Effect of household processing on pesticide residues in field-sprayed tomatoes

Tomatoes sprayed with chlorothalonil, oxadixyl, and thiophanate-methyl in a greenhouse were cooked to juice and puree using washing, blanching, peeling, and boiling. Washing reduced amounts of chlorothalonil, oxadixyl, and thiophanate-methyl pesticide residues by 92, 52, and 84%, respectively. A concentration of 3.66% chlorothalonil remained in peeled tomatoes, 0.32% in juice, with no detection in puree. Oxadixyl remained at a concentration of 40% in peeled tomatoes, 54% in juice, and 77% in puree, and the remaining concentration of thiophanate-methyl was 6.2% in peeled tomatoes, 8.7% in juice, and 16.2% in puree. Non-systemic pesticide residues on tomato surfaces could be largely removed through washing and peeling. Reductions in levels of systemic pesticides in tomato pulp during boiling were dependent on the physico-chemical characteristics of pesticides.