I have experienced a food allergy for approximately two years and have only just discovered that the allergen is annatto.  I experienced turning sunburn red, itching, stinging, burning from my scalp to my toes.  The reaction was always the same, lasted  one and one-half hours each occurrence, was painful, and occurred after eating varying foods: mustard, seasoned sausage, desserts, crackers, salads from my favorite deli.  After eating a Sargento’s cheddar cheese stick and having this painful reaction, I read the label of this cheese product and annatto was listed.  I researched the additive and have since avoided it and have not had another reaction.  It is dose related for me.  If I ingest a small portion of this additive, I do not react - Christi USA

(Note that annatto can even cause life-threatening anaphylactic reactions in some people http://www.fedup.com.au/factsheets/additive-and-natural-chemical-factsheets/160b-annatto)