Screening-level microbial risk assessment of urban water locations: a tool for prioritization

“People in urban areas are exposed to microbial hazards in urban
waters. In this study, various hazards, diseases, and water systems, where different
recreation activities take place, are compared in an integrated quantitative microbial
risk assessment (QMRA). The event and annual probability of gastrointestinal
illness (GI) and Legionnaires’disease (LD) were analyzed in QMRA models using
selected literature data. Highest mean event probabilities of GI were found for
playing in pluvial flood from a combined sewer overflow (34%), swimming (18%),
and rowing (13%) in the river, swimming (8.7%) and rowing (4.5%) in the lake, and
playing in a water playground (3.7%) and in the pluvial flood from stormwater
sewers (4.7%). At these locations, the GI probability was above the EU Bathing
Water Directive threshold for excellent water quality (3%). All the annual risk
medians were below the national incidence of legionellosis of 0.002%. The illness
probability was most sensitive to the pathogens concentration (particularly
Campylobacter, Norovirus, and Legionella) and exposure frequency. Therefore, site-specific pathogen data collection is the
best next step to strengthen the certainty of the risk estimates. This study created an evidence-base that was used by water
authorities to understand the health risks and set priorities for risk management.”
(Citaat: Sales-Ortells, H., Medema, G.J. Screening-level microbial risk assessment of urban water locations: a tool for prioritization – Environmental Science and Technology 48(2014)16, p.9780-9789)