PARENT SESSION
PM16 - Probabilistic Ecological Risk Assessment
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P369) Probabilistic Assessment of Spray Drift Exposure to Non-Target Plants from a Pre-Emergence Corn Herbicide.

Ramanarayanan, Tharacad^*,1, Allen, Richard¹, Dobbs, Michael¹, ¹ Bayer CropScience (formerly Aventis CropScience), Research Triangle Park, North Carolina

ABSTRACT- Using a probabilistic methodology, distributions of off-target drift exposure from pre-emergence herbicide ground sprays were developed. A biphasic deposition model was fitted to appropriate datasets from the ground spray experiments conducted by the Spray Drift Task Force (SDTF). Off-target drift exposure was estimated for two zones, Zone 1 and Zone 2 at 10 to 25 ft (3.1 to 7.6 m) and 25 to 50 ft (7.6 to 15.2 m), respectively, downwind from the edge of the treated area. The exposure distributions were calculated by conducting a Monte Carlo simulation of sampling the random vectors of the biphasic model parameters. The estimated median values of the spray drift deposition distributions for Zone 1 and Zone 2 are 1 % and 0.6 % of the applied spray rate, respectively. A risk assessment was conducted by comparing the spray drift exposure distributions to the effects data (SSD) and the presented through another poster (Dobbs, et al.).

Key words: terrestrial non-target plants, spray drift, uncertainty, Monte Carlo simulation