Industry has voluntarily agreed to develop and use manufacturing techniques to reduce urethane's levels as much as possible. In addition, at FDA's request, the National Toxicology Program, a federally funded research group, has done an initial study in animals to help FDA determine if urethane in alcohol poses a significant risk to humans. Follow-up studies are not complete, and for now, according to the Cancer Assessment Committee of FDA's Center for Food Safety and Applied Nutrition, there is not yet enough information to assess the risk. Urethane by Nature Urethane formation is not a new phenomenon produced by high-tech processing. The chemical forms naturally in wine during yeast fermentation of fruit juice.
Fermentation also produces urea from the yeast metabolism of arginine, an amino acid in grapes.
Recent studies show that when urea reacts with ethyl alcohol after fermentation, ethyl carbamate, another name for urethane, results. Alcoholic beverages other than wine present variations on this process, which complicates studies. Levels of urethane differ with each type of alcoholic beverage, explains Benjamin J. Canas, of FDA's division of food chemistry and technology. For example, heat seems to accelerate the production of urethane. Some sherries are baked to provide a rich taste, and bourbons are distilled at high temperatures.