A new study shows neonicotinoids — a commonly used pesticide that many scientists say is harmful to honeybees — are widely found in honey samples from around the world.
The study, published in the journal Science, found neonicotinoids in 75 per cent of honey samples collected between 2012 and 2016 at levels known to be neuroactive in bees, meaning they can affect the insects' cognitive function.
Researchers found the level of contamination highest in North America at 86 per cent, followed by Asia (80 per cent), Europe (79 per cent) and lowest in South America (57 per cent).
Neonicotinoids have been found to be toxic to bees and have been identified as one of the factors linked to the widespread decline of honeybee colonies.
The global die-off of honeybees could have dire implications for food production because the insects are vital to plant and crop pollination.
Shows pervasiveness of pesticide
Mark Winston, Simon Fraser University professor and bee researcher, says this study adds to the developing understanding of how pervasively the pesticide can spread throughout an ecosystem.
"We used to think that neonicotinoids are only found in areas where they are heavily used on one particular crop, but this study is consistent with others that have found neonicotinoids up to quite a few kilometres away from the place where they are used," Winston said.
He said bees are more likely to encounter neonicotinoids when pesticides are so pervasive in the environment.
Even at the relatively low levels found in the honey samples, Winston said neonicotinoids can still have sublethal effects on bees, causing disorientation and other cognitive problems that can influence bee colony survival.
Though bees can tolerate a low level of the pesticide, they become more vulnerable to the effects of other pesticides or diseases, he said.
"We really have to be looking at what happens when we put them all together," Winston said.
Bees are often essential for the pollination of certain food crops and plants. (Tori Weldon/CBC)
Health Canada studying effects
One of the reasons this group of pesticides is used so widely, according to the pesticide industry, is while the chemicals are extremely toxic to insects, they are not considered harmful to mammals.
Winston said it's unlikely that the presence of neonicotinoids in honey could be harmful to humans who consume it — although he said he personally tries to limit eating foods with a lot of pesticides.
Health Canada is studying whether to ban a particular type of neonicitinoid pesticide that is especially harmful to aquatic insects. A final decision is expected in December 2018.
Parts of the country have already started phasing out the use of the pesticide group, including Ontario. Vancouver and Montreal have banned the chemical within city limits.
