In vitro toxicity profiling of ultrapure non-dioxin-like polychlorinated biphenyl congeners and their relative toxic contribution to PCB mixtures in humans.
Toxicol Sci
; 121(1): 88-100, 2011 May.
Article
en En
| MEDLINE
| ID: mdl-21357386
ABSTRACT
The toxic equivalency concept used for the risk assessment of polychlorinated biphenyls (PCBs) is based on the aryl hydrocarbon receptor (AhR)-mediated toxicity of coplanar dioxin-like (DL) PCBs. Most PCBs in the environment, however, are non-dioxin-like (NDL) PCBs that cannot adopt a coplanar structure required for AhR activation. For NDL-PCBs, no generally accepted risk concept is available because their toxicity is insufficiently characterized. Here, we systematically determined in vitro toxicity profiles for 24 PCBs regarding 10 different mechanisms of action. Prior to testing, NDL-PCB standards were purified to remove traces of DL compounds. All NDL-PCBs antagonized androgen receptor activation and inhibited gap junctional intercellular communication (GJIC). Lower chlorinated NDL-PCBs were weak estrogen receptor (ER) agonists, whereas higher chlorinated NDL-PCBs were weak ER antagonists. Several NDL-PCBs inhibited estradiol-sulfotransferase activity and bound to transthyretin (TTR) but with much weaker potencies than reported for hydroxylated PCB metabolites. AhR-mediated expression of uridine-glucuronyl transferase isozyme UGT1A6 was induced by DL-PCBs only. Hierarchical cluster analysis of the toxicity profiles yielded three separate clusters of NDL-PCBs and a fourth cluster of reference DL-PCBs. Due to small differences in relative potency among congeners, the highly abundant indicator PCBs 28, 52, 101, 118, 138, 153, and 180 also contributed most to the antiandrogenic, (anti)estrogenic, antithyroidal, tumor-promoting, and neurotoxic potencies calculated for PCB mixtures reported in human samples, whereas the most potent AhR-activating DL-PCB-126 contributed at maximum 0.2% to any of these calculated potencies. PCB-168 is recommended as an additional indicator congener, given its relatively high abundance and antiandrogenic, TTR-binding, and GJIC-inhibiting potencies.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Bifenilos Policlorados
Tipo de estudio:
Risk_factors_studies
Límite:
Humans
Idioma:
En
Revista:
Toxicol Sci
Asunto de la revista:
TOXICOLOGIA
Año:
2011
Tipo del documento:
Article
País de afiliación:
Países Bajos
Pais de publicación:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
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UNITED STATES
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UNITED STATES OF AMERICA
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US
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USA