Maple Leaf has said it's unlikely it will be able to determine how its meat was contaminated, explaining that the listeria bacterium is common and pervasive.
"It's very, very, very difficult, if not impossible, to pinpoint a cause," Chief Financial Officer Michael Vels told analysts on Monday before the latest health announcement.
"I don't know how important that is to consumers. I think our perspective is what's more important is we let them know what's going on and we take swift and conservative action to safeguard their health," Vels said.
Maple Leaf is double-checking procedures at all of its 23 plants but has no reason to believe any other products are at risk of contamination, he said.
Reimbursing customers for returned products, cleaning the plant and other direct expenses will cost the company C$20 million before taxes, Vels said.