Residues of Mancozeb, Maneb and Ethylenethiourea in Fungicide-Treated Field and Greenhouse Tomatoes

Abstract

Residues of the ethylenbisdithiocarbamate (EBDC) fungicides maneb and mancozeb on tomato fruits ranged between 0.03 and 0.80 ppm (mean 0.31 ppm) when field crops were sprayed five or eight times at intervals of 3–4 days. Ethylenethiourea (ETU) was detected only in one sample, at 0.03 ppm. In canned juice made from whole fruit, EBDC levels ranged from non-detectable to 0.62 ppm (mean 0.31 ppm) and ETU levels from non-detectable to 0.07 ppm (mean 0.02 ppm). These levels were generally higher than in canned peeled fruit where the range of EBDC was from non-detectable to 0.27 ppm (mean 0.09 ppm) and of ETU from non-detectable to 0.05 ppm (mean 0.01 ppm). On greenhouse tomatoes, two or four sprays with mancozeb resulted in residues of up to 2.81 ppm EBDC (mean 0.714 ppm) and 0.08 ppm ETU (mean 0.0097 ppm) on the fruit. All levels of EBDC were below the Canadian tolerance level of 4 ppm but ETU is unacceptable in food in Canada.

Rückstandstoxikologische Bewertung des Einsatzes von Pflanzenschutzmitteln und Mitteln zur Steuerung biologischer Prozesse in Gemüse unter Glas und Plasten

“…Bei der Gemuseverarbeitung, z. B. Tomaten zu Juice, konnen hohere ETH-Ruckstande erwartet werden [22], die in dieser Matrix in Abhangigkeit von der Hohe des Ruckstandes nur langsam abgebaut werden [23].…”

Recent Advances in the Chemical Control of Oomycetes

“…In neutral or alkaline conditions, a rise in temperature favors the formation of ETU. ETU can also be present as an impurity in EBDCs after their preparation or storage [27,28], or can be formed as a metabolite in crops [29][30][31][32][33][34]. If EBDCs are still present in food crops they can readily give rise to ETU during the cooking process [35][36][37][38].…”

Procedures for the removal of field residues of ethylenebis(dithiocarbamate) (EBDC) fungicide and ethylenethiourea (ETU) from tomatoes prior to processing into juice

“…Tomatoes were chosen as a matrix for a feasibility study of decontamination because of the economic importance of their production, because the fruit is directly exposed to the EBDC spray and because high temperatures are used in converting the raw fruit into juice. The generally higher levels of EBDC's and of ETU residues found in juice as opposed to "whole pack" tomatoes (von Stryk and Jarvis, 1978) are usually attributed to increased contact time between the skins and the interior of the fruit during processing into juice. Thus, it was felt that juice resulting from field-treated tomatoes would represent a more severe test for any decontamination technique.…”