Protection by ordinary light clothing against pesticide spray drift for bystanders and residents

There are stringent EU regulatory requirements to assess pesticide exposure to bystanders and residents to direct spray drift. A “light clothing” adjustment factor (AF) of 0.82 is applied in the exposure assessment, based on simple assumptions for covered body surface and penetration through clothing. To assess the appropriateness of the AF, we collated data from 32 field studies. The mean and 25th percentile % reduction from ordinary light clothing (“reduction %”) in children and adults for all crops and standard and drift-reducing nozzles were 42.7% and 36.2%, resulting in AF of 0.573 and 0.638, respectively. Sources of variation were investigated, e.g. crop type, leaf coverage, buffer, spray pressure, and nozzle type, which indicated that reduction % could be impacted by several conditions. The reduction % is similar between crops; therefore, a single AF value covering all crops can be derived. One exception was for early-stage vineyard scenarios (the reduction % is lower (27%) than late stage (42–47%)) and could be considered individually to avoid unnecessary conservatism for the other scenarios. This evaluation demonstrates the current AF to be overly precautionary, and a more realistic, exposure scenario-relevant value could be applied for bystander/resident risk assessments.