Proposed Re-evaluation Decision PRVD2022-12, Silica Aerogel and Silicon Dioxide and Its Associated End-use Products

Pest Management Regulatory Agency
June 16, 2022
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2022-12E-PDF (PDF version)

Table of contents

• Proposed re-evaluation decision
• Risk mitigation measures
• Next steps
• Other information
• Additional scientific information

Proposed re-evaluation decision

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

This document (PRVD2022-12, Silica Aerogel and Silicon Dioxide and Its Associated End-use Products) presents the proposed regulatory decision for the re-evaluation of silica aerogel and silicon dioxide, including the science evaluation on which the proposed decision is based.

Silicon dioxide and its amorphous form, silica aerogel are non-conventional and non-selective insecticides, acaricides and molluscicides. These active ingredients have a physical mode of action (MOA) that kill arthropod and terrestrial mollusc pests. Silicon dioxide and silica aerogel are used both inside and outside at commercial buildings, storage structures, agriculture structures, schools, hospitals, transport containers, modes of transportation, food processing plants, as well as stored food and feed grains. Silicon dioxide is also registered for commercial greenhouse uses on tomatoes, cucumber, peppers, indoor plants and cannabis. Furthermore, silicon dioxide has registered domestic uses, which include, points of entries, general outdoor and garden areas, home structures, animal burrows, and indoors where insects crawl and hide, such as, furniture, mattresses, and sleeping quarters for pets. The end-use products are formulated as dust/powder, bait, wettable powder or as pressurized spray to be applied by hand, various dusters/spreaders, or trigger spray. Currently registered products containing silica aerogel and silicon dioxide are listed in Appendix I of PRVD2022-12.

Silicon dioxide and silica aerogel are found naturally in soil with a low potential for resistance due to its physical MOA. Due to its low toxicity profile and its history of use as a food/feed additive, dietary risk to silicon dioxide and silica aerogel is not anticipated. There is potential for occupational, residential, and bystander exposure from registered commercial and residential uses. Label statements (for all uses except greenhouse use), including updates to personal protection equipment (PPE), restricted-entry interval, clarifying label use directions and precautionary statements in accordance to the PMRA Guidance Document, Structural Pest Control Products: Label Updates (SPCP Guidance Document) are being proposed to further mitigate potential human health risks. To support the label update process, registrants are required to provide detailed use information. The potential environmental risk is considered acceptable when products containing silicon dioxide and silica aerogel are used according to the current label directions. Thus, products containing silicon dioxide and silica aerogel are considered to be acceptable with the proposed label updates (Appendix II of PRVD2022-12).

Under the authority of the Pest Control Products Act and based on an evaluation of currently available scientific information, products containing silicon dioxide and silica aerogel (Appendix I of PRVD2022-12) are being proposed for continued registration in Canada, with the proposed updates to label statements. Additional label updates will be required in the final decision document based on the use information provided by the registrants.

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 proposed label updates as a result of the re-evaluation of products containing silicon dioxide and silica aerogel are summarized below:

• Update PPE for all commercial products.
• Add precautionary statements in accordance to the Structural Pest Control Products: Label Updates document for commercial and domestic structural pest control products (SPCP) applications.
• Update restricted-entry interval (REI) for all commercial products with structural uses.
• Improve clarity on use directions.
• Registrants, as part of the label updates resulting from re-evaluation, will be required to include relevant updates in accordance to the Structural Pest Control Products: Label Updates document for both domestic and commercial marketing class SPCPs to limit bystander and residential exposure for humans and pets.

All products containing silicon dioxide and silica aerogel registered in Canada are subject to this proposed re-evaluation decision. This document is subject to a public consultation,^{Footnote 1} during which written comments and additional information may be submitted to PMRA Publications. The final re-evaluation decision will be published taking into consideration the comments and information received during the consultation period.

Next steps

The public, including the registrants and stakeholders, are encouraged to submit written comments and additional information during the 90-day public consultation period upon publication of this proposed re-evaluation decision.

All comments received during the 90-day public consultation period will be taken into consideration in preparation of the re-evaluation decision document,^{Footnote 2} which could result in revised risk mitigation measures. The re-evaluation decision document will include the final re-evaluation decision, the reasons for it and a summary of comments received on the proposed re-evaluation decision with Health Canada's responses.

Other information

When Health Canada makes its re-evaluation decision, it will publish a Re-evaluation Decision on silicon dioxide and silica aerogel (based on the Science evaluation of PRVD2022-12). In addition, the test data referenced in this consultation document will be available for public inspection, upon application, in the PMRA's Reading Room.

Additional scientific information

In order to update and improve the clarity on current product labels, Health Canada has requested registrants to submit Use Information.