After July 9, 1987, every bottle of wine must have a label affixed that is a declaration of sulfites. Sulfur (or sulphur) is a non-metallic element that is one of the most common present in nature. It is used to maintain the stability and potency of some medications and as a part of common compounds used to preserve a wide variety of foods and food products. Sulfur is readily digested by the human body and is one small component of fats, bodily fluids, and skeletal minerals and is essential to life itself.
Wine producers around the world have used sulfur for centuries and currently no other compound has been found that provides all the beneficial effects of sulfur while being so relatively benign. According to the U.S. Food and Drug Administration, approximately 1% of the population has some sensitivity to sulfur compounds and sulfites and about 5% of asthma sufferers can have adverse sulfite reactions.
To put the issue in perspective, in order to avoid affixing a warning label on a bottle of wine sold in the United States is only 10 parts per million (ppm). The maximum legal limit for sulfites in wine in most countries is about 335-350 parts per million. In practice, the average amount of sulfites in bottled wine is between 20 and 50 ppm. This is a much lower level than virtually all sulfur-containing processed foods, which may range from as little as 6 to 6,000 ppm. The maximum legal limit for sulfites in dried fruit, for example, is 2000 parts per million.
Some sulfur is naturally occurring in the environment and in grapes, as well as in nearly all fruit and vegetables. Even without the addition of sulfur, yeast fermentation produces a natural sulfur level of between 15-20 ppm, so it is virtually impossible to avoid this labeling requirement. There are no wines that are sulfite-free.