Hi. I agree with the post saying that different populations (and also different regulations) will look at the issue from different points of view. Even scientific community disagrees on the threshold levels. Example: celery is not an allergen in South America.
To get independent from thresholds, will be wise to think about cleaning validation. A quite good criteria to consider will be visual absence in solid matter systems (like bakery for example).
An additional issue to consider is sampling. Some systems like liquid piping systems could be easy to obtain a representative sample but others very difficult.
Best regards.
Carlos
The different populations will look at allergens differently because they have slightly varying genetics based on their racial origins.
By this I mean that in the UK wheat allergy is more prominent than say in Japan, where rice allergies are more prevalent. Western Europe has celery and an individual with Buckwheat allergies can also be hypersensative to proteins from latex, rice and poppy seed.
With the level of migration the world has seen in the past 50 years any population group in 1st and 2nd world countries is going to have a large mix of allergenic sensativities, which is what we are now experiencing if the level of discussion in these forums are any measure.
Each person will have an individual reaction threshold, but within a normal distribution curve for their population and it is the lower limit that threshold levels are based on.
Agreed that some areas of the world have vastly differing standards (Gluten: Australia <5ppm, USA and Europe <20ppm), however I would suggest that these limits are set by scientific analysis by the relevant food standards authority based on their populations.
With cleaning validations, if an allergen swabbed for and found to be detected, I would suggest the surface is not clean, regardless of how visually clean it is. As I have posted before, if you have determined an acceptable level of allergen, then the test used must either react (detected/Not detected) at a known concentration or a quantitative test needs to be used (gives result in ppm of contaminant).
Cosmo