Health Canada says it will not reverse its ban on strychnine, maintaining that environmental and human health risks outweigh concerns raised by Prairie governments and farm groups.

The federal department confirmed it reviewed requests from Alberta and Saskatchewan to reconsider the use of the rodent poison to control gopher populations that farmers say are damaging crops and pastureland. Health Canada concluded the risks associated with strychnine remain too significant to justify its use.

Strychnine has been prohibited for most pest control uses because of its high toxicity and the risk it poses to wildlife, pets and people. Health Canada said those safety concerns continue to take priority over agricultural challenges linked to rodent infestations.

Both Alberta and Saskatchewan had urged Ottawa to allow strychnine under limited or emergency conditions, arguing that existing tools are not sufficient to deal with increasing gopher numbers in some rural areas. The provinces said crop losses and added costs are putting pressure on producers.

Health Canada rejected the emergency-use proposal, stating it did not include new safeguards or effective measures that would reduce the known risks of the poison. The department added that it continues to encourage the use of alternative pest management methods that are safer for the environment.