The Swiss study was misleading and the methodology used to measure concentrations was ‘illogical,’ says toxicologist
The story was based on a Swiss study that analyzed honey samples from around the globe.
The study, published in the journal Science, found that 75 percent of honey contains neonicotinoids, a class of insecticides commonly used as a seed treatment on canola, corn and soybean crops.
The CBC story was factual but omitted a key point. The levels of neonics found in the honey samples were insignificant.
“The concentrations detected in honey are very, very low, or absent,” said Chris Cutler, a Dalhousie University professor who specializes in pollinator risk assessment and insect toxicology.
“This recent Science paper is a monitoring survey that does not report anything unexpected. The concentrations detected align with that in previous reports.”
For neonics commonly used in North America, the study determined that median levels in honey were less than one part per billion:
- For thiamethoxam, a Syngenta product, the median concentration was 0.1 nanograms per gram of honey.
- Clothianidin, a Bayer product, had median concentration of 0.2 ng per gram.
- Imidacloprid, a Bayer product, had median concentration of 0.08 ng per gram.
- At those concentrations, the presence of neonics in honey is not a threat to human health because some neonics are less toxic than aspirin or caffeine, Cutler said in an email.
“When one considers how much honey the average person consumes… the risk to humans is de minimis (too small to be a concern).”
The authors of the paper said there probably isn’t a risk to humans, but they believe the concentrations in honey are a threat to bees.
They said there are detrimental effects on bees when they are exposed to neonic concentrations as low as 0.1 parts per billion. The effects listed in the paper include reduced foraging efficiency and lower queen survival.
Cutler rejects the argument.
“Regarding the assertion that 0.1 ng per gram is problematic for bees, I disagree. The authors cite papers that actually provide no real support for this claim.”
He also takes issue with the methodology of the Swiss paper. The authors added up the concentrations of different neonics found in honey to arrive at a total neonic level in honey. That is not a normal practice, as toxicologists usually study individual compounds.
“The presentation of their data in this way is misleading and illogical, in my opinion,” he said.
A news story suggesting 75 percent of honey is contaminated with insecticides is worrisome for beekeepers, as honey is marketed as pure and natural.
“Honey that’s produced in Canada is still tested and analyzed for food safety. We produce some of the cleanest, highest quality honey in the world,” said Kevin Nixon, a beekeeper from Red Deer.
Nixon, Canadian Honey Council chair, said the study authors are based in Europe, where scientific decisions around pesticides can be compromised by politics.
“We know in Europe there’s a very heavy lobby, a political movement, to ban neonics.”
Neonics and how the insecticides affect bee health is an issue for beekeepers, but it’s not top of mind.
A Canadian Association of Professional Apiculturists survey of beekeepers, conducted earlier this year, found that apiarists are most worried about queen bees and varroa mites — parasites that infect hives and spread disease.
Canadian beekeepers do discuss neonics but it doesn’t dominate the conversation around bee health, Nixon said.
“Beekeepers, across Canada, continue to (operate) on fields that are neonic seed-treated and bee health seems good,” he said.
“(But) there’s always the lingering question among beekeepers: does the exposure, even a low exposure to neonics, is it compounding other problems?”
Putting that question aside, bee colony numbers are on the rise in many provinces and that’s a positive sign, Nixon said.
In Alberta, colony numbers have gone from 305,000 in 2016 to 315,000 this year.
“Not huge growth, but still growth. That’s a good indicator that bee health is fairly stable right now.”