Sulfates are mineral salts containing sulfur. Sulfate salts are found in some Wisconsin soils. The decay of plants, animals, and some industrial processes produce these salts. Mines, tanneries, steel mills, pulp mills, and textile plants also release sulfates into the environment. Understanding the difference between sulfates and sulfites: Sulfites are different sulfur-containing chemicals used as food preservatives. Sulfites are not the same as sulfates. Some people, especially asthmatics, are sensitive to sulfites and can experience severe allergic reactions. Since 1987, food containing more than 10 parts per million (ppm) sulfites and drugs containing sulfites must be labeled.