| The Healthy Men Study: An Evaluation of Exposure to Disinfection By-Products in Tap Water and Sperm Quality Thomas J. Luben,1 Andrew F. Olshan,1 Amy H. Herring,2 Susan Jeffay,3 Lillian Strader,3 Rebecca M. Buus,3 Ronna L. Chan,1 David A. Savitz,4 Philip C. Singer,5 Howard S. Weinberg,5 and Sally D. Perreault3 1Department of Epidemiology, and 2Department of Biostatistics, University of North Carolina School of Public Health, Chapel Hill, North Carolina, USA; 3Reproductive Toxicology Division, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA; 4Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA; 5Department of Environmental Sciences and Engineering, University of North Carolina School of Public Health, Chapel Hill, North Carolina USA Abstract
Background: Chlorination of drinking water generates disinfection by-products (DBPs) , which have been shown to disrupt spermatogenesis in rodents at high doses, suggesting that DBPs could pose a reproductive risk to men. In this study we assessed DBP exposure and testicular toxicity, as evidenced by altered semen quality. Methods: We conducted a cohort study to evaluate semen quality in men with well-characterized exposures to DBPs. Participants were 228 presumed fertile men with different DBP profiles. They completed a telephone interview about demographics, health history, water consumption, and other exposures and provided a semen sample. Semen outcomes included sperm concentration and morphology, as well as DNA integrity and chromatin maturity. Exposures to DBPs were evaluated by incorporating data on water consumption and bathing and showering with concentrations measured in tap water. We used multivariable linear regression to assess the relationship between exposure to DBPs and adverse sperm outcomes. Results: The mean (median) sperm concentration and sperm count were 114.2 (90.5) million/mL and 362 (265) million, respectively. The mean (median) of the four trihalomethane species (THM4) exposure was 45.7 (65.3) µg/L, and the mean (median) of the nine haloacetic acid species (HAA9) exposure was 30.7 (44.2) µg/L. These sperm parameters were not associated with exposure to these classes of DBPs. For other sperm outcomes, we found no consistent pattern of increased abnormal semen quality with elevated exposure to trihalomethanes (THMs) or haloacetic acids (HAAs) . The use of alternate methods for assessing exposure to DBPs and site-specific analyses did not change these results. Conclusions: The results of this study do not support an association between exposure to levels of DBPs near or below regulatory limits and adverse sperm outcomes in humans. Key words: disinfection by-products, environmental exposure, epidemiology, haloacetic acids, human, male, reproduction, semen, sperm count, trihalomethanes. Environ Health Perspect 115:1169–1176 (2007) . doi:10.1289/ehp.10120 available via http://dx.doi.org/ [Online 22 May 2007]
Address correspondence to T.J. Luben, U.S. Environmental Protection Agency, National Center for Environmental Assessment, MD B 243-1, Research Triangle Park, NC 27711 USA. Telephone: (919) 541-5762. E-mail: luben.tom@epa.gov Supplemental Material is available online at http://www.ehponline.org/docs/2007/10120/suppl.pdf We thank J. Smith and Y. Shen for programming and statistical contributions to this project, and L. Lansdell for assistance with the study. This research was supported in part by grants from the U.S. Environmental Protection Agency (EPA ; R-82932701) , National Institute of Environmental Health Sciences (P30ES10126, T32ES007018) , and American Water Works Association Research Foundation (CR825625-01, CR827268-01, CR828216-01) . Although the research described in this article has been supported by the U.S. EPA, it does not necessarily reflect the views of the agency, and no official endorsement should be inferred. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. The authors declare they have no competing financial interests. Received 29 January 2007 ; accepted 22 May 2007.
Correction In the "Results" (second paragraph of "Disinfection by-product exposure and sperm outcomes") of the original manuscript published online, the authors stated that "negative beta coefficients and correlation coefficients indicate decreased adverse semen quality . . ." and "positive beta coefficients and correlation coefficients indicate increased adverse semen quality . . . ." This has been corrected here. Also, in the first paragraph of the "Discussion," "TOX" has been expanded to "DBPs" in reference to sperm morphology and sperm numbers.
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