As part of the regular review process, Health Canada has completed its re-evaluation of imidacloprid, and has published its draft risk assessment for public comment. The assessment proposes current use of imidacloprid is not sustainable, and the levels of this pesticide that are being found in waterways and aquatic environments are harmful to aquatic insects, such as mayflies and midges, which are important food sources for fish, birds and other animals.
Concentrations of imidacloprid in surface water can range from non-detectable to, in some rare cases, levels as high as 11.9 parts per billion, according to Health Canada. Scientific evidence indicates levels above 0.041 parts per billion are a concern.
To address the risks identified, Health Canada has published a proposed risk management plan for public comment, which includes a proposed three-year phase-out of agricultural uses of imidacloprid in order to address risks to aquatic insects. In some cases, where there are no alternative pest control products available, a longer phase-out transition period of five years is being proposed.
In a press release, Health Canada said it is consulting on these proposed mitigation measures, and the final re-evaluation decision and risk management plan will take into consideration any comments received during the consultations.
The consultation phase includes a 90-day commentary period in addition to a multi-stakeholder forum that will discuss any proposals for potential alternative mitigation strategies that would achieve the same outcomes in a similar timeframe.
Any proposals for continued registration will need to clearly demonstrate concrete actions to ensure levels of imidacloprid in water will be reduced below the level of concern.
Based on the findings of the re-evaluation assessment on imidacloprid, Health Canada is also launching special reviews for two other widely used neonicotinoids: clothianidin and thiamethoxam. These special reviews will examine any potential risks these pesticides may pose to aquatic invertebrates, including insects, as they are also being detected frequently in aquatic environments.
In the press release, Health Canada said it will provide updates as new information becomes available.