The substance Benzenamine N-phenyl-Reaction Products with Styrene and 2,4,4-Trimethylpentene (BNST), and products containing BNST, are prohibited under the Prohibition of Certain Toxic Substances Regulations, 2012 with a limited number of exemptions. The regulations were published in the Canada Gazette, on the 2nd of January 2013 and came into force on the 14th of March the same year. BNST can to be used in lubricants until the 14th of March 2015 therefore the exemption has expired.

What is BNST?

Benzenamine, N-phenyl-Reaction Products with Styrene and 2,4,4- Trimethylpentene also known as BNST is an industrial chemicaland is a UVCB. The two structures are representative of the UVCB as shown below.


BNST is an antioxidant used as an additive in engine oil and in some commercial and industrial lubricants. The information available also suggests that there may also be a minor use of BNST as an additive in rubber applications for industrial equipment, machinery and in rubber parts used in vehicles.

Regulated Rules on BNST

Substance nameCas No.ProhibitionExemptions
Benzenamine, N-phenyl-, reaction products with styrene and 2,4,4- trimethylpentene(BNST)68921- 45-9manufacture, use, sale, offer for sale or import of BNST and products containing BNST are prohibited• rubber products containing BNST (except rubber tires)• products containing BNST that are for a personal use• BNST to be used in lubricants until March 14, 2015(need a permit)

CTI Suggests:

Manufacturers of related products should follow the updated requirements of Canadian legislation and look for new environmentally friendly substitutes to make sure that products exported to Canadian market are compliant.

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