Exposure of forestry ground workers to 2,4‐D, picloram and dichlorprop

Urine samples from 80 forest workers applying 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] plus dichlorprop [(±)‐2‐(2,4‐dichlorophenoxy)propanoic acid] or picloram (4‐amino‐3,5,6‐trichloro‐2‐pyridinecarboxylic acid) by ground techniques were monitored to determine the dose of chemical absorbed. Four crews of 20 workers each were studied to compare the exposures during application by backpack, injection bar, Hypohatchet or a hack‐and‐squirt method. Total urine output was analyzed to compare the absorbed dose to each worker under two operational modes. In the first, designated T‐1, the workers wore their usual clothing and followed the work habits they ordinarily used on the job. In the second mode, designated T‐2 and conducted 6 d after the first, workers were given new leather gloves and boots and asked to take all feasible precautions to prevent herbicide exposure and to wash immediately if they come into contact with the chemical. For all application methods except that with backpacks, the T‐2 treatment decreased the absorbed dose. During both T‐1 and T‐2 the clothing of backpack sprayers often became saturated with spray, dew or perspiration, and these workers received a higher absorbed dose of 2,4‐D (0.04–0.24 mg/kg body weight) than did workers in other crews. The absorbed dose of dichlorprop ranged from undetectable to 0.18 mg/kg. Hypohatchet workers received a greater dose than did injection bar or hack‐and‐squirt workers. The absorbed dose of picloram ranged from undetectable to 0.02 mg/kg. If equal dermal penetration of 2,4‐D and picloram is assumed, this represents much less dermal absorption than would have been predicted from the relative amounts of 2,4‐D and picloram in Tordon 101‐Rr̀.