Microbial health risks related to irrigation of fresh produce with wastewater. Gertjan Medema ILSI Workshop, March 2011, Brussels, Belgium

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1 Microbial health risks related to irrigation of fresh produce with wastewater Gertjan Medema ILSI Workshop, March 2011, Brussels, Belgium

2 Wastewater reuse in agriculture 0-16% 16-31% 31-47% 47-63% 63-79% % Polluted water Wastewater Jimenez et al, 2010

3 Wastewater reuse in agriculture Incentives Source of water Source of nutrients Available all year Available in vicinity of settlements Economical value: - Increased harvest - Reduced cost for fertilizer - Reduced cost for wastewater treatment Ecological value: - Less discharge of wastewater to surface water 0-16% 16-31% 31-47% 47-63% 63-79% % Polluted water Wastewater

4 Water stress in Europe? Total freshwater resource Europe: 2270 km 3 /yr Abstraction: 288 km 3 /yr (13%) Energy production: 44% Agriculture: 24% Water supply: 21% Industry: 11%

5 Water uses in European regions Abstractions (mio m3/year) Early 1990s Early 1990s Early 1990s Eastern Western Southern Turkey Energy Industry Irrigation Public Water Supply

6 Water stress agriculture stress Prognosis: increased stress Maps: EEA

7 Wastewater reuse in Europe Bixio et al, 2008 (EU AQUAREC)

8 Wastewater reuse in Europe Grain Sugarbeet (Eggplant, tomato, pepper, carrot, spinach) Citrus Olives Alfalfa Potatoes EU MEDAWARE

9 Wastewater reuse in Europe Banana Tomato Potato Citrus Fruit trees Market gardening crops Cereals Olives EU MEDAWARE

10 Microbial health hazards Fecal-oral transmission Ascaris example:

11 Pathways of exposure to pathogens Very prominent Consumption of contaminated wastewater-irrigated produce Human contact with the wastewater before, during or after irrigation (farmers, their families, vendor, local communities) Less prominent Consumption of contaminated drinking-water as a result of wastewater use activities Inhalation of wastewater aerosols (workers, local communities). Consumption of animals or animal products that have been contaminated through exposure to wastewater.

12 Pathogens in domestic wastewater Drechsel et al, 2010

13 Categories of diseases relevant in wastewater-irrigated agriculture (Mara & Bos, 2010)

14 Burden of disease and mortality of diseases relevant to wastewater reuse in agriculture

15 Ascaris: distribution of disease burden

16 EU guidelines are lacking MEDAWARE (Despo Fatta, Univ Cyprus)

17 Wastewater reuse guidelines WHO, 2006 Different categories of irrigation (fresh produce: unrestricted irrigation) Risk-based approach: - safe health target: 10-6 DALY - demonstration of safety with Quantitative Microbial Risk Assessment Multiple-barrier approach: combination of wastewater treatment, irrigation and farming practice and post-farm treatment to achieve required pathogen reduction Protection of workers and consumers

18 ILSI Framework for Quantitative Microbial Risk Assessment

19 Problem formulation Water reuse guidelines Australia Specific risk assessment question Is a wastewater recycling system able to meet the health-based target of 10-6 DALY / y?

20 Problem formulation Water reuse guidelines Australia Wastewater may contain a wide range of pathogens QMRA for each is not feasible Selection of reference pathogens Parasites: Cryptosporidium (small, resistant, infectious) Viruses: Adenovirus/Rotavirus (infectious, available data) Bacteria: Campylobacter (very prevalent, infectious)

21 Risk assessment Water reuse guidelines Australia [Pathogen] wastewater Application System performance requirements Health target

22 Risk assessment Water reuse guidelines Australia [Campylobacter] Wastewater 7000/L Application System performance requirements Health target <10-6 DALY

23 Risk assessment Water reuse guidelines Australia [Campylobacter] Wastewater 7000/L Application System performance requirements Annual dose <0.037 pp

24 Exposure assessment Water reuse guidelines Australia Concentration of reference pathogens in wastewater Exposure through various applications

25 Risk assessment Water reuse guidelines Australia [Campylobacter] Wastewater 7000/L Commercial crop irrigation System performance requirements 5.0 log Annual dose <0.037 pp Exposure pppy Lettuce: 70 x 5 ml Other raw food crops: 140 x 1 ml Total: 490 ml <0.075/L

26 Risk assessment Water reuse guidelines Australia [Campylobacter] Wastewater 7000/L Commercial crop irrigation Annual dose <0.037 pp Activated sludge/sedimentation treatment 2.0 log Witholding period 6 days 3.0 log 5.0 log

27 Application of QMRA for wastewater reuse in irrigation of fresh produce Proactive risk assessment / risk management approach Science-based, objective (fair trade) State-of-the-art approach, accepted in food industry Data needed: pathogens, surrogates occurrence and fate

28 Europe: guidance needed No EU guidelines for wastewater reuse Existing criteria in EU countries Need for harmonized guidance EUREAU: recommends development of EU guidance framework to promote safe wastewater reuse for irrigation WHO guidelines as basis Bixio et al, 2006