Thiocarbamates Group - information sheet

Thioperoxydicarbonic diamide ([(H₂N)C(S)]₂S₂), tetramethyl- (TMTD, also referred to as Thiram)
CAS Registry Number 137-26-8

Piperidine, 1, 1'-(tetrathiodicarbonothioyl)bis- (DPTT)
CAS Registry Number 120-54-7

Publications summarized:

Final Assessment for the Thiocarbamates Group (published on January 9, 2021). Public comments received on the draft assessment and risk management scope were considered and a summary of the comments with Government responses was published.
Risk Management Approach for TMTD (published on January 9, 2021 for a 60-day public comment period).
Associated notice: Canada Gazette, Part I, Vol. 155, No. 2.

Overview

The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA) to determine whether they present or may present a risk to human health or to the environment.
- The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent that people or the environment are exposed.
- When needed, the Government applies risk management instruments under CEPA and other federal acts to help prevent or reduce potential harm.
The Government concluded that TMTD is harmful to the environment, but not to human health, based on exposures from non-pesticidal uses considered in the assessment. Risk management actions were proposed to help address the ecological concerns.
Although TMTD is associated with human health effects of concern, the risk is considered low at levels of exposure considered in the assessment. It was also concluded that DPTT is not harmful to human health or to the environment, as the risk posed by this substance is low at levels of exposure considered in the assessment.

About these substances

The assessment focused on 2 substances: thioperoxydicarbonic diamide ([(H2N)C(S)]2S2), tetramethyl- and piperidine, 1,1'-(tetrathiodicarbonothioyl)bis-, also referred to as TMTD (or thiram) and DPTT, respectively. They were assessed under the Chemicals Management Plan (CMP) as the Thiocarbamates Group .
According to information gathered by the Government, TMTD and DPTT are industrial chemicals that do not occur naturally in the environment.
According to the assessment, in Canada, TMTD is primarily used as a process regulator (accelerator and curing agent) in the manufacture of solid rubber products. It is used as a component in automotive parts, in sealants and adhesives, and it may be used as a component in the manufacture of a limited number of food packaging materials.
TMTD is also registered as an active ingredient in pest control products in Canada, under the name thiram. Health Canada's Pest Management Regulatory Agency (PMRA) final re-evaluation decision for thiram included a risk assessment and risk mitigation measures to protect human health and the environment from pesticidal uses of TMTD, under the authority of the Pest Control Products Act. Therefore, exposures to TMTD resulting from pesticidal sources and uses of thiram are not characterized further in the assessment summarized here.
In Canada, DPTT is only used in the manufacture of rubber products.

Human and ecological exposures

Exposure of people in Canada to TMTD from products available to consumers (for example, rubber products, adhesive tape products, automotive parts), or from food packaging materials, is minimal or not expected.
The human health risk of DPTT was characterized using the Threshold of Toxicological Concern (TTC)-based Approach for Certain Substances. The estimate of exposure generated for DPTT was lower than the TTC value, indicating low concern to human health on the basis of current levels of exposure.
TMTD and DPTT have the potential to be released to the environment through discharges from wastewater treatment systems associated with manufacturing facilities for solid rubber products. Such releases are likely to result in exposure to aquatic organisms near points of release.

Key health and ecological effects (hazard)

To identify human health and ecological effects information, national and international reports on TMTD were reviewed and used to inform the assessment. This includes the PMRA's review of thiram as well as reviews of TMTD internationally through the Organisation for Economic Cooperation and Development and the European Chemicals Agency, among others.
The health effects of concern identified for TMTD include developmental neurotoxicity (potential effects on the developing nervous system) and carcinogenicity (potential to cause cancer).
Data based on observations suggest that TMTD is highly toxic to aquatic organisms.
There were limited ecological effects (hazard) data for DPTT; therefore, a comparative approach using a similar chemical, called read-across, was used to inform the ecological assessment. Based on the read-across data, DPTT is not expected to demonstrate any effect on aquatic organisms at water solubility limits.

Risk assessment outcomes

Using the Threshold of Toxicological Concern (TTC)-based Approach for Certain Substances, DPTT is considered to be a low concern for human health at levels of exposure current at the time of the assessment.
Considering all the information presented in the assessment, there is a low risk of harm to the environment from DPTT.
Based on the information presented in the assessment, the risk to human health from non-pesticidal uses of TMTD is low.
Although TMTD is not expected to remain in the environment for a long time or to accumulate in organisms, it is highly toxic to aquatic organisms. Exposure associated with uses of this substance considered in the assessment poses a risk of harm to the environment.

Assessment conclusions

The Government concluded that TMTD is not harmful to human health at levels of exposure considered in the assessment.
However, the Government concluded that TMTD is entering or may enter the environment at levels that are harmful, from its uses in the manufacture of rubber products.
The Government also concluded that DPTT is not harmful to human health at levels of exposure considered in the assessment and is not entering the environment at levels that are harmful.

Preventive actions and risk reduction

The proposed order adding TMTD to Part 2 of Schedule 1 to CEPA was published for a 60-day public comment period ending on December 7, 2022. Adding a substance to Schedule 1 does not, in itself, restrict its use, manufacture or import. Rather, it enables the Government to take risk management actions under CEPA.
- Toxic substances that pose the highest risk (that is, meet certain criteria) are added to Part 1 of Schedule 1. These are prioritized for total, partial or conditional prohibition.
- Other toxic substances are added to Part 2 of Schedule 1 and are prioritized for pollution prevention actions, which may include prohibition.
The Risk management approach for Thioperoxydicarbonic diamide, tetramethyl- (TMTD) in the Thiocarbamates Group was published on January 9, 2021. The following risk management actions were taken to address ecological concerns:
- On April 4, 2026, the Release Guidelines for Chemicals Used in the Rubber Product Manufacturing Sector (Guidelines) were published in the Canada Gazette, Part I. The substances included in the Guidelines are TMTD and BENPAT (CAS RN 68953-84-4). These Guidelines incorporate the Code of Practice for the Environmentally Sound Management of Chemical Substances in the Chemicals, Plastics and Rubber Sectors that was published on February 4, 2023.
Additionally, the Government published an order to apply the Significant New Activity (SNAc) provisions of CEPA to TMTD on October 21, 2026.
- This requires that the Government be notified of certain proposed new activities related to TMTD, and that the new activity be assessed for potential risks to human health and the environment before being undertaken.
- The order outlines the proposed definition of a significant new activity in relation to TMTD, as well as the information that would need to be provided to the Government for assessment before the new activity is undertaken.
Risk management actions may evolve through consideration of assessments and risk management actions published for other substances. This is to ensure effective, coordinated, and consistent risk management decision-making.

Additional considerations

Although TMTD is not considered to be harmful to human health at levels of exposure from non-pesticidal uses at the time of the assessment, this substance is recognized as having potential health effects of concern (developmental neur otoxicity and potential to cause cancer). Therefore, there may be a potential risk if exposures were to increase. For this reason, additional tracking of TMTD for changes in exposure are being considered.

Where to find updates on risk management actions

Updates on actions can be found on the timeline for the Thiocarbamates Group.
Up-to-date information on environmental release guidelines as well as additional information on the risk management of substances and a table of risk management actions for substances addressed under the CMP is available.
Also, information about SNAc provisions applied to substances, including new notices and orders and those already published, can be found in the SNAc publications dataset.
Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.

Related resources

Assessments conducted under CEPA focus on risks of exposure of the general population. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). If a substance is harmful to the general population, it could also be of concern for individuals in situations where a higher volume of the substance is used or where the substance is used for a longer duration (for example, the workplace). The Government of Canada recognises that it is the responsibility of the federal, provincial and territorial occupational health and safety organizations to coordinate legislation for the safe use of chemicals in the workplace. We are working to support this role by integrating the information, tools, and/or technical expertise of the CMP and Health Canada’s Workplace Hazardous Products Program.

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2026-10-21