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Andrew B. Lindstrom,¹ Joachim D. Pleil,¹ and David C. Berkoff²

¹National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711 USA; ²Department of Environmental Studies, University of Montana, Missoula, Montana 59802 USA

Abstract

Alveolar breath sampling was used to assess trihalomethane (THM) exposures encountered by collegiate swimmers during a typical 2-hr training period in an indoor natatorium. The breath samples were collected at regular intervals before, during, and for 3 hr after a moderately intense training workout. Integrated and grab whole-air samples were collected during the training period to help determine inhalation exposures, and pool water samples were collected to help assess dermal exposures. Resulting breath samples collected during the workout demonstrated a rapid uptake of two THMs (chloroform and bromodichloromethane) , with chloroform concentrations exceeding the natatorium air levels within 8 min after the exposure began. Chloroform levels continued to rise steeply until they were more than two times the indoor levels, providing evidence that the dermal route of exposure was relatively rapid and ultimately more important than the inhalation route in this training scenario. Chloroform elimination after the exposure period was fitted to a three compartment model that allowed estimation of compartmental half-lives, resulting minimum bloodborne dose, and an approximation of the duration of elevated body burdens. We estimated the dermal exposure route to account for 80% of the blood chloroform concentration and the transdermal diffusion efficiency from the water to the blood to in excess of 2%. Bromodichloromethane elimination was fitted to a two compartment model, which provided evidence of a small, but measurable, body burden of this THM resulting from vigorous swim training. These results suggest that trihalomethane exposures for competitive swimmers under prolonged, high-effort training are common and possibly higher than was previously thought and that the dermal exposure route is dominant. The exposures and potential risks associated with this common recreational activity should be more thoroughly investigated. Key words: alveolar breath sampling, bromodichloromethane, chloroform, exposure assessment, swimming, trihalomethanes (THMs) . Environ Health Perspect 105:636-642 (1997)

Address correspondence to J.D. Pleil, U.S. EPA, Mail Drop - 44, NERL, Research Triangle Park, NC, 27711 USA.

We thank the anonymous study subjects, Brent Ruby, and his students at the University of Montana ; Jim Bowyer of ManTech Environmental Services, Inc. ; EPA's Lance Wallace ; and David Shelow of Restek Corporation for their participation in this study and for their excellent advice. Breath analysis methods were developed for analytical equipment furnished under a Cooperative Research and Development Agreement (CRADA #0026-92) between the U.S. Environmental Protection Agency and Graseby Nutech Corporation. Specialty equipment, chromatographic supplies, and advice were provided under a CRADA between EPA and Restek Corporation. The information in this document has been funded wholly by the EPA. 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 10 December 1996 ; accepted 25 February 1997.