Drinking Water Turbidity and Emergency Department Visits for Gastrointestinal Illness in New York City, 2002-2009

Abstract

BackgroundStudies have examined whether there is a relationship between drinking water turbidity and gastrointestinal (GI) illness indicators, and results have varied possibly due to differences in methods and study settings.ObjectivesAs part of a water security improvement project we conducted a retrospective analysis of the relationship between drinking water turbidity and GI illness in New York City (NYC) based on emergency department chief complaint syndromic data that are available in near-real-time.MethodsWe used a Poisson time-series model to estimate the relationship of turbidity measured at distribution system and source water sites to diarrhea emergency department (ED) visits in NYC during 2002-2009. The analysis assessed age groups and was stratified by season and adjusted for sub-seasonal temporal trends, year-to-year variation, ambient temperature, day-of-week, and holidays.ResultsSeasonal variation unrelated to turbidity dominated (~90% deviance) the variation of daily diarrhea ED visits, with an additional 0.4% deviance explained with turbidity. Small yet significant multi-day lagged associations were found between NYC turbidity and diarrhea ED visits in the spring only, with approximately 5% excess risk per inter-quartile-range of NYC turbidity peaking at a 6 day lag. This association was strongest among those aged 0-4 years and was explained by the variation in source water turbidity.ConclusionsIntegrated analysis of turbidity and syndromic surveillance data, as part of overall drinking water surveillance, may be useful for enhanced situational awareness of possible risk factors that can contribute to GI illness. Elucidating the causes of turbidity-GI illness associations including seasonal and regional variations would be necessary to further inform surveillance needs.

An evaluation of changes in opinion from an expert workshop on turbidity in drinking water supplies and acute gastrointestinal illness

“…Confounding cannot be ruled out with certainty in a non-randomised study design but appropriate analyses were performed by most studies to adjust for potential confounders including temperature, seasonality, and day of the week. The results do not match patterns that might be expected for recreational water transmission (associations found in spring rather than summer by Hsieh et al (2015).…”

Climate change-induced increases in precipitation are reducing the potential for solar ultraviolet radiation to inactivate pathogens in surface waters

“…For example, in the United States extreme precipitation events precede on the order of 68% of waterborne disease outbreaks 6 . Heavy precipitation has been implicated in cryptosporidiosis in Milwaukee, USA 53 , New Zealand 54 and Spain 55 , as well as in emergency visits for diarrhea in the springtime in New York 56 . Recreational waters and harvesting of shellfish are often closed following extreme precipitation events due to the high probability of contamination 6 .…”

Effects of location on the physico-chemical properties of water in the Matatiele Local Municipality, South Africa

“…These water sources are not good for drinking turbidity wise and people who drink water from these water sources may have health problems. They may suffer from water-borne diseases [13]. Other water sources in all categories were below 5 NTU and this means as far as turbidity is concerned, they are good for drinking.…”

“…Turbidity is a standard drinking water quality indicator which is related to the amount and physical characteristics of suspended particles but does not indicate the type or source of particles Hsieh et al [13]. The standard recommended maximum turbidity limit, set by [10] for drinking water is less than or equal to 5 nephelometric turbidity units (NTU).…”