You've probably encountered many products containing sodium metabisulfite without even realizing it. Sodium metabisulfite preserves food and is used extensively in commercial wine making. It is a bleaching agent in the textile, pulp and paper industries. It is also used in the chemical, pharmaceutical, film and photographic industries, and even in water and sewage treatment plants. However, pure sodium metabisulfite can be quite hazardous.
Inhalation of sodium metabisulfite irritates your respiratory tract. Symptoms include coughing and shortness of breath. In some individuals, sodium metabisulfite may cause an allergic, asthma-type reaction.
Ingesting pure sodium metabisulfite irritates your gastrointestinal system as it reacts with acid in your stomach by releasing sulfurous acid. Ingesting high amounts may cause nausea, vomiting, diarrhea, abdominal pains, circulatory disturbance and central nervous system depression. A fatal dose is estimate to be 10 g for the average adult.
When placed in direct contact, pure sodium metabisulfite can irritate skin causing redness, itching and pain.
Similar to skin irritation, direct contact of sodium metabisulfite with your eyes can cause irritation, pain, stinging, tearing, redness, swelling, corneal damage and blindness. These effects may be irreversible.
Sodium metabisulfite causes extreme allergic reactions in certain sulfite-sensitive individuals, resulting in broncho constriction, shortness of breath, wheezing, coughing, gastrointestinal disturbances, rapid swelling of the skin, flushing, tingling sensations and shock.