Special Review Decision SRD2021-04, Special Review Decision: Thiamethoxam Risk to Aquatic Invertebrates

Pest Management Regulatory Agency
31 March 2021
ISSN: 2561-6269 (PDF version)
Catalogue number: H113-17/2021-4E-PDF (PDF version)

Summary

Table of contents

• Special review decision
• Outcome of science evaluation
• Regulatory decision for thiamethoxam
• Risk mitigation measures to protect aquatic invertebrates
• Next steps
• Other information
• Appendix I     Registered products containing thiamethoxam in Canada that are subject to this special review decision
• Appendix II   Registered commercial class uses of thiamethoxam in Canada as of 31 July 2020 that are subject to this special review

Special review decision

Pursuant to subsection 17(1) of the Pest Control Products Act, Health Canada’s Pest Management Regulatory Agency (PMRA) conducted a special review of all agricultural, greenhouse and ornamental uses for registered pest control products containing thiamethoxam. The decision to conduct the special review was based on a preliminary analysis of available information on the concentration and frequency of detections of thiamethoxam in the aquatic environment. The aspect of concern for this review is to assess potential risk to aquatic invertebrates exposed to thiamethoxam applied as a seed, foliar or soil treatment.

Health Canada evaluated the aspect of concern that prompted the special review in accordance with subsection 18(4) of the Pest Control Products Act. The proposed special review decision was published for consultation in Proposed Special Review Decision (PSRD2018-02), Special Review of Thiamethoxam Risk to Aquatic Invertebrates: Proposed Decision for Consultation.^{Footnote 1} Since the publication of PSRD2018-02 on 15 August 2018, a significant number of comments were received during the consultation period. In addition, extensive information obtained from published literature, as well as data received from registrants and environmental monitoring networks^{Footnote 2} was also considered.

In addition, during the consultation period, Health Canada issued a final re-evaluation decision examining the effects of thiamethoxam on pollinators Re-evaluation Decision RVD2019-04, Thiamethoxam and Its Associated End-use Products: Pollinator Re-evaluation. Final Decision. This special review decision takes into consideration the additional mitigation measures put in place as a result of the pollinator re-evaluation. Health Canada has completed the special review for thiamethoxam, and this final special review decision has resulted in changes to the proposed regulatory decision as described in PSRD2018-02.

A reference list of information used as the basis for the proposed special review decision is included in PSRD2018-02. Further information used in the special review decision is listed in Appendix IX of Special Review Decision: Thiamethoxam Risk to Aquatic Invertebrates (SRD2021-04). Therefore, the complete reference list of all information used in this final special review decision includes both the information set out in the list of references of the PSRD2018‑02 and the information set out in Appendix IX of SRD2021-04.

This document presents the final regulatory decision^{Footnote 3} for the special review of thiamethoxam, including the required risk mitigation measures to protect aquatic invertebrates. All pest control products containing thiamethoxam that are registered in Canada for agricultural, greenhouse and ornamental uses are subject to this special review decision (see Appendix I). Appendix II lists all of the registered uses of Commercial Class end-use products containing thiamethoxam that were subject to this special review, taking into consideration the required use restrictions identified in RVD2019-04. Appendix III of SRD2021-04 summarizes the comments received during the consultation period and provides Health Canada’s response to these comments. All of the data that were used as the basis for the proposed special review decision are published in PSRD2018‑02. Additional data used in the final special review decision, including data received during the consultation period, are listed in Appendix IV for toxicity information and in Appendix VII of SRD2021-04 for monitoring information.

Under the authority of the Pest Control Products Act, Health Canada has determined that continued registration of products containing thiamethoxam is acceptable with additional risk mitigation measures (that is, with changes to the conditions of registration). An evaluation of available scientific information found that some uses of thiamethoxam products meet current standards for protection of the environment when used according to revised label directions, which include mitigation measures. Certain uses of thiamethoxam are cancelled as risks to aquatic invertebrates were not shown to be acceptable. Label amendments, as summarized below and listed in Appendix VIII of SRD2021-04, are required.

Outcome of science evaluation

The environmental risk assessment took into consideration revisions to thiamethoxam uses as outlined in RVD2019-04, scientific comments received on study interpretations during consultation of PSRD2018-02, newly published relevant toxicity data and additional water monitoring data. Based on these data it was determined that the risks to aquatic invertebrates resulting from chronic exposure following application of thiamethoxam under certain currently registered conditions are acceptable. For uses where the risks were not shown to be acceptable, mitigation measures are required to minimize exposure to aquatic invertebrates which include changes to the use pattern or cancellation in cases when other mitigation options were not considered viable. In addition to the prescribed mitigation measures, label amendments including the addition of best management practices and label statements informing users of the toxicity to aquatic organisms are required. When thiamethoxam is used in accordance with these new risk reduction measures, the reduced environmental exposure is sufficient to address concerns and risks are acceptable.

Regulatory decision for thiamethoxam

Health Canada has completed the special review of thiamethoxam’s risk to aquatic invertebrates. Following an evaluation of the aspect of concern, under the authority of the Pest Control Products Act, Health Canada has determined that, with additional risk mitigation measures, continued registration of products containing thiamethoxam is acceptable. An evaluation of available scientific information found that some uses of thiamethoxam products meet current standards for protection of aquatic invertebrate communities when used according to the revised conditions of registration, which include required amendments to label directions. Label amendments, as summarized below and listed in Appendix VIII of SRD2021-04, are required for all end-use products. Certain uses of thiamethoxam are cancelled as risks to aquatic invertebrates were not shown to be acceptable.

Risk mitigation measures to protect aquatic invertebrates

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 this Special Review Decision, are summarized below. Refer to Appendix VIII of SRD2021-04 (Label Amendments).

In order to protect aquatic invertebrate communities, Health Canada is cancelling the following uses of thiamethoxam:

• Soil drench application on potato.
• Foliar application on lowbush blueberries.

Health Canada is changing the conditions of use of thiamethoxam for the following crops:

• The maximum seed treatment rate for field corn (including seed corn production) is reduced to 200 g a.i./100 kg seed. This will result in the cancellation of the use for planting in Canada for corn rootworm (including for seed corn production). No change is required for popcorn or sweet corn.
• The maximum seed treatment rate for soybean is reduced to 30 g a.i./100 kg seed. This will result in the cancellation of the use for bean leaf beetle, European chafer, soybean aphid, and wireworm.
• The maximum soil drench and in-furrow rate for leafy vegetables is reduced to 90 g a.i./ha. This will result in the cancellation of the use for cabbage looper, beet armyworm, corn earworm and fall armyworm.
• The maximum soil drench and in-furrow rate for brassica vegetables is reduced to 90 g a.i./ha. This will result in the cancellation of the use for dipteran leafminers, cabbage looper, diamondback moth, imported cabbageworm, thrips, beet armyworm, corn earworm, fall armyworm, and yellowstriped armyworm.
• The number of foliar applications is reduced to one per year on dry shelled bean, potato, soybean.
• The number of foliar applications is reduced to one per year for the following vegetables and listed pests: all pests on celeriac and for pepper weevil on peppers. In the case of fruiting vegetables, for stink bug, tarnished plant bug and brown marmorated stink bug the number of applications at the highest application rate (52.5 g a.i./ha) is reduced to one per year.
• The number of foliar applications is reduced to one per year on cranberry. There is also a requirement to hold flood water for 30 days for cranberries that require flooding.
• New or revised spray buffer zones are required for freshwater and terrestrial habitats.

Next steps

To comply with this decision, the required amendments (mitigation measures and label updates) must be implemented on all product labels no later than 24 months after the publication date of this special review decision (SRD2021-04). The risks identified are not considered imminent and serious because they are not expected to cause irreversible harm over this phase-out period. Potential effects include reduced aquatic insect abundance. Affected populations have the potential to recover following implementation of the additional restrictions which will reduce overall exposure. Accordingly, both registrants and retailers will have up to 24 months from the date of this decision document to transition to selling the product with the newly amended labels. This approach is consistent with Health Canada’s current policy and practice with respect to phase out of uses as a result of a re-evaluation (Regulatory Directive DIR2018-01, Policy on Cancellations and Amendments Following Re-evaluation and Special Review).

Similarly, users will also have the same 24-month period from the date of SRD2021-04 to transition to using the newly amended labels, which will be available on the Public Registry.

Refer to Appendix I for details on specific products impacted by this decision.

Other information

Any person may file a notice of objection^{Footnote 4} regarding this decision on thiamethoxam within 60 days from the date of publication of this special review decision. For more information regarding the basis for objecting (which must be based on scientific grounds), please refer to the Pesticides section of the Canada.ca website (Request a Reconsideration of Decision) or contact the PMRA’s Pest Management Information Service by phone (1-800-267-6315) or by e-mail (hc.pmra-info-arla.sc@canada.ca).

The relevant confidential test data on which the decision is based (as referenced in PSRD2018‑02 and Appendix IX of SRD2021-04) are available for public inspection, upon application, in the PMRA’s Reading Room. For more information, please contact the PMRA’s Pest Management Information Service.

Appendix I Registered products containing thiamethoxam in Canada that are subject to this special review decision

Appendix II Registered commercial class uses of thiamethoxam in Canada as of 31 July 2020 that are subject to this special review