441-00763 (Animals)

Under the authority of the Pest Control Products Act, before a pesticide is allowed to be used or sold in Canada, it must undergo a rigorous scientific assessment process to determine that the health and environmental risks of using the product are acceptable, when used according to label directions. In addition, all registered pesticides must be re-evaluated to ensure that they continue to meet current health and environmental standards and continue to have value. The re-evaluation considers data and information from pesticide manufacturers, published scientific reports and other regulatory agencies.

The public was consulted on the proposed re-evaluation decision for strychnine (Proposed Re-Evaluation Decision PRVD2018-13: Strychnine and Its Associated End-use Products [Ground Squirrel Use]). 

Considering all comments and available information, Health Canada concluded that the environmental risks associated with the use of strychnine for the control of the Richardson’s Ground Squirrel were not shown to be acceptable when used according to label directions, and that no further mitigation measures feasible to users of the product could be implemented. As a result, the outcome of the re-evaluation was the cancellation of the use of strychnine to control Richardson’s Ground Squirrels. There are other registered alternatives, such as chlorophacinone and diphacinone, that were shown to have acceptable risks and value for the control of Richardson’s Ground Squirrels when used according to the label directions. These chemical alternatives can be used in combination with monitoring, cultural controls, and physical controls to form an integrated pest management program for ground squirrels.

The Re-evaluation Decision RVD2020-06, Strychnine and Its Associated End-use Products (Richardson’s Ground Squirrels) was published on March 4, 2020. Under the Act, the public has the opportunity to file a notice of objection to request a reconsideration of the decision. Health Canada’s Pest Management Regulatory Agency (PMRA) received a total of 42 notices of objection, including some against the decision to cancel and others seeking immediate cancellation rather than a three-year phase out period. Objectors included members of the public and representatives from municipal and provincial governments. These objections were reviewed by a team of Health Canada scientists that were not involved previously in the review of strychnine. The assessment of the objections did not raise scientifically founded doubt as to PMRA’s decision to cancel the use of strychnine to control Richardson’s Ground Squirrels.

However, in reviewing the notices of objection, the PMRA identified a potential risk during the phase-out period to the chestnut-collared longspur (bird), a species at risk. The doubt raised was 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. In December of 2021, PMRA established an expert External Advisory 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 on the use of strychnine to control Richardson’s Ground Squirrels.

An Information Note summarizing the findings of the Expert Advisory Review Panel was published on May 31, 2022. The Expert Panel 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, and thus that a shorter cancellation period was not warranted. Therefore, the original phase-out timeline was confirmed. The full report of the Panel is available in the PMRA Public Registry.