Health risks devired from consumption of lettuces irrigated with tertiary-effluent containing novovirus

“Wastewater is a valuable resource for water-scarce regions, and is becoming increasingly important due to the
rising frequency of droughts as a result of climate change. The health risks derived from ingestion of lettuce
that has been irrigated with effluent from a wastewater treatment plant (WWTP) in Catalonia (Spain) were estimated
following a quantitativemicrobial risk assessment (QMRA) approach using site-specific data. Norovirus
(NoV) was selected for this analysis, since it is the most common cause of acute gastroenteritis outbreaks in
Catalonia. Two scenarios, irrigation with secondary and with tertiary effluent, were analysed. An uncertainty
analysiswas conducted to determine the impact of possible internalization of NoV into edible parts of the lettuce.
The mean disease burden for ingestion of lettuce irrigated with secondary and tertiary effluent was 7.8 × 10⁻⁴
Disability Adjusted Life Years (DALYs) per person per year (pppy) and 3.9 × 10⁻⁴ DALYs pppy, respectively. A
sensitivity analysis revealed that the model parameters with higher influence on the probability of disease are
the concentration of NoV in the effluent and the consumption of lettuce. In order to decrease the disease burden
to the guidance level of 10⁻⁶ DALYs pppy, the tertiary treatment should be able to achieve a 4.3 log reduction of
the concentration of NoV. If internalization of NoV into lettuces occurs, this would require a reduction of 7.6 log.
This is the first time that site specific data and virus internalization in crops are incorporated in a QMRA of
irrigation of lettuce and its impact is quantified.”
(Citaat: Sales-Ortells, H., Fernandez-Cassi, X., Timoneda, N., Dürig, W., Girones, R., Medema, G.J. – Health risks devired from consumption of lettuces irrigated with tertiary-effluent containing novovirus – Food Research Intern 68(2015), p.70-77)