Water toxicity experts estimate that at least 200,000 Canadian households are at risk of being exposed to lead through their drinking water as Americans in Flint, Mich., grapple with a drinking water scandal.
Research funded by the Canadian Water Network found that many of the country's older cities still have lead service lines connecting the home to the municipal water supply.
Lead researcher Michele Prevost says that while newer communities may not feature lead anywhere in their water infrastructure, cities built before 1950 often have thousands of homes that still rely on lead service lines.
Prevost, the principal chair on drinking water with the National Science and Engineering Research Council, says many municipalities aren't even aware of how many of the potentially dangerous lines are in use.
But she says some municipalities have made a concerted effort to address the issue and protect residents from lead exposure, which the study says is unsafe for human consumption in any quantity.
Despite those efforts, Prevost says the prospect of a crisis like the one in Flint can't be ruled out.
"We have several large cities that date way back before 1950 in Canada," Prevost said in a telephone interview. "So all of these older cities have lead service lines, and some of them have large numbers over and above 65,000 per city.
The size of a community can also present another risk factor, according to Prevost and other researchers.
Graham Gagnon, director for the Centre of Water Resources Studies at Dalhousie University, said smaller communities are at a disadvantage compared to large centres with the means of cataloguing and replacing problematic pipes.
"For the smaller to mid-sized municipalities ... it wouldn't necessarily surprise me, only from the standpoint that the resources needed to mount a lead service line replacement program are pretty substantial," Gagnon said of the likelihood of a Flint-style situation in Canada. "Knowing some of these cities, they would be challenged to really take this on."
Gagnon also stressed that the home is not the only potential source of exposure. Lead service lines are more prevalent in large buildings such as schools, he said, adding that toxicity could also come about through fixtures, faucets or other components containing lead.
Not all cities are at equal risk of lead exposure through their main infrastructure.
Bu Lam, manager of municipal programs at the Canadian Water Network, said communities built before about 1950 are far more likely to have used lead in either their municipal water mains or the service lines connecting them to local buildings.
The period between 1950 and 1990 served as a transition period, when cities began shifting away from the toxic material, he said. Buildings erected after 1990 are far less likely to feature potentially poisonous pipes, Lam added.
The bulk of problems arise, he said, when lead-free municipal water lines are connected to old lead pipes. Cities can't take charge of making those upgrades, he said, since service lines run off city property and become the responsibility of each individual homeowner.
That responsibility can't be fulfilled on a tight budget. Lam says he's heard of prices ranging anywhere from $2,000 to $5,000, with rates in each city varying according to labour cost, property size and a host of other factors.
Despite the cost, Lam says Canadians must take some responsibility to guarantee their own safety.
"The ideal situation, of course, is not to have any lead pipes at all," he said. "That's not the reality. The reality is that municipalities and homeowners have to play an equal role in trying to address that situation."
Research conducted by Prevost and colleagues in Halifax, Quebec City, Toronto and St. Catharines found that failure to upgrade service lines can in fact leave the residents of a home at greater risk than they were before cities improved their water mains.
Prevost said lead service lines connected to copper city pipes are more likely to cause an initial spike in the amount of lead released through a homeowner's taps due to a chemical reaction between the two metals.
Other metals and compounds pose less risk, and Prevost said municipalities can do much to mitigate risk by keeping careful track of the quality of their water supply.
"If you don't control the water quality and you have a lead service line, then the exposure can be very high and the risk unacceptable," she said. "Some of our Canadian utilities have a lot of service lines, but they're doing a great job in controlling the lead release with chemicals, and it works."
Gagnon said cities have started introducing some innovative strategies to lessen the cost for residents, including zero-interest loans that get repaid through the home water bill.
Gagnon said awareness of situations like the one in Flint, combined with a 2010 corrosion control guideline from Health Canada and the "greater outreach" that municipalities have undertaken, may help to reduce the number of Canadians at risk in the years to come.
Flint switched in 2014 to the Flint River from Detroit's water system. The river water was not treated properly and lead from pipes leached into Flint homes.