PRESS Environmental Toxicology and Chemistry. Vol. 26, No. II. pp. 2455-2464. 2007 © 2007 SETAC Printed in the USA 0730-7268/07 $12.00 + .00 Hazard/Risk Assessment EVALUATION OF VEGETABLE PRODUCTION MANAGEMENT PRACTICES TO REDUCE THE ECOLOGICAL RISK OF PESTICIDES PAMELA J. RicE,'t CATHLEEN J. HAPEMAN,t LAURA L. MCCONNELL4 ALT M. SADEGHI,1 JOHN R. TEASDALE4 C. BENJAMIN COFFMAN4 GREGORY W. MCCARTY4 AREF A. ABDUL-BAKT,t and JAMES L. STARR tU.S. Department of Agriculture, Agricultural Research Service, 1991 Upper Buford Circle, St. Paul, Minnesota 55108 (U.S. Department of Agriculture. Agricultural Research Service, 10300 Baltimore Avenue, Beltsville, Maryland 20705 (Received 29 December 2006; Accepted 21 Mar 2007) Abstract—The ability of agricultural management practices to reduce the ecological risks of pesticides was evaluated. Risk quotients, a mathematical description of the relationship between exposure and toxicity, and hazard ratings, a rank of the potential risk of pesticides to aquatic environments, were calculated for conventional and alternative cultivation practices for tomatoes: Poly-Bare, raised beds covered with polyethylene mulch with bare-soil furrows; Poly-Rye, raised beds covered with polyethylene mulch with cereal rye (Secale cereale) grown in the furrows; and Vetch, raised beds and furrows planted with hairy vetch seed (Vicio vu/usa). Evaluations were conducted using measured pesticide concentrations in runoff at the edge-of-field and estimated environmental concentrations in an adjacent creek and a theoretical pond receiving the runoff. Runoff from Poly-Bare presented the greatest risk to ecosystem health and to sensitive organisms, whereas the use of Vetch minimized these risks. Previous studies have shown that harvest yields were maintained and that runoff volume, soil loss, and off-site transport of pesticides measured in runoff were reduced using the alternative management practices (Poly-Rye and Vetch). Together, these results indicate that the alternative management practices (Poly-Rye and Vetch) have a less adverse impact on the environment than the conventional management practice (Poly- Bare) while providing growers with an acceptable economic return. In addition, the present study demonstrates the need to consider the management practice when assessing the potential risks and hazards for certain pesticides. Keywords—Vegetable production Pesticide Hazard potential Risk quotient Vegetative mulch INTRODUCTION Pesticide use in agricultural production systems and their effects on human and environmental health have been of public concern for many years. Much research has focused on quan- tifying the potential risks posed by pesticide use, including transport beyond the intended target. In the United States, risk assessment procedures for pesticides frequently have focused on meeting the requirements for pesticide registration as de- scribed in the Federal Insecticide, Fungicide, and Rodenticide Act and in the Food Quality Protection Act (http://www.epa. gov/pesticides/regulating/laws.htm) . The pesticide registration process in the European Union also requires risk information, and researchers have made significant contributions in mod- eling potential fate pathways and estimating the potential ex- posures [1-4]. Policy makers, producers, and regulators then develop strategies to mitigate these calculated and/or estimated risks. A range of detailed approaches has been developed to assess the potential risks of pesticides as they are transported away from the crops [5-9]. Regulators typically use a tiered ap- proach to risk assessment and frequently need to overestimate exposure and toxicity, because not all the parameters con- trolling pesticide fate and bioavailability are readily quantified. Often, strategies to mitigate the identified potential and doc- umented negative effects of pesticides need to be developed on a case-by-case basis. These strategies need to consider the properties of the pesticide product, commodity end points, * To whom correspondence may be addressed (pamela.rice @ ars.usda.gov ). Published on the Web 6/14/2007. cultivation practices, surrounding ecosystems, and both or- ganism and human health. One of the most economically important vegetables grown in the United States is the tomato, with annual average yields of 1.6 and 8.9 billion kg for fresh-market and processing to- matoes, respectively, at an estimated value of nearly $2 billion [10]. A cultivation method widely accepted by vegetable pro- ducers and growers is the use of polyethylene mulch, in which a thin sheet of black plastic is placed over a raised bed with bare-soil furrows between the beds. In 1996, polyethylene mulch was used on an estimated 47.4 km2 of Virginia farmland, much of it located in the Chesapeake Bay watershed (USA) [11]. Polyethylene mulch is a preferred practice, because it can control weeds, warm the soil, and prevent soil from de- positing on the crops. Nearly 50 to 75% of the field, however, is covered with an impervious surface, which reduces water infiltration, enhances runoff, and can lead to significant neg- ative environmental effects [12-14]. For example, runoff from polyethylene mulch has been implicated in the failure of com- mercial shellfish farms [15]. Furthermore, greater runoff vol- umes, soil erosion, and pesticide losses have been observed from fields and plots where polyethylene mulch was used when compared to other cultivation methods [16-19]. To address the environmental aspects of plastic mulch, two field experiments were conducted over five years to examine two alternative management strategies. In the first experiment, tomatoes were grown in raised beds covered in polyethylene mulch with bare-soil furrows between the beds (Poly-Bare) and then compared to tomatoes grown in plots completely covered with a vegetative residue mulch (Vetch) from the cover crop, hairy vetch (Vicia vu/usa Roth). In the second experi- 2455