Drinking water disinfection by-products and time to pregnancy.
BACKGROUND
Laboratory evidence suggests tap water disinfection by-products (DBPs) could have an effect very early in pregnancy, typically before clinical detectability. Undetected early losses would be expected to increase the reported number of cycles to clinical pregnancy.


METHODS
We investigated the association between specific DBPs (trihalomethanes, haloacetic acids, brominated-trihalomethanes, brominated-haloacetic acids, total organic halides, and bromodichloromethane) and time to pregnancy among women who enrolled in a study of drinking water and reproductive outcomes. We quantified exposure to DBPs through concentrations in tap water, quantity ingested through drinking, quantity inhaled or absorbed while showering or bathing, and total integrated exposure. The effect of DBPs on time to pregnancy was estimated using a discrete time hazard model.


RESULTS
Overall, we found no evidence of an increased time to pregnancy among women who were exposed to higher levels of DBPs. A modestly decreased time to pregnancy (ie, increased fecundability) was seen among those exposed to the highest level of ingested DBPs, but not for tap water concentration, the amount absorbed while showering or bathing, or the integrated exposure.


CONCLUSIONS
Our findings extend those of a recently published study suggesting a lack of association between DBPs and pregnancy loss.
MacLehose
Richard F
RF
Biostatistics Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709-2233, USA. maclehoser@niehs.ni.gov
Savitz
David A
DA
Herring
Amy H
AH
Hartmann
Katherine E
KE
Singer
Philip C
PC
Weinberg
Howard S
HS
D000328:Adult; D003627:Data Interpretation, Statistical; D004202:Disinfectants / Q000009:adverse effects*; D004781:Environmental Exposure / Q000009:adverse effects / Q000032:analysis; D005260:Female; D006801:Humans; D006846:Hydrocarbons, Halogenated / Q000009:adverse effects / Q000032:analysis; D011247:Pregnancy; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D022882:Trihalomethanes / Q000009:adverse effects / Q000032:analysis; D014481:United States / Q000453:epidemiology; D014874:Water Pollutants, Chemical / Q000009:adverse effects* / Q000032:analysis; D018508:Water Purification / Q000379:methods*; D014881:Water Supply / Q000032:analysis*
D004202:Disinfectants; D006846:Hydrocarbons, Halogenated; D022882:Trihalomethanes; D014874:Water Pollutants, Chemical