Threshold, routes of exposure, and eliciting doses are questions that are best addressed with two people in the loop (and are probably flatly inappropriate for anyone ELSE to be discussing with them out of it):
1. The allergic individual-- who, once an adult, is almost certainly THE expert in their own condition, and
2. That allergic individual's personal physician, preferably an experienced and highly competent FOOD allergy specialist (they don't grow on trees, either-- there are a lot of plain vanilla allergists out there who don't really know a lot about food allergy).
I know that you're reading some responses to your posts as "hostile" but you have to understand that having someone that we trust implicitly "test" our (or our kids') allergies in the way that some of those posts hint at... well, that is the stuff of our nightmares. Because there is no way to be mentally prepared for that level of betrayal. I have no idea whether or not your wife's allergies are fabricated, exaggerated, or anything else. But if she trusts you with those allergies, "trying" them without her knowledge is a level of betrayal that is so profound that not even infidelity comes close. I'm not kidding.
Some things that you should be aware of, that said--
a. The few studies that examine aerosol (smell) reactivity have significant limitations-- making them useless for the most sensitive tail of the food-allergic distribution, IMHO as a scientist (and yes, I really am one, and I'm basing that statement on the statistics and methodology in those studies).
b. The few studies that attempt to determine what a lowest "eliciting dose" is have ALL had participants which reacted to the lowest levels offered, albeit with "subjective" symptoms that didn't BECOME objective ones until higher doses were reached. What that means is that those allergic people KNEW that they were being dosed before the researchers did.
c. One pretty well-designed study demonstrated rather convincingly that those who react to those super-low doses are the ones that have MORE SEVERE reactions, in general.
Add all of that together and what emerges is this:
there are peanut-allergic persons who react to amounts that are so low that they are mind-bogglingly small, and difficult to even measure using the best methodology-- and that those people tend to be at very grave risk from exposures. They are NOT most people with the allergy, but for obvious reasons they are quite difficult to study. Once you are in that group of people via reaction history, you are automatically ineligible for most studies that might require you to be exposed to (or react to) peanut-- because the risk of a life-threatening reaction (and possibly death) is too high for Institutional Review Board (IRB) approval to be obtained, if you are designing a study.
So research studies DO NOT INCLUDE people with that kind of sensitivity. The few early studies that did found some disturbing differences with that group relative to the larger peanut allergic population as a whole-- their thresholds are unstable, and they react severely to low doses-- unpredictably.
Additional research studies have hinted that this population is quite real-- desensitization work has had failure rates (with some pretty spectacular failures, in fact) that indicate that there is something very different about those people.
I'm stating all of that as a caution-- if someone tells you that they have that kind of allergy, you CANNOT afford to go behind their back to prove them wrong. EVER. You really could kill them if it turns out that they were not exaggerating or lying.
Please take a look at the events surrounding Chandler Swink's recent death. This is definitely possible.
My own DD is fifteen-- and she KNOWS when someone has eaten peanuts-- even hours before they are talking to her. She knows. She can sense them on someone's breath-- she truly has a super-human sense for them. She is one of those super-sensitive people. A LOT of people have been unwilling to believe her over the years-- and mostly she avoids those people because they are really, really dangerous for her to be around.
Another example for you-- she had a recent reaction that was pretty spectacular-- vomiting, some disorientation and a few hives that popped up late in the reaction. The cause was something that we'll never know for sure, probably, but the best we can determine this was caused by her boyfriend TOUCHING her after driving a car-- that another driver had driven after consuming nuts. Is that too farfetched for you? We have estimated based on the sum of her life experiences and ours that her reaction threshold fluctuates between 50 micrograms and somewhere close to 1 milligram of peanut. REALLY not kidding. Those are invisible amounts. Any environment where peanut IS regularly consumed poses a dreadful danger to someone like my daughter, and putting them away does little to mitigate the myriad places where the protein has built up or can be stirred up to recontaminate things.