Acrylonitrile

Acrylonitrile was first synthesized in 1893 but became industrially important in the 1940s when its potential as a polymer precursor was recognized [1]. About 6 billion pounds are produced annually worldwide, primarily for making polyacrylonitrile fibers (used in textiles and carbon fiber precursors), ABS and SAN plastics (used in electronics, automotive parts, and appliances), and nitrile rubber. Industrial production and use is concentrated in chemical manufacturing complexes, with significant facilities in Texas and Louisiana [2]. Workers at acrylic fiber manufacturing facilities in the early decades of industrial production had significant exposures that revealed the carcinogenic potential. Community exposures occur through ambient air emissions from manufacturing facilities and through tobacco smoke (cigarettes contain acrylonitrile) [3].

Occupational inhalation and dermal contact are the primary routes for people who manufacture acrylonitrile or use it in polymer production [1]. Cigarette smoke is the most significant general-population exposure source — tobacco contains acrylonitrile and its combustion products are present in smoke. Community ambient air near acrylonitrile manufacturing and use facilities contains measurable concentrations [2]. Drinking water contamination has been documented near spill sites and industrial facilities — acrylonitrile is soluble in water. Residues in acrylic polymers are very low and generally not a significant consumer exposure concern for final products [3].

Acrylonitrile is classified as a probable human carcinogen (IARC Group 2A), with the strongest evidence for lung cancer and possible evidence for colorectal cancer in occupationally exposed workers [1]. The mechanism involves both direct reactivity of acrylonitrile and metabolic conversion to cyanoethylene oxide, a reactive epoxide that forms DNA adducts and generates cyanide — explaining why high-level acrylonitrile poisoning has a component of cyanide toxicity [2]. Acute high-level exposure causes cyanide-like symptoms: headache, weakness, nausea, and in severe cases, seizures and cardiovascular collapse. Chronic lower exposures cause neurological effects and hepatotoxicity [3].

Workers in acrylonitrile production, acrylic fiber manufacturing, and ABS/SAN plastic production face occupational exposures [1]. People who live near acrylic fiber and nitrile rubber manufacturing facilities face ambient air exposures. Smokers receive acrylonitrile from tobacco smoke [2].

Quit smoking to eliminate the largest personal acrylonitrile exposure source [1]. If you live near an acrylonitrile manufacturing or use facility, check EPA's ECHO database for emissions data and support local air quality monitoring programs [2]. Workers in acrylonitrile environments: use local exhaust ventilation, wear organic vapor respirators during operations with vapor generation, and monitor blood cyanide or thiocyanate levels as biomarkers of exposure. Annual lung function testing and chest imaging should be part of occupational health protocols [3].