Beyond voluntary labeling by food manufacturers, we do not yet have widespread food allergen certifications or defined food allergen thresholds that are considered safe with the exception of gluten and sulphites.
To put it into perspective, the threshold for gluten is 20 ppm (parts per million). Anything under 20 ppm is considered safe by the leading scientists in gluten research, even when taking into account eating many products under 20 ppm during the day - the cumulative effect. Sulphites are given the threshold of 10 ppm. Following these accepted levels, the government can then create labeling laws that specify the threshold and food producers follow this in the labeling/marketing of their own products.
To date, no other food allergens have been given a definitive ppm below which they are considered safe for people with food allergies. Therefore, the current level that they are considered safe at is at the lowest amount that an allergen can be tested at using scientifically valid methods. At this time, there are no scientifically valid tests available down to 0 ppm of a specific allergen.
In November 2011, an Allergy Task Force called VITAL was put together with researchers around the globe including the widely renowned Stephen Taylor from the University of Nebraska's Food Allergy Research and Resource Program (FARRP). The VITAL program has now determined threshold amounts for the top 14 food allergens.
So what does that mean for food allergens? The task force both reviewed and conducted scientific research to determine at what level food allergens must be present in a specific serving/weight of food to create an allergic reaction. Just because we can test a food down to 2 ppm for an allergen doesn't mean that anyone would react to it at that level. If, for example, it is determined that the threshold for peanut allergy reactions is 10 ppm, only food products consistently testing less than 10 ppm could be labelled as peanut free.
It could also help determine the "may contain" statements. Perhaps on occasion, a product tests at over 10 ppm. A food manufacturer could then put a "may contain peanut" on the label. If a product consistently tested above 10 ppm, the "may contain" may no longer be appropriate because peanut is consistently in the product so it must be labelled "contains peanut" or peanut must be placed on the ingredient list.
For governments, these definitive thresholds can be placed into labeling laws and governments would have the authority to recall products that are unsafe and/or conduct legal investigations and actions for producers disregarding the law.
For food producers, it means that they can also stop guessing and create specific sanitation and testing protocols for their products and food production lines. They can also label very specifically and if indeed they are putting blanket "may contains" on all of their products, they can stop doing that and allow more of their products to become available to allergic consumers.
Unfortunately, we do not have a timeline for when Canada will accept the recommended thresholds of this international team. However, Australia and New Zealand have already begun implementing the thresholds for food manufacturing and the FDA in the USA is currently reviewing them, as is the European Union.