In response to concerns about the the impact of neonicotinoid-based pesticides on aquatic insects, Canadian health officials have announced plans to limit the use of clothianidin and thiamethoxam, which are sold under brand names like Arena, Talstar and others.
Health Canada issued a statement on March 31, indicating that restrictions will be placed on the two neonicotinoid pesticides, which are used to control insects on agricultural crops, including seed treatments for most of the corn and canola seeds in Canada and on soybeans. The pesticides are also used on turf, ornamental plants, vegetables, fruit and berry crops.
In the United States the two chemicals are registered and approved by the U.S. Environmental Protection Agency and remain legal for use on crops and other plants under federal law. However, data from a Canadian study indicates the insecticides accumulate in ponds, creeks and other bodies of water near agricultural land, which may be harmful to aquatic insects.
The levels of pesticides are harmful to mayflies and midges, also posing a threat to other animals that rely on insects for food, like birds, the agency determined. They have been linked to the deaths of birds and fish that feed on insects.
Health Canada conducted a special review of science-based assessments, consulting with industry, stakeholders, and Canadian residents reviewing 47,000 comments from the public. The agency also reviewed new water monitoring data and scientific studies and papers.
While the review indicated some uses do not pose a risk to aquatic insects, other uses do pose a significant risk. In 2018, Canada originally planned to ban all outdoor use of these pesticides but decided to conduct a full review. Now, the agency has revised conditions of use for both pesticides and mandates the uses must be placed on all product labels within 24 months.
Registered approved uses under the new guidelines include reduced application rates, reduction in number of applications, and spray buffer zones. The ministry restricted use for onion, lettuce, blueberry, and potato crops. When used according to the new guidelines the pesticides will not pose additional risks to aquatic insects, Canadian health officials claim.
Companies that manufacture the chemicals have two years to adjust directions on labels. Similar changes are reportedly being considered by the EPA, but have not been enacted.