MONTREAL (AP) — Hundreds of thousands of Canadians have been unwittingly exposed to high levels of lead in their drinking water, with contamination in several cities consistently higher than they ever were in Flint, Michigan, according to an investigation that tested drinking water in hundreds of homes and reviewed thousands more previously undisclosed results.

Residents in some homes in Montreal, a cosmopolitan city an hour north of the U.S.-Canada border, and Regina, in the flat western prairies, are among those drinking and cooking with tap water with lead levels that exceed Canada's federal guidelines. The investigation found some schools and day care centers had lead levels so high that researchers noted it could impact children's health. Exacerbating the problem, many water providers aren't testing at all.

It wasn't the Canadian government that exposed the scope of this public health concern.

A yearlong investigation by more than 120 journalists from nine universities and 10 media organizations, including The Associated Press and the Institute for Investigative Journalism at Concordia University in Montreal , collected test results that properly measure exposure to lead in 11 cities across Canada. Out of 12,000 tests since 2014, one-third — 33% — exceeded the national safety guideline of 5 parts per billion; 18% exceeded the U.S. limit of 15 ppb.

In a country that touts its clean, natural turquoise lakes, sparkling springs and rushing rivers, there are no national mandates to test drinking water for lead. And even if agencies do take a sample, residents are rarely informed of contamination.

"I'm surprised," said Bruce Lanphear, a leading Canadian water safety researcher who studies the impacts of lead exposure on fetuses and young children. "These are quite high given the kind of attention that has been given to Flint, Michigan, as having such extreme problems. Even when I compare this to some of the other hotspots in the United States, like Newark, like Pittsburgh, the levels here are quite high."

Many Canadians who had allowed journalists to sample their water were troubled when they came back with potentially dangerous lead levels. Some private homeowners said they plan to stop drinking from the tap.

"It's a little bit disturbing to see that there's that much," said Andrew Keddie, a retired professor who assumed his water was clean after replacing pipes years ago at his home in Edmonton, a city of almost 1 million in western Canada. What he couldn't do is replace public service lines delivering water to his house. After learning his water lead levels tested at 28 ppb, Keddie said he was "concerned enough that we won't be drinking and using this water."

Sarah Rana, 18, was one of tens of thousands of students who weren't alerted when her brick high school in Oakville, a town on the shores of Lake Ontario, found lead levels above national guidelines in dozens of water samples, the highest at 140 ppb. She found out on her own, looking at reports posted online.

"I was getting poisoned for four years and did not know about it," she said. "As a student, I think I should be told."

Leona Peterson learned of the contamination in her water after journalists found excessively high lead levels in 21 of 25 homes tested in her small, northwest port town of Prince Rupert. Peterson, who lives in subsidized housing for Indigenous people, had water that registered at 15.6 ppb.

"I was drinking from the tap, directly from the tap, without any knowledge that there was lead in the water," said Peterson. Her son was as well. Her response: "Hurt, real hurt."

The town of Prince Rupert, where whales, grizzly bears and bald eagles are common sights, is among more than a dozen communities along Canada's wild west coast where residents — many Indigenous — are living in homes with aging pipes, drinking corrosive rainwater that is likely to draw lead. But their province of British Columbia doesn't require municipalities to test tap water for lead.

Canadian officials where levels were high said they were aware that lead pipes can contaminate drinking water and that they were working to replace aging infrastructure.

And some localities are taking action. Montreal Mayor Valérie Plante vowed to test 100,000 homes for lead and speed up replacement of lead-lined pipes immediately after journalists sent her an analysis of the city's internal data revealing high lead levels across the city.

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