| Effect of Water Temperature on Dermal Exposure to Chloroform Sydney M. Gordon,1 Lance A. Wallace,2 Patrick J. Callahan,1 Donald V. Kenny,1 and Marielle C. Brinkman1 1Battelle Memorial Institute, Columbus, OH 43201 USA
2National Exposure Research Laboratory, U.S. Environmental Protection Agency, Reston, VA 20192 USA Abstract
We have developed and applied a new measurement methodology to investigate dermal absorption of chloroform while bathing. Ten subjects bathed in chlorinated water while breathing pure air through a face mask. Their exhaled breath was delivered to a glow discharge source/ion trap mass spectrometer for continuous real-time measurement of chloroform in the breath. This new method provides abundant data compared to previous discrete time-integrated breath sampling methods. The method is particularly well suited to studying dermal exposure because the full face mask eliminates exposure to contaminated air. Seven of the 10 subjects bathed in water at two or three different temperatures between 30°C and 40°C. Subjects at the highest temperatures exhaled about 30 times more chloroform than the same subjects at the lowest temperatures. This probably results from a decline in blood flow to the skin at the lower temperatures as the body seeks to conserve heat forcing the chloroform to diffuse over a much greater path length before encountering the blood. These results suggest that pharmacokinetic models need to employ temperature-dependent parameters. Two existing models predict quite different times of about 12 min and 29 min for chloroform flux through the stratum corneum to reach equilibrium. At 40°C, the time for the flux to reach a near steady-state value is 6-9 min. Although uptake and decay processes involve several body compartments, the complicating effect of the stratum corneum lag time made it difficult to fit multiexponential curves to the data ; however, a single-compartment model gave a satisfactory fit. Key words: breath, chloroform, dermal exposure, drinking water, pharmacokinetics, real time, residence times. Environ Health Perspect 106:337-345 (1998) . [Online 13 May 1998] http://ehpnet1.niehs.nih.gov/docs/1998/106p337-345gordon/ abstract.html Address correspondence to S.M. Gordon, Battelle Memorial Institute, 505 King Avenue, Columbus, OH 43201-2693 USA. We thank the subjects for agreeing to participate in this study and for providing breath samples. We are grateful to Teledyne Electronic Technologies for the loan of the 3DQ Discovery ion trap mass spectrometer. The research described in this paper has been funded wholly or in part by the U.S. Environmental Protection Agency under contract 68-D4-0023 and Cooperative Agreement CR 822062-01-0 to Battelle Memorial Institute. It has been subjected to agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. Received 3 November 1997 ; accepted 29 January 1998.
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