Spraying mixer-loaders

Applicators, mixers, loaders, and others who mix, spray, or apply pesticides to crops face potential dermal and/or inhalation exposure when handling bulk quantities of the formulated active ingredients. Although the exposure periods are short and occur only a few times annually, an estimate of this exposure can be obtained by quantifying the excreted polar urinary metabolites. Atrazine is the most studied triazine for potential human exposure purposes, and, therefore, most of the reported methods address the determination of atrazine or atrazine and its metabolites in urine. To a lesser extent, methods are also reported for the analysis of atrazine in blood plasma and serum. 

Nigg, H.N. and Stamper J. (1983) Exposure of spray applicators and mixer-loaders to chlorobenzilate miticide in Florida citrus groves, Arch. Environ. Contam. Toxicol, 12 477-482. 

In California, mixer-loaders and spray applicators who work with toxicity category I and II organophosphates or N-methyl carbamates more than 30 hours per 30-day period are required to have medical supervision. Supervision consists of an interview and a medical examination to determine if a medical condition exists which would make the worker unusually susceptible to poisoning due to cholinesterase inhibition, and to caution the individual about the use of certain drugs such as the pheno-thiazine tranquilizers vdtich potentiate the effects of cholinesterase (ChE) inhibition. Two blood samples, taken several days apart, are analyzed to determine the individual s preexposure plasma and red blood cell (RBC) ChE activity (baseline value). The physician arranges a routine ChE testing program and provides for extra ChE tests should the worker be accidently exposed to OP s. If ChE activity is depressed to 50 percent of the baseline value, the physician may ask the employer to place the worker on... 

Applicators. The workers involved in the ground applications of carbaryl received considerably less exposure than the mixer-loaders. Most of the exposure was to the hands and was attributed to adjusting the nozzles on the spray equipment. Thus, for the ground application of the 80S formulation, the total HDE was 1.6 mg/h and the HDE to the hands was 1.5 mg/h. For a similar application of Sevimol-4, the total HDE was 2.8 mg/h and the HDE to the hands was 2.7... 

The aerial applicators also had considerably less exposure than the mixer-loaders. Again, most of this exposure was to the hands and was acquired from adjusting nozzles on the spray equipment. For the 80S and the XLR formulations, the total HDE s were 7.4 and 3.4 mg/h, respectively, and almost 100% of the exposure was to the hands in both cases. Here, as for the ground application, the highest HDE was obtained from Sevimol-4 because of the more frequent plugging of the spray nozzels. Thus the total HDE for Sevimol-4 was 26.5 mg/h, and the HDE on the hands was 25.7 mg/h. 

In addition, when considering the appropriateness of the area dose levels in the dermal absorption study to the subpopulations under consideration in the risk assessment, it is important to recognize that different area dose levels may be experienced depending on the scenario. For instance, with an agricultural worker, the mixer/loader may be exposed to the concentrated product, the applicator to the diluted spray mixture and the re-entry worker to dried residues on vegetation. As such, it is possible that different dermal absorption values have to be used for each work-function scenario. 

Nigg, H. N. Stamper, J. H. Exposure of Spray Applicators and Mixer Loaders to Chlorobenzilate mltlclde in Florida Citrus. Arch. Environ. Contam. Toxicol. 1983, 12, 477-482. 

Applicator and Mixer/Loader Exposure to Pesticides During Ground Boon Spraying Operations," Environnental Protection Agency, 1984. 

Estimates of Field Worker Exposure to Pesticides An example will be presented to show how estimates of lifetime field worker exposure can be made and show how a number of the factors above come into play during such calculations. These calculations apply only to chemicals which demonstrate chronic toxicity predominantly. Shorter term estimates must be made for chemicals showing acute toxicity. For this exercise consider only field crops such as wheat, corn, and soybeans. The example presented here will deal with one application type, i.e., ground boom spray application. Mixer-loaders, cleanup workers and applicators will be considered. Factors such as effectiveness of protective clothing will also be considered. Further, this example will consider only an individual farm operation scenario. 

Mixer-Loader and Cleanup Worker Boom Spray Operation Exposure (Individual Farm Operation) ... 

Exposure Time Estimate Mixer-loader-cleanup worker total exposure time - for ground boom spray operation. 

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