Spatially Explicit Assessment of Pathogen-Related Health Impacts in Life Cycle Assessment.

Pathogen-related human health impacts from wastewater emissions are not normally addressed in life cycle impact assessment (LCIA), limiting the use of life cycle assessment (LCA) to compare wastewater infrastructure and management options that differ in treatment performance, discharge location, and exposure context. Building on quantitative microbial risk assessment (QMRA), which has identified recreational water use as an important exposure pathway for wastewater-related pathogens, this study translates QMRA into a spatially explicit LCIA framework for pathogen emissions to surface waters. The framework links wastewater treatment plant emissions, pathogen fate in rivers and lakes, recreational exposure at bathing sites, dose-response relationships, and disability-adjusted life years (DALYs) to derive characterization factors (CFs) compatible with LCA. In a national-scale application to Switzerland, we assess six wastewater-related pathogens transported through the river and lake network to 503 designated bathing sites. The estimated annual health burden is 1150 DALYs, with strong spatial concentration: the top 10 bathing sites account for 64 % of the total burden. Basin- and pathogen-specific CFs span up to five orders of magnitude, showing that generic or spatially averaged factors can obscure decision-relevant variation. The framework provides the first pathogen-specific CFs for wastewater emissions to surface waters and enables pathogen-related human health impacts to be integrated into LCA.