Information Note: Outcome following External Advisory Review Panel from Notices of Objections for RVD2020-06: Strychnine and Its Associated End-use Products (Richardson’s Ground Squirrels)

Pest Management Regulatory Agency
May 31, 2022

Background

Health Canada's Pest Management Regulatory Agency (PMRA) is responsible for administering the Pest Control Products Act. Under the Act, pesticides must be assessed before they are sold or used in Canada in order to determine that they do not pose unacceptable risks to humans or the environment and have value when used according to the label instructions. The Act also requires that registered pesticides be re-evaluated to ensure that they continue to meet current health and environmental standards and continue to have value.

A final re-evaluation decision is published after the PMRA conducts any necessary evaluations and the required public consultation. Once the final decision is made public, anyone can submit a Notice of Objection to the decision as per section 35 of the Act. The Act and the Review Panel Regulations set out requirements concerning the Notice of Objection process. The PMRA must take into account whether the objections raise scientifically founded doubt as to the validity of the PMRA's evaluations on which the decision is based, and whether the advice of expert scientists would assist in addressing the subject matter of the objection. After considering these factors, a panel of one or more individuals can be established to review the decision and to recommend whether the decision should be confirmed, reversed or varied.

Objections to re-evaluation decision for strychnine and its associated end-use products (ground squirrel use)

The final re-evaluation decision for strychnine and its associated end-use products (ground squirrel use) (RVD2020-06) was published March 4, 2020. The decision was to cancel the use of strychnine to control Richardson's ground squirrel with a phase-out timeline as follows:

1. Last Sale by Registrant: 2021-03-04
2. Last Sale by Retail: 2022-03-04
3. Last date of use: 2023-03-04

Following the publication of RVD2020-06, the PMRA received 42 Notices of Objection to this decision; 39 against cancellation and 3 for immediate cancellation or a ban of strychnine. The Notices of Objection did not raise scientifically founded doubt as to the PMRA's decision to cancel the use of strychnine to control Richardson's ground squirrel. However, in reviewing the Notices of Objection, the PMRA identified a potential risk to the chestnut-collared longspur, a species at risk. A question was raised with respect to whether the current three-year phase-out timeline from the use of strychnine would affect the population of the chestnut-collared longspurs.

Therefore, the PMRA established a review panel to request the advice of experts as to whether the current phase-out timeline, scheduled to be completed by March 4, 2023, should be confirmed or varied. Specifically, the PMRA sought advice from the panel on whether there was a risk to the chestnut-collared longspur that warranted a shorter cancellation timeline for the use of strychnine to control Richardson's ground squirrels. An External Advisory Review Panel consisting of two subject matter experts was convened in December 2021. The panel members were Dr. Mark Hanson and Dr. Nicola Koper, both from the University of Manitoba. Dr. Hanson is the Head of the Department of Environment and Geography. He is an aquatic ecotoxicologist and ecological risk assessor focussing on fate and effects of pesticides, wastewater contaminants and their impact on non-target species. Dr. Koper is a conservation biologist and has expertise in ecology and conservation of grassland songbirds, including the chestnut-collared longspur.

All relevant information was made available to the panel to assist them in developing a recommendation. These were studies reviewed in the re-evaluation of strychnine that evaluated the potential threat to non-target species from the use of strychnine.

The charge question for the External Advisory Review Panel was as follows:

Based on the background information provided and your knowledge of the biology and conservation status of the chestnut-collared longspur, will the use of strychnine to control Richardson's ground squirrel until March 2023 result in irreversible damage to the chestnut-collared longspur species?

Report by External Advisory Review Panel

The panel report, which is summarized below, includes the assessment and recommendation from the External Advisory Review Panel. The full report can be found in the Public Registry (Pesticide Product Information Database under Application Number 2021-6314).

During the PMRA's review of the Notices of Objection, it was confirmed that a Canadian field study used in the re-evaluation provided evidence of the deaths of three chestnut-collared longspurs (Calcarius ornatus). This species is listed as "Threatened" under the Species at Risk Act (SARA). The breeding habitat for this species is found in the areas where strychnine is used for the control of Richardson's ground squirrel. Non-target organisms may be exposed to strychnine-treated baits on the soil surface. The panel report noted that due to the feeding habits of chestnut-collared longspurs with preference for insects, the potential for direct ingestion of strychnine-treated bait is low. According to the External Advisory Review Panel, it is reasonable to assume that there may be some accidental mortalities of chestnut-collared longspur due to the use of strychnine baiting, but these would be limited in number and a small proportion of the overall population.

The External Advisory Review Panel concluded:

"After reviewing the life history and feeding strategies, current conservation status of chestnut-collared longspurs, the manner in which strychnine is used currently in Canada, and available evidence for mortality of chestnut-collared longspurs from buried strychnine baits, we determined that accidental mortalities related to strychnine baiting for Richardson's ground squirrels are possible but highly unlikely to have a significant impact on the chestnut-collared longspur population. The number of chestnut-collared longspurs losses relative to current population estimates (approximately 580,000 birds in Canada at this time) means continued strychnine use until March 4, 2023 is not likely to result in irreversible damage to chestnut-collared longspur populations in Canada."

As a result of its conclusion, the recommendation of the External Advisory Review Panel was that "the use of strychnine for the control of Richardson ground squirrel may continue until its planned phase-out on March 4, 2023".

Outcome

The report and recommendation from the External Advisory Review Panel on the risk to the chestnut-collared longspur as a result of strychnine use during the phase-out period was presented to the PMRA's Science Management Committee. The PMRA accepted the External Advisory Review Panel's recommendation that the use of strychnine can continue until the end of its planned phase-out date without irreversible damage to the chestnut-collared longspur population in Canada.

As per subsection 39(1) of the Act, after considering the recommendation of the External Advisory Review Panel, the PMRA, on behalf of the Minister, confirms the decision to cancel the use of strychnine to control Richardson's ground squirrel over a three-year phase-out period ending March 4, 2023.