Dialifor and methidathion were added to diluted "Zinfandel" grape concentrate at 25 ppm and dimethoate at 1.0 and 25 ppm prior to fermentation with Saccharomyces cerevisiae. The finished wine 56 days later contained 10% (2.5 ppm) of the dialifor, 46% (12 ppm) of the methidathion and 85% (21 and 0.98 ppm) of the dimethoate added to the grape must. Residues in wine stored at 24 degrees C dissipated by hydrolysis; half-lives in wine were 7 days for dialifor and methidathion and 30 days for dimethoate. Residues were unchanged in wine in frozen storage for one year. Analysis of seven commercial wines for dimethoate indicated less than 0.03 ppm dimethoate was present; identity could not be confirmed by thin-layer chromatography at this level.

their stability to the hepatic carboxylesterases (Soderlund and Casida, 1977). However, it apparently has little effect on metabolism and elimination in vivo.The difference between the cis and trans isomers of cypermethrin in the amounts retained in the fat is of interest. In terms of lipophilic character, there is little difference between the two isomers, and experiments in mice (Hutson et al., 1981) show that the amount reaching fat is similar with both isomers. The difference lies in the rate of release from this tissue. It is possible that hydrolysis of the ester bond occurs in the fatty tissue, perhaps catalyzed by a lipase. This hydrolysis would be expected to proceed much more rapidly with the trans isomer than with the cis isomer.The rapid elimination of cypermethrin from rats is due primarily to the efficient cleavage of the ester bond giving rise to polar metabolites which are further oxidized and conjugated before excretion. The structural elucidation of these metabolites and their mechanisms of formation will be described in a subsequent paper. ACKNOWLEDGMENT We thank P. A. Harthoorn of the Shell Biosciences Laboratory, Sittingboume, for the synthesis of the various radiolabeled forms of cypermethrin. LITERATURE CITED

Abstract. An investigation was made into an illness episode characterized by cholinesterase depression and cholinergic symptoms reported among 118 field workers harvesting grapes treated with Torak | (dialifor) and Zolone | (phosalone) in a vineyard near Madera, California. Dialifor had been applied at the rate of 1.0 pound per acre in 30 gallons of water between 15 and 40 days earlier using a Kinkelder air blast sprayer. Dissipation studies in an earlier study in Soledad, California, using concentrated spray resulted in initial dislodgeable residues of 2.1 ug/cm 2 with a half-life of 14 to 15 days. A similar level of dislodgeable residue resulted at the time of application in the vineyard at Madera. Dislodgeable residues as high as 0.7 ug/cm 2 were encountered by workers at the time of entry with most residues being in the range of 0.11 to 0.45 ug/cm 2. Residue of dialifor on the foliage in 36 other grape vineyards in the San Joaquin Valley were determined at the time of harvest and were shown to be 0.13 ug/cm 2 or less. In four of the 36 vineyards, blood was obtained from workers harvesting grapes. None of the field workers had blood cholinesterase values outside control values.The investigation indicated that with initial dislodgeable residues of dialifor as high as 2.3 ug/cm 2, a period of at least 65 days is required before a possibly safe level of something less than 0.06 ug/cm 2 is reached. The analysis of the residues in the 36 other vineyards indicated that the initial deposits and/ or the half-life of dialifor varied considerably throughout the San Joaquin Valley. Because of this variation, the use of reentry intervals for dialifor may require replacement by on-site residue tests prior to entry. The results indicated that phosalone residues were not responsible for the illness in the field workers.

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