Montreal re-allows use of rat poison after home-infestation complaints

The City of Montreal has backtracked on its list of banned chemicals to allow the use of one rodenticide commonly used to exterminate rats.

Montreal has decided to allow exterminators to use diphacinone, which until this week was banned alongside glyphosate, a controversial herbicide, Bromethaline, a neurotoxin with no known antidote, and about 30 other fungicides, herbicides, insecticides, and rodenticides.

“We took the statistics from 311 in the borough of Ville-Marie,” said Montreal Executive Committee Member Marie-Andree Mauger. She says the number of rat complaints have remained relatively stable over recent years.

“Every year it’s about a hundred calls to 311 about rats,” she said. “It’s an issue that we take very seriously.”

Experts say fighting those infestations, however, has become much more difficult without the use of diphacinone.

“It kind of limits (the work),” said Denny Andrade, a technician with Extermination Platinum. He says that without the use of recently banned chemicals, exterminators have relied exclusively on mechanical traps.

“You’re just putting a trap outside,” he said. “The trap can only catch one rat at a time. With the poison, the diphacinone, you can eliminate 10-15 rats from one station.”

Pest control expert Jeff Bow demonstrates a typical spring-loaded rat trap in Ottawa, Nov. 13, 2014

During the pandemic, rats migrated out of their usual stomping grounds – alleys and dumpsters near restaurants – because people were not eating out nearly as much.

Experts say that sent them scurrying elsewhere to find food, and Andrade says his company has seen an increase in calls from people complaining of mice and rat infestations inside their homes.

“It’s good business for us, but for the people, it’s not very good, because rats carry a lot of diseases,” he said.

What’s more, getting rid of them can cost thousands of dollars, and rats can gnaw into concrete, stone, plastic, and wood. They can also chew on wires, creating fire hazards.

WHY ALLOW DIPHACINONE?

Diphacinone is an anti-coagulant, which is considered highly toxic when consumed orally or inhaled, and irritating to the skin and eyes.

While it is potentially dangerous to humans and animals, it’s considered to be tamer than other rodenticides, such as bromadiolone, which remains off-limits.

“(The rats) have to digest it two, three, four times before they die,” said Andrade. “The other products, they eat them once, and the day after, they’re done.”

From the city’s perspective, Mauger said the list of banned chemicals, and its revision, was created with input from experts.

“It’s always a balance between sanitation and (risks to the) environment,” said Mauger.

Get the full list of off-limits chemicals, click here.