As the American whiskey market grows—particularly the single-malt style—more distillers are beginning to recognize a concern that’s been flying under the regulatory radar in the United States: glycosidic nitrile, a carcinogen precursor.
Often referred to as GN, glycosidic nitrile is a compound produced in certain varieties of malting barley. It’s commonly found in domestic varieties, but it’s regulated in Canada and Europe and rarely found in newer varieties there. (Beloved historic varieties such as Maris Otter are, unfortunately, GN producers.)
Because the brewing industry dominates the domestic supply of malting barley, GN hasn’t had the attention of U.S. growers and breeders until fairly recently. (Brewing with malt that contains GN results in a beer that contains negligible levels in the final product, but distillation can concentrate GN and help to catalyze it into more dangerous substances.) In consumables such as whiskey, the European Union caps the amount of ethyl carbamate—the carcinogenic compound that results from GN—at 150 parts per billion. In the United States, the federally recommended limit is 125 parts per billion, but it’s not enforced. However, GN and ethyl carbamate may eventually land on the government’s radar as a higher priority, and the regulations in Britain, Canada, and Europe can create issues for distillers who export.