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Benzenamine, N-phenyl-, Reaction Products with Styrene and 2,4,4-Trimethylpentene (BNST)

CAS Registry Number 68921-45-9

What is it?

  • Benzenamine, N-phenyl-, Reaction Products with Styrene and 2,4,4-Trimethylpentene, also known as BNST, is an industrial chemical. It is not expected to occur naturally in the environment.

How is it used?

  • BNST is predominantly used as a lubricant antioxidant additive in vehicle engine oils and commercial/industrial lubricants. BNST is also used as an antioxidant and anti-degradant additive in the manufacture of rubber products.
  • BNST was added to the Prohibition of Certain Toxic Substances Regulations, 2012, in 2013. These Regulations prohibit the manufacture, use, sale, offer for sale, and import of BNST with exemptions for certain activities.
  • BNST may still be used as an additive in lubricants until March 2018 if a permit has been granted under these Regulations. The use of BNST as an additive in rubber is exempted; except in tires, where this use has been prohibited in Canada.

Why did the Government of Canada assess it?

  • In 2006, BNST was identified as a potential concern to the environment based on available information regarding possible persistence, accumulation in organisms and potential to cause harm to organisms.

How is it released into the environment?

  • Small amounts of BNST may be released to surface water or sewers as a result of manufacturing of the substance and blending of lubricating oils.
  • A small portion of the BNST used may be released to sewers and soil due to leaks from vehicle engines and other equipment. A small portion may also be placed into waste disposal sites.
  • When BNST is released, it remains in the environment for a long time. It also has the potential to build up to high levels in the bodies of organisms.

What is the Government of Canada doing?