Pesticide Exposure during Greenhouse Applications, Part I. Dermal Exposure Reduction Due to Directional Ventilation and Worker Training

Abstract

Workers conducted benchtop handgunning spray operations in a commercial greenhouse in Florida with the ventilation system either on or off. Five workers were experienced applicators, while four had little or no previous application experience. Applications were conducted for 1 hour with a fluorescent tracer substituted for pesticides in an aqueous mixture. Dermal exposure was monitored by video imaging and by patches attached to the arms and legs. The greenhouse ventilation system produced strong unidirectional air movement (> 5 m/s) and therefore had a pronounced effect on the aerosol drift pattern generated during application. Both video-imaging analysis and patch sampling indicated that when spraying occurred with ventilation on rather than off, exposure was reduced for experienced applicators, but increased for inexperienced applicators. Average exposure reductions due to ventilation for the experienced applicators were 63 and 83 percent for the upper arms, and 74 and 94 percent for the upper legs, as measured by video imaging and patches, respectively. When ventilation was in operation inexperienced applicators exhibited a tenfold to thirtyfold increase in exposure compared with the experienced applicators, whereas no difference was observed between the two groups with ventilation off. These results indicate that experienced applicators can employ strong unidirectional ventilation to their advantage by remaining upwind of the aerosol drift pattern, and that such behavior can reduce exposure dramatically during greenhouse handgunning applications. Greenhouse applicators can benefit substantially from training which includes proper instruction regarding ventilation under working conditions similar to those examined in this study.