Trihalomethanes in public water supplies and risk of stillbirth.
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 microg/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.
Dodds
Linda
L
Perinatal Epidemiology Research Unit, Department of Obstetrics and Gynecology, Dalhousie University, 5980 University Avenue, Halifax, Nova Scotia, Canada B3H 4N1. l.dodds@dal.ca
King
Will
W
Allen
Alexander C
AC
Armson
B Anthony
BA
Fell
Deshayne B
DB
Nimrod
Carl
C
D000328:Adult; D016022:Case-Control Studies; D002713:Chlorine / Q000009:adverse effects; D004522:Educational Status; D005260:Female; D006801:Humans; D007182:Income; D009674:Nova Scotia / Q000453:epidemiology; D009864:Ontario / Q000453:epidemiology; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D012307:Risk Factors; D022882:Trihalomethanes / Q000009:adverse effects*; D018508:Water Purification / Q000379:methods*
D022882:Trihalomethanes; D002713:Chlorine