Trihalomethanes in Public Water Supplies and Risk of Stillbirth

• Published in: Epidemiology (Cambridge, Mass.) Mass.), 2004-03, Vol.15 (2), p.179-186
• Main Authors: Dodds, Linda, King, Will, Allen, Alexander C., Armson, B. Anthony, Fell, Deshayne B., Nimrod, Carl
• Format: Article
• Language: English
• Subjects: Adult; Bathing; Case-Control Studies; Chlorination; Chlorine - adverse effects; Educational Status; Epidemiology; Female; Humans; Income; Ingestion; Nova Scotia - epidemiology; Ontario - epidemiology; Potable water; Pregnancy; Pregnancy Outcome - epidemiology; Risk Factors; Stillbirth; Tap water; Trihalomethanes - adverse effects; Water consumption; Water Purification - methods; Water samples
• ISSN: 1044-3983; 1531-5487
• DOI: 10.1097/01.ede.0000112209.47765.d9

Background: The chlorine used to disinfect public drinking water supplies reacts with naturally occurring organic matter to form a number of chemical byproducts. Recent studies have implicated exposure to chlorination byproducts in drinking water, trihalomethanes (THMs), in particular, with intrauterine death. Methods: We conducted a population-based case-control study in Nova Scotia and Eastern Ontario, Canada, to examine the effect of exposure to THMs on stillbirth risk. Cases were women who had a stillborn infant, and controls were a random sample of women with live births. Subjects were interviewed, and women with a public water source provided a residential water sample. Risks were examined according to residential THM level in tap water and to a total exposure metric incorporating tap water ingestion, showering, and bathing. Results: We enrolled 112 stillbirth cases and 398 live birth controls. Women with a residential total THM level of 80 or more μg/L had twice the risk of a stillbirth compared with women with no exposure to THMs (adjusted odds ratio [OR] = 2.2; 95% confidence interval [CI] = 1.1-4.4). The highest quintile of total THM exposure using the total exposure metric was associated with an adjusted odds ratio of 2.4 (95% CI = 1.2-4.6) compared with women not exposed to THMs. Similar results were seen for specific THM compounds. A monotonic dose-response relationship was not seen. Conclusions: Our results provide evidence for an increased risk of stillbirth associated with exposure to chlorination byproducts through ingestion and showering and bathing, although there was not a clear dose-response relationship.