Drinking asbestos is safe? Health Canada’s new study can’t see why not

While Canadians navigated a sweltering 2024 summer, scientists were polishing a study that could impact the health of millions at home—at their faucets. 

Canadians need not worry about drinking asbestos fibres, according to “Review of epidemiological and toxicological studies on health effects from ingestion of asbestos in drinking water.” Published in Critical Reviews in Toxicology,  a journal previously criticized regarding asbestos, it echoes conclusions dating to 1989, “Overall, the currently available body of evidence is insufficient to establish a clear link between asbestos contamination in drinking water and adverse health effects.”

The new paper claims to be a “systematic review”— a gold standard study of all available data, like gathering pixels to see a clearer picture of what the science shows. It is not.

Contamination from asbestos-reinforced cement (AC) drinking water supply pipes are the stated reason for the study, but “pipe” was omitted from the elaborate literature search. What important information was missed?

Scholars build careers in pursuit of “the truth,” compiling original data. Systematic reviews avoid the “game of telephone” where a message is whispered around a circle, and everyone laughs at the garbled result. A “review of reviews” of half a century of research on asbestos and disease will suffer this problem. Unfortunately, the new review largely relied on previous reviews, and even misconstrued some primary data. 

One example. In 1980, Donham et al. published the largest animal study at the time, involving 501 rats. The 200 rats fed Canadian chrysotile asbestos had:

• asbestos fibres in colon tissue;
• lower levels of a cellular biochemical regulator; and
• more colon tumours, plus an asbestos-related mesothelioma. 

A smaller proportion of “control” animals developed tumours.

The U.S. regulates asbestos in drinking water. Canada doesn’t. 

This saga began in 1973 when the newly-founded U.S. Environmental Protection Agency (EPA) discovered high levels of asbestos in Duluth, Minnesota’s drinking water. The Reserve Mining Co. was dumping asbestos-laden tailings in Lake Superior.  By the 1970s, fine airborne fibres of the “miracle mineral” asbestos afflicted workers and their families with lung disease (asbestosis) and cancers. Breathing asbestos was known to be harmful, but was it safe to drink?

The EPA said, “No.” Reserve Mining lost its historic two-year court battle, and the EPA ordered them to stop polluting the lake. 

After two decades of research, including the Donham study, the U.S. EPA regulated asbestos under the Safe Drinking Water Act in 1992.

In contrast, Canada’s hands-off approach has been based on a 1989 evaluation. Unpublished re-evaluations in 2005, 2013 and 2018 all reaffirmed: “There is no consistent, convincing evidence that asbestos ingested through drinking water is harmful to your health.” This doubt rests on the absurdity of whether asbestos-related cancers throughout the abdomen — in the stomach, liver, colon, pancreas and other tissues — result from migration of inhaled fibres, swallowing asbestos-laden mucus cleared from the lungs, or swallowing contaminated water. For whatever reasons, gastrointestinal cancers are increasing rapidly in younger Canadians.

Surprisingly, the “consistent, convincing …” standard is not in Canadian law. Asbestos is listed as “toxic” under the Canadian Environmental Protection Act, because it “may … constitute a danger to human life or health” (s.64). How can inaction based on more stringent criteria be consistent with the Precautionary Principle under the Act? 

It could be a long wait for “consistent, convincing evidence,” because Canadian labs don’t measure asbestos in water. Authorities have not established a Canadian method, at best referencing the U.S. EPA. Nevertheless, CTV’s W5 “Something in the Water” revealed asbestos levels exceeding the U.S. standard. 

Millions of people in North America drink water from AC water supply pipes — hundreds of thousands of kilometres of aging infrastructure that is degrading, breaking, and shedding increasing quantities of asbestos into drinking water.  Over the 35 years since Canadians were first reassured that swallowing asbestos is safe, AC pipes have been breaking with increasing frequency, requiring expensive, disruptive emergency repairs.

Fortunately, a recently patented technology, “close tolerance pipe slurrification” is available in Canada to replace asbestos cement water pipes safely, with minimal digging and disruption.

Statistics Canada reports that more than 15 percent of Canada’s water supply pipes are in poor shape. Details on AC pipes are expected in 2025. Using maps of AC pipes over time, the CANUE research consortium might be able to study links between drinking water supply and cancers. Health Canada told us this might occur, if the data is “fit for purpose.” 

Close to 100 percent of the asbestos imported into the U.S. came from Canada. The American Cancer Society highlights cancer risks from “swallowing asbestos” and “water that flows through asbestos cement pipes.” The World Health Organization states, “The main source of asbestos in drinking water is from the release of asbestos fibres from A/C pipes.” 

Reserve Mining Co. focused attention on waterborne asbestos. Half a century later, Health Canada owes Canadians, and the rest of the world, credible science, and action to stop drinking asbestos. The pipes are failing. We cannot afford delay.