Estimating the number of cases of acute gastrointestinal illness (AGI) associated with Canadian municipal drinking water systems by Murphy HM1, Thomas MK1, Medeiros DT2, McFADYEN S2, Pintar KD1. Epidemiol Infect. 2015 Nov 13:1-15. [Epub ahead of print]
1 Centre for Food-borne, Environmental and Zoonotic Infectious Diseases, Public Health Agency of Canada, Guelph, ON, Canada.
2 Water and Air Quality Bureau, Healthy Environments and Consumer Safety Branch Health Canada, Ottawa, ON, Canada.
The estimated burden of endemic acute gastrointestinal illness (AGI) annually in Canada is 20·5 million cases. Approximately 4 million of these cases are domestically acquired and foodborne, yet the proportion of waterborne cases is unknown. A number of randomized controlled trials have been completed to estimate the influence of tap water from municipal drinking water plants on the burden of AGI. In Canada, 83% of the population (28 521 761 people) consumes tap water from municipal drinking water plants serving >1000 people. The drinking water-related AGI burden associated with the consumption of water from these systems in Canada is unknown. The objective of this research was to estimate the number of AGI cases attributable to consumption of drinking water from large municipal water supplies in Canada, using data from four household drinking water intervention trials. Canadian municipal water treatment systems were ranked into four categories based on source water type and quality, population size served, and treatment capability and barriers. The water treatment plants studied in the four household drinking water intervention trials were also ranked according to the aforementioned criteria, and the Canadian treatment plants were then scored against these criteria to develop four AGI risk groups. The proportion of illnesses attributed to distribution system events vs. source water quality/treatment failures was also estimated, to inform the focus of future intervention efforts. It is estimated that 334 966 cases (90% probability interval 183 006-501 026) of AGI per year are associated with the consumption of tap water from municipal systems that serve >1000 people in Canada. This study provides a framework for estimating the burden of waterborne illness at a national level and identifying existing knowledge gaps for future research and surveillance efforts, in Canada and abroad. [Emphasis added]
Study by Public Health Agency of Canada and Health Canada reveals hidden dangers of tap water: Millions of Canadians drinking from substandard sources by Tom Blackwell, November 26, 2015, National Post in Calgary Herald
More than 300,000 Canadians contract an acute stomach bug every year from the municipally-supplied water that comes out of their taps, some likely ending up in hospital or even dying, a new government study suggests.
The research also concludes millions of people are still getting their drinking water from substandard municipal and private systems — despite repeated safety warnings after the tainted-water disaster in Walkerton, Ont.
The authors at Public Health Agency of Canada and Health Canada argue the overall figures show the risk of getting sick from drinking water in Canada remains low.
But they suggest that more municipalities look at implementing multiple, fail-safe treatment “barriers,” shown to be the most effective way to keep water safe. The majority of Canadians get their tap water from such sources.
Almost 1.5 million people, however, are still served by municipal systems that have only one form of treatment or none at all, often drawing on surface water prone to contamination, the researchers say.
[Who makes industry pay when community drinking water reservoirs blow up after companies illegally fracture aquifers supplying that community?
A water-safety expert whose organization advised the Walkerton judicial inquiry said she was “shocked” by that number. [Is she shocked by the Alberta government and regulators fraudulently helping Encana break the law, cover-up and get away with contaminating an entire community’s drinking water supply, including from municipal and private water wells? Or is there no shock factor because the oil and gas industry contaminated the water, instead of bacteria? Where are the experts publicly stating their shock at the harm and fraud done by Encana, the Alberta government and regulators, including the “No Duty of Care,” completely legally immune, “Best in Class” AER?]
Such higher-risk systems were banned in Ontario after tap water contaminated with E. coli killed seven people in Walkerton in 2000, said Theresa McClenaghan of the Canadian Environmental Law Association. She thought everyone else had followed suit.
“(Walkerton) was a huge wake-up call, but here we are 15 years later and as the tragedy and the events recede in time, people start to forget the lessons,” McClenaghan said.
“It’s kind of an inexcusable risk to impose on people.”
There are also another 5.5 million Canadians who rely on private wells or smaller systems, another federal study notes, which leads to about 103,000 gastro illnesses a year.
The research is part of an effort to trace the source of an estimated 20.5 million acute gastrointestinal illnesses that occur every year in Canada, stomach upsets triggered by viruses and bacteria from Norwalk to salmonella.
A previous study attributes four million of these cases to food-borne pathogens, with the rest stemming from causes like person-to-person contact, touching animals and swimming in tainted water.
The gastrointestinal bugs can have minor effects, such as a day or two of diarrhea, vomiting or nausea, but sometimes lead to far more serious cases, notes Katarina Pintar, lead author and the agency’s manager of food-safety policy.
“We consider this to be a burden on the Canadian population,” she said. [What about the burden to Canadians losing their water because of hydraulic fracturing, or living in explosive risk in their homes because of industry’s known hazard of gas migration from fracing and leaking well bores?]
A study by Pintar and colleagues published this year suggested the four million food-caused cases result in 11,000 hospitalizations and 238 deaths.
Applying those figures to the estimated 430,000 water-borne cases would mean about 1,100 Canadians end up in hospital and 23 die from contaminated drinking water annually.
The problem, though, is that few of the acute cases are reported to authorities; the figures are all estimates.
In one of the new studies, the government team categorized municipal water systems serving 1,000 people or more according to the level of treatment, then used the results of earlier research on water-caused disease to extrapolate the total number of cases.
They came up with 334,000 illnesses from those larger systems. Using a similar method, they estimated 103,000 cases from smaller systems and private wells.
The methodology was sound, but the data used to reach the estimates are thin, making the results less than definitive, said Ron Hofmann, a civil engineering professor at the University of Toronto who advises water-system operators on safety.
Still, the estimates indicate that drinking water in Canada is very reliable, he said.
“They’ve shown, I believe … that personal hygiene and food are much more important than drinking water for these illnesses,” he said. “Overall, compared to other countries in the world, we have things really good in Canada.”
That’s true for most Canadians whose municipal water systems have multiple forms of treatment, coupling methods like chlorine disinfection, filters and ultraviolet light, said McClenaghan. New laws mandated that approach in Ontario after Walkerton.
But the story is different for those relying on systems without such protections, she said.
As for people who depend on private wells, they should have their water tested at least twice a year, and use some form of treatment, said McClenaghan. But a 2011 survey found just 27 per cent of people on private supplies tested their water at all. [How are Canadians to test their wells properly when companies refuse to completely disclose all chemicals injected during drilling, cementing, perforating, fracturing, acidizing and servicing? How are Canadians to “treat” toxic oil patch chemicals when they have no way of knowing what they are or if companies are fracturing the aquifers that supply their water wells? Emphasis added]