A Systematic Review of the Time Series Studies Addressing the Endemic Risk of Acute Gastroenteritis According to Drinking Water Operation Conditions in Urban Areas of Developed Countries

Abstract

Time series studies (TSS) can be viewed as an inexpensive way to tackle the non-epidemic health risk from fecal pathogens in tap water in urban areas. Following the PRISMA recommendations, I reviewed TSS addressing the endemic risk of acute gastroenteritis risk according to drinking water operation conditions in urban areas of developed countries. Eighteen studies were included, covering 17 urban sites (seven in North-America and 10 in Europe) with study populations ranging from 50,000 to 9 million people. Most studies used general practitioner consultations or visits to hospitals for acute gastroenteritis (AGE) as health outcomes. In 11 of the 17 sites, a significant and plausible association was found between turbidity (or particle count) in finished water and the AGE indicator. When provided and significant, the interquartile excess of relative risk estimates ranged from 3–13%. When examined, water temperature, river flow, and produced flow were strongly associated with the AGE indicator. The potential of TSS for the study of the health risk from fecal pathogens in tap water is limited by the lack of specificity of turbidity and its site-sensitive value as an exposure proxy. Nevertheless, at the DWS level, TSS could help water operators to identify operational conditions most at risk, almost if considering other water operation indicators, in addition to turbidity, as possible relevant proxies for exposure.

Water safety plans and risk assessment: A novel procedure applied to treated water turbidity and gastrointestinal diseases

“…The article is framed around the increasingly important issue of Water Safety Plans (WSPs) (Bartam et al, 2009;WHO, 2004) and their health impacts (Gelting et al, 2012;Gunnarsdottir et al, 2012;Setty et al, 2017). It cites our own analyses of relationships between sitespecific drinking water-related exposures and health impacts (Beaudeau, 2018;De Roos et al, 2017;Setty et al, 2018). Muoio et al (2019) suggest epidemiological analyses are overly complex and that risk management for drinking water treatment systems can more easily be optimized to improve health through engineered turbidity reduction.…”

“…Second, Muoio et al assume and encourage adoption of a fixed relationship between turbidity exposure and disease risk, which is known to vary widely and depend on context. Based on a sizeable body of evidence, our research (Beaudeau, 2018;De Roos et al, 2017;Setty et al, 2018) indicates that the association between turbidity and disease risk is context specific. The nature of the turbidity indicator (cloudiness of a water sample) may or may not relate to disease in a given contextlogically, a water source displaying raised turbidity due to suspended silt or algal growth might present a similar turbidity value but radically different health risk than a sewage-contaminated sample containing viable human pathogens.…”

“…The nature of the turbidity indicator (cloudiness of a water sample) may or may not relate to disease in a given contextlogically, a water source displaying raised turbidity due to suspended silt or algal growth might present a similar turbidity value but radically different health risk than a sewage-contaminated sample containing viable human pathogens. Several reviewed studies have found seasonal or local conditions such as river flow rate and water temperature to modify the relationship between turbidity and gastroenteritis (Beaudeau, 2018;De Roos et al, 2017). Additionally, several studies have reported evidence of a non-linear relationship, suggesting exposure-response significance only at the highest levels of measured turbidity.…”

“…Further, their justification for using the median value improperly implicates outlying values as "out of range" rather than a reflection of true variability. Beaudeau (2018) specifically discouraged such meta-analyses and health impact assessments, which require attention to the choice of locally adapted risk functions. Lacking local calibration of the health risk relationship, the Muoio et al (2019) approach simply targets reducing turbidity to the greatest extent possible, which ignores cost and other tradeoffs.…”

Drinking Water Quality and Human Health: An Editorial

“…A time-series study evaluated the association between general indicators of drinking water quality (mainly turbidity) and the occurrence of gastroenteritis in 17 urban sites in the USA and Europe. [12] The other evaluated the performance of an algorithm to predict the occurrence of waterborne disease outbreaks in France [13].…”