At the 2006 Annual Society for Risk Analysis Meeting in Baltimore, Maryland on December 3-6, 2006, Kathleen Neuber, Ph.D., Ann Bradley, and Judi Durda gave the following presentation:
Comparative Sensitivity of Bird Species of the Gulf Coast to Environmental DDTr Contamination: A Meta-Analysis of Existing Dose-Response Data for Egg Residue of DDE and Eggshell Thinning.
Authors: Kathleen Neuber, Ph.D., Ann Bradley, and Judi Durda (Integral Consulting, Annapolis, MD, USA)
Due to its persistence, DDT and its degradation products, DDE and DDD are still present in the environment of the Gulf Coast. There is a large body of published work available that measures the effects of DDE in egg residue on eggshell thinning and associated reproductive impacts for various species. It has been estimated that excess eggshell thinning of approximately 20 percent over a breeding population will result in a negative impact on population-wide reproductive success. Given that there is a fairly consistent population effect threshold of 20 percent eggshell thinning, it is theoretically possible to estimate and compare the concentrations of DDE in egg residue that result in the population effect threshold. We examined available data by first establishing acceptability criteria to identify reliable quality data for analyzing dose response. Next, we evaluated published studies and reported data against these criteria and ranked them according to usability. Where data were considered usable for a particular genus or species, they were included in a meta-analysis to establish a single dose-response relationship for each genus or species. Based upon the estimated population-level adverse effect level of 20 percent eggshell thinning, a toxicity reference value for DDE in egg residue was determined for each dose-response assessment. The resulting toxicity reference values were then compared across species to rank various species in terms of reproductive sensitivity to DDE in egg residues. The results of the comparison should prove useful in the identification and selection of sensitive species for future monitoring of the health of Gulf Coast ecosystems and site-specific ecological risk assessments.
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