Health Canada is defending its recently-announced plans for stricter regulations aimed at reducing honeybees’ exposure to a class of commonly-used pesticide that’s suspected of killing them.

A number of bee farmers have expressed anger with the proposed new rules, saying they don't go far enough.

Health Canada's Pest Management Regulatory Agency (PMRA) announced Friday it was proposing new rules to address the problem of neonicotinoid pesticides, which are commonly used on corn and soybean crops grown in Canada. The new rules would require corn and soy farmers to use safer planting practices and take efforts to reduce dust during the planting process; they would also require new warning labels on pesticide-coated seeds.

Many bee farmers and environmental experts say the proposed changes aren't enough and that the pesticides should be banned altogether. But the PMRA’s Scott Kirby says neonicotinoids are only one factor currently affecting bee health.

"There are all kinds of things assaulting the bee population," Kirby told CTV's Canada AM on Monday.

"These include climate change, Varroa mites, disease such as Nosema, as well as bee husbandry practices. Pesticides are also in the mix. At this point we're looking at all angles."

The PMRA said that its own testing of dead bees in 2012 determined that the majority of the deaths were caused by exposure to the pesticides -- likely through dust generated during seed planting.

“We have concluded that current agricultural practices related to the use of neonicotinoid treated corn and soybean seed are not sustainable,” the agency said in its notice of intent.

Kirby says it's clear the science is pointing to problems with bees in southern Ontario and Quebec being exposed to pesticide-contaminated dust, and that's why his agency is proposing the new measures.

"We're letting our actions be determined by the science and what we've seen is clear evidence of issues with corn and soy planting," Kirby said, adding. "…but at this time, the science does not point to the need for a broader action with respect to these pesticides."

Scientists, beekeepers and environmental groups have been concerned with the world's declining bee populations for years, with many noting that bee die-offs escalated along with the increased use of neonicotinoid-coated seeds. The Canadian Honey Council estimates that Canada's bee population has dropped by approximately 35 per cent in the past three years.

Bee farmer Dave Schuit, of Saugeen Country Honey in Elmwood, Ont., has lost half of his bee colonies over the past two years and believes the pesticides are poisoning his bees. He told CTV News last week that a ban is the only way to save his business.

The European Union decided in May to ban three types of neonicotinoid pesticides on crops that attract bees, after the European Food Safety Authority found the pesticides posed "high acute risks" to the insects.

Jon Bennett, executive director of the Sierra Club of Canada, told CTVNews.ca last week that the PMRA's proposed new rules were inadequate and that a full ban on neonicotinoids was the only way bee populations were going to be able to recover. He said the planned measures to make planting more safe wouldn't help, because neonicotinoids get into the water and the soil.

"The problem is much greater than just the planting technique," he said.

Bennett suggested the government take the pesticides out of use for two years and continue doing research on the topic.

Kirby says Health Canada has asked the pesticide companies involved to provide the agency with data to help them determine how necessary these treated seeds are to farmers. But he says that the issue of declining bee populations is about more than just pesticides.

"As I say, there are a number of factors affecting bee health, not the least of which is the Varroa mite; it's a very serious problem globally. There's also diseases as well as bee husbandry issues," Kirby said.

"We're going to be looking at those broader issues as part of the re-evaluation, but right now, we're focusing on what the science is telling us and it's telling us there's a problem with corn and soy planting and exposure to these contaminated dusts."