Health impact assessment of wastewater reuse for replenishing an urban landscape lake by disability-adjusted life year

Wastewater reuse for landscape water replenishment has raised severe public concerns over potential health hazards. Thus, this study aims to quantify the health impacts due to the replenishment of Lake Cui in Kunming with reclaimed water. Based on experimental analyses, Escherichia coli and norovirus were determined as the major pathogens in Lake Cui. Three typical exposure routes, namely river cleaning, boating and road flushing were identified during a field investigation. The disease burden, expressed by disability-adjusted life year (DALY) was evaluated and compared with the infection risk obtained by quantitative microbial risk assessment. Findings showed that the disease burden due to road flushing was highest compared to the other pathways. For the different pathogens, E. coli was the leading cause of DALYs. As well, infection risk for the two pathogens exceeded the United States Environmental Protection Agency (USEPA) risk level of 10(-4), while the disease burdens were below the WHO threshold of 10(-6) DALYs. Thus, infection risk should not be regarded as the endpoint for health impact assessment. By contrast, the disease burden is much more suitable for quantifying the health hazard due to environmental pollution. The methodology introduced in this study provides new directions for the evaluation of health impacts related to water reuse for landscape ecology.