Drinking water and pregnancy outcome in central North Carolina: source, amount, and trihalomethane levels.

Abstract

In spite of the recognition of potentially toxic chemicals in chlorinated drinking water, few studies have evaluated reproductive health consequences of such exposure. Using data from a case-control study of miscarriage, preterm delivery, and low birth weight in central North Carolina, we evaluated risk associated with water source, amount, and trihalomethane (THM) concentration. Water source was not related to any of those pregnancy outcomes, but an increasing amount of ingested water was associated with decreased risks of all three outcomes (odds ratios around 1.5 for 0 glasses per day relative to 1-3 glasses per day, falling to 0.8 for 4+ glasses per day). THM concentration and dose (concentration x amount) were not related to pregnancy outcome, with the possible exception of an increased risk of miscarriage in the highest sextile of THM concentration (adjusted odds ratio = 2.8, 95% confidence interval = 1.1-2.7), which was not part of an overall dose-response gradient. These data do not indicate a strong association between chlorination by-products and adverse pregnancy outcome, but given the limited quality of our exposure assessment and the increased miscarriage risk in the highest exposure group, more refined evaluation is warranted.

Drinking water contaminants and adverse pregnancy outcomes: a review.

“…Only the study in Denver, Colorado, had a maximum level of TTHMs below 100 ppb (6). Table 1 summarizes the characteristics of the eight DBP studies that based their exposure assessments on measurements of THMs in tap water supplies (6,12,(19)(20)(21)(22)(23)(24)(25)(26). Seven of these studies used THM monitoring data concurrent with the time of pregnancy, and one study used THM monitoring data occurring several years before the study period (19).…”

“…Three case-control studies (21,25,26) and one prospective cohort study (12) conducted maternal interviews to determine water consumption habits during pregnancy. Table 3 presents risk estimates (relative risk or odds ratio) for DBPs and the various adverse reproductive outcomes for those studies utilizing THM monitoring data.…”

“…A study of three counties in central North Carolina identified 586 preterm births and 464 low-birth-weight births during September 1988 through August 1989 (extended to April 1991 in one county) (21). (27) Preterm delivery treatment; address at delivery A sample of 782 term, normal-weight live births, matched to the cases on race, date of birth, and hospital of birth, constituted the control group.…”

Developmental Toxicity of Drinking Water Disinfection By-Products to Embryos of the African Clawed Frog (Xenopus laevis)

“…One drawback to this beneficial practice is the generation of drinking water disinfection by-products (DWDB), some of which have been implicated as causing adverse human health outcomes (Savitz et al 1995;Waller et al 1998;Weisel et al 1996). In this article we report the results of 96 h developmental toxicity tests with embryos of the South African clawed frog Xenopus laevis used to evaluate four individual DWDB: bromodichloromethane (BDCM), sodium chlorate, chloroform, and dibromoacetic acid (DBAA).…”

A sensitivity analysis of bias in relative risk estimates due to disinfection by-product exposure misclassification

“…Several reproductive epidemiologic studies of DBPs have used town average concentrations to estimate maternal exposure (Kramer et al, 1992;Bove et al, 1995;Savitz et al, 1995;Gallagher et al, 1998;Waller et al, 1998;Dodds et al, 1999;Klotz and Pyrch, 1999;Wright et al, 2003Wright et al, , 2004. Gallagher et al (1998) used geographic information system mapping and water hydraulic models to limit the impact of spatial variability on exposure misclassification.…”