ARS | Publication request: Fungicide residue remediation on table grapes using ozone fumigation

Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2011
Publication Date: August 15, 2011
Citation: Walse, S.S., Karaca, H., Smilanick, J.L. 2011. Fungicide residue remediation on table grapes using ozone fumigation. Environmental Science and Technology. 45(6):6961-6969.

Interpretive Summary: Pesticides are used conventionally to mitigate reduced commodity yield and quality, as well as, to minimize food-borne risk toward consumer health. A serious concern of contemporary commercial agricultural, including grape producers, involves the juxtaposition of the benefits of pesticide use relative to unfavorable artifacts associated with residue left on the commodity. Concerns regarding non-target residue exposures necessitates the development of safe and effective methodology for residue reduction. The use of ozone as a pesticidal fumigant is well established and has been explored world-wide by grape industries. However, virtually no data exists on reducing fungicide residues on grapes using this gaseous ozone approach, despite considerable research which indicates that gaseous ozone can be effectively degrade surface-sorbed organic chemicals. The practicality/feasibility of using gaseous ozone for fungicide residue reduction depends on the degradative potential of contemporary fungicides that needs to be mapped. This study documents for the first time, the ability of gaseous ozone to degrade several of the most popular contemporary fungicides used in grape production.

Technical Abstract: Ozone fumigation was explored as a means for degrading contemporary organic fungicides related to table grape production. Separate fumigations were conducted in a flow-through chamber on fungicides sorbed to model abiotic glass surfaces or to table grapes. Gaseous ozone at constant ozone concentration of 150 ± 10 ppm selectivity oxidized fungicides sorbed to model surfaces. Over 140 min, boscalid and iprodione levels did not change significantly based on one-way analysis of variance (p>0.05), however, pseudo first-order losses were observed and resulted in respective half-lives of approximately 29.7, 41.3, and 54.6 min for fenhexamid, cyprodinil, and pyrimethanil. The relative degradation of fungicides over 2 h was similar on table grapes at gaseous ozone concentrations of 900±12 ppm; significant reductions (P>0.01) were observed for only fenhexamid (~ 64%), cyprodinil (~ 38%), and pyrimethanil (~ 40%). The kinetics and mechanism of gaseous ozonation, supported by gas chromatography- and liquid chromatography-mass spectrometry product analyses, is discussed in the context of mitigating fungicide residue quotas for table grapes.