Leaf dislodgeable residues of deltamethrin applied in different types of formulations in staked cucumbers

Pesticide residues, especially in fruit and vegetsble production, raise worries about the consumers' health and the workers who need to return to the treated crops with these pesticides. The objective of this work was to study the occurence and behavior of dislodgeable residues of deltamethrin pyrethroid inseticide, applied in different types of formulations on leaves of a staked cucumber crop as a starting point for occupation exposure studies. The treatments were: (a)control; (b)three applications of 30 mL Decis 25 EC.100 L-1 water; (d) three applications of 3.75 mL Decis 200 CS.100 L-1 water. All decis treatments consisted of 0.75 g a.i deltamethrin 100L-1 water. Samples were taken (-1); zero; 1; 3; 5; 7 and 14 days after the last application. The analytical method consisted of the extraction of deltamethrin residues with Sur-ten solution, clean-up of the extracts by gel permeation chromatography (GPC), with elution made with a mixture of ethyl acetate/cyclohexane. The quantitative determination was done by gas chromatograph, using electron capture detector. The dislodgeable residues of deltamethrin were righerin CS as compared to the both EC's (4-20 times), with hal-life values of 2.8; 3.8 and 32.2 days, respectively for the formulation ma pose higher danger to workers, it is emphazide the need of the proper use of individual protection equipament when applying thse chemicals or returning to treated areas to perform other crop tasks...

Metabolism of carbosulfan to carbofuran and to 3-hydroxy-carbofuran in orange leaves

The biochemical degradation pathway of pesticides under field conditions can yield metabolites that require a more complete toxicological evaluation once they might be so or even more toxic than the parent compounds. The objective of this study was to evaluate the metabolism of the inseticide/acaricide carbosulfan to carbofuran and to 3-hydroxy-carbofuran, based on their residues in orange leaves. Two field experiments were carried out, both with the following treatments: a - control; b - one application of 10 g of carbosulfan . 100 L-1 of water; c - one application with twice the amount applied in treatment b; d - four applications with the same amount applied in treatment b. Samples were taken at (-1), zero, 1, 3, 7, 14, 21 and 28 days after the last or unique application. The quantitative determinations were done by by gas chromatography, using a nitrogen-phosphorus detector. The carbosulfan metabolism to carbofuran was fast and both had low persistence in the leaves (3 days). The same trend was observed for the carbofuran metabolism to 3-hydroxy-carbofuran, which was produced in very low amount and rapidly dissipated

Pirimiphos-methyl residues in corn and popcorn grains and in some of their processed products

Insecticides are used for stored cereal protection against insect attack and the occurrence of their residues needs to be evaluated not only in grain but also in the processed products. This study evaluates the residue degradation/persistence of the organophosphorous insecticide pirimiphos-methyl in corn and popcorn grains and in some of their processed products such as bran, hominy and corn flour from corn and popped popcorn. Grains were treated with pirimiphos-methyl at the rate of 12 mg.kg-1 (a.i.). Samples were taken and analyzed at zero, 15, 30, 60, 120 and 240 days after treatment. The analytical method consisted of residue extraction with acetone, clean-up partition with acetonitrile/hexane and silica gel column chromatography eluted with a mixture of hexane + acetone. Quantitative measurements were made by gas chromatography, using flame photometric detector (GLC/FPD). The limits of quantitation (LOQs) were: corn grain, hominy and popped popcorn 0.05 mg.kg-1; bran, corn flour and popcorn grain 0.1 mg.kg-1. Pirimiphos-methyl residues were not persistent in either types of grains or in their processed products. At the end of sampling period (240 days), 5 to 8-fold less residues were found in corn bran and popcorn. Hominy and corn flour showed low levels of contamination. Higher residue concentrations in corn bran than in grains are related to the higher oil content in that processed product