PT01 Assessing Contaminated Soil Sites
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT001) Forensic Analysis of the pelican die-off on Lake Apopka: Probabilistic analysis of potential exposure to organochlorine pesticides.
Mackay, C1, Gard, N1, 1 Exponent, Bellevue, WA, USA
ABSTRACT- In the fall and winter of 1998, an estimated 400 American white pelicans and numerous other avian species died suddenly at a restoration area on the north shore of Lake Apopka. This region was previously an area of intensive agricultural production that had recently been acquired for the purpose of restoring natural wetlands. Soil analysis indicated the presence of elevated concentrations of dieldrin, toxaphene, and metabolites of DDT. In order to determine whether these organochlorine pesticides could prove to be causative agents in the pelican die-off, we undertook a forensic investigation of potential exposure during and after the event. Results of soil, sediment, and fish analyses for organochlorine content were modeled on a spatial and temporal basis. Models of pelican, stork, and least sandpiper populations were overlaid on this construct to determine exposure rates for the respective avian populations. Results indicated that the American white pelican was exposed to the highest organochlorine concentrations. However, exposure concentrations were not significantly different except at the lowest exposure probabilities. Physiologically based pharmacokinetic modeling indicated that about 7 percent of the pelican population would have received a cumulative toxaphene body burden in excess of the most conservative estimate of toxaphene′s LD50. None of the birds exceeded the median or high-end predictions of LD50 concentrations.
Key words: Forensic Toxicology, Lake Apopka, American White Pelican, Pesticides