Risk estimation of bystander and residential exposure from orchard spraying based on measured spray drift data. International Advances in Pesticide Application

In Dutch municipalities there is a discussion on the safe distance between houses and agricultural activities, especially the application of plant protection products (PPP) in fruit orchards. At this moment a generic safety distance or buffer zone of 50 m is taken into account. Based on general drift reducing measures taken by growers to reduce spray drift to the surface water it is questioned whether this safety distance can be reduced. An evaluation of spray drift data of standard and drift reducing techniques in orchard spraying is analysed for spray drift deposition to the soil and airborne spray drift next to the orchard. Based on spray drift deposition and estimated concentration in the air a comparison is made with dermal, inhalatory and secondary dermal Acceptable Exposure Limits (AEL) for humans. Based on the available spray drift data for standard conventional spraying and the use of venturi low-drift nozzles safety distances are estimated for people standing in the home garden, and at the front of the house. These distances are calculated for often used fungicides and insecticides in orchard, such as captan, thiram, fenoxycarb, flonicamid, methoxyfenozide, and pirimicarb. Safety distances are calculated for both the dormant and the full leaf stage of the trees. Such safety distances are based on the most important scenario by thiram in the full leaf stage and captan in the dormant leaf stage, and range between 20 and 50 m. Safe distances are more dependent on the toxicity of the PPP than on the spray drift level.