2. Relevance to Public Health 2.1 Background and Environmental Exposures to Cyanide in the United States

Cyanides, a diverse family of compounds containing the highly reactive cyanide anion (CN), are produced from both anthropogenic and natural sources. The cyanide compounds most commonly found in the environment include sodium cyanide, potassium cyanide, and gaseous hydrogen cyanide, the latter being the main form present in air. The use of the term ‘cyanide’ in this section refers to the cyanide ion or the cyanogen radical (CN) in a compound. Cyanides may be released into the environment during the course of industrial usage or from smoke or vehicle exhaust containing the incomplete combustion products of nitrogen-containing organic polymers. Numerous plant species contain cyanogen glycosides that can release hydrogen cyanide upon biodegradation or ingestion. The edible portions of dietary plant species commonly used in the United States contain relatively low levels of cyanogen glycosides, although some pits and seeds of common fruits (e.g., apple, apricot, peach) contain significantly higher concentrations. The cassava root (tapioca), which is a major dietary staple in tropical countries, contains a sufficient amount of cyanogen glycosides to require special processing to reduce the danger of toxicity.