documented or reported. Consequently, the recommendations in this paper are applicable
wherever romaine lettuce is grown and sold.
It is anticipated that observations and recommendations contained in this paper will be a
valuable resource for growers and their customers for determining when to implement and how
to design sampling/testing programs, and provide a guideline for FDA and other regulatory
agencies around the world.
1.4. How the paper is to be used
It is anticipated that this paper will serve as guideline for developing and revising sampling
plans, and provide quality assurance professionals with the information they need to evaluate
sampling plans and the meaning of test results from their sampling plans. This paper can also
be used for informing a public health performance standard.
2. Description of the challenge (Joe Holt, PeymanFatemi)
2.1. Current reasons for field sampling
Fresh produce can become microbiologically contaminated at several points along the farm to
table food chain. This is because contamination of fruits and vegetables with foodborne
pathogens like Salmonella and pathogenic E. coli, unlike cattle that are known reservoirs of
such pathogens, is typically a consequence of association with human or animal feces (it is
important to note that Listeria monocytogenes is a soilborne microorganism and contamination
of produce with L. monocytogenes may not be a fecal-associated event). Considerable
research has been done to identify the routes by which produce can come in contact with these
contaminants. These include the source and quality of the water, worker hygiene, animal
intrusion, harvesting equipment, field inputs other than water, and how contamination frequency,
levels and persistence can be affected by temperature, humidity, time and perhaps other
environmental factors. It is also important to consider the physiological differences among
produce, such as surface properties and the background flora that may or may not make the
environment suitable for foodborne human pathogens. As a result, the produce industry, in
cooperation with the government and academia, has outlined control measures as part of Good
Agricultural Practices to reduce the risk of contamination. However, the perceived risk and
ways by which to identify and mitigate the risk can vary.
2.1.1. Testing to verify food safety controls are working
Sampling and testing in most food production environments can serve as a verification tool for
control measures. In the produce fields, however, testing may serve, at best, as an indicator of
whether or not the field is grossly contaminated. This is because produce are grown in an open
environment with access by a multitude of potential sources of contamination. While
implementing food safety controls will undoubtedly reduce the risk, the limited numbers of
samples evaluated are not likely to be capable of verifying the effectiveness of these measures.
2.1.2. Perception that testing can demonstrate field lots are safe to harvest
