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A server brings drinks to patrons on the patio at Banditos, a restaurant in Ottawa, on its first day of reopening as Ontario moves into Stage 2 of its plan to lift pandemic lockdowns on June 12, 2020.Justin Tang/The Canadian Press

People who adhere to Canada’s guidelines for low-risk drinking are still vulnerable to alcohol-related cancers and other harms, according to a new modelling study that suggests Canadians should be advised to have no more than one drink a day.

The study, published in the Journal of Studies on Alcohol and Drugs, found more than 50 per cent of cancer deaths resulting from alcohol use in British Columbia in 2014 were among people who drank within the national guidelines or were former drinkers. That is, they consumed within the recommended limit of 10 drinks a week for women and 15 drinks a week for men.

British Columbians drinking within these guidelines also account for nearly 40 per cent of the alcohol-attributed deaths due to injuries that year.

“Basically, if you’re drinking any amount of alcohol, you’re increasing your risk of cancer – and that’s very clear – and for many other conditions as well,” said lead researcher Adam Sherk, a postdoctoral fellow at the Canadian Institute for Substance Use Research at the University of Victoria.

He and his team suggest that Canada follow the lead of the Netherlands, which recommends not drinking alcohol at all or, if people do, not more than one drink a day.

Canada’s low-risk drinking guidelines released in 2012 by the Canadian Centre on Substance Use and Addiction (CCSA), a non-governmental organization that reports to Parliament, are higher than those of many other wealthy countries, including France, Britain, Germany and the United States. The advised weekly limits of 10 and 15 drinks for women and men respectively equate to about 135 grams of ethanol for women and around 202 g for men, the researchers noted. By comparison, France recommends no more than 100 g of ethanol each week for both women and men, while the U.S. recommends no more than 98 g a week for women and 196 g a week for men.

“There's no doubt that the Canadian low-risk drinking guidelines are too high,” Dr. Sherk said.

Yet a recent Nanos poll, commissioned by CCSA, shows that even though 80 per cent of Canadians are drinking the same amount or less now than before the pandemic, many are exceeding the guidelines. On average, women said they were drinking 2.4 drinks on the days they consumed alcohol, while men said they had 2.8 drinks. One in 10 women said they had four or more drinks on the days they drank, and one in 10 men said they had five or more.

The margin of error for the poll is plus or minus 3.1 percentage points, 19 times out of 20.

Dr. Sherk and his team used computer modelling to analyze data on hospital stays, deaths and alcohol use in British Columbia for 2014.

Some health records they used provided information for conditions that are 100-per-cent attributable to alcohol use, such as alcohol-use disorder, Dr. Sherk explained. But other conditions, such as breast cancer, are only partly attributable to alcohol use. Although decades of research have established that ethanol causes cancer, he said, he and his team could not tell from the health records whether a patient’s breast cancer was caused by alcohol consumption. So, they relied on calculations of the risk relationship between breast cancer and alcohol use to estimate how many cases in their data set were attributable to alcohol.

The researchers found a total of 2,054 alcohol-attributable deaths and 13,760 alcohol-attributable hospital stays. Those who drank more than the national guidelines accounted for only a slim majority of the total harms. The rest – 38 per cent of the deaths and 32 per cent of the hospital stays – were among former drinkers and those who drank within the guidelines.

Besides cancer and injuries, those who drank within the guidelines experienced other harms, such as digestive conditions like liver cirrhosis and pancreatitis, and communicable diseases, including HIV, tuberculosis and lower respiratory tract infections. Dr. Sherk said with a communicable disease such as HIV, alcohol consumption can make people less likely to use protection when they have intercourse.

These findings support a body of recent research that suggests the harms of alcohol likely start at lower levels of consumption than previously thought, said Sheryl Spithoff, a staff physician at Women’s College Hospital and assistant professor at the University of Toronto, who was not involved in the study.

The study “adds weight to the call to re-evaluate our low-risk drinking guidelines,” Dr. Spithoff said, noting there is still debate about how much alcohol is safe. Some experts now think the harms start as soon as people consume alcohol, she said, while other studies suggest up to a drink per day is okay.

Catherine Paradis, a senior research and policy analyst at CCSA who was involved in creating the Canadian guidelines, said they were based on the best available research at the time. The recommended limits are higher than those of other countries likely because they are older and have yet to be updated, Dr. Paradis said.

While the current guidelines were designed with a focus on the health outcomes associated with drinking, she said there is now also much more evidence about the social harms related to alcohol, such as violence, financial problems and relationship problems, which should be taken into consideration.

Although Dr. Paradis did not have a timeline for when CCSA would be revisiting the Canadian guidelines, an update is overdue, she said. “It’s time.”

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