Hundreds of thousands of Canadians have been unwittingly exposed to high levels of lead in their drinking water, according to a yearlong investigation conducted by more than 120 journalists. The investigation found that contamination in several cities was consistently higher than it ever was in Flint, Michigan, where lead-contaminated water sparked a public health crisis.

The media consortium that conducted the investigation, which included reporters from The Associated Press and the Institute for Investigative Journalism at Concordia University in Montreal, measured lead exposure in 11 cities across Canada. Out of 12,000 tests conducted since 2014, the group found that 33% exceeded Canada's national safety guideline of 5 parts per billion; 18% exceeded the U.S. limit of 15 ppb.

"I'm surprised," leading Canadian water safety researcher Bruce Lanphear told The Associated Press. "These are quite high given the kind of attention that has been given to Flint, Michigan, as having such extreme problems."

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Canada is one of the only developed countries in the world that does not have a nationwide drinking water standard. Even countries that struggle to provide safe drinking water have established acceptable lead levels: India's is 10 ppb and Mexico and Egypt's are 5 ppb, according to those nations' government websites.

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

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

Studies have shown that even low levels of lead exposure can affect a child's IQ and their ability to focus. Children who are younger than seven and pregnant women are most at risk from lead exposure, which can damage brains and kidneys. Yet the consortium's investigation found day cares and schools are not tested regularly. And when they are tested, those results are also not public.

The media consortium filed more than 700 FOIA requests and collected more than 79,000 water test results. But the findings are neither comprehensive nor an indication of overall drinking water quality in Canada.

"Because there is no federal oversight, everybody does what they want," engineering professor Michèle Prévost, who quit working on a government study of school drinking water in frustration over the lack of lead testing, told AP. "Most provinces ignore this very serious problem."

The government's approach to limiting lead in drinking water in Canada is starkly different from that in the U.S., where the Environmental Protection Agency sets legal standards and every citizen is supposed to receive an annual Consumer Confidence Report from their water provider detailing lead test results.

There's no similar, routine testing or notice in Canada — with the exception of the 14 million-person province of Ontario, which posts results online.

"If that's not public, that's a problem," Tom Neltner, a chemical engineer at the Environmental Defense Fund, told AP. "The public is more sensitive to the risks of lead, especially on children's development. Where you have transparency you have advocacy, and where you have advocacy you have action."

In the U.S., however, even public water quality reports weren't enough to prevent the Flint, Michigan, drinking water crisis, brought on by a 2014 decision to temporarily pull water from a river as a cost saver while installing new pipelines. The Flint crisis sparked congressional hearings, lawsuits and scrutiny of lead testing across the country.

In Canada, where lawsuits are less frequent and provinces — not the federal government — set water safety rules, the main source of lead in drinking water is antiquated pipes. At one government hearing, an expert estimated some 500,000 lead service lines are still delivering water to people in the country.

Some cities, like Montreal, are already working to replace them, tearing up streets and sidewalks with massive and expensive construction. But homeowners are almost always responsible for the cost of replacing the pipe that's on their property, which provincial studies say can range from $3,000 to $15,000.

Montreal's mayor, Valérie Plante, also vowed to test 100,000 homes for lead and speed up the 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.