Manitoba's former chief medical officer of health says there's no need to worry about the effects of malathion when fogging for mosquitoes.

"I think that if done properly, and according to the standards that have been established, the actual harmful effects of malathion spraying is extremely low," said Joel Kettner.

"For those that are outdoors when the spraying truck goes by, studies have not shown any evidence of harmful effects within the short term or expected to be a problem in the long term."

Kettner said when he worked for the province and ordered fogging, it was because of health concerns over the threat of West Nile Virus, carried by the Culex tarsalis species.

"When there's virus in the mosquitoes ... which can cause disease in humans, than the use of malathion," said Kettner. "Then I think the importance of adequate spraying and full protection is much more significant."

When it comes to spraying for nuisance mosquitoes, Kettner agreed people should have the right to register for buffer zones.

Disagreement over malathion use

The use of malathion has been a controversial issue in Winnipeg this mosquito-filled summer.

It has sparked debate between those who want to be bug-free outside and those who don't want the collateral damage of dragonflies, butterflies and other beneficial insects being also killed by the malathion.

Some Winnipeg residents have suggested the city execute a mass release of dragon flies to help curb mosquito populations in the city.

'The evidence we have is that the dosage of exposure for humans is so small that it would not be expected to have short or long term impacts' - Joel Kettner

Maria Bromilow said she'd take mosquito bites over malathion if it means less of the city's wildlife are put in harms way from collateral damage due to fogging.

"I think it's okay to get stung a few times for the sake of saving birds and bees," said Bromilow.

For Jennifer Bisch spraying for mosquitoes in Winnipeg is fine, so long as it is done by professionals.

"If it's being professionally administered, not administered by me or someone who may not read the labels," said Bisch.

Other Winnipeggers just want the blood-suckers gone either way.

"I live in Charleswood," said Kelly Smith. "And it's been hard getting in my front door without hordes of them coming in."

Science says: malathion 'safe'

 While there's always some uncertainty in science, Kettner said the safety of malathion, used under proper regulations, is supported by the majority of available evidence.

"The evidence we have is that the dosage of exposure for humans is so small that it would not be expected to have short or long term impacts," he said. "That's not to say that some people don't sense it, smell it or are irritated by it." 

For now, adult mosquito trap counts are down around the city, meaning scheduled fogging Wednesday evening has been cancelled — allowing anti-foggers a chance to breathe a deep sigh of relief. 

Listen to the full interview with Kettner by clicking the audio link at the top left of this page.