Pesticide applicators

Division of Plant Industry Pesticide Applicator Section... 

Problems that rank relatively high in cancer and non-cancer health risks but low in ecological and welfare risks include hazardous air pollutants, indoor radon, indoor air pollution other than radon, pesticide application, exposure to consumer products, and worker exposures to chemicals... 

Crop Rotations and Diversification. For thousands of years farmers have known that planting their crops in a new location about every 2 years helped reduce Insect, disease, and weed problems. Indeed, crop rotations are effective in reducing many pest problems and are often highly cost effective (15, 16). Unfortunately for many crops, the trend has been toward abandonment of rotations and increased monocultures. Where rotations are not practiced, certain pests tend to multiply as the crops are cultured on the same land year after year (23). As a result, the density of pest populations increases to levels that necessitate heavy pesticide applications. 

When pesticides are applied to crops, many natural enemies that help control pests are destroyed (37). This causes pest outbreaks that subsequently are controlled with additional pesticide applications. The control of such pest outbreaks is estimated to cost at least 520 million each year. 

CDC. 2001. Pesticide applications and field posting. New Jersey Agricultural Experiment Station. Center for Disease Control. Http //search.cdc.gov/search97cgi/s...xt=methvl-Fparathion Sortfield=Score. January 17, 2001. 

Gladen BE, Sandler DP, Zahm SH, et al. 1998. Exposure opportunities of families of farmer pesticide applicators. Am J Ind Med 34 581-587. 

Izmirova H. 1980. Methods for determination of exposure of agricultural workers to organophosphorus pesticides. In Tordoir WF, Van Heemstra EA, eds. Field worker exposure during pesticide application. New York, NY Elsevier Sci. Publ. Co., 169-172. 

Melnyk LJ, Berry MR, Sheldon LS. 1997. Dietary exposure from pesticide application on farms in the agricultural health pilot study. J Expo Anal Environ Epidemiol 7 61-80. 

The most important routes of exposure to endosulfan for the general population are ingestion of food and the use of tobacco products with endosulfan residues remaining after treatment. Farmers, pesticide applicators, and individuals living in the vicinity of hazardous waste disposal sites contaminated with endosulfan may receive additional exposure through dermal contact and inhalation. 

When pure P-endosulfan was allowed to equilibrate in the apparatus, the ratio of the P-isomer to the a-isomer in the gas phase became 8 92 at 20 , suggesting that the P-isomer converts to the a-isomer (Rice et al. 1997). Several investigators have reported rapid initial losses of endosulfan residues from treated plant surfaces due to volatilization (Archer 1973 Terranova and Ware 1963 Ware 1967). One research group (Willis et al. 1987) attributed the limited runoff losses found in soybean fields treated with endosulfan to early losses of the compound during application and to volatilization/degradation of the compound from plant surfaces. Air sampling performed in a wind tunnel under defined conditions (20 air velocity 1 m/sec relative humidity 40-60%) showed that 60% of the initial dose of endosulfan is volatilized from Trench bean surfaces after 24 hours (Rudel 1997). Influences of various pesticide application formulations were not tested. 

O2 availability, water content. Structural - soil type, porosity, clay content, fertility. Agricultural - Fertilizer addition, herbicide pesticide application, tillage, cropping systems etc. 

Pesticides used on crops grown on the test site in previous seasons may also have an impact on the outcome of a field residue trial. Carryover of prior pesticide applications could contaminate samples in a new trial, complicate the growth of the crop in a trial, or cause interference with procedures in the analytical laboratory. For this reason, an accurate history of what has transpired at the potential test site must be obtained before the trial is actually installed. The protocol should identify any chemicals of concern. If questions arise when the history is obtained, they should be reviewed with the Study Director prior to proceeding with the test site. In most annual crop trials, this will not be a significant issue owing to crop rotations in the normal production practices, because the use of short residual pesticides and different chemical classes is often required for each respective crop in the rotation. However, in many perennial crops (tree, vines, alfalfa, etc.) and monoculture row crops (cotton, sugarcane, etc.), the crop pesticide history will play a significant role in trial site selection. 

Environmental pollution caused by pesticides has become a serious problem. Especially during and/or after pesticide application to crops, the pesticides are released into sensitive environmental areas, and also into ground and surface water, and could be harmful or dangerous to humans and other species. Therefore, very low concentrations of diphenyl ether herbicides in environmental waters must be monitored. 

Table 3 provides general guidelines used in toxic air assessments in California for sampling common agricultural pesticides in ambient air at near-field sampling monitors before, during, and shortly after a field application. For communities that are near the site of the candidate pesticide application, concurrent ambient air samples are taken over durations of 24 h and are collected 4 days per week for a period of 4 weeks. 

One fact that is often given too little attention is the actual variability inherent in pesticide application under normal use scenarios. Part of the reason for discounting this variability is that well controlled pesticide applications are often made with standard deviations that are 40% of the mean. Using this variance, and the equation... 

All maintenance pesticide applications must be approved in advance and documented. Pesticides that do not interfere with analysis may be applied in order to control weeds, pathogens, and other pests if they appear in the treated plot and control area only if absolutely necessary. The treated plot and control area should be maintained with the same compound and rate and at the same time. 

Spray drift is defined for this topic by the National Coalition On Drift Minimization (NCODM) as The physical movement of pesticide through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site . Secondary drift, defined by NCDOM as vapor drift or subsequent dust and particle movement after the application , is only partially addressed, although most key principles discussed will still also apply to such secondary movements. 

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