Nitrite is a compound of the nitrite anion and some other element. An anion is a negatively charged ion. Inorganic nitrites are stable and soluble in water. Most organic nitrites are made from alcohols. They are unstable when in the presence of acid, but they are preserved satisfactorily in neutral or mildly alkaline solutions. Nitrites are used in medicine for heart ailments. Sodium nitrite is important in making dyes. It is also used to cure meats, such as bacon, to prevent botulism and to give the meat a pinkish color. Under certain conditions, sodium nitrite may combine with chemicals called amines to form nitrosamines, which can cause cancer. The U.S. Department of Agriculture limits the amount of sodium nitrite allowed in cured meats. Nitrites are also used in photography and in the manufacture of organic materials.