Foliage oxons

This paper establishes toxicologically-safe levels for total residues of parathion, azinphosmethyl, methidathion and their oxons on tree foliage and reports these levels in terms of absorbance units as determined by the rapid field method. Safe levels for a new insecticide, chlorthiophos, are also proposed based on preliminary residue data. Chemical structures of the four insecticides mentioned above are shown in figures 1, 2, 3 and 6. 

Safe Levels for Parathion, Azinphosmethyl, Methidathion and Their Oxons on Tree Foliage... 

Table II gives a procedure for establishing safe levels for total dislodgeable thion + oxon residues on tree foliage.

The safe levels established for parathion + paraoxon, azinphosmethyl + azinphosmethyl oxon and methidathion + methi-dation oxon on foliage have absorbance values determined by the rapid field method (4 ) equal to those given in Table III. Absorbance values greater than those listed in Table III signal an unsafe working condition. Field testing can also be conducted by standard gas chromatographic analysis of the leaf disk samples by state-approved laboratories. 

We can expect the forest pesticides similarly to respond to such natural forces, and our very limited knowledge indicates that they do. 2,4,5-T applied to a sunlit forest was photoreduced our recent experiments at the University of California s Blodgett Forest with a standard 2,4-D/2,4,5-T ester application showed that the trace of contained TCDD was largely photolyzed within a single sunlit day and undetectable after two days forest application of fenitrothion produced continuous low levels of the expected oxon and nitrocresol on foliage. 

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