Allergen - Is it chemical or physical hazard
Well, the allergic reaction is caused by on the interactions between the protein molecule that is the allergen and the epitope on the immunoglobulin molecule which also is a protein, which then signals the cells to dump out what they are holding just for this kind of event. Protein-protein interactions follow the laws of thermodynamics as do all chemical reactions, with some special additional laws just for proteins. The resulting reaction in the body is the result of the actions of chemical mediators that were dumped out of the cells. So I would call it a chemical hazard, since there is so much chemistry involved.
It's definitely not a physical hazard.
As others have said and cannot be said too many times....no matter what you call a hazard, you still have to perform the appropriate risk analysis. Just make sure it gets done and documented.
Martha
"...everything can be taken from a man but one thing: the last of the human freedoms--to choose one's attitude in any given set of circumstances, to choose one's own way." Viktor E. Frankl
"Life's like a movie, write your own ending." The Muppets