ISPAM September 6 2014 Meeting

A culture negative provides evidence that the lot has a lower level of contamination than a lot that is at the RQL. The probability of a culture negative from a lot at the RQL is the Type 2 error value (typically 10%). 6. Recommendations for a sampling plan for cause (Trevor Suslow, David Oryang) 6.1. What is a “cause”(e.g., suspected contamination) 6.1.1. The inability to find a field a field safe for harvesting based on sampling should be reiterated. Perhaps this is better described as “Investigative Sampling” 6.1.2. Evidence of unusually heavy animal intrusion, observation of a recognized potential hazard in a specific location of the field, localized flooding, unanticipated

field-side deposits of manure/compost, unanticipated proximity of domestic animals, non-compliant water test or recognized potential for irrigation water contaminations (upstream event), windblown debris from a hazard source,

6.2. Location and number of samples collected 6.2.1. Directional/gradient sampling

6.2.1.1. Sampling from least likely to more likely (avoid transferring contamination). 6.2.1.2. Shadowing identified path of contamination 6.2.1.3. Sampling close to the source may not be best (e.g., windblown may settle farther away from the source) 6.2.1.4. Sampling at tail water end of field (where field slopes and runoff collects) as a collection point for the field 6.2.2. Number of samples 6.2.2.1. Increased number of samples in risk zones vs. moving where samples are collected 6.3. Size and quantity of samples collected 6.3.1. Larger number of smaller samples and wet compositing 6.3.2. Ten 75 or five 125 gr samples (manageable enrichment volumes), enriched separately and composite aliquots after enrichment. Enrich entire sample, not a portion. Retain enrichments for subsequent testing 6.4. Which part(s) of the produce to collect 6.4.1. Harvest portion within wrapper leaves, take the entire plant, chop (don’t blend) and mix edible portion at laboratory, take sample from mixed pieces 6.5. Individual vs. composite testing 6.6. Reaction to test results 6.6.1. Statistical meaning of a detected positive 6.6.2. Statistical meaning of a non-detect 7. Alternative sampling procedures 7.1. Swabs in field 7.2. Testing wash water 8. Research Needs

9. References 10. Appendices 10.1. Sampling strawberries for EHEC