A holistic QMRA tool to assess current and future health risks from the drinking water production process

ABSTRACT Climate and socioeconomic changes have the potential to impact waterborne pathogens and associated health risks, although the extent of these impacts remains uncertain. Quantitative microbial risk assessment (QMRA) is a widely used method for estimating health risks from waterborne pathogens. While many QMRA studies focus on assessing current risks, limited attention has been given to forecasting future risks arising from changes in climate and socioeconomic factors. Furthermore, while some QMRA tools incorporate climate-related variables, none have integrated both climate and socioeconomic factors to assess health risks. This study aims to apply the Swedish QMRA tool to evaluate both current (2020s) and future (2050 and 2100) health risks associated with drinking water production from Lake Vomb, Sweden, by considering the impact of climate and socioeconomic changes. The proposed approach introduces a novel framework that incorporates both climatic and socioeconomic factors, offering a holistic assessment of future risks. The results indicated that under current conditions (2020s), the infection risks for Campylobacter, norovirus, and Cryptosporidium were within the thresholds of 10−4 infections per person per year (as proposed by USEPA scientists). However, during extreme events such as sewer overflow and agricultural runoff, the risk from norovirus surpassed these thresholds. Future scenario analysis showed improvements in infection risks in some cases, while the uncontrolled scenario with large population growth, partial or no wastewater treatment, and rapid change in rainfall patterns predicted a significant increase in risks in both the near and distant future. The introduction of an additional UV treatment barrier proved to reduce these risks substantially. This approach has the potential for broader application worldwide, contributing to more accurate projections of waterborne pathogen-related health risks in a changing world.