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CHLORINATION BY-PRODUCTS IN DRINKING WATER AND MENSTRUAL CYCLE FUNCTION
Citation:
Mendola, P, Windham, Gayle C, K. Waller, M. Anderson, L. Fenster, AND S. Swan. CHLORINATION BY-PRODUCTS IN DRINKING WATER AND MENSTRUAL CYCLE FUNCTION. ENVIRONMENTAL HEALTH PERSPECTIVES. National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, 111(7):935-941, (2002).
Description:
Chlorination by-Products in Drinking Water and Menstrual Cycle Function
Gayle C. Windham1, Kirsten Waller2, Meredith Anderson2, Laura Fenster1, Pauline Mendola3, Shanna Swan4
1California Department of Health Services, Division of Environmental and Occupational Disease Control, 1515 Clay St., Suite 1700, Oakland, CA 94612 (site where work was conducted).
2 Sequoia Foundation, La Jolla, CA 92037. Dr. Waller is currently with the Division of Infectious Disease Epidemiology, Pennsylvania Department of Health, Harrisburg, PA 17108.
3National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC 27711
4University of Missouri, Department of Family and Community Medicine, Columbia, MO 65212
ABSTRACT
We analyzed data from a prospective study of menstrual cycle function and early pregnancy loss to further explore the effects of trihalomethanes (THM) on reproductive endpoints. Premenopausal women (n=403) collected urine samples daily during an average of 5.6 cycles for measurement of steroid metabolites that were used to define menstrual parameters such as cycle and phase length. Women were asked about consumption of various types of water, as well as other habits and demographics. A THM level was assigned to each cycle based on residence and quarterly measurements made by water utilities during a 90-day time period starting 60 days before the cycle start date. We analyzed menstrual parameters as continuous and categorical variables in relation to various categorical exposure indices, accounting for repeated measures and controlling for several potential confounders. We found a monotonic decrease in cycle length with increasing total THM (TTHM) level; at >60 ug/L the adjusted decrement was 1.1 day (95% confidence interval (CI) ?1.8, -0.40), compared to <40 ug/L. This finding was also reflected as a reduced follicular phase length (difference ?0.92 day; 95% CI ?1.6, -0.23). Examining the individual THMs by quartile, we found the greatest association with chlorodibromomethane and the least with chloroform. Incorporating the amount of tap water usually consumed, we saw a similar pattern of reduced cycle length with increasing TTHM exposure. Considering the amount of time spent showering did not reveal additional risks. These findings suggest that THM exposure may affect ovarian function and should be confirmed in other studies.
Key words: trihalomethanes, chlorination by-products, menstrual cycle, drinking water, reproductive health