A directive from Ottawa that forced the city to stop fogging for mosquitos, has been reversed.
In 2014, Health Canada quietly changed the label for malathion.
It said the product used to control mosquitos must only be stored for a year after it is manufactured, because the insecticide could degrade and become more toxic.
The city said it was caught off-guard by the new label and only discovered the change this week.
This summer the Insect Control Branch used malathion made in 2003, and its current stock is nine years old.
"You always want to have an expiry date on any kind of chemicals,” said Megan Krohn, with the Manitoba Eco Network.
The city said it stores malathion in the proper way to prevent degradation and regular testing shows the city's batches are above the 95 per cent purity standard required.
"Our tests have consistently shown that the active ingredient has remained stable,” Nawolsky said.
In an email statement late Friday evening, a City of Winnipeg spokesperson said the program was cleared to continue.
The city said Health Canada, "would not object to the use of Malathion stock which is older than one year provided the laboratory test results show that the isomalathion content within PRO Malathion ULV falls within acceptable standards."
The city said that applies to its nuisance mosquito fogging program.
It's now testing its current malathion stock for isomalathion.
Health Canada also said the province can use malathion to fog when West Nile Virus is a problem, as long as the chemical is at the current quality standard.
The province said it is testing its supplies.
The city is hoping to have a more environmentally friendly product, Delta Guard, approved for use by 2017.
