Special Review Decision SRD2022-03, Special Review Decision: Diodofon and Its Associated End-use Products

Pest Management Regulatory Agency
8 December 2022
ISSN: 2561-6269 (PDF version)
Catalogue number: H113-17/2022-3E-PDF (PDF version)

Summary

Table of contents

• Special Review Decision for Diodofon and Associated End-use Products
• Special review decision for diodofon
• Risk mitigation measures
• Next steps
• Other information
• Legislative Framework
• Appendix I - Registered products containing diodofon in Canada as of 8 September 2022

Special Review Decision for Diodofon and Associated End-use Products

Under the authority of the Pest Control Products Act, pesticides are regulated by Health Canada's Pest Management Regulatory Agency (PMRA) on behalf of the Minister of Health. The Pest Control Products Act prescribes both the pre-market and post-market assessment (re-evaluations and special reviews) of pesticides to determine the acceptability or continued acceptability of human health and environmental risks, and, acceptable value of a pesticide in Canada. Unlike a re-evaluation, a special review is triggered only under certain circumstances, as described in section 17 of the Pest Control Products Act, and the intent of a special review is to specifically address the identified aspect(s) of concern. The special review approach is described in the PMRA Guidance Document: Approach to Special Reviews of Pesticides.^{Footnote 1} More details on the legislative framework are provided under the section Legislative Framework of this document.

Health Canada evaluates the aspects of concern that prompted the special review in accordance with subsection 18(4) of the Pest Control Products Act. The internationally accepted science-based approach is used for the assessment of the aspect(s) of concern, similar to all other scientific assessments (for example, new product registrations, re-evaluations). This step includes both risk (or value, if applicable) assessments and risk management to address the concerns identified. Health Canada's approach to risk and value assessments as well as risk management is outlined in the Framework for Risk Assessment and Risk Management of Pest Control Products.^{Footnote 2}

Pursuant to subsection 17(1) of the Pest Control Products Act, Health Canada conducted a special review of all registered pest control products containing diodofon, based on the toxicology and exposure information submitted under section 12 of the Pest Control Products Act, following the re-evaluation of diodofon (RVD2010-13). The identified aspects of concern for this special review are potential risks to workers using products containing diodofon and were assessed as per subsection 18(4) of the Pest Control Products Act.

Diodofon is an antimicrobial active ingredient used as a material preservative in a variety of aqueous based products and building materials (for example, pigment dispersions, caulks and adhesives (ceramic tile adhesives, vinyl wallpaper pastes), wallboard joint compound, mastics, and latex exterior and interior paints) to provide protection against bacterial and fungal degradation of the finalized products. It is also used in leather tanning to protect tanned leather from mould and mildew during in-tanning wet processing and during storage and transportation. All currently registered pest control products containing diodofon (Appendix I) are considered in this special review.

This document (Special Review Decision SRD2022-03, Special Review Decision: Diodofon and Its Associated End-use Products) presents the final regulatory decision^{Footnote 3} for the special review of diodofon. All pest control products containing diodofon that are registered in Canada are subject to this special review decision. Prior to finalizing this decision, Health Canada published the Proposed Special Review Decision PSRD2020-01, Special Review of Diodofon and Its Associated End-use Products^{Footnote 4} on 9 July 2020 for a 90-day consultation period. An additional 60 days for consultation was provided in response to requests from stakeholders to accommodate time constraints imposed by pandemic measures; the 150-day consultation period ended on 6 December 2020.

Comments were received during the public consultation period conducted in accordance with section 28 of the Pest Control Products Act. Commenters are listed in Appendix II of SRD2022-03. These comments are summarized in Appendix III of the SRD2022-03 with the responses from Health Canada. The comments were considered and did not result in a change to the risk assessments in PSRD2020-01. Therefore, the decision in SRD2022-03 is consistent with the proposed special review decision as described in PSRD2020-01.

A reference list of information used as the basis for the proposed special review decision is included in PSRD2020-01; no further information was used in the final special review decision. Therefore, the complete reference list of all information used in this final special review decision is set out in PSRD2020-01.

Special review decision for diodofon

Health Canada has completed the special review for diodofon. Under the authority of the Pest Control Products Act, Health Canada has determined that continued registration of some uses of diodofon are acceptable with additional risk mitigation measures. The assessments of the aspects of concern from this special review indicated that the risks to human health from the use of diodofon as a material preservative for interior paint and all building material uses, except wallboard joint compounds, are shown to be acceptable provided that the label amendments, as summarized below and listed in Appendix IV of SRD2022-03, are implemented. Environmental exposure from the registered use of diodofon is expected to be minimal.

The assessments of the aspects of concern from this special review indicated that the risk to human health from the uses of diodofon in exterior paints, wallboard joint compounds and leather tanning were not shown to be acceptable; therefore, these uses are cancelled.

Risk mitigation measures

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment and must be followed by law. The required amendments, including any revised/updated label statements and/or mitigation measures, as a result of the special review of diodofon, are summarized below. Refer to Appendix IV of SRD2022-03 for details.

Risk mitigation

To mitigate risks to individuals using diodofon as a material preservative or handling diodofon-treated products:

For primary handlers (mixers/loaders) working in manufacturing facilities:

• Require closed transfer systems for liquid formulations
• Require additional personal protective equipment (chemical-resistant coveralls and a respirator) for solid formulations and a reduction in the maximum amount of product handled per person per day to 1.045 kg a.i./person/day

For secondary professional handlers applying interior paints using an airless sprayer:

• Require additional protective equipment (cotton coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, a painter's hat, and a respirator with a NIOSH-approved organic-vapour-removing cartridge with a prefilter approved for pesticides, or a NIOSH-approved canister approved for pesticides)

For secondary handlers (professional and residential):

• Reduction of the maximum application rate for uses in building materials (except caulks and mastics) to 0.391 g a.i./kg product and to 0.50 g a.i./kg product for caulks and mastics
• Cancel the use of diodofon in wallboard joint compound
• Cancel the use of diodofon in exterior paints
• Cancel the use of diodofon in leather tanning

Implementation of product stewardship/outreach plan for paint use.

Next steps

Pest control products requiring label amendments

To comply with this decision, the required amendments (Appendix IV of SRD2022-03) must be implemented no later than 24 months after the publication date of the SRD2022-03. Accordingly, both registrants and retailers will have up to 24 months from the date of the SRD2022-03 to transition to selling the product with the newly amended labels. Similarly, users will also have the same 24-month period from the date of the SRD2022-03 to transition to using the newly amended labels, which will be available on the Public Registry. This 24-month period also applies to the requirement that manufactured paint products containing the preservative diodofon must be labelled with the stipulation that professional painters wear personal protective equipment when using an airless sprayer (refer to Appendix IV of the SRD2022-03).

Health Canada has determined that the identified risks from the use of diodofon as a material preservative under the current conditions of use were from longer-term exposure durations and therefore, the potential risks to human health are considered acceptable during the 24-month time period required to implement the required mitigation measures.

Cancelled product and leather use

To comply with the decision of SRD2022-03, one commercial product, Amical WP (Reg. No. 22910), which is only registered for leather tanning use is cancelled (as of the date of publication) pursuant to paragraph 20(1)(b) of the Pest control Products Act. Where risks of concern are not considered imminent and serious, existing stocks of the cancelled product are phased out in Canada following a general timeline of three (3) years from the publication date of the decision and following a sequential timeline provided for each level of the supply chain (in other words, at registrant, retail/distribution, and user levels). Health Canada has determined that the identified risks of concern from the use of diodofon in leather tanning under the current conditions of use are not expected to be serious or imminent over the three-year phase-out period, as risks of concern were from long-term exposure durations. Therefore, continued possession, handling, storage and use of existing stock in Canada of Amical WP (Reg. No. 22910) will be authorized under paragraph 21(5)(a) of the Pest Control Products Act as per the schedule below:

• Authorized for sale (of existing stocks in Canada) by registrant one (1) year from the date of decision, followed by;
• Authorized for sale by retailer/distributor (if applicable) one (1) year from the last date of sale by registrant, followed by;
• Authorized for use one (1) year from the last date of sale by retailer/distributor.

During the phase-out period, import or manufacture in Canada of PCP22910 is prohibited. In addition, the registrant is required to continue to comply with sales and incident reporting obligations during the phase-out period.

Diodofon-treated articles

Information Note – Treated Articles^{Footnote 5} (September 2022) provides regulatory requirements for articles that have been treated with pesticides.

• Building materials treated with diodofon (except wallboard joint compounds):
  The import and sale of products treated with diodofon at the unamended label rates is permitted during the 24-month implementation period. However, after 24 months, the import and sale of products treated at the unamended label rate will be prohibited; all products sold after 24 months must be treated at the new label rate.
• Interior paints treated with diodofon:
  The import and sale of diodofon-treated interior paint without PPE requirements on the paint labels is permitted during the 24-month implementation period. However, after 24 months, the import or sale of interior paint without the requirement for PPE (for professional painters using airless sprayers) on the label will be prohibited.
• Wallboard joint compounds treated with diodofon:
  The import and sale of wallboard joint compound and exterior paints treated with diodofon is permitted during the 24-month implementation period. However, after 24 months, the import and sale of diodofon-treated wallboard joint compound and exterior paints will be prohibited.
• Leather products treated with diodofon:
  During the three-year phase-out period, the import of leather treated with diodofon into Canada is permitted. After 3 years from the publication date of the decision document, the import of diodofon-treated leather will be prohibited.

Refer to Appendix I and Appendix IV of SRD2022-03 for details on specific products impacted by this decision.

Product stewardship/outreach plan

The product stewardship/outreach plan is intended to inform professional painters of the requirement for additional personal protective equipment (coveralls, chemical-resistant gloves, painter's hat and respirator) to mitigate risks when applying paint using airless sprayers. The plan will also have the general goal of increasing awareness of the presence of pesticide preservatives in paint and how to reduce health risks for painters. Health Canada is creating communication materials for this outreach program.

Registrants are required to notify paint manufacturers of the new paint labelling requirements related to PPE for professional painters using an airless sprayer. Paint manufacturers are required to directly label paint cans with the required label statements.

Other information

Any person may file a notice of objection^{Footnote 6} regarding this decision on diodofon within 60 days from the date of publication of SRD2022-03. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the Pesticides and Pest Management portion of the Canada.ca website (Request a Reconsideration of Decision) or Health Canada's Pest Management Information Service.

The relevant confidential test data on which the decision is based (as referenced in PSRD2020-01) are available for public inspection, upon application, in PMRA's Reading Room. For more information, please contact Health Canada's Pest Management Information Service.

Legislative Framework

The Minister of Health's primary objective under the Pest Control Products Act (or the Act) subsection 4(1) is to prevent unacceptable risks to individuals and the environment from the use of pest control products.

As noted in the preamble of the Act, it is in the national interest that the attainment of the objectives of the federal regulatory system continue to be pursued through a scientifically-based national registration system that addresses risks to human health, the environment and value both before and after registration and applies to the regulation of pest control products throughout Canada; and that pest control products with acceptable risk and value be registered for use only if it is shown that their use would be efficacious and if conditions of registration can be established to prevent unacceptable risks to human health and the environment.

For the purposes of the Act, the health or environmental risks of a pest control product are acceptable if there is reasonable certainty that no harm to human health, future generations or the environment will result from exposure to or use of the product, taking into account its conditions of registration as per subsection 2(2) of the Pest Control Products Act.

Risk for the human health and environment, and value are defined under the Act subsection 2(1) as follows:

• health risk, in respect of a pest control product, means the possibility of harm to human health resulting from exposure to or use of the product, taking into account its conditions or proposed conditions of registration.
• environmental risk, in respect of a pest control product, means the possibility of harm to the environment, including its biological diversity, resulting from exposure to or use of the product, taking into account its conditions or proposed conditions of registration
• value, in respect of a pest control product, means the product's actual or potential contribution to pest management, taking into account its conditions or proposed conditions of registration, and includes the product's (a) efficacy; (b) effect on host organisms in connection with which it is intended to be used; and (c) health, safety and environmental benefits and social and economic impact.

When evaluating the health and environmental risks of a pesticide and determining whether those risks are acceptable, subsection 19(2) of the Pest Control Products Act requires Health Canada to apply a scientifically-based approach. The science-based approach to assessing pesticides considers both the toxicity and the level of exposure of a pesticide in order to fully characterize risk. Health Canada's approach to risk and value assessment is outlined in A Framework for Risk Assessment and Risk Management of Pest Control Products.^{Footnote 7}

For this special review on diodofon, the aspects of concern are related to human health.

Appendix I Registered products containing diodofon in Canada as of 8 September 2022