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Differential toxicity of three polychlorinated biphenyl congeners in developing sea urchin embryos
Author(s) -
Schweitzer Linda E.,
Hose Jo Ellen,
Suffet I. H.,
Bay Steven M.
Publication year - 1997
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620160726
Subject(s) - congener , toxicity , ec50 , polychlorinated biphenyl , developmental toxicity , sea urchin , ecotoxicology , biphenyl , environmental chemistry , biology , toxicology , chemistry , in vitro , biochemistry , ecology , gestation , genetics , pregnancy , organic chemistry
The relationship between body burden and toxicity of three individual polychlorinated biphenyl (PCB) congeners in developing sea urchin embryos was investigated to evaluate the validity of current predictive models of PCB toxicity in an invertebrate system. Body burdens of radiolabeled PCB congeners (IUPAC 47, 77, and 153) accumulated from seawater were used to determine median effective concentrations (EC50s) for developmental and cytogenetic effects following a 72‐h exposure. Congener 47, a di‐ ortho ‐substituted tetrachlorobiphenyl, was found to be at least four times more toxic than congener 77, a non‐ ortho ‐substituted (coplanar) tetrachlorobiphenyl, with EC50s of 47 and >218 mmol/kg, respectively, using an embryo development assay. This result contradicts the structure–activity prediction of the mammalian‐based toxic equivalents (TEQs) approach, demonstrating the need for an ecotoxicologic model. Congener 153, a di‐ ortho ‐substituted hexachlorobiphenyl, was virtually nontoxic in terms of developmental effects at the highest dose (102 mmol/kg) achievable at its limit of water solubility. Cytogenetic analysis was a more sensitive method for assessing toxicity than the embryo development assay. Dose–response relationships were established with mitotic activity being the most sensitive endpoint because the PCBs appeared to inhibit mitosis. At the highest doses, complete mitotic arrest was observed. Congener 77 was found to be at least two times more toxic (EC50 = 30 mmol/kg) than congener 153 (EC50 = 67 mmol/kg) but not as toxic as congener 47 (EC50 < 16 mmol/kg) using mitotic activity as the endpoint for toxicity. Thus, the developmental and cytogenetic endpoints ranked the toxicity of the congeners similarly, but established different EC50s.