Suchergebnisse

AbstractThe objective of this study was to leverage quantitative risk assessment to investigate possible root cause(s) of foodborne illness outbreaks related to Shiga toxin‐producing Escherichia coli O157:H7 (STEC O157) infections in leafy greens in the United States. To this end, we developed the FDA leafy green quantitative risk assessment epidemic curve prediction model (FDA‐LG QRA‐EC) that simulated the lettuce supply chain. The model was used to predict the number of reported illnesses and the epidemic curve associated with lettuce contaminated with STEC O157 for a wide range of scenarios representing various contamination conditions and facility processing/sanitation practices. Model predictions were generated for fresh‐cut and whole lettuce, quantifying the differing impacts of facility processing and home preparation on predicted illnesses. Our model revealed that the timespan (i.e., number of days with at least one reported illness) and the peak (i.e., day with the most predicted number of reported illnesses) of the epidemic curve of a STEC O157‐lettuce outbreak were not strongly influenced by facility processing/sanitation practices and were indications of contamination pattern among incoming lettuce batches received by the facility or distribution center. Through comparisons with observed number of illnesses from recent STEC O157‐lettuce outbreaks, the model identified contamination conditions on incoming lettuce heads that could result in an outbreak of similar size, which can be used to narrow down potential root cause hypotheses.

[EN] The presence of Cryptosporidium and Giardia in waste water is a main concern because water reuse for irrigation can jeopardize human health. Spanish Legislation for water reuse does not oblige to analyze the presence of both pathogens Cryptosporidium and Giardia in reused water for irrigation. Therefore, the objective of this paper is to determine the influence of wastewater treatment in the increase of the consumer safety margin in relation to the presence of Cryptosporidium and Giardia in leafy green vegetables. With this aim in mind, a total of 108 samples from raw (influent) and treated wastewater (effluent) from three wastewater treatment plants in Spain were analysed according to USEPA Method 1623. Effluent results show that Cryptosporidium oocysts average counts ranged from 1.38 to 2.6/L oocysts and Giardia cysts ranged from 0.6 to 1.7/L cysts, which means a removal values of 2.7 log, 2.5 log and 1.8 log for Cryptosporidium oocysts and 1 log, 2 log and 2.2 log for Giardia cysts in the three wastewater treatment plants analysed. In relation to safety margin the highest probability that exposure exceed the dose response was observed for Giardia. In addition, the sensitivity analysis showed that (oo) cysts concentration present in the leafy green vegetables and the human dose-response were the most influential inputs in the safety margin obtained. ; We thank EPSAR for authorizing us sampling of WWTP and the personnel of WWTP for providing with WWTP samples. We also thank members of GAMASER for concentrating the secondary and tertiary WWTP samples with the Envirocheck capsules. This study has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO), in the frame of the collaborative international consortium WATERJPI2013-095-C03-02-METAWATER of the Water Challenges for a Changing World Joint Programming Initiative (Water JPI) Pilot Call. ; Doménech Antich, EM.; Amoros, I.; Moreno Trigos, MY.; Alonso Molina, JL. (2018). Cryptosporidium and Giardia safety margin increase in leafy green ...

The content of nitrates in foods of plant origin permanently comes into notice of consumers, society. Nitrates in large quantities are harmful to the human body, especially children. The legislation of the Republic of Moldova, which regulates the maximum acceptable limit (MAL) of nitrates, namely Government Decision No 115 on The control of nitrates in foods of plant origin, was brought into line with European legislation just in September 2020. In the present study, some aspects related to these normative changes were analyzed. It was determined that the vast majority of spinach samples from local agricultural market exceed 1.1-1.6 times the MAL of nitrates with reference to national legislation and 1.9-2.7 times concerning the legislation of the Russian Federation. Rucola practically falls within the limits established in the national legislation, the MAL being 6000 mg nitrate·kg-1 , but it exceeds by far (in 2.1 times) the MAL established in the Russian Federation. Fresh salad falls within the limits set by national and international laws.

AbstractWe developed a probabilistic mathematical model for the postharvest processing of leafy greens focusing on Escherichia coli O157:H7 contamination of fresh‐cut romaine lettuce as the case study. Our model can (i) support the investigation of cross‐contamination scenarios, and (ii) evaluate and compare different risk mitigation options. We used an agent‐based modeling framework to predict the pathogen prevalence and levels in bags of fresh‐cut lettuce and quantify spread of E. coli O157:H7 from contaminated lettuce to surface areas of processing equipment. Using an unbalanced factorial design, we were able to propagate combinations of random values assigned to model inputs through different processing steps and ranked statistically significant inputs with respect to their impacts on selected model outputs. Results indicated that whether contamination originated on incoming lettuce heads or on the surface areas of processing equipment, pathogen prevalence among bags of fresh‐cut lettuce and batches was most significantly impacted by the level of free chlorine in the flume tank and frequency of replacing the wash water inside the tank. Pathogen levels in bags of fresh‐cut lettuce were most significantly influenced by the initial levels of contamination on incoming lettuce heads or surface areas of processing equipment. The influence of surface contamination on pathogen prevalence or levels in fresh‐cut bags depended on the location of that surface relative to the flume tank. This study demonstrates that developing a flexible yet mathematically rigorous modeling tool, a "virtual laboratory," can provide valuable insights into the effectiveness of individual and combined risk mitigation options.

In the last decade, high-volume industrial production of fresh leafy greens including spinach and romaine lettuce has become increasingly linked to outbreaks of dangerous foodborne pathogens such as E. coli O157:H7. Current approaches to food safety risk management seek to prevent the introduction of pathogens at field level, through wildlife exclusion practices and the removal of habitat near farms, which can damage environmental conservation efforts. Farmers must balance multiple overlapping requirements coming from government regulation and privately-operated food safety standards, in which food safety concerns may be given priority over environmental sustainability. Improving food safety in fresh leafy greens without compromising environmental health will require policy solutions that consider the structural roots of food safety problems, and how food safety regulation impacts farmers. This dissertation presents an international comparative policy case study of leafy greens production in the United States and the United Kingdom, in which I evaluate public and private risk management mechanisms that have combined to shape national approaches to food safety, in the context of current political and regulatory trends. Deepening traditional comparative politics literature, this study draws on a structural comparison of public and private standards and interviews with leafy greens producers in both nations to illuminate the social and environmental impacts of various regulatory mechanisms. I demonstrate that food safety standards containing a balance of process-oriented and prescriptive requirements, and a balance between food safety and environmental concerns, are correlated with more environmentally friendly agricultural practices and more favorable farmer perceptions of food safety regulation. From a perspective situated at the convergence of agri-food studies, regulatory practice, and comparative policy, I suggest regulatory changes and supply chain solutions for balancing food safety and environmental sustainability.

AbstractAddition of chlorine‐based antimicrobial substances to fresh‐cut leafy green wash water is done to minimize microbial cross‐contamination during processing. We developed the FDA Leafy Green Risk Assessment Model (FDA‐LGRAM) to quantify the impact of free chlorine concentration in wash water during fresh‐cut lettuce processing on the extent of water‐mediated cross‐contamination between shredded lettuce and the associated risk of illness due to exposure to Escherichia coli O157:H7. At different contamination prevalence and levels of E. coli O157:H7 on incoming lettuce heads, the model compared the predicted prevalence of contaminated fresh‐cut lettuce packages and the risk of illness per serving between: (1) a scenario where fresh‐cut lettuce was packaged without washing; and (2) scenarios involving washing fresh‐cut lettuce with different levels of free chlorine (0 ppm, 5 ppm, 10 ppm, 15 ppm, and 20 ppm) prior to packaging. Our results indicate that the free chlorine level in wash water has a substantial impact on the predicted prevalence of contaminated fresh‐cut lettuce packages and the risk of illness associated with E. coli O157:H7 in fresh‐cut lettuce. Results showed that the required level of free chlorine that can minimize water‐mediated cross‐contamination and reduce the corresponding risk of illness depended on contamination prevalence and levels of E. coli O157:H7 on incoming lettuce heads. Our model also indicated that the pathogen inactivation rate in wash water via free chlorine was a key model parameter that had a significant impact on the extent of cross‐contamination during washing and the predicted associated risk of illness.

"Serial no. 111-126." ; Shipping list no.: 2011-0341-P ; Includes bibliographical references ; Mode of access: Internet.