Springer Online Journal Archives 1860-2000
Energy, Environment Protection, Nuclear Power Engineering
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/cm2 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/cm2 were encountered by workers at the time of entry with most residues being in the range of 0.11 to 0.45 ug/cm2. 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/cm2 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/cm2, a period of at least 65 days is required before a possibly safe level of something less than 0.06 ug/cm2 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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