The Pesticide That Is Killing Bees Is Also Harming Humans


Scientists believe that the widespread use of pesticides such as neonicotinoids are not only harmful to bees and other pollinators, but also to humans.

Although neonics are used to target invertebrates, there is mounting evidence that suggests they are have far-reaching effects.


The European Food Safety Authority concluded in 2013 that neonics could affect the human nervous system.

An international symposium on the use of neonicotinoids held recently at York University in Toronto which focused mainly on the effects on pollinators and integrated pest management.  However, one of the issues discussed was the effects neonicotinoids had on humans.

Global News reports:

The symposium was a gathering of scientists from the international Task Force on Systemic Pesticides, as well as the David Suzuki Foundation and the Canadian Association of Physicians for the Environment (CAPE).

Neonicotinoids, also called NNIs or neonics, are the most widely used pesticide around the world. It consists of a group of pesticides that target the neuron pathway found most in insects rather than in vertebrates. However, studies on vertebrates such as mice, rats and fish have found that there is some level of toxicity, which varies on the specific type of neonic used.

A study found that one such neonic, called imidacloprid, was toxic (which is referred to as LD50) in many birds as well as fish. (Another similar insecticide called fipronil, which is similar to neonics, was also as toxic.) Sub-lethal levels, meaning that it didn’t result in death, but neurological effects such as reduced learning and cognitive abilities, was also found in birds and fish exposed to those two pesticides as well as in another neonic called clothianidin.

Neonics came into use in the 1990s, but their use skyrocketed within a decade. Today, almost 100 per cent of corn seeds are treated with it here in Canada.

The alarm bells for neonics reached a peak in 2014 in Canada when beekeepers in Ontario and Quebec noticed that their bees were dying off at an alarming rate. Health Canada’s Pest Management Regulatory Agency (PMRA) visited some southern Ontario beekeepers and collected samples of their dead bees. They found that 70 per cent tested positive for neonics.

Human effects

Neonics is water-soluble: it is absorbed and carried throughout a plant, protecting it against pests. The catch is only 2 to 30 per cent is taken in by the plant. The remaining amount is taken in by the soil which can then spread to non-targeted organisms, like butterflies, bees, fish — and recent evidence suggests even humans.

Kumiko Tairo, who spoke at the symposium in Toronto, has studied the effects of NNIs on humans in Gunma Prefecture, near Tokyo. In 2004 and 2005, 78 and 63 patients respectively — young and old — began experiencing symptoms such as headaches and memory loss. When examined, many had abnormal ECGs. Then, in 2006 and 2007, there were 1,111 more patients with similar symptoms. The most prevalent symptom in all cases was a headache, followed by shoulder and chest pain.

Urinalysis detected high doses of neonics. Brain scans revealed that the mid-brain was clearly affected.

Tairo and her team found that the likely culprit was tea leaves which were affected by pesticide leaching into the soil. Aerial spraying also put residents at risk of increased exposure due to drift.

“Now we are facing the increasingly dangerous presence of neonics in humans,” Tairo said on Tuesday.

“We speculate that nenoics are retained in the human body, and continuous use may pollute human tissue.”

All patients eventually recovered.

While no such human studies have been conducted here in Canada, Glenn Murray, Ontario’s Minister of the Environment and Climate Change, who also addressed the symposium, said there isn’t enough evidence on the extended use of NNIs in our environment.

“No one has a clue of long-term use,” he said.

The problem, he acknowledged, is that neonics were only conditionally approved in Canada but have been widely used without much solid, independent research done on the consequences or the pervasiveness in the environment.

As a result, the Ontario government became the first province to restrict the widespread use of NNIs. It plans on reducing the number of hectares planted with neonic-treated corn and soybean seeds by 80 per cent by 2017.