Gauging pesticide exposure of handlers (mixer/loaders/applicators) and harvesters in California agriculture.

Agricultural workers acquire pesticide exposures as a function of the properties of the product, crop, and work task. Mixer/Loaders and Applicators have greater exposure potential than other workers since concentrated formulations are handled during preparation and application of spray mixes. Exposures can be estimated using passive dosimetry and biological monitoring. Measured exposures are invariably less than estimates derived from surrogate data due to a series of conservative "worst case" assumptions and exposure estimates derived from small portions of the work day. Data have also been collected to estimate the exposure potentials of harvesters. We are establishing a set of empirical transfer factors (cm2/h) that can be used to estimate daily harvester exposure (transfer factor x dislodgeable foliar residue x hours). These estimates are important to current efforts to establish exposure-based reentry intervals to protect against acute and chronic toxicity.