Toxic substances list: PREPOD

PREPOD is manufactured and used in Canada as an antioxidant, mainly in rubber applications.

The substance reaction products of 2-propanone with diphenylamine (CAS RN 68412-48-6), referred to as “PREPOD”, is included in Batch 11 of the Challenge under the Chemicals Management Plan (CMP). PREPOD is the reaction product of N-phenyl-benzenamine (diphenylamine or DPA) and 2-propanone (acetone).  It is a UVCB (Unknown or Variable Composition, Complex Reaction Products, or Biological Materials) mixture, and, as such, contains a number of components in different concentrations. 

The final screening assessment report (FSAR) concluded that PREPOD is entering or may enter the environment in a quantity or concentration or under conditions that have or may have an immediate or long-term harmful effect on the environment or its biological diversity, as defined in section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999).

Many components of PREPOD meet the criteria for persistence and at least one component, diisopropyldimethylacridan (DIPDMA), meets the criteria for both persistence and bioaccumulation, as defined in the Persistence and Bioaccumulation Regulations made under CEPA 1999.

The risk management objective of the pollution prevention planning notice is to reduce the presence of PREPOD in industrial effluents such that the concentration of DIPDMA is below its limit of quantification.

History of risk management activities

The Proposed Risk Management Approach document  (September 2011) listed the activities to be conducted in order to develop appropriate and efficient controls. The primary focus of these activities was the quantification of releases and environmental presence to inform risk management development. The development of an analytical method to measure PREPOD and its components was a critical element to support this work.

A technical study (Environment Canada, March 2012, Technical Study of the Manufacture and Use of PREPOD, prepared by Environmental Health Strategies Inc.) indicated that, based on management practices and the manufacturing processes currently used in Canada, releases of PREPOD are expected to be lower than estimated in the screening assessment report. The Government of Canada added PREPOD to the CMP Monitoring and Surveillance Program. 

Analytical methods to measure individual components of the substance in wastewater and in sediments were developed by Environment and Climate Change Canada (ECCC). Samples were collected from the wastewater treatment plant receiving input from the PREPOD manufacturing facility. Analytical results informed the development of a control instrument.

On June 15, 2019, ECCC published a final pollution prevention planning notice in respect of PREPOD in Canada Gazette, Part 1. The risk management objective of the notice is to reduce the presence of PREPOD in industrial effluents such that the concentration of DIPDMA is below its limit of quantification of 0.12 ng/L.

ECCC has proposed that PREPOD be added to the National Pollutant Release Inventory (NPRI) and the application of the Significant New Activity (SNAc) provisions to this substance was reconsidered and is not being pursued at this time.

For more information on this substance, please visit the Chemical Substances website.

Risk assessment


Current public consultations on PREPOD

Past public consultations


Substances Management Information Line
Chemicals Management Plan
Gatineau, QC K1A 0H3

Telephone: 1-800-567-1999  (in Canada) or 819-938-3232
Fax: 819-938-3231


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