Shorter Menstrual Cycles Associated with Chlorination By- Products in Drinking Water Gayle Windham, K Waller, M Anderson, L Fenster, P Mendola, S Swan California Department of Health Services Environmental Health Investigations Branch (Work supported in large part by USEPA)
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Shorter Menstrual Cycles Associated with Chlorination By-Products in Drinking Water Gayle Windham, K Waller, M Anderson, L Fenster, P Mendola, S Swan California.
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Shorter Menstrual Cycles Associated with Chlorination
By-Products in Drinking Water
Shorter Menstrual Cycles Associated with Chlorination
By-Products in Drinking Water
Gayle Windham, K Waller, M Anderson,
L Fenster, P Mendola, S SwanCalifornia Department of Health Services
Environmental Health Investigations Branch
(Work supported in large part by USEPA)
TTHM Levels and Menstrual CyclingTTHM Levels and Menstrual CyclingBackground• Found association of SAB and high consumption of water
with high TTHM and BDCM levels.• Other studies confirm increased risk of adverse pregnancy
outcomes with chlorination by-products.
Purpose• THMs associated with other reproductive endpoints? • Identify possible mechanisms for the SAB effects. • Examine THM exposure and menstrual cycle function in a
study of 400 premenopausal women.
Women’s Reproductive Health Study Methods
Women’s Reproductive Health Study Methods
• Prospective Study of Kaiser members in Santa Clara County
• Women “at risk” of pregnancy, married, ages 18-39
• Baseline Questionnaire — phone– # glasses unheated tap water at home– # glasses hot tap at home– # glasses bottled water/day (and brand)– # showers at home (and length)/week– Demographics and covariates
• Geocode residence address to identify water utility company
• Obtain utility THM monitoring data (total and individual)
• Cycle-specific THM levels estimated:– 90-day window, starting 60 days before cycle start– average all utility monitoring points– weighted if moved– average two closest to window, if none during
• Woman-level TTHM from average of cycle-specific levels
Sum of Brominated 17.2 (0.35) -0.66 (-1.3, 0.02) -1.1 (-1.9, -0.29)
TTHM Levels and Menstrual CyclingTTHM Levels and Menstrual Cycling
Strengths• Prospective study• TTHM exposure from existing records in narrow time frame• Information on some water use patterns• Endpoint determined from biologic measures (vs. self-report)• Adjusted for several potential confounders• First study of reproductive function in non-pregnant women
Limitations• Potential exposure misclassification (utility average)• No information on exposure outside the home• Study sample may not represent full range of cycle variability
Conclusions and SummaryConclusions and Summary
• Increasing TTHM level is associated with decreasing cycle length, primarily in the follicular phase
• This decrease is associated with the brominated THMs, primarily chlorodibromomethane
• Combining consumption and TTHM level reveals similar, but not greater, associations
• Accounting for showering also does not reveal stronger associations
Confirm effects on ovarian function in other studies