Washington State has approximately 168,000 acres of apples and produces roughly half of the U.S. apple crop. With this intense level of production, the potential spray drift of pesticides from orchard airblast applications is a health concern for workers, neighboring farmers, and residents. The purpose of this project is to analyze the effectiveness of new pest control practices, including pesticide product substitutions, and application technologies to reduce the risk of pesticide handler exposure to pesticide products and worker exposure to pesticide drift.
Aim 1. Evaluate interventions designed to reduce agricultural worker exposure and risk during pesticide applications in tree fruit and measure dermal and inhalation exposures of pesticide handlers using conventional and new pesticide products during airblast applications.
Aim 2. Evaluate new engineering controls to reduce agricultural worker exposure due to pesticide drift during pest control applications in tree fruit orchards.
Aim 3. Develop recommendations for optimal pest control methods to minimize handler exposure and pesticide drift.
Our field study of dermal and inhalation exposure for pesticide handlers indicated that skin is the primary route of exposure, supporting previous studies. The body areas with the highest skin exposures were the upper legs, thought to occur during the mixing of pesticides before the application. It was demonstrated that the currently available and most frequently-used pesticide compounds for apple orchards are, in general, safer for pesticide applicators (when following label instructions) than alternatives of 10 years ago, when organophosphate use was more prevalent. However, in many cases, pesticide handlers exceed the level of concern set by a benchmark dose. The field study supported the finding that workers can exceed the risk estimates, even under normal work conditions. A comparative risk analysis of nine different alternatives to the organophosphorus insecticide, azinphosmethyl, confirms the scientific basis for phase-out of azinphosmethyl due to associated acute occupational health impacts. Results also indicated that acetamiprid exposures may be higher than anticipated for pesticide handlers who wear protective clothing according to label instructions. Study results were given to participating pesticide handlers, managers and crop consultants as well as recommendations on how to minimize dermal exposure.
Novel methods were developed to measure pesticide drift, including use of micronutrient tracers (zinc, molybdenum, and copper), real-time particle monitoring, and water sensitive paper. We conducted 18 field-based trials to compare three spray technologies—one traditional sprayer and two tower sprayers—based on minimizing downwind drift exposure. We hypothesized that newer tower sprayers would have lower drift measurements due to shorter nozzle-to-tree distances and a smaller risk of canopy escape. Three micronutrient tracers were applied separately with each sprayer to the same one-acre orchard block. Tracer aerosols were collected downwind on passive polyester line samples suspended from masts in 15 locations. Results were expressed as tank mix volume equivalents deposited on each 2 m section of the passive samples to illustrate the vertical drift profile at each location. Our trials of three airblast sprayers showed that drift was occurring at distances approximately 1.7 times greater than the Application Exclusion Zone for orchard airblast applications, as defined by the recently revised EPA Worker Protection Standard. Vertical profiles demonstrated greater deposition at the highest sampling level with increasing distance. Compared to traditional application technology, new tower sprayers can reduce downwind worker exposure to drift by up to 35%. Additional systematic evaluation of orchard sprayers is essential for developing recommendations about pesticide drift reduction.
Partners and Advisories
Washington State Department of Health
Washington State University
Washington Tree Fruit Research Commission
Pouzou J. G., Cullen A. C., Yost M. G., Kissel J. C., Fenske R. A. Comparative Probabilistic Assessment of Occupational Pesticide Exposures Based on Regulatory Assessments. Risk Anal. doi: 10.1111/risa.12936. 2017 November 6 PubMed PMID: 29105804; PMCID: PMC5936674.
Video: Reducing Agricultural Worker Risks through New and Emerging Technology - Feature on Student, Jane Pouzou.
Pouzou, J. G. The Use of Multi-Criteria Decision Analysis in Performing Alternatives Assessment and Comparative Risk Analysis: The Case Study of Codling Moth Pesticides. 2016 PhD Dissertation. Department of Environmental and Occupational Health Sciences, University of Washington.
Kasner E. J. On Preventing Farmworker Exposure to Pesticide Drift in Washington Orchards. 2017 PhD Dissertation. Department of Environmental and Occupational Health Sciences, University of Washington.
Blanco M. Real-Time Particle Monitoring of Pesticide Drift from Two Different Orchard Sprayers. 2017 MS Thesis. Department of Environmental and Occupational Health Sciences, University of Washington.