Zero Risk Does Not Exist: Lessons Learned from Microbial Risk Assessment Related to Use of Water and Safety of Fresh Produce

Abstract

Risk assessments related to use of water and safety of fresh produce originate from both water and food microbiology studies. Although the set-up and methodology of risk assessment in these 2 disciplines may differ, analysis of the current literature reveals some common outcomes. Most of these studies from the water perspective focus on enteric virus risks, largely because of their anticipated high concentrations in untreated wastewater and their resistance to common wastewater treatments. Risk assessment studies from the food perspective, instead, focus mainly on bacterial pathogens such as Salmonella and pathogenic Escherichia coli. Few site-specific data points were available for most of these microbial risk assessments, meaning that many assumptions were necessary, which are repeated in many studies. Specific parameters lacking hard data included rates of pathogen transfer from irrigation water to crops, pathogen penetration, and survival in or on food crops. Data on these factors have been investigated over the last decade and this should improve the reliability of future microbial risk estimates. However, the sheer number of different foodstuffs and pathogens, combined with water sources and irrigation practices, means that developing risk models that can span the breadth of fresh produce safety will be a considerable challenge. The new approach using microbial risk assessment is objective and evidence-based and leads to more flexibility and enables more tailored risk management practices and guidelines. Drawbacks are, however, capacity and knowledge to perform the microbial risk assessment and the need for data and preferably data of the specific region.Keywords: fruits and vegetables, health risk, mitigation strategies, quantitative microbial risk assessment, water Practical Application: This manuscripts intends to give an extensive overview of approaches and challenges of past and future quantitative microbial risk assessment studies in the fresh produce chain related to the use of water in order to aid further research efforts in this area.

Guidance on the requirements for the development of microbiological criteria

“…Usually in this situation, the information on prevalence of pathogens is scarce. But even if data are available, caution should be taken in extrapolation of relationships between indicator microorganisms and pathogenic microorganisms as defined in a particular study to situations very different from those encountered in the initial data collection (De Keuckelaere et al., ). For example, the diversity of pathogens present and their concentrations in animals, human or (sewage) water depends upon the origin of faecal input and the epidemiological status of the contributing populations (Hamilton et al., ), both of which can differ by region and time frame.…”

“…In addition, it is important to take into account whether the behaviour of the indicator microorganism is comparable with that of the pathogen in terms of survival and growth under the conditions of food processing. For example, it is known that in general bacteria are poor indicators of the presence of viruses and parasitic protozoa (De Keuckelaere et al., ). In the case of using E. coli as an indicator microorganism for human NoV, E. coli levels might be associated with a non‐human source of faecal contamination (thus the presence of the indicator microorganism overestimates the presence of these viruses), but there is also evidence that NoV (and other enteric viruses, and parasites) may persist for a long time, and also survive some disinfection treatments that eliminate bacteria.…”

Consumer perceptions of fruit and vegetable quality: certification and other options for safeguarding public health in West Africa

“…Yet, even countries with very advanced safety systems can be affected. For example, a broad range of stakeholders under the EU FP7 Veg-i-Trade project ranked bacterial pathogens to be the most important food safety issue for fresh produce, followed by food-borne viruses, pesticide residues and mycotoxins (Van Boxstael et al 2013;De Keuckelaere et al 2015). The high ranking was explained by the fact that in case of a food-borne outbreak the consequences are often severe both from a public-health point of view (large number of cases and high severity of disease) and from the economic point of view (loss of sales, tourists, and trust).…”

Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries – case studies from Cochabamba, Bolivia

“…Recognizing the complexity of the situation, the WHO has proposed an approach in which several risk management alternatives (conventional and non-conventional) are compared in terms of risk outcomes and feasibility of their implementation (WHO 2006). Since then, many studies have been carried out to assess different strategies for management of risks from irrigation with wastewater (Keuckelaere et al 2015). However, the published risk assessment studies assume either no wastewater treatment at all, or treatment processes that function adequately.…”