Regional dermal deposition of the dimethylamine salt of 2,4-(dichlorophenoxy) acetic acid (2,4-D DMA) on farmers when handling, mixing, and spraying the herbicide was determined following 30 separate exposures. Before each spraying operation, the farmers were issued a standardized set of laundered cotton clothing that covered most of the body with two layers of clothing. Dermal samplers were placed under the clothing at nine locations and also on the neck and head regions. Two additional dermal samplers, attached over the clothing in the chest and elbow regions, provided direct comparison of outside/inside deposits.
Three distinct levels of dermal deposits could be clearly ascertained. The lowest median 2,4-D (acid equivalent; a.e.) deposit densities occurred under two layers of cotton clothing. These densities were quite uniform and indicated a greatly reduced but nevertheless general permeation of the herbicide through two layers of protective clothing. Somewhat higher median deposit densities were found on exposed body regions less likely to be contaminated during the mixing process, such as the head, neck, and outside elbow regions. The highest median deposit densities occurred on regions of the body most likely to be contaminated during the mixing process, that is, the wrist and chest regions. In the two body regions (chest and left elbow) where direct comparison could be made between deposits outside and beneath the clothing, a significant protective effect was observed, with the median deposit density suggesting a three- to eight-fold protective effect. It may, however, be pointed out that the overall body deposits, minus the hand regions, were only 10 to 20% of the total body deposits and thus, when protective garments equivalent to those used in this study are worn, hand protection must remain a major concern when spraying herbicides with ground-rigs.