Usage of QMRA studies in risk assessments related to use of water and fresh produce. Liesbeth Jacxsens. Ghent University

Transcription

1 Usage of QMRA studies in risk assessments related to use of water and fresh produce Liesbeth Jacxsens Ghent University

2 Risk of water in fresh produce chain Water pre harvest andpost harvestpotential risk factor in microbiological contamination of fresh produce Pre harvest (irrigation water) post harvest(washwater transport water cooling water) Manyguidelinesandstandardsavailable aboutapplication of water e.g. source or quality(criteria?) E.g. WHO, (inter)national research organisations, (legalframework), voluntary standards e.g. Global G.A.P.

3 Source versus quality Source and quality of water? - In manyguidelinesandstandardsthe source of water is inherent related tothe qualityof the water : - useof tap water = potablewater - useof rainfall water = non potablewater Source : wheredoes the water comefrom? Quality: whatis the (micro)biologicalload of the water? However: - Different sources can supply to the same quality - Due to water treatment technology water quality can be influenced towhichextendwater EFSA BIOHAZ treatment opinion needtobeapplied?

4 Quality of water linked to source of water Many research papers available with information of the quality of the water Rain wateris generally of relatively good microbial quality, although it may vary and the quality is less than what is expected of potable quality, strongly influenced by the collection recipients. Ground water is generally of good microbial quality if infiltration of surface runoff is avoided. There can however be large variations between shallow ground water and water from deeper aquifers. Surface water sources have the most variable levels of contamination because they may be subject to temporary or intermittent contamination sources subject to discharges of (treated) wastewater, storm water runoff, livestock or wild life feces, etc. Wastewateris usually of very poor physico-chemical as well as microbial quality and consequently requires intensive treatment unless other safety measures are in place where treatment is not feasible

5 Examples of criteria for irrigation water Country/region Watertype Regulation/Guideline Criteria a, b Reference Australia & New Guideline Zealand Irrigation water for non food crops (trees/flowers) -Secondary treatment or primary Treatment with lagoon detention < 1000 E. coli/100 ml Australian Guidance for Water Recycling, 2006 Australia & New Zealand Irrigation water for commercial crops raw or unprocessed (salads crops and spray irrigation) - Advanced treatment to achieve total pathogen removal required (eg secondary, filtration and disinfection) Guideline < 1 E. coli/100 ml Australian Guidance for Water Recycling, 2006

6 Examples of criteria for irrigation water Country/region Watertype Regulation/Guideline Criteria a, b Reference Australia & New Zealand FDA(2013) Irrigation water for commercial food crops -Secondary treatment with >25 days lagoon detention and disinfection Directly contacts produce during/after harvest Food contact surface Washing hands Guideline < 100 E. coli/100 ml Australian Guidance for Water Recycling, many other regions e.g. Canada, Italy, Spain, Different indicators : total coliforms fecal coliforms E. coli Different criteria for same type of water. EU-28 Direct water application during growing (no standards for drip irrigation water) Potable or clean water Regulation No E. coli per 100 ml Food Safety Modernization Act Regulation Regulation <235 E. coli/100 ml (single sample) and <126/100 ml (5 samples rolling geometric mean) Clean water is case-by-case EFSA BIOHAZ definedopinion proposal Food Safety Modernization Act proposal EU regulation 852/2004

7 From empirical evidence towards science based guidelines. Guidelines on water quality for irrigation/post harvest water mostly based on historical data knowlegde acquired by observations and experiments empirical knowlegde WHO recommendations: fit-for-purpose guidelines on water quality for specific situations/case studies based on actual Quantitative Microbial Risk Assessment (QMRA) studies

8 Water risk assessment versus food risk assessment?

9 Water risk assessment versus food risk assessment? Objective of microbial risk assessment is to facilitate adequate microbial risk management HEALTH TARGETS Acceptable risk Risk Management Assess Environmental Exposure Assessment of risk PUBLIC HEALTH STATUS WHO: Stockholm framework for safe water ILSI : framework of risk analysis in food safety

10 Many work on QMRA towards potable water and health based targets

11 MRA to calculate contamination of irrigation water towards contamination of fresh produce setting science based criteria for irrigation water Water RA andlink tofreshproduce FreshproduceRA and link to water

12 ILSI paper : literature review on Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce Objective: systematic review on MRA related to water and fresh produce with focus on data gap identification and assumptions made 41 studies (1992 till december 2013) were retained and classified on : Type of pathogen Application of water (irrigation, wash water, etc.) Water research group or Food research group Deterministic or probabilistic

13 ILSI paper : literature review on Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce Objective: systematic review on MRA related to water and fresh produce with focus on data gap identification and assumptions made MainlyWater Research groups(28/41) withrecent shift towardsfood Research groups and only 5/41 both research groups Wide spread of pathogens: Water Research Groups maily human enteric virusses (20/28) Food Research Groups Salmonella, Listeria and pathogenic E. coli Evolution towards more stochastic calculations (29/41) Evolution also to include other application of water than solely irrigation water (wash water, transport water, etc.) Half of the studies on leafygreens

14 ILSI paper : literature review on Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce RA studies Norovirus Rotavirus Hepatitis A virus Enterovirus Enteric virus Giardia spp. Cryptosporidium spp. Entamoeba histolytica Campylobacter L. monocytogenes Pathogenic E. coli b Salmonella Enteric pathogenic bacteria Ascaris Water treatment Irrigation Washing Processing Washing consumer Water-perspective Food-perspective Deterministic RA Stochastic RA Asano and others (1992) X X X X X Shuval and others (1997) X X X X* X X Tanaka and others (1998) X X X X X van Ginneken and Oron X X X X X (2000) Petterson and Ashbolt X X X X (2001) Petterson and others X X X X (2001a); Petterson and others (2002) Stine and others (2005) X X X X X X Hamilton and others X X X X (2006a) Hamilton and others X X X X (2006b) NRMMC-EPHC-AHMC X X X X X X (2006); O'Toole and others (2010) Mara and others (2007) X X X X X X Bastos and others (2008) X X X X X X X Diallo and others (2008) X X X X X X Seidu and others (2008) X X X X X X Finley and others (2009) X X X X Mota and others (2009) X X X X X Navarro and others (2009) X X X X

15 ILSI paper : literature review on Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce Al-Juaidi and others (2010) X X X X Barker-Reid and others (2010) X X c X X Carrasco and others (2010) X X X X Forslund and others (2010) X X X X X Mara and Sleigh (2010a) X X X X Mara and Sleigh (2010b) X X X X Munoz and others (2010) X X X X Oron and others (2010) X X X X X Ayuso-Gabella and others (2011) X X X X X X X X Danyluk and Schaffner (2011) X X X X Drechsel and Seidu (2011) X X X X X X X X Navarro and Jimenez (2011) X X X X X Ottoson and others (2011) X X X X X Rodriguez and others (2011) X X X X Stine and others (2011) X X X a X X X Ferrer and others (2012) X X X X X Forslund and others (2012) X X X X X Barker and others (2013) X X c X X X X Ding and others (2013) X X X X Domenech and others (2013) X X X X Lim and Jiang (2013) X X X c X X Pavione and others (2013) X X X X X* X X Puerta-Gomez and others X X X X (2013) Seidu and others (2013) X X X X X

16 ILSI paper : literature review on Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce Further identification of data gaps, assumptions and suggorate data in those studies on : (1) pathogen contamination prevalence data; (2) transfer rates for pathogens from water to produce; (3) behavior (growth, survival, inactivation, removal) of microorganisms in the environment and produce; (4) consumer behavior and consumption patterns; (5) dose-response information; (6) diversity in risk end-point and characterization/benchmarking, such as the use of a tolerable or acceptable risk level

17 Example 1 : Water reuse guidelines Australia [Pathogen] wastewater Application System performance requirements Health target

18 Example 1 : Water reuse guidelines Australia [Campylobacter] Wastewater 7000 cfu/l Australian data (95%) Application System performance requirements Health target <10-6 DALY per person per year Australian target e.g. DALY per Campy case = (1 DALY = ca. 200 cases)

19 Example 1 : Water reuse guidelines Australia [Campylobacter] Wastewater 7000 cfu/l Australian data (95%) Application System performance requirements Health target <10-6 DALY per person per year Australian target e.g. DALY per Campy case = (1 DALY = ca. 200 cases)

20 Example 1 : Water reuse guidelines Australia [Campylobacter] Wastewater 7000 cfu/l Application System performance Requirements Efficiency of water treatment? Dose equivalent <0.037 cfu Campy per person per year

21 Example 1 : Water reuse guidelines Australia

22 Example 1 : Water reuse guidelines Australia [Campylobacter] Wastewater 7000 cfu/l Commercial crop irrigation 5.0 log reduction System performance requirements Annual dose <0.037 cfu Campy ppy Exposure per person per year Total: 490 ml <0.075 cfu/l Lettuce: 70 consumptions x 5 ml hold up/serving Other raw food crops: 140 consumptions x 1 ml hold up/serving

23 Example 1 : Water reuse guidelines Australia Step Cryptosporidium removal (log) Rotavirus removal (log) Campylobacter removal (log) Required removal Secondary treatment Lagoon detention Filtration Disinfection With-holding period Total

24 Example 2 : Ottoson et al. Journal of Food Protection Dec 2011, 74, EHEC outbreak lettuce river water (Sweden)? Guidelines irrigation water quality E.coli <100 or < 1000/100mL? 48 h withholding period MRA: evaluate contribution of other control measures Rinsing, extra withholding time, different E. coli levels Water quality guideline 100 Ecoli/100ml Water quality guideline 1000 Ecoli/100ml Expected illnesses/10000 servings Expected illnesses/10000 servings 1000 no rinse 800 rinse 600 Holding time (days) Holding time (days) Ottoson et al. Journal of Food Protection Dec 2011, 74, no rinse rinse

25 Example 3 : QMRA studies with a Water-perspective that used one of the benchmark acceptable risk levels and their outcome. RA studies with W-background Outcome Used benchmark acceptable risk level Diallo and others (2008); Ferrer and others (2012); Hamilton and others (2006a,b); Munoz and others (2010); Navaro and Jimenez (2011);Shuval and others (1997); Tanaka and others (1998); van Ginneken and Oron(2000) Infection riskpppy Petterson and others(2001a) Likelihood of infection (number of people/ exposed) Stine and others(2005, 2011) Maximum concentration of pathogens allowable in water to meet acceptable risk level Seidu and others(2013) Number of days of irrigation cessation required to achieve annual tolerable infection risk U.S.EPAbenchmark 10-4 infectionrisk pppy Health based targets expressed as DALYs infection risk pppy NRMMC-EPHC-AHMC(2006) Health basedlogreduction targets WHObenchmark 10-6 DALY losspppy Ayuso-Gabella and others (2011); Barker and others Annual burden of disease (DALY loss pppy) (2013) Al-Juaidi and others (20101); Barker-Reid and others Infection riskpppy QMRAs that refer to the benchmark 10-6 DALY loss (2010); Bastos and others (2008); Lim and Jiang (2013); Mara and others (2007); Seidu and others (2008); Mara and Sleigh (2010b); Pavione and others(2013) pppy, but used as tolerable risk level a translated tolerable infection risk pppy of this initial tolerable risklevel of 10-6 DALYlosspppy. E.g. a tolerable infection risk of 10-3 pppy for rotaviruses and Cryptosporidium and 10-4 pppy for Campylobacter(WHO(2006)).

26 Example 3 : Risk outcome of RA with solely a Food-backgroundand their used acceptable risk reference. RA studies with solely F- background Mota and others (2009) Carrasco and others (2010) Rodriguez and others (2011) Outcome Annual risk of infection from exposure to Cryptosporidium or Giardia through the consumption of tomatoes, or bell peppers, or cucumbers, or lettuce Mean number of cases of listeriosisper year in Spain due to ready-to-eat lettuce salads, and prevalence and concentration of the pathogen in the food at time of consumption. Estimates on concentration and prevalence of E. coli O157:H7 populations in commercially fresh-cut bagged lettuce (an exposure model). The probability of illness (P ill ) and number of illnesses per servings. Used acceptable risk level at the end they mention that the U.S. EPA recommends that drinking water not pose an annual microbial risk of infection greater than But did NOT compare their risk estimates with this value. A desirable general goal was a level of 100 CFU/g in the product at the time of consumption (as in regulation (CE) N 2073/2005). Ottoson and others (2011) Is absent, but is not relevant as the goal was to compare the relative difference due to different risk-mitigation strategies. Danyluk and Schaffner (2011) Number of illnesses / Ding and others (2013) Contamination level of lettuce at the time of consumption, probability of listeriosis illness per person per day eating lettuce, annual probability of listeriosis illness for consuming lettuce per person and annual cases of listeriosis per year in Korea Domenech and others (2013) The mean, 5% and 95% percentile of probability of illness at home per person per serving depending on the initial load of lettuce at retail. Puerta-Gomez and others (2013) Acceptable risk level expressed as number of pathogens per servingprobability on illness The probability of infection from a serving of ready-to-eat spinach. / Compared contamination level of lettuce with food safety limit of L. monocytogenes on fresh produce fixed at 2 log CFU/g. To comply with the U.S. Healthy People 2020 initiative which aimed to reduce the rates of listeriosis by 50 percent it was calculated that the probability of illness must be less than 1.32 x 10-8 listeriosis cases per serving to attain this level of protection. Since more than 1% (i.e., 10-2 ) of probability infection is considered unsafe for food processors, this value was used as the tolerance level in this study (=1.33 log 10 CFU/g of sample)

27 Lessons learned from ILSI review on QMRA on water and fresh produce Majority of current studies focus on virusses and leafy greens One QMRA study cannot always be translated to other situations or regions because of : aspects on the use of water in the fresh produce chain cultural differences in food preparation susceptibility of different populations regional variation in the prevalence and concentration of pathogens in (waste) water and environmental conditions (e.g. solar radiation). There are many sources of uncertainty that might arise from inputs to a risk assessment: measurement errors, sampling errors, systematic errors, estimated (using surrogates) or excluded variables, incorrect model forms, and abnormal conditions (not allowed for that particular situation).

28 Lessons learned from ILSI review on QMRA on water/crops The QMRA models are constructed based on the best knowledge and available information (parameters and data) at the time of development. For example, QMRAs that make use of ratios to estimate the concentration of pathogens in water may need to be revised if better data become available. QMRA studies are particularly useful in evaluating different control scenarios, but as the outcomes rely partly on assumptions, results should be interpreted as an indication of the level or degree of safety and not as absolute values.

29 Lessons learned from ILSI review on QMRA on water/crops The link from risk assessment to risk managementis still challenging as clearly demonstrated by Bichaiand Smeets(2013). These authors found that QMRA played a different function in Australia and the Netherlands, despite both countries being considered leaders in the use of QMRA in water regulation. Where the Netherlands placed more emphasis on the value of knowledge gained from the process of constructing QMRAswhereas Australia relies more heavily on a strict decision-making value. Overall, the use of QMRA is leading to more flexibility and more tailored guidelines on water treatment and levels of pathogens in irrigation or processing water for the fresh produce in certain regions. Drawbacks are, however, capacity and knowledge to perform the QMRA and the need for data relevant to the specific regions.

30 Usage of QMRA studies in risk assessments related to use of water and fresh produce Liesbeth Jacxsens on behalf of Ann De Keuckelaere, Philip Amoah, Gertjan Medema, Peter McClure, Lee-Ann Jaykus, Mieke Uyttendaele Paper available in Comprehensive Reviews in Food Science and Food Safety Ghent University