title: Refined assessment of associations between drinking water residence time and emergency department visits for gastrointestinal illness in Metro Atlanta, Georgia.
abstract: Recent outbreak investigations suggest that a substantial proportion of waterborne disease outbreaks are attributable to water distribution system issues. In this analysis, we examine the relationship between modeled water residence time (WRT), a proxy for probability of microorganism intrusion into the distribution system, and emergency department visits for gastrointestinal (GI) illness for two water utilities in Metro Atlanta, USA during 1993-2004. We also examine the association between proximity to the nearest distribution system node, based on patients' residential address, and GI illness using logistic regression models. Comparing long (≥90th percentile) with intermediate WRTs (11th to 89th percentile), we observed a modestly increased risk for GI illness for Utility 1 (OR = 1.07, 95% CI: 1.02-1.13), which had substantially higher average WRT than Utility 2, for which we found no increased risk (OR = 0.98, 95% CI: 0.94-1.02). Examining finer, 12-hour increments of WRT, we found that exposures >48 h were associated with increased risk of GI illness, and exposures of >96 h had the strongest associations, although none of these associations was statistically significant. Our results suggest that utilities might consider reducing WRTs to <2-3 days or adding booster disinfection in areas with longer WRT, to minimize risk of GI illness from water consumption.
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA E-mail: karen.levy@emory.edu; Center for Global Safe Water, Sanitation and Hygiene at Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Levy
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA E-mail: karen.levy@emory.edu.
authors.forename: Mitchel
authors.initials: M
authors.lastname: Klein
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA E-mail: karen.levy@emory.edu.
authors.forename: Stefanie Ebelt
authors.initials: SE
authors.lastname: Sarnat
authors.affiliation: Center for Global Safe Water, Sanitation and Hygiene at Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA; Hubert Department of Global Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA; Present address: Oregon Health Authority, 500 Summer St. NE, E52, Salem, OR 97301, USA.
authors.forename: Samina
authors.initials: S
authors.lastname: Panwhar
authors.affiliation: Center for Global Safe Water, Sanitation and Hygiene at Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA; Hubert Department of Global Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Huttinger
authors.affiliation: Department of Environmental Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA E-mail: karen.levy@emory.edu.
authors.forename: Paige
authors.initials: P
authors.lastname: Tolbert
authors.affiliation: Center for Global Safe Water, Sanitation and Hygiene at Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA; Hubert Department of Global Health, Rollins School of Public Health, Emory University, 1518 Clifton Rd NE, Atlanta, GA 30322, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Moe
mesh_terms: D060766:Drinking Water / Q000032:analysis / Q000382:microbiology*; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000382:microbiology; D005845:Georgia / Q000453:epidemiology; D014872:Water Movements; D014881:Water Supply
chemical_list: D060766:Drinking Water