In November, Health Canada said that a nation-wide ban of imidacloprid, a neonicotinoid insecticide, was necessary because the chemical is a threat to aquatic insects.
In late December a University of Guelph expert said the government’s conclusion was an “over-reaction” and a mistake.
“I’m not in agreement with the decision to ban (imidacloprid)…. I don’t agree that the weight of evidence suggests that that particular action is needed,” said Paul Sibley, a U of G professor in environmental sciences.
“I do think some action is needed, but I think that (a ban) is essentially a politicized response, much as we saw in Europe when they banned (neonicotinoids) because of a pollination concerns.”
Health Canada surprised many people in the agricultural trade when it proposed to phase out the use of imidacloprid over three to five years.
Scientists with Health Canada’s Pest Management Regulatory Agency determined that levels of imidacloprid in water bodies near agricultural land are unacceptably high, which is putting aquatic insects at risk and a threat to animals that depend on those insects for food.
The Bayer insecticide is used as a seed treatment on field crops, but it is applied primarily to fruit, vegetables and potatoes in Canada. It was once the most popular insecticide in the world.
Because of the risk to aquatic insects such as midges and mayflies, Health Canada will also conduct a special review of two other neonicotinoid insecticides: thiamethoxam, a Syngenta product, and clothianidin, a Bayer product.
Neonicotinoids are applied as seed treatments to almost all of the corn and canola planted in North America and a portion of soybean acres.
The class of insecticides has been highly controversial over the last five years because of their link to bee deaths and bee colony losses. In 2013, the European Commission banned the use of neonics in an effort to protect bees.
Sibley compared Health Canada’s proposed phase out for imidacloprid to Europe’s ban on all neonics because political pressure likely influenced both decisions.
“There is a heavy, heavy lobby from beekeepers and others, largely environmentalists, to outright ban these chemicals,” Sibley said.
“They (the PMRA) say it’s driven by their risk assessment, but there is a lot of pressure from other groups.”
Sibley tempered his remarks, saying the PMRA is a “model organization on how to deal with pesticides.”
However, in this case he disagrees with its position.
“What bothers me … is there was no consideration of intermediate, middle of the (road) approaches in dealing with this problem,” he said.
“There are a number of so-called best management practices that we could incorporate, (which) would lead to a reduction in the environmental concentration of the neonics. The decision not to do that (middle ground) and the decision to phase out, I think that’s where the politics comes in…. That little bit of politicization really made the difference between what I say (is) a slightly more rational approach and what I see as a fairly irrational approach.”
Sibley studies how pesticides affect aquatic species, and this year one of his graduate students has been working with Ontario’s environment ministry to study thresholds, or concentrations in water where neonicotinoids and other pesticides become a threat to aquatic insects such as mayflies and midges.
“She has developed a very robust set of acute toxicity exposures,” he said.
Based on the student’s lab research, Health Canada’s proposed thresholds for imidacloprid are too low, Sibley said.
Government scientists have suggested an acute, or maximum, level of 360 nanograms per litre for imidacloprid in ponds and water bodies, he said.
“On the chronic side, .041 ng/l. We’re talking 41 nanograms per litre…. Extremely low.”
Environment Canada monitoring has found that concentrations of neonicotinoids, in water bodies in southern Ontario, are typically 10 to 40 ng/l, although much higher levels have been found in creeks in regions with intense fruit and vegetable production.
The Ontario government is the primary funder of Sibley’s study on pesticide thresholds. His graduate student plans to publish a paper sometime this year.
Sibley said the government and the public’s focus on neonicotinoids is myopic and misguided, particularly when it comes to water bodies in rural Canada.
“Compared to what is driving problems in streams and ponds, neonics aren’t the issue. The issue is things like habitat loss or (excessive) nutrients,” he said.
“I think a lot of this is being overlooked when (people) think of about things just in terms of a chemical or a class of chemicals.”
Health Canada will accept comments on its proposed phase out of imidacloprid until Feb. 21.