ONLY WHERE NECESSARY
City cautious with mosquito toxin
A group of concerned people has convinced Edmonton to pull the neurotoxin Dursban from its arsenal to fight mosquitoes.
Edmonton was the last municipality in Canada to use the product, which causes lasting neurological defects in children if pregnant women are exposed at low levels. The restricted insecticide was being dropped by helicopter in pebble form into temporary pools of standing water around the outskirts of Edmonton, in road allowances and industrial areas. It kills mosquito larvae.
“We’re not going to use it unless we have absolutely no choice,” said Ron Gabruck, a city director whose area includes pest management.
Chlorpyrifos, the active ingredient, is also toxic to birds, wild mammals, bees and many beneficial insects, according to the label, which warns against letting the product drift to flowering plants or weeds if bees are in the area.
In place of Dursban, crews will also be using a natural alternative called VectoBac, which uses a bacteria that only attacks mosquitoes. It’s the solution Calgary adopted more than 15 years ago, but poses a challenge for Edmonton crews because it only works in warm weather.
The city will continue to use Pyrate, which has the same active ingredient as Dursban, but is sprayed in ditches from a truck.
“We want to be as environmentally responsible as possible,” said Gabruck, saying crews will keep stores of Durban until its registration expires in 2019. It will only be used if there’s an outbreak of the Zika or West Nile virus.
It is important the city controls mosquitoes, Gabruck said. “If we don’t keep the mosquito population down, people will find their own ways of doing that,” he said. If people are driven to apply insecticides to their properties, that puts the risk much closer to children and pregnant women.
Mike Jenkins, who manages Edmonton’s mosquito program, said Dursban might also be used “if there’s some catastrophic weather event” that threatens to inundate Edmonton with mosquitoes. City officials are still writing the policy, he said. They’ll also experiment with an ATV-based distribution system for VectoBac in ditches this season, which could eliminate the use of Pyrate and chlorpyrifos.
Pesticide Free Alberta lobbied the city for years to give up Dursban. It also helped publicize gaps in the city’s record-keeping system, which meant Edmonton couldn’t say where they dropped the pesticide, only where their helicopter flew. In 2014, that included Terwillegar Park. The local activist group is still upset the city is using Pyrate, worried spray from the trucks will drift to places were people are. “People here still don’t know where this has been applied,” said co-ordinator Sheryl McCumsey.
Chlorpyrifos is a common agricultural insecticide environmental lobby groups are fighting to have banned in the United States. One 2014 study found a higher incidence of autism spectrum disorders in children when pregnant mothers lived within 1.5 kilometres of sprayed fields, and other studies have documented learning disabilities in the children of agricultural workers. Canada still allows its use. Pest Management Regulatory Agency officials proposed banning its use for several kinds of crops in 2003, because of the effects on the environment, but backed down after farmers complained there were no viable alternatives.