MP5 Agrochemicals and Pesticides
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(WON-1126-036713) A Retrospective Assessment of 2-4D Concentrations in Suncook Lake: Implications for Risk Assessment.

Wongsearaya, E¹, ¹ New Hampshire Department of Environmental Services

ABSTRACT- Analysis of previously collected water samples from Lower Suncook Lake were used as a part of an investigation to determine how closely an analysis of degradation rates of herbicide 2-4D butoxyethyl ester formulation (Aqua-Kleen) matched a theoretical consideration conducted in advance of the herbicide application for risk assessment purposes. Time and depth-specific samples were taken at two sites in the lake (Sites A and B). Aqua-Kleen water concentration data were measured at depths of 1m, 2.5m, and 2.75m for day 7 and 0.5m, 2.5m, and 2.75m for day 14 with n=6 for both data sets. The _day7 = 90.5 ppb with a 95% C.I. ± 15.15. _day14 = 110.5 ppb with 95% C.I. ± 7.90. The analysis suggests 2-4D concentrations do not comport with the half-life degradation patterns assumed to occur over a 7 to 28 day period. Instead, 2-4D concentrations tended to rise over a twenty-one day period then precipitously dropped by day twenty-eight. The derived theoretical 2-4D concentrations appear to overestimate the observed concentrations strongly pointing to the need for more extensive chemical environmental fate and transport data for purposes of conceivably more precise assessments of exposure and risk.

Key words: butoxyethyl