Manganese ethylenebis(dithiocarbamate) (maneb)/ethylenethiourea (ETU) residue studies on five crops treated with ethylenebis(dithiocarbamate) (EBDC) fungicides

Abstract

MANEB/ETU RESIDUE STUDIES capsule wall concentration of 1.6 ppm) and the mixture was subjected to the analysis procedure, a fluorescence reading of 3.5 was obtained. Background fluorescence from uncontaminated lettuce subjected to the analysis procedures was negligible. From the standard curve the amount

Ethylenethiourea in air and in urine as an indicator of exposure to ethylenebisdithiocarbamate fungicides.

“…EBDC do not belong to the systemic fungicides, and they remain on plant surfaces (15). In addition, ETU has been found on plants treated with EBDC (16). However, intact ETU disappears from plants and soil with a half-time of less than one week and much more rapidly than EBDC, the half-time of which is four to eight weeks.…”

Stability of the dithiocarbamate pesticide maneb in tomato homogenates during cold storage and thermal processing

“…The per cent conversions found in the present study are slightly lower than the 37% conversion reported by Newsome (1976) when field-treated tomatoes with maneb were boiled for 10 min. In that case however, ETU residues were measured by gas-chromatography following derivatization, a method for which other workers (Pease andHolt 1977, Ripley and reported substantial conversion of parent compounds to ETU during analysis.…”

Residue Reviews

“…A criticism ofthis method was that it did not account for the possible interference caused by conversion of EBDCs to ETD. Pease and Holt (1977) claimed that up to 10% of added maneb could be converted to "apparent" ETD. A later revision of this method by Onley et al (1977) claimed to minimize EBDC conversions to ETU to less than 2 %.…”

“…In most of the derivatization procedures developed to date the thiocarbonyl group is alkylated to give the strongly basic alkylthio-2-imidazoline. Various alkyl halides have been employed, including I-bromobutane (Onley and Yip 1971, Haines and Adler 1973, Watts et al 1974, Onley et al 1977, Pease and Holt 1977, benzyl chloride (Newsome 1972, Nash 1974, Pecka et al 1975, Onji et al 1979), o-chlorobenzyl chloride (Nash 1975), and m-trifluoromethylbenzyl chloride (King 1977). In some of the methods a second derivatization step was used to attach a multi-halogenated compound such as the pentafluorobenzoyl group (Nash 1974 and, the trifluoroacetyl group (Newsome 1972, Pecka et al 1975, and King 1977, or the methane sulphonyl group (Onji et al 1979) on to the nitrogen of the imidazoline ring.…”