Proposed Re-evaluation Decision PRVD2018-09, Dazomet and Its Associated End-use Products

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Pest Management Regulatory Agency
22 March 2018
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2018-9E-PDF (PDF version)

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Table of Contents

Proposed Re-evaluation Decision

Under the authority of the Pest Control Products Act, all registered pesticides must be regularly re-evaluated by Health Canada’s Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet current health and environmental safety standards and continue to have value. The re-evaluation considers data and information from pesticide manufacturers, published scientific reports, and other regulatory agencies. The PMRA applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Dazomet is a non-selective pre-plant soil fumigant used to control pathogens including insects, nematodes, bacteria, fungi and weeds in soil. This active ingredient is also used as a material preservative in water-based materials and suspensions (for example, clay slurries, adhesives, coatings, paint and concrete admixtures) and as a slimicide in industrial process fluids (that is, pulp and paper mills, recirculating water cooling towers and industrial air washers, oilfield industry and cutting fluid).

This proposed re-evaluation decision (Proposed Re-evaluation Decision PRVD2018-09, Dazomet and Its Associated End-use Products) follows risk reduction measures implemented in 2012 for dazomet to limit user exposure, and to further protect the environment (Re-evaluation Notes REV2012-07, Chloropicrin, Dazomet, Metam Sodium and Metam Potassium Label Improvements for Antimicrobial Products, REV2012-08, Chloropicrin, Dazomet, Metam Sodium and Metam Potassium Label Improvements for Soil Fumigant Products and REV2012-10, Label Amendments for Soil Fumigant Products Containing Dazomet).

The soil fumigation and industrial process fluid uses of dazomet have been re-evaluated based on the health and environmental risk assessments published in the USEPA Reregistration Eligibility Decision (RED)Footnote 1 (2008) and the amended REDFootnote 2 (2009) documents. Additional risk assessments were conducted by the PMRA where deemed necessary. The material preservative uses of dazomet are not included in PRVD2018-09. The PMRA plans to publish a document in the future providing a broader examination of the pesticides registered for the preservation of materials (such as paint, coatings, clay slurries, adhesives and concrete), including products containing dazomet. In addition, the use of dazomet for the preservation of cutting fluid is no longer supported by the registrants. Therefore, this use was not included in the current risk assessment and will be removed from the end-use product labels.

This document (PRVD2018-09) presents the proposed regulatory decision for the re-evaluation of the soil fumigation and industrial process fluid uses of dazomet including the proposed risk mitigation measures to further protect human health and the environment, as well as the science evaluation on which the proposed decision was based. All products containing dazomet registered in Canada for soil fumigation or use in industrial process fluids are subject to this proposed re-evaluation decision.

PRVD2018-09 is subject to a 90-day public consultation period, during which the public including the pesticide manufacturers and stakeholders may submit written comments and additional information to the PMRA Publications Section. The final re-evaluation decision will be published taking into consideration the comments and information received.

Outcome of Science Evaluation

Upon application, dazomet is broken down into several degradates; the primary being methyl isothiocyanate (MITC), which accounts for most of the pesticidal properties. Dazomet has value as a pre-plant soil fumigant for the control of soil pests and pathogens in Canada, which can disrupt plant growth and production. Dazomet also has value as an antimicrobial agent for control of microbial activity in industrial process fluids (that is, pulp and paper mills, recirculating water cooling towers and industrial air washers and oilfield industry).

Additional risk-reduction measures and label updates are proposed for all end-use products containing dazomet registered for soil fumigation or use in industrial process fluids to further mitigate risk to workers. Occupational risks are not expected to be of concern when products containing dazomet are used according to the proposed label directions.

Dazomet is not registered for residential use in Canada. Risk from bystander exposure is not expected to be of concern when products containing dazomet are used according to the proposed label directions.

Risk from dietary exposure is not of concern when products containing dazomet are used for soil fumigation and in industrial process fluids under the current conditions of use.

With respect to the environment, dazomet enters the environment when applied for soil fumigation. Environmental exposure from some industrial process fluid uses is expected to be minimal under the current conditions of use; however, there may be exposure to the environment from other industrial processes, such as in oilfields.

Currently registered labels include the risk reduction measures required to minimize potential exposure to non-target organisms. When used according to the current label directions, dazomet is not expected to pose risks of concern to the environment. No additional risk reduction measures are proposed. However, minor label amendments are proposed to meet current labelling standards.

Proposed Regulatory Decision for Dazomet

Under the authority of the Pest Control Products Act, and based on the evaluation of currently available scientific information, Health Canada is proposing that products containing dazomet registered for soil fumigation or use in industrial process fluids are acceptable for continued registration for use and sale in Canada, provided that the proposed risk mitigation measures and label amendments are in place.

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment that must be followed by law.

As a result of the re-evaluation of dazomet, further risk mitigation measures and label updates are being proposed for the end-use products containing dazomet registered for soil fumigation or use in industrial process fluids, including:

  • Hazard label statements for all product labels.
  • Additional personal protective equipment for workers handling dazomet for use in water cooling systems and air washers.
  • Closed delivery system for liquid formulations used in industrial process fluids.
  • Precautionary statements regarding the need for adequate ventilation in enclosed facilities for the pulp and paper uses.

Details of the proposed label amendments are presented in Appendix III of PRVD2018-09.

International Context

Dazomet is currently acceptable for use in other Organisation for Economic Co-operation and Development (OECD) member countries, including Australia, the European Union and the United States. As of 31 October 2017, no decisions by any OECD member country to prohibit all uses of dazomet for health or environmental reasons have been identified.

Next Steps

Before making a final re-evaluation decision on dazomet, the PMRA will consider all comments received from the public in response to PRVD2018-09. A science-based approach will be applied in making a final decision on dazomet. The PMRA will then publish a Re-evaluation DecisionFootnote 3 that will include the decision, the reasons for it, a summary of comments received on the proposed decision and the PMRA’s response to these comments.

Additional Scientific Information

No additional data is required.

Footnotes

Footnote 1

United States, 2008c

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Footnote 2

United States, 2009a

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Footnote 3

“Decision statement” as required by subsection 28(5) of the Pest Control Products Act.

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