shy of a doctors recommendation maybe a person who is paranoid about it could just bust a cap open and rub it on their hands to see if they have a reaction?
For most people, pollen doesn't have a contact allergy with the skin, so it wouldn't likely work quite that way.
I think starting off with a lower dose just to gauge it would likely be a better way.
No harm in trying it the way you suggested, just for me, like with my pollen allergies, I can be outside all day and get covered in pollen and it doesn't bother my skin, it would be my nasal allergies like if it got in my nose, eyes, etc.