Proposal to Add Thallium (and its Compounds) to the National Pollutant Release Inventory Substance List at an Alternate Threshold

Environment Canada proposed to add thallium (and its compounds) to the National Pollutant Release Inventory (NPRI) substance list at an alternate mass reporting threshold commencing with the 2014 reporting year. Consultations on this proposed change were conducted with the NPRI Multi-Stakeholder Work Group (WG) in November and December of 2013. After considering the comments received, Environment Canada has decided to proceed with the change, and it is reflected in the 2014-2015 NPRI Canada Gazette notice.

A) Proposal (November 2013)

B) Summary of Stakeholder Comments and Environment Canada’s Response (July 2014)

A) Proposal (November 2013)

The following is a summary of the proposal. To obtain a copy of the proposal, please contact the NPRI.

1.Summary of Proposed Modification

Environment Canada is proposing to add thallium (and its compounds) to the NPRI Substance List at an alternate threshold of 100 kg manufactured, processed or otherwise used (MPO), and with a concentration threshold of 1%, commencing with the 2014 reporting year.


Addition to NPRI Substance List

Thallium meets the NPRI decision factors for addition to the NPRI Substance List.

1) Does the substance meet the NPRI substance criteria?

i) Is the substance MPO in in Canada?

Thallium is primarily MPO in Canada as a by-product released by industries such coal-fired power plants.

ii) Is the substance of health and/or environmental concern?

The scientific literature suggests that thallium is one of the more toxic metals, with adverse effects on living organisms comparable to those of mercury and lead. As a result, it is listed on the U.S. Toxic Release Inventory. According to the North American Commission for Environmental Cooperation, thallium is considered one of the 25 substances with the highest Toxic Equivalency Potentials (TEPs). TEPs provide a chemical ranking system by quantifying the human risk linked with one unit of release of a given pollutant compared to that of a reference chemical (i.e., benzene for carcinogens and toluene for non-carcinogens).

iii) Is the substance released to the Canadian environment?

The major industrial emitters of thallium are coal burning power plants, metal smelters, mines, and cement manufacturers using coal as fuel.

iv) Is the substance present in the Canadian environment?

Thallium is a naturally occurring element in the earth’s crust and is therefore naturally present in the Canadian environment at low levels. However, concentrations of thallium in certain parts of the environment can be elevated due to anthropogenic activities and releases.

2. Do facilities contribute significant releases of the substance?

In Canada, thallium has been detected in elevated concentrations in bodies of water and sediments in close proximity to industrial facilities releasing thallium.

3. Does inclusion of the substance support one or more of the objectives of NPRI?

Inclusion of thallium supports several of the objectives of the NPRI, namely to: encourage voluntary action to reduce releases, allow tracking of progress in reducing releases, improve public understanding and identify priorities for action.

4. Is the substance reported elsewhere?

Thallium is not reported elsewhere in Canada in a consistent and accessible manner.

5. Is the substance already on the NPRI in some form?

Thallium is not on the NPRI in any form.

Alternate Threshold

Based upon the data available to Environment Canada, an alternate mass threshold of 100 kg is recommended as this would provide adequate coverage of the major industrial releasing facilities. Also, the Canadian Council of Ministers of the Environment (CCME) Canadian Water Quality Guidelines for the Protection of Aquatic LifeFootnote 1 for Thallium (Aquatic, Freshwater) is 0.8 µg/L which is comparable to that of the following toxic heavy metals which are also listed on the NPRI at a reduced threshold: arsenic (5.0 µg/L), mercury (0.1 µg/L), and lead (1 to 7 µg/L). Thallium (and its compounds) be would be reported in kilograms.

3. Proposed Timing for the Change

Environment Canada is proposing for this change to be implemented as of the 2014 reporting year. Environment Canada first proposed to add thallium to the NPRI substance list in 2003Footnote 2 . After consulting with the NPRI Multi-Stakeholder Work Group (MSWG) a consensus was reached to add thallium (and its compounds)Footnote 3 . However, consensus could not be reached on determining an appropriate reporting threshold. Environment Canada and the NPRI MSWG agreed to reopen the proposal to add thallium after the MSWG completed their discussion on a Draft Framework for Listing of Substances at an Alternate Threshold in the National Pollutant Release Inventory.

4.Industrial Sectors Affected

Thallium is primarily released as a by-product by the following sectors:

  • Coal-fired power plants;
  • Metal mines;
  • Metal smelters;
  • Cement manufacturers using coal as fuel;
  • Lime manufacturers;
  • Steel coke production; and
  • Waste treatment and disposal.

Thallium can also be intentionally MPO, mainly in the semiconductor industry to fabricate electronics, switches and closures and in creating specialized electronic research equipment.

With the addition of thallium at a reduced threshold, it is expected that facilities from the sectors above may be required to submit an NPRI report for thallium from 2014 onwards (the proportion of facilities that are expected to meet the threshold varies from sector to sector). It is expected that most of the facilities that would be required to report for thallium are already reporting to the NPRI for one or more other substances.

B) Summary of Stakeholder Comments and Environment Canada's Response (July 2014)

The NPRI Multi-Stakeholder WG provided input on Environment Canada’s proposal to add thallium (and its compounds) at an alternate mass reporting threshold.  After considering stakeholder input, thallium (and its compounds) has been added at a mass threshold of 100 kg manufactured, processed or otherwise used instead of the standard mass threshold of 10 tonnes MPO. The concentration threshold is 1% by weight. Thallium (and its compounds) is listed as a Part 1B NPRI substance commencing with the 2014 reporting year.

The table below summarizes comments received from the Multi-Stakeholder WG and provides Environment Canada’s responses.

Comments were received from the following stakeholders:

  • Canadian Association of Petroleum Producers
  • Canadian Energy Partnership for Environmental Innovation and Canadian Gas Association (joint comment)
  • Canadian Environnemental Law Association
  • Canadian Vehicle Manufacturers’ Association
  • Cement Association of Canada
  • Chemistry Industry Association of Canada and Canadian Fuels Association (joint comment)
  • International Institute of Concern for Public Health and Citizens’ Network on Waste Management (joint comment)
Table 1. Summary of Stakeholder Comments and Environment Canada's Response
No./TopicStakeholder CommentEnvironment Canada’s Response
1. SupportThe addition of thallium (and its compounds) to the NPRI Substance List at the proposed threshold is supported.Support for the change proposal by Environment Canada is acknowledged. No response is required.
2. Threshold Level Selected The addition of thallium (and its compounds) to the NPRI Substance List is supported.  However, mass and concentration reporting thresholds of 5 kg manufactured, processed and otherwise used, and 0.1% by weight, are recommended. These suggested thresholds would be similar to those of other toxic metals listed on the NPRI.

Based on the analysis conducted to estimate coverage of reporting at different thresholds, the key sources of releases will be captured at a mass threshold of 100 kg. Additional information received after the publication of the initial proposal suggests than many of the cement manufacturing facilities will also be required to report at a 100 kg threshold. Implementing a threshold lower than 100 kg will not result in significantly more reporting from the key sources, but may result in additional reporting burden on other smaller sources.

A threshold similar to that of other metals would not be appropriate at this time. Thallium compounds have yet to be assessed to determine if they meet the criteria for toxic substances outlined in section 64 of the Canadian Environmental Protection Act, 1999 (CEPA 1999). The other metals which are listed with mass thresholds below 100 kg have already been assessed and were added to Schedule 1 of CEPA 1999 (i.e., the List of Toxic Substances). The reporting threshold for thallium (and its compounds) can be re-evaluated following its risk assessment under the Chemicals Management Plan, depending on the result of the assessment.

A concentration threshold of 1% is aligned with Material Safety Data Sheet ingredient disclosure requirementsfor thallium compounds. This concentration threshold will apply to intentional manufacture, processing or other use of thallium (and its compounds). Since the majority of thallium compounds are expected to be manufactured, processed or otherwise used incidentally (i.e., as by-products), the concentration threshold will not apply and thallium will need to be considered in threshold calculations regardless of concentration. Therefore, the 1% concentration threshold is not expected to be a barrier to achieving good reporting coverage.

3. TimingThe tentative publication of March 2014 for the 2014-2015 NPRI Canada Gazette Notice containing this reporting change is too late. Facilities require sufficient time to implement appropriate methodologies and field sampling/analysis to support accurate estimate of release quantities.

Environment Canada feels that it is important to proceed with this change for the 2014 reporting year in order to prevent further delay in reporting on this substance of concern.   

Environment Canada recognizes that the publication of notices for the NPRI should occur as early as possible. However, under CEPA 1999, NPRI reporting is based on information in the possession of the facility or that can be reasonably accessed. If a facility genuinely has little or no information on this substance, they would be required to report only the information that they do have for 2014, and should take reasonable steps to gather the full required information for future years.


Footnote 1

Canadian Environmental Quality Guidelines provide nationally endorsed science-based goals for the quality of atmospheric, aquatic, and terrestrial ecosystems.
Available at:

Return to footnote 1

Footnote 2

Environment Canada, EC Proposal for the Addition of Thallium at an Alternate Threshold (2003).
Available at:

Return to footnote 2

Footnote 3

NPRI MSWG Response to Proposed Addition of Thallium (2003).
Available at:

Return to footnote3

Date modified: