Although sulfite salts are relatively nontoxic, their use has led to controversy, resulting in extensive regulations.
[1][2][3] Sulfites are commonly introduced to arrest fermentation at a desired time, and may also be added to wine as preservatives to prevent spoilage and oxidation at several stages of the winemaking.
[6] In fruit canning, sodium bisulfite is used to prevent browning (caused by oxidation) and to kill microbes.
The sulfur dioxide released by these salts kills yeasts, fungi, and bacteria in the grape juice before fermentation.
Once the levels of sulfur dioxide have subsided (about 24 hours), fresh yeast is added for fermentation.
Sodium bisulfite is also added to leafy green vegetables in salad bars and elsewhere, to preserve freshness, under names like LeafGreen.
[11] In the European Union, "EU law requires food labels to indicate “contains sulfites” (when exceeding 10 milligrams per kilogram or per litre) without specifying the amount".
[16] In 1986, the U.S. Food and Drug Administration banned the addition of sulfites to all fresh fruit and vegetables that are eaten raw.
was banned from use by the U.S. FDA on fresh fruits and vegetables following the deaths of 13 people and many illnesses, mainly among asthmatics.
[27] Chronic skin conditions in the hands, perineum, and face have been reported in individuals that regularly use cosmetics or medications containing sulfites.
[32][33][34] A 2017 study has shown negative impacts from sulfites on bacteria found in the human microbiome.