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Acrylonitrile (AN) is a colorless to pale yellow liquid substance with a sharp, onion- or garlic-like odor. It is also known as AN, acrylon, carbacryl, cyanoethylene, fumigrain, 2-propenenitrile, VCN, ventox and vinyl cyanide. Acrylonitrile does not occur naturally in the environment. It is found in the manufacture of acrylic and modacrylic fibers, acrylostyrene plastics, synthetic rubber, nitrile rubber, chemicals, adhesives, surface coatings, ABS and SAN resins (often used in production of recreational watercraft), and as a grain fumigant.
This chemical is corrosive to metals, and will corrode some forms of plastics, rubber, and coatings. It can penetrate leather and at high concentrations will corrode aluminum. It is explosive and highly flammable and, when heated to decomposition, emits highly toxic fumes of hydrogen cyanide gas, nitrogen oxides, and carbon monoxide. This chemical may polymerize (its molecules may chain together with simple molecules to form a more complex molecule with different physical properties) spontaneously and violently.
Acrylonitrile evaporates when exposed to air. It dissolves when mixed with water. Most releases of acrylonitrile to the environment are to underground sites or to air. Acrylonitrile evaporates from water and soil exposed to air. Once in air, AN breaks down to other chemicals. Microorganisms living in water and in soil can also break down AN. Because it is a liquid that does not bind well to soil, acrylonitrile that makes its way into the ground can move through the ground and enter groundwater. Plants and animals are not likely to store acrylonitrile.
Scope
OSHA’s requirements apply to all occupational exposures to acrylonitrile (AN), except to exposures which result solely from the processing, use, and handling of the following materials:
- ABS resins, SAN resins, nitrile barrier resins, solid nitrile elastomers, and acrylic and modacrylic fibers, when these listed materials are in the form of finished polymers, and products fabricated from such finished polymers;
- Materials made from and/or containing AN for which objective data is reasonably relied upon to demonstrate that the material is not capable of releasing AN in airborne concentrations in excess of 1 ppm as an eight (8)-hour time-weighted average, under the expected conditions of processing, use, and handling which will cause the greatest possible release; and
- Solid materials made from and/or containing AN which will not be heated above 170 deg. F during handling, use, or processing.
Regulatory citations
- 29 CFR 1910.1045 — Acrylonitrile
Key definitions
- Acrylonitrile or AN: Acrylonitrile monomer, chemical formula CH(2)=CHCN.
- Action level: A concentration of AN of 1 ppm as an eight (8)-hour time-weighted average.
- Authorized person: Any person specifically authorized by the employer whose duties require the person to enter a regulated area, or any person entering such an area as a designated representative of employees for the purpose of exercising the opportunity to observe monitoring procedures.
- Decontamination: Treatment of materials and surfaces by water washdown, ventilation, or other means, to assure that the materials will not expose employees to airborne concentrations of AN above 1 means the Director, National Institute for Occupational Safety and Health, U.S. Department of Health and Human Services, or designee.
- Emergency: Any occurrence such as, but not limited to, equipment failure, rupture of containers, or failure of control equipment, which results in an unexpected massive release of AN.
- Liquid AN: AN monomer in liquid form, and liquid or semiliquid polymer intermediates, including slurries, suspensions, emulsions, and solutions, produced during the polymerization of AN.
- PEL or Permissible Exposure Limit: An airborne exposure of two (2) parts acrylonitrile per million parts of air (2 ppm) as an eight (8)-hour time-weighted average. Note: The employer shall assure that no employee is exposed to an airborne concentration of acrylonitrile in excess of ten (10) ppm as averaged over any fifteen (15)-minute period during the work day.
Summary of requirements
Employers must:
- Survey the workplace for any storage or usage of AN.
- Implement a medical surveillance program for all workers exposed to the action level as outlined in the standard.
- Implement a monitoring program to obtain an estimate of employee exposures. Repeat per the requirements in the standard.
- Notify employees within 15 days of monitoring results.
- Establish a regulated area when exposures exceed the PEL.
- Establish a written compliance program.
- Ensure employees are aware of the hazards involved with acrylonitrile.
- Implement a training program for all employees who are subject to exposure to acrylonitrile has been instituted.
- Provide employees with proper protective equipment when working with acrylonitrile.
- Use engineering and work practice controls to reduce exposures to a permissible level.
- Ensure caution labels and signs are used to warn of acrylonitrile.
- Ensure employees who work with acrylonitrile wash their hands after assigned tasks are completed and before engaging in other activities.
- Maintain appropriate records (exposure monitoring, medical surveillance, etc.).
- Instruct employees in proper first aid and other emergency procedures.
- Ensure emergency procedures are in place for dealing with emergency situations involving acrylonitrile.