Sulfite

Sulfites (also sulphites) are compounds that contain the sulfite ion SO32−. They are often used as preservatives in wines (to prevent spoilage and oxidation), dried fruits, and dried potato products. Sulfites also occur naturally in almost all wines.

Regulation of commercial use
Sulfites occur naturally in wine. They are also added to wine. In the US, wine bottled after mid-1987 must have a label stating that they contain sulfites if they contain more than 10 parts per million. In the EU an equivalent regulation came into force in November 2005. Organic wines are not necessarily sulfite-free but they have no added sulfites. Wines made with organic grapes, however, may contain up to 100 ppm, compared to conventional wines which may contain up to 350 ppm. Most beers no longer contain sulfites. Although shrimp is sometimes treated with sulfites on fishing vessels, the chemical may not appear on the label. In 1986, the Food and Drug Administration in the United States banned the addition of sulfites to all fresh fruit and vegetables which are usually eaten raw.

Health risks
Sulfites are sometimes added to foods to act as enhancers or preservatives. They may come in various forms, such as:


 * Sulfur dioxide
 * Potassium bisulfite or potassium metabisulfite
 * Sodium bisulfite, sodium metabisulfite or sodium sulfite

Some humans are allergic to sulfites, it is an undeclared allergen and may have difficulty breathing within minutes of eating a food containing sulfites. Asthmatics and people with allergies to aspirin (also known as salicylate sensitivity) are at an elevated risk for reaction to sulfites. Preserved radish, for example, may contain sulfites, and it is known to smell like hospital sheets in some counties. The reaction can be fatal and requires immediate treatment at an emergency room, and can include sneezing, swelling of the throat, and hives. Those who are allergic to sulfites are urged to avoid products that could contain them.