This has been my understanding since dealing with a friend who had hives that were triggered by eating any sulferized items, like frozen dinners, seafood ect.
Ths sulfer dioxide used to preserve food , like other elemental sulfer derivitives, is poisonous on a cellular level and the body reacts by producing chemicals to protect and eliminate it. Most of us dont experience any of this but to those who have comprimised/congested organs ect the swelling of tissue can range from uncomfortable to life threatening as in the instance of the bodies reaction of swelling in the breathing airways. People had died from salad bar lettuce dosed with sulfer preservative so it was prohibited in that use some years ago. Tho it is a strict poison I think many of us just eliminate the small amounts of toxic elemental sulfer derivative we ingest without implication but if we are already internally sub par we best avoid it.
( elemental sulfer being toxic, nutricinal sulfer not. Nutritional sulfer, most commonlly used in the form known as MSM, is a necessary constituant of our body).