W. Addo J. van Pul – författare

This volume contains the proceedings of an international workshop on the issue of "Fate of pesticides in the atmosphere - implications for risk assessment" held in 1998 in The Netherlands. Topics include emission, dispersion, transport and transformations of pesticides in the atmosphere, and the ecotoxicological risks of pesticides in remote areas. Laboratory and field measurements are reviewed, and modelling of the atmospheric processes that affect pesticides are discussed. Various risk assessment approaches are presented, and possible statutory environmental criteria that could be incorporated into pesticide regulation in order to limit their atmospheric dispersion are explored. This book presents a complete review of the science of this subject with the aim of investigating the possibilities of incorporating long-range transport potential of pesticides into protocols for estimating their environmental risks and their registration.

Global pesticide use is currently estimated at approximately 2. 5 billion kg per year (Pimentel eta/. , 1998). To be effective, pesticides need to persist for a certain period of time. However, the longer their persistence, the greater the potential for transport of a fraction of the amount applied away from the target area. Pesticides are dispersed in the environment by water currents, wind, or biota. Pesticides can directly contaminate ground and surface waters by leaching, surface run-off and drift. Pesticides can also enter the atmosphere during application by evaporation and drift of small spray droplets, that remain airborne. Following application, pesticides may volatilise from the crop or the soil. Finally, wind erosion can cause soil particles and dust loaded with pesticides to enter the atmosphere. The extent to which pesticides enter the air compartment is dependent upon many factors: the properties of the substance in question (e. g. vapour pressure), the amount used, the method of application, the formulation, the weather conditions (such as wind speed, temperature, humidity), the nature of the crop and soil characteristics. Measurements at application sites reveal that sometimes more than half of the amount applied is lost into the atmosphere within a few days (Spencer and Cliath, 1990; Taylor and Spencer; 1990; Van den Berg et a/. , this issue).