Impact of Wind Speed and Direction and Key Meteorological Parameters on Potential Pesticide Drift Mass Loadings from Sequential Aerial Applications

Abstract

Pesticide spray drift is potentially a significant source of exposure to off‐target, adjacent aquatic habitats. To estimate the magnitude of pesticide drift from aerial or ground applications, regulatory agencies in North America, Europe, and elsewhere rely on spray drift models to predict spray drift deposition for risk assessments. Refined assessments should ultimately depend on best‐available data for exposure modeling. However, when developing lower tier “screening” assessments designed to indicate whether further refinement is needed, regulators often make conservative assumptions with a resulting increased level of uncertainty in estimating environmental exposure or risk. In the United States, it is generally accepted that, to ensure conservative regulatory assessments, it is reasonable to assume that the wind speed might be 4.47 m/s (10 miles per hour [mph]), the relative humidity and temperature are highly conducive to drift, and the wind is blowing directly toward a receiving water for any given single spray event in a season. However, what is the probability these conditions will all co‐occur for each of 4 sequential spray events spaced a week apart (common practice for insecticides)? The refined approach in the present study investigates this question using hourly meteorological data sets for 5 United States Environmental Protection Agency (USEPA) standard crop scenarios to understand how real‐world data can reduce unnecessary uncertainty for sequential applications. The impact of wind speeds, temperatures, relative humidity, and wind direction at different times of day on annual drift loadings has been examined using a stepwise process for comparison with corresponding regulatory default loading estimates. The impacts on drift estimates were significant; interestingly, the time of day of the applications impacted variability more than did the selected crop scenario. When all these real‐world factors were considered, estimated 30‐y total drift loads ranged from 2% to 5% greater than the default estimate (2 of 30 cases due to high afternoon wind speeds) to 51% to 86% reductions (25 of 30 cases) with an overall average reduction of 63%. Integr Environ Assess Manag 2020;16:197–210. © 2019 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of Society of Environmental Toxicology & Chemistry (SETAC)

A national probabilistic characterization of local crop proximity and density for refining US screening level exposure estimates of pesticides in surface water arising from agricultural use

“…In a full probabilistic risk refinement, many other input parameter distributions would have been considered at the same time to replace the conservative, single-point values assumed for screening assessments. For example, see the effect of wind speed, temperature, and humidity on drift loads [8] and wind direction relative to water body [18,40]. The current study merely demonstrates the effect of one of the more important drivers of transport to aquatic systems.…”

Pesticide Toxicity Prevention in Farmer’s Community Movement

“…Spraying patterns in Sumber Mufakat villagers generally do not pay attention to the direction of the wind and are done by going back and forth following the plant beds. That action results in exposing the pesticide sprayed directly on the organs of the eye that are not protected with protective goggles, wind speed, and wind blow as the potential factor to increase the pesticide toxicity [37], [41], [42], [43].…”

An Assessment of School Going Population Exposure Pathways to Agropesticide in the Mungo Corridor of Cameroon

“…Spray drift continues to be a major problem in agropesticides. Numerous studies (Hanna & Schaefer, 2014;Graeme, 2017;Baio et al, 2019;Desmarteau et al, 2019) have confirmed that air is one of the main pathways through which pesticides reach undesirable targets. This current study has shown that air drift triggered by wind from nearby banana plantations where aerial sprays are done, carry particles of pesticides to undesirable targets like schools and residence.…”