This report focuses on the mechanisms underlying the various sources of exposure during two replicate exposure studies of two ground crews applying Difolatan 80 Sprills (80% captafol) in central Florida orange groves.
Aerosolized captafol concentrations averaged 56 µg/m3 for mixer-loaders and 34 µg/m3 for spray applicators but were not statistically different.
Dermal “exposures” (outside the coveralls) were consistent within participants but not within operations for reasons that are compatible with observed differences in work conditions. The density of exposure ranged roughly from 1 to 10 µg/h/cm2 to the hands, legs, and arms (but up through 20 when direct contact with captafol solutions was evident) to 0.1 to 1 µg/h/cm2 for other locations. Whole-body exposures had a mean of 40 mg/h and ranged from 15 to 116 mg/h, with the hands accounting for around 40% of these totals.
Dermal “doses” (inside the coveralls) were reduced and generally more uniform than either dermal exposures or aerosols. Penetration through the cotton-polyester coveralls differed from a mean of 2% for the spray applicators to 7% for the mixer-loaders, for reasons believed to be related to wet versus dry deposition, respectively. This protection reduced skin dosing densities under the coveralls to 0.01 to 0.1 µg/h/cm2 except to the largely horizontal upper legs and lower arms that ranged from 0.1 to 0.5 µg/h/cm2. Whole-body doses had a mean of 19 mg/h and ranged from 10 to 30 mg/h, with hands accounting for around 90% of these totals. Laboratory methods to predict the clothing penetration rates in similar field settings are needed.