Assessment of Dermal Exposure to Chlorophenols in Timber Mills

Abstract

The quantitative assessment of dermal exposure among nine timber mill workers was conducted in conjunction with biological monitoring. A fluorescent tracer was included in a sapstain control application of an aqueous tetrachlorophenol (TCP) formulation in a planing mill. Workers grading and pulling the lumber were examined under longwave ultraviolet light before and after work, and the pattern of fluorescence on the skin was quantitated with a computer-based video imaging system. Urine samples were collected from the workers at the end of the day. Wipe samples and glove monitors were employed to determine the amount of TCP represented by the tracer on the skin. Less than two percent of the TCP applied to the wood was available by wipe sampling 30 seconds later. Six of nine workers received measureable exposure to the hands despite the consistent use of chemical-resistant gloves. All pullers exhibited exposure to the forearms. TCP exposure was highly correlated with time worked (R² = 0.84). Dermal exposure represented 95 percent of estimated total exposure. Levels of TCP recovered in urine confirm that dermal exposure is the major contributor to the total absorbed dose and that percutaneous absorption under these work conditions is at least 30 percent and may be as much as 100 percent of the amount of TCP deposited on the skin.