Reduction of Pesticide Residues on Produce by Rinsing

Abstract

In 1997 this laboratory initiated a research program with the objective of examining the effect that\nrinsing of produce with tap water would have on pesticide residues. Samples were obtained from\nlocal markets and/or grown at our experimental farm. Because approximately 35% of produce from\nretail sources contains pesticide residues, growing and treating produce at an experimental farm\nhad the advantage that all such samples contain pesticide residues. Pesticides were applied under\nnormal field conditions to a variety of food crops and the vegetation was allowed to undergo natural\nweathering prior to harvest. The resulting samples contained field-incurred or “field-fortified"\nresidues. This experimental design was employed to mimic as closely as possible real world samples.\nCrops were treated, harvested, and divided into equal subsamples. One subsample was processed\nunwashed, whereas the other was rinsed under tap water. The extraction and analysis method\nused was a multi-residue method developed in our laboratory. Twelve pesticides were included in\nthis study: the fungicides captan, chlorothalonil, iprodione, and vinclozolin; and the insecticides\nendosulfan, permethrin, methoxychlor, malathion, diazinon, chlorpyrifos, bifenthrin, and DDE (a\nsoil metabolite of DDT). Statistical analysis of the data using the Wilcoxon signed-rank test showed\nthat rinsing removed residues for nine of the twelve pesticides studied. Residues of vinclozolin,\nbifenthrin, and chlorpyrifos were not reduced. The rinsability of a pesticide is not correlated with\nits water solubility.\nKeywords: Field-incurred residues; pesticide water solubility