Potential exposure to diazinon during yard applications.

Applicators applying diazinon to yards were monitored to determine potential exposures received while using this commonly available pesticide around the home. Diazinon was applied to lawns and shrubs using compressed air or hose-end sprayers. Even with minimal clothing, the largest mean exposure received during any of the applications was estimated to be less than 0.2% of a lethal dose per hour. Exposure to the hands accounted for 85% or more of the total exposure, so simply protecting the hands would have essentially eliminated exposure.

Methyl parathion persistence in soil following simulated spillage.

Simulated spillage of emulsifiable concentrate (E.C.) and microencapsulated formulations of methyl parathion on soil were studied. Persistence of residues from both formulations spilled as concentrates and as simulated from rinses were followed for up to 45 months. Spillage of encapsulated formulation resulted in the formulation of a solid cake-like deposit on the soil surface, which could be a particularly attractive hazard to small children. At 45 months, soil residues had decreased by 64% for emulsifiable concentrate spills, and 68% for the soil beneath the microencapsulated cake. Residue in the cake itself only decreased by 31%. Soil residue levels from simulated drum rinses were essentially innocuous by 45 months for the emulsifiable concentrate and by one year for the microencapsulated material. The leaching of methyl parathion from the microencapsulated cake into soil and the relationship between available residue and wet weather were also investigated.

Field disposal of methyl parathion using acidified powdered zinc.

The degradation of methyl parathion in soil with various amounts of acidified powdered zinc under field conditions was studied. Treatment was progressively more effective with increasing amounts of zinc. Disappearance of parent compound was followed for 2 1/2 years. The expected conversion product aminomethyl parathion and its N-methyl derivative were formed. In addition, N,N-dimethylamino, and the azo and azoxy condensation products were characterized by high resolution mass spectrometry. Aminomethyl parathion was shown to be identical to an authentic standard. The other specific positional isomers were considered likely, but were not proven by mass spectrometry. Structure elucidation was made with high resolution mass spectrometry, using the direct insertion probe, and with gas chromatography/low resolution mass spectrometry.

Reductive degradation of dieldrin and endrin in the field using acidified zinc.

The reductive dechlorination of dieldrin and endrin was investigated as a possible procedure for field disposal of small quantitites of these pesticides. The objective was to convert the parent compounds to environmentally less objectionable materials. Emulsifiable concentrate formulations of the pesticides in a soil slurry were mixed with powdered zinc, dilute acetic acid, and acetone to facilitate reaction. Analysis of the mixtures by GC-MS indicated essentially complete conversion of endrin and partial conversion of dieldrin to products probably formed by replacement of the bridge anti chlorines with hydrogen. Partial confirmation of the desired anti dechlorodieldrin product was made by nmr. Disappearance of the parent compounds and production of conversion products was monitored for 2 1/2 years by GC in an outside soil plot, and accelerated destruction of parent compounds was achieved by the treatment. By analogy to the bridge anti dechloro products of aldrin and isodrin, the anti dechloro products probably are much less toxic than the parent compounds and are therefore environmentally less objectionable.