Rapid screening of substances of lower ecological concern: summary of results

Summary of results

The results obtained at each step of the rapid screening approach are summarized in Figure 2. A simplified spreadsheet, that provides the outcome of each step of the approach for each of the substances, is also available (Environment Canada, 2007c).

Of the 1066 substances assessed using rapids screening, 4 organic substances were found to have chemical structures similar to those of substances identified as PBiT through the categorization process (step 1). These structural categories have been identified as priorities for screening assessment. Therefore, these 4 substances were identified as requiring further assessment, and did not proceed to subsequent steps of rapid screening.

Of the 1062 substances evaluated using exposure scenarios (step 2), results for 836 gave no indication of a potential for ecological harm based on the conservative exposure scenarios considered. The other 226 substances were identified as requiring further assessment, and did not proceed to subsequent steps of rapid screening.

The remaining 836 substances were evaluated using the mechanical filters (step 3). Twenty-nine of these appear on international lists of high production volume (HPV) chemicals, and were therefore identified as requiring further assessment. A further 390 substances proceeded to the manual process stage. Of these, 53 were identified as requiring further assessment.

Figure 2: Summary of rapid screening results

Summary of rapid screening results

Conclusion

In total, 312 of the 1066 substances evaluated using the rapid screening approach were identified as requiring further screening assessment. The other 754 were concluded to be unlikely to cause ecological harm, and therefore do not meet the criterion set out in paragraph 64(a) of the Canadian Environmental Protection Act, 1999 (CEPA). A list of these two groups of substances is provided in Appendix B and Appendix C, respectively.

Uncertainties and further activities

It is recognized that conclusions resulting from use of rapid screening have associated uncertainties, as the approach makes use only of data that is relatively easy to obtain. However, it is believed that the number of false negative conclusions will be low, due to the use of a wide range of filters (relating to both use quantity and ecological hazard concerns identified for a substance), as well as the use of different conservative exposure scenarios. The high fraction of these lower concern substances that have been identified by rapid screening as requiring further assessment (30%) is a reflection of the conservative basis of the approach.

Values for physical/chemical and hazard properties derived during categorization of the DSL were used as input for the RAIDAR modelling work. As is recognized in documentation associated with categorization, there are uncertainties in these values, in particular with those that have been estimated using different modelling approaches. Extreme values that were estimated by models were replaced by limiting values of physical/chemical properties or alternatively derived toxicity values, prior to using them as input for RAIDAR modelling as part of rapid screening (CEMC, 2007a). A supplementary document (Environment Canada, 2007d) further discusses some of these factors in the context of rapid screening.

Additionally, rapid screening is based in part on consideration of use and volume data that were submitted when the DSL was first created 20 years ago. Information sources consulted at step 3 of rapid screening were used to verify whether assumptions regarding current quantities in commerce were appropriate. As announced by the Government of Canada in December 2006, new requirements will be coming into place for the updating of this information. Conclusions from this rapid screening assessment will be revisited as new information on quantities and uses become available.

In the meantime, it is important to recognize that the Government of Canada can identify substances for assessment based on a number of different considerations. Substances may be subject to assessment whether or not they meet categorization criteria, and whether or not the Existing Substances Program has previously concluded that the substance did not meet criteria in section 64 of CEPA.

Substances for which it is proposed, based on the outcome of the rapid screening approach and other considerations, that they do not meet the criteria in section 64 of CEPA remain subject to re-assessment if information is identified that indicates that further evaluation of the substance is warranted. Examples of the types of information that may trigger further evaluation of a substance include:

  • Evidence of higher quantities in commerce. Since the rapid screening approach is driven in part by use quantity information, updated information to suggest that higher quantities of a substance are now in use could indicate that a substance should be subject to further evaluation.
  • Evidence of higher releases. The exposure scenarios used assumptions that are expected to be conservative for most substances. Updated information indicating that the assumed conditions are not protective for a particular substance owing to its routine handling and use could indicate that a substance should be the subject of further evaluation.
  • Evidence of ecological exposure. Monitoring data demonstrating the detectable presence of a substance in environmental media could indicate that a substance should be the subject of further evaluation.
  • Evidence of other possible ecological risk. Information that was not considered in the rapid screening approach, but that could be of significance in establishing an ecological risk from a substance, could trigger further evaluation of the substance.
  • Evidence that a substance is a PBiT. Since PBiTs are not candidates for the rapid screening approach, any information to suggest that the substance is PBiT could trigger further evaluation of the substance.
  • Identification as part of a category undergoing assessment. If the substance is part of a group that is prioritized for a category assessment at some time in the future, the substance may be subject to this further evaluation.

Information of these types may be identified from a number of different sources, including:

  • direct submission of information by stakeholders
  • research, monitoring and DSL update activities taking place under the Chemicals Management Plan
  • other assessment or regulatory activities in Canada or in foreign or international forum

References

Canadian Environmental Modelling Centre (CEMC). 2007a. Risk Prioritization for a Subset of Domestic Substances List Chemicals Using the Risk Assessment, IDentification And Ranking (RAIDAR) Model. Report prepared by the Canadian Environmental Modelling Centre, Trent University, ON, for the Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

CEMC. 2007b. Spreadsheet of results associated with the report "Risk Prioritization for a Subset of Domestic Substances List Chemicals Using the RAIDAR Model". Prepared by the Canadian Environmental Modelling Centre, Trent University, ON, for the Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

Environment Canada. 2007a. Technical Approach for "Rapid Screening" of Substances of Lower Ecological Concern. Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

Environment Canada. 2007b. Results of the Rapid Screening Assessment of Substances of Lower Ecological Concern - Detailed Spreadsheet. Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

Environment Canada. 2007c. Results of the Rapid Screening Assessment of Substances of Lower Ecological Concern - Summary Spreadsheet. Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

Environment Canada. 2007d. Results of the Rapid Screening Assessment of Substances of Lower Ecological Concern - Supplementary Evaluation of RAIDAR Modelling Results. Existing Substances Division, Environment Canada, Gatineau, QC, Canada. Available on request from the Existing Substances Division.

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