1-, 5-, and 15-day).
• The 2,2$\sp\prime$,5-triCB was very rapidly metabolized to at least 19 different metabolites, whereas 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB was metabolized very slowly. The dose dependent half-lives of elimination of 2,2$\sp\prime$,5-triCB were from 5-8 hours, whereas 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB half-lives ranged from 49-112 hours. The absorption of 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB was very slow, but metabolism was relatively rapid. Half-lives of elimination of 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB ranged from 32 to 280 hours.
• All three PCBs were absorbed by simultaneous rapid and slow absorption processes, penetrating through the thoracic cuticle and spreading laterally to the head and abdomen, probably through the waxy monolayers. Peak concentrations of 2,2$\sp\prime$,5-triCB were found in the alimentary canal within 6 hours, whereas 2,2$\sp\prime$,4,4$\sp\prime$-tetraCB took longer and the concentration was lower. The slowly absorbed 3,3$\sp\prime$,4,4$\sp\prime$-tetraCB reached peak concentrations in the alimentary canal much later (12-48 hours).

Type of Resource

text

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Copyright 1994 Saghir, Shakil Ahmed

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