Critics question use of neurotoxin against mosquitoes

Edmonton officials stopped using the neurotoxin Dursban to fight mosquitoes two years ago, but failed to clearly tell the public they were still using a pesticide with the same active ingredient.

That’s left people unsure what risks they face, and city pestcontrol experts are making public health decisions on their own, without being transparent, anti-pesticide advocates told city council’s audit committee Monday.

“The existing policy is really just ‘Trust us to do the right thing,’ ” said Raquel Feroe, a medical doctor.

She argued health officials need to be at the table, especially those specialized in children’s health and environmental risk factors: “(Children are) the canary in the coal mine.”

Council heard from city auditor David Wiun, who agreed Edmonton’s policy around pesticides is unclear, and its practices lack full transparency.

City officials said they’ll review the pest management policy and public communications, and develop a GPS-based app to yield real-time public data on what is being sprayed.

The review will include information if the city continues to use the pesticide Pyrate, which is sprayed from the ground along rural roads and highways. It contains the same neurotoxin as Dursban — chlorpyrifos.

Edmonton is the last city in Canada to use Dursban after Winnipeg sold its stockpile to Edmonton. Health Canada kept it registered for use as a pesticide at Edmonton’s request.

Responding to public pressure, Edmonton officials shelved the product in 2016 and sent council a memo saying it would only be used to respond to a public health emergency such as a re-emergence of the mosquito-borne West Nile virus.

That led most to believe the issue was settled. Even Mayor Don Iveson told members of the public the city was no longer using chlorpyrifos, the active ingredient.

“It’s on me if I missed something,” Iveson said at the committee Monday.

But “from everything I saw ... the impression left was that we were out of the chlorpyrifos game. So, I have to say, I have reservations about our continued use of it at all.”

Several researchers told councillors the problem with chlorpyrifos is that it’s a persistent chemical that lasts a long time in the environment.

It kills the dragonflies that eat mosquitoes and is a threat to several endangered species, bees and other beneficial insects, said Elisabeth Beaubien, a biologist at the University of Alberta.

Several public and environmental health officials agreed to help weigh the risks for a new policy, including the U of A’s Children’s Environmental Health Clinic and Canadian Association of Physicians for the Environment.

The alternative — VectoBac — is a bacteria only toxic to mosquito larvae. It comes in a corn huskbased product that floats on the surface of the water long enough for the mosquito larvae to eat it, but has to be applied during a very short window in their development to be effective.

Details around the continued use of Pyrate were still foggy, even Monday. Officials told councillors they only used four kilograms of the active chemical chlorpyrifos, down from about 1,000 kilograms 10 years ago. They told councillors it was only used in “remote areas with heavy vegetation.”

But by remote, they mean any ditch along a rural road where the grass does not get mowed regularly, officials clarified outside the meeting. Most locations are outside the Anthony Henday Drive ring road and in the surrounding counties.

They struggle to use VectoBac in ditches because the small pellets get caught in the grass rather than float on the surface of the water.