WINNIPEG, Manitoba (Reuters) - Maple Leaf Foods Inc Chief Executive Michael McCain said on Thursday it was not surprising to find listeria bacteria lingering in a Maple Leaf meat plant in Toronto whose products have been linked to at least 20 deaths in a food-poisoning outbreak.
"Listeria exists in 100 percent of all (meat) plants, and it is impossible to eliminate it," McCain told reporters, noting the company sanitizes its plants for six to eight hours a day to reduce the risk of the bacteria contaminating food at levels high enough to cause illness or death.
Maple Leaf, one of Canada's largest meat processors, and the Canadian Food Inspection Agency announced late on Wednesday that four samples of meat products at the plant had tested positive for the bacteria.
Earlier this summer, contaminated meat from the same plant caused an outbreak of listeriosis.
The company said two slicers in the plant were behind the outbreak, which prompted one of the largest meat recalls in Canada's history.
"What occurred a month ago was not about the existence of listeria in the plant," McCain said. "It was about a harborage point ... deep inside a slicer that avoided our sanitation process."
Maple Leaf shares have plunged more than 30 percent since the outbreak, and were down 43 Canadian cents at C$7.31 on the Toronto Stock Exchange on Thursday.
The plant resumed processing three weeks ago and has been running at 30 percent capacity as government officials rigorously test meats produced there, all of which are being held in warehouses.
Maple Leaf has not been permitted to distribute any meat products from the plant as government officials try to make sure it has eliminated the source of the outbreak.
The Canadian Food Inspection Agency is evaluating the findings, and a senior official declined to speculate on what impact they would have on the decision on when to allow meat from the plant to be sold to the public.
"What we want to understand is, in terms of the plant and its environment and its production, if the issues that may have contributed to the original contamination event have been addressed," said CFIA official Paul Mayers.
The four new findings were "somewhat routine," McCain said, One to 10 percent of all ready-to-eat foods contain the bacteria, and most people do not get sick from consuming it, he said.
Officials are taking 60 samples from each production line every day, which is one sample every 8 to 12 minutes, McCain said, or a total of 3,850 tests.
"We understood the day that we opened the door that this plant was going to be a fishbowl," McCain said.
The new findings are within accepted limits for meat processing plants in Canada and the United States, said Mansel Griffiths, a food scientist with the University of Guelph.
Reporting by Roberta Rampton; Editing by Peter Galloway