Contact allergy and intolerance to sulphite compounds: clinical and occupational relevance

Background Sulphites are widely used as preservatives and antioxidants, e. g., in the food, cosmetic, and pharmaceutical industries. They are known to trigger epidermal sensitizations and associated eczematous contact allergic skin reactions; to identify these, patch testing is performed using sodium disulphite (= sodium metabisulphite; CAS 7681-57-4). In addition to this, inhalation or oral exposure to sulphite can cause the clinical picture of sulphite intolerance, including bronchoconstriction, urticaria, cardiovascular, intestinal, and/or life-threatening anaphylactic reactions, the identification of which requires challenge testing.