Health Canada is inviting comments through the end of February 2017 on its preliminary plans to ban the chemical imidacloprid, an active ingredient in neonicotinoid-based-insecticides. Following an initial assessment, the Canadian agency said it thinks the chemical should be phased out within five years, due to its increasing presence in waterways at levels harmful to aquatic insects.

Imidacloprid is also being eyed as a threat to bees, and Canada is conducting a separate evaluation into chemical’s role in Colony Collapse Disorder, which has massively affected bee populations in North America as well as Europe. The EU still has a moratorium in place, which restricts the use of neonics in certain crops attractive to bees.

A potential stumbling block to a phase-out, reports said, could be a lack of access to data about how much of the insecticide finds its way into the pollen and nectar of soybeans – the most common crop on which it is used – despite the chemical having been on the market for 20 years. Health Canada is conducting a separate evaluation of how the chemical affects bees.

The agency’s position that imidacloprid poses so great a risk to waterborne insects that it should be banned is “striking,” said Mark Winston, a professor of apiculture at Simon Fraser University. “To take an action to phase out a chemical that is so ubiquitous, and for which there is so much lobbying pressure from industry is a really bold move,” he added.

Health Canada previously initiated reviews of two other prominent neonics: clothianidin and thiamethoxam. While Germany’s Bayer is the major producer of clothianidin – as well as imidacloprid – Switzerland’s Syngenta is believed to be the sole importer of thiamethoxam products into Canada. In the US, a report published by the Environmental Protection Agency at the beginning of 2016 concluded that neonics pose a “significant risk” to honeybees when used on cotton and citrus or in concentrations of 25 parts per billion or higher, but probably not when used on other large crops like corn, berries and tobacco.

The EPA subsequently came under pressure from Bayer and environmentalists, from opposite standpoints. Although the German chemical and life science group currently in the process of acquiring US rival Monsanto initially criticized the agency for overestimating the threat, in a subsequent about-face it called the report “scientifically sound.”

Environmentalists working in tandem with groups representing beekeepers and farmers earlier this year said they would sue the EPA for allowing seeds coated in neonicotinoids to be planted without proper assessments of the impact. Bayer and Monsanto already cooperate in the seeds segment.