Apple growing and packing microbial risk factors and their potential to lead to foodborne disease outbreaks.

In view of the passing of the Food Safety Modernization Act, the food industry, including the specialty crop industry, is under increased pressure to demonstrate the safety of their products. Although apples have a reputation with consumers as being a safe commodity, the fresh market apple industry would like to deepen its understanding of why their commodity is safe and how it can be made safer if needed. To this end, our proposal seeks to provide the industry with a microbiological risk assessment for apples. We will use data collected by the apple industry in their food safety programs to examine the potential occurrence of pathogens on apples in the production and packing environments. This data, along with data on apple consumption, will be used to estimate the exposure of American consumers to potentially contaminated apples. The risk assessment will conclude with an estimate of the risk of becoming ill from consuming apples potentially contaminated with pathogens. Information about specific areas of risk will allow apple growers and packers to adjust their practices and allocate their food safety resources more effectively while enhancing the safety of fresh market apples for consumers.

This proposal seeks to examine fresh market apple production and packing house data for microbiological pathogens of concern and to use these data to determine the potential for pathogen levels to result in illness. Using pathogen test data collected from production and packing operations, we will describe the significance of various production and packing house processes relative to the potential occurrence of pathogens of concern. To estimate the risk of illness associated with consuming apples contaminated with pathogens, we will develop a risk assessment that estimates the probability of exposure to potentially contaminated apples and then characterizes the nature and likelihood of an adverse health effect associated with the estimated exposure levels (Lammerding, 2000). To address the research priorities presented in the Request for Proposals, this proposal plans to apply quantitative risk assessment techniques determine the likelihood of foodborne illness from consumption of fresh market apples using data from industry, the Centers for Disease Control (CDC), and other published research related to particular pathogens. To address the uncertainty in the data used in the risk assessment, we will develop the model using probabilistic methods to quantitatively characterize the uncertainty and variability in estimates of exposure or risk. Intertox is currently working with the Washington apple industry to gather data on baseline levels of microbial pathogens on fresh market apples in packing houses, as well as measures being used to mitigate these levels. This proposal suggests using similar methods to collect grower data in order to extend the risk assessment to production operations. The risk assessment will be conducted and written in accordance with the four components of the generally-accepted risk assessment framework: Hazard identification, exposure assessment, dose-response assessment (also known as hazard characterization), and risk characterization. The proposal consists of five primary objectives: grower data collection, correlation of process pathogen data to end product data, development of a risk assessment model customized for apple packing operations to estimate the risk of foodborne illness, preparation of a written risk assessment document detailing the results, and advisory panel review and oversight. Information about specific areas of risk will allow apple packing businesses to adjust their practices and/or allocate resources to reduce risk more effectively. In addition, regulatory agencies are expanding the use of commodity-specific risk assessments to focus limited resources on commodities according to associated food safety risks. The result of this project will be an assessment of the microbial risks associated with apple production and packing operations and a methodology for evaluating other tree fruit and/or additional industry practices as further data become available. When completed, the risk assessment will provide apple production and packing operations with information about particular areas of their process that will enable them to focus their food safety efforts and determine the appropriateness of current practices in these areas. It will also provide the industry, regulatory agencies, and consumers with an overview of the risk to public health from consumption of fresh market apples.

1. Gather pathogen testing data and information about mitigation measures from apple growers. 

2. Correlate pathogen levels in water used in fresh market apple production and packing operations at different points in the system to levels measured on apples before they leave the packinghouse. 

3. Characterize potential exposure to pathogens from consumption of fresh market apples and describe potential human health effects associated with these exposure levels; combine the results to estimate the risk of becoming ill from eating contaminated apples. 

4. Prepare a written risk assessment report about the findings of Objectives 1-3. 5. Submit the risk assessment model and report for review to an advisory panel consisting of the WTFRC, the Northwest Horticultural Council and other experts in the field of quantitative microbiological risk assessment.

Key findings of this study include: 

•The QMRA model results suggest that the risk of EHEC-associated illness from consumption of apples contaminated with EHEC through evaporative cooling water is low based on currently available data and industry practices. As more data becomes available, the model can be updated to more accurately predict the potential risk of illness if contamination were to occur.

• Sensitivity analysis indicates that washing with cleaners during packing is the most effective control step. This highlights the importance of washing apples with appropriate cleansers and concentrations in order to ensure reduction of EHEC on apples. 

• The time interval between evaporative cooling water application and harvest is another effective control step as indicated by the sensitivity analysis. This QMRA indicates that maximizing the time between application and harvest reduces the probability of illness if water is contaminated with EHEC. 

• The QMRA supports current practices such as those related to evaporative cooling and exclusion of bruised and dropped apples are protective of human health. While risk estimates from this QMRA suggest that consumption of an apple exposed when growers apply evaporative cooling water exposed to containing 2400 MPN/100 mL E. coli is unlikely to result in illness, , consideration should be given to water quality and time intervals between application and harvest as preventive controls in the orchard.