Heterocycles Group

These substances were identified for action under the Chemicals Management Plan (CMP). This screening assessment focuses on 3 of 7 substances referred to collectively under the CMP as the Heterocycles Group.

Information sheet

Summary of publications
Substance group CAS RN Common name DSL name Public comments on the draft screening assessment Final screening assessment Conclusion on section 64 criteria Follow-up activities
Heterocycles Group 100-97-0 Methenamine 1,3,5,7-tetraazatricyclo[,7]decane HTML HTML Does not meet None planned at this time
110-91-8 Morpholine Tetrahydro-1,4-oxazine
4174-09-8 N/A 3H-pyrazol-3-one, 2,4-dihydro-4-[(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)methylene]-5-methyl-2-phenyl-
Date Activity
June 8, 2019 Publication of the final screening assessment. The related notice was published in the Canada Gazette, Part I: Vol. 153, No. 23.
November 11, 2017 Publication and start of 60-day public comment period on the draft screening assessment [including follow-up activities for ethylene thiourea (ETU) and CAS RN 4174-09-8].  The related notice was published in the Canada Gazette, Part I: Vol. 151, No. 45.


One additional substance, ETU (CAS RN 96-45-7), was originally included in the Draft Screening Assessment for the Heterocycles Group. To better align with the re-evaluation of certain pesticides, it was subsequently removed from this group and has been assessed in a separate screening assessment. For more information on ETU, please visit the ethylene thiourea web page.

Three other substances (CAS RNs 132-65-0, 28984-69-2, and 68909-18-2) were identified as being a part of the Heterocycles Group at the outset of the third phase of the CMP. These substances were subsequently determined to be of low concern to both human health and the environment, through other approaches. Conclusions for these 3 substances are provided in the Final Screening Assessment for Substances Identified as Being of Low Concern based on the Ecological Risk Classification of Organic Substances and the Threshold of Toxicological Concern (TTC)-based Approach for Certain Substances.

Page details

Date modified: