| Environmental Health Issues Diane S. Henshel,1,2,5 J. William Martin,1 Ross
Norstrom,3 Phillip Whitehead,4 John D. Steeves,2
and Kimberly M. Cheng5 1School of Public and Environmental Affairs, Indiana University,
Bloomington, Indiana; 2Department of Zoology, University of British
Columbia, Vancouver, British Columbia, Canada; 3National Wildlife
Research Center, Canadian Wildlife Service, Hull, Quebec, Canada; 4Canadian
Wildlife Service, Pacific and Yukon Region, Delta, British Columbia, Canada;
5Department of Animal Science, University of British Columbia,
Vancouver, British Columbia, Canada Abstract
Great blue heron hatchlings from colonies in the Strait of Georgia, British Columbia, Canada are being monitored for environmental contaminant exposure and effects by the Canadian Wildlife Service. The contaminants of concern are polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) , primarily derived from kraft pulp mill effluent. The levels of PCDDs and PCDFs in eggs from the most contaminated colonies peaked in 1988 and 1989 and dropped dramatically through 1990 to 1992. Brains of heron hatchlings (taken as eggs from the wild and hatched in the laboratory) were analyzed for gross morphological abnormalities. Brains from highly contaminated colonies (Crofton, British Columbia and University of British Columbia Endowment Lands) in 1988 exhibited a high frequency of intercerebral asymmetry. The frequency of this abnormality decreased in subsequent years as the levels of TCDD and TCDD-TEQs (toxic equivalence factors) decreased. The asymmetry was significantly correlated with the level of TCDD and TCDD-TEQs in eggs taken from the same nest. Yolk-free body weight negatively correlated and the brain somatic index positively correlated with the TCDD level in such pair-matched eggs. These results indicate that gross brain morphology, and specifically intercerebral asymmetry, may be useful as a biomarker for the developmental neurotoxic effects of PCDDs and related chemicals.
-- Environ Health Perspect 103(Suppl 4) :00-00 (1995) Key words: polychlorinated dibenzodioxin, polychlorinated dibenzofuran, development, birds, asymmetry, TCDD, morphology, central nervous system, brain, kraft pulp mill effluent
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