Iodine, called yodo in Spanish and black in slang terms, is a naturally occurring mineral. Iodine crystals, which are used legally for commercial and medical purposes are also used illegally to produce hydriodic acid, the reagent producing the final product of d-methamphetamine. Hydriodic acid is produced through combining iodine crystals with water and some form of phosphorus. In 1993, the Drug Enforcement Administration (DEA) rendered hydriodic acid unavailable in the United States. The Federal Government regulates the sale of iodine crystals as indicated through the passing of the Comprehensive Methamphetamine Control Act of 1996. The producers of methamphetamine typically acquire iodine crystals through theft, diversion, and smuggling. The theft and diversion of iodine crystals occurs most frequently in the western half of the United States. Iodine can be a potentially dangerous chemical. If it comes in contact with the skin, it can result in painful irritation and chemical burns and in contact with the eyes, it can cause permanent damage. Law enforcement officers are urged to use extreme caution when handling, storing, or transporting the chemical. With iodine being readily available and its chemical properties easily converted into hydriodic acid, the use of iodine in methamphetamine production is likely to increase.