The study confirms that large CSO events increase the risk of gastrointestinal illness in downstream communities. The similar risk across different drinking water sources suggests that exposure pathways beyond drinking water contamination—such as recreational water contact or aerosolized pathogens—may contribute to illness. The findings support concerns that climate change-driven increases in heavy precipitation and CSO events could lead to more frequent gastrointestinal illness outbreaks. Limitations include lack of individual exposure data, inability to track repeated AGI visits by the same individuals, and focus on severe cases presenting to EDs only. Strengths include the use of detailed daily CSO volume data, a self-matched study design controlling for confounders, and stratification by drinking water source
The study “Association between Combined Sewer Overflow Events and Gastrointestinal Illness in Massachusetts Municipalities with and without River-Sourced Drinking Water, 2014–2019” was written by the following authors:
Beth M. Haley (lead and corresponding author), Boston University School of Public Health
Yuantong Sun, Boston University School of Public Health
Jyotsna S. Jagai, University of Chicago
Jessica H. Leibler, Boston University School of Public Health
Robinson Fulweiler, Boston University (Departments of Earth & Environment and Biology)
Jacqueline Ashmore, New Leaf Energy
Gregory A. Wellenius, Boston University School of Public Health
Wendy Heiger-Bernays, Boston University School of Public Health