Cancer study attacked by Agriculture Canada
When international cancer experts warned last fall that eating some meats can cause cancer, staff at Agriculture Canada responded by attacking the warning ’s credibility, government documents show.
The warning on Oct. 26 came from the International Agency for Research on Cancer (IARC), part of the World Health Organization.
Its announcement that consuming too much processed meat causes cancer — and eating too much red meat probably does, too — has worried meat producers.
The producers asked Agriculture Canada for help.
The department has a mandate to support Canadian food producers, and its staff drew up a set of criticisms of the IARC and its work, labelled “confidential” but now released under an access to information request.
The documents give an inside look at how the department formulated its position, briefed the minister in charge and prepared for dealings with Health Canada.
The criticisms drafted by Agriculture Canada attack IARC for allegedly considering too small a set of studies, and for not giving its panel of 22 experts time to read and analyze all the relevant material.
Among the critiques in its pointform list:
“IARC’s decision simply cannot be applied to people’s health because it considers just one piece of the health puzzle: theoretical hazards. Risks and benefits must be considered together before telling people what to eat, drink, drive, breathe or where to work.”
“Over 900 published papers were considered but fewer than 50 were deemed of sufficient scientific validity to warrant consideration by the panel,” it says, calling this a “reason for concern.”
Another reason for concern: “Researchers were still being given evidence to review and analyze a few minutes before the meeting was adjourned.”
“Final decisions were based on majority NOT consensus.” It says one-quarter of the experts voted against the position that IARC approved.
Agriculture Canada says some of the experts may have left the meeting early without voting, though it doesn’t say where this information came from.
It also notes that putting processed meat into a group of things that cause cancer doesn’t mean it’s a frequent cause. “For example, a peanut can cause someone to choke, but in reality this doesn’t happen very often.”
The documents also list possible risks to the meat industry, such as “calls by anti-meat NGOs for warning labels on processed meat packaging,” and reduced use of processed meat in schools, hospitals and seniors’ homes.
They also forecast that the IARC warning may have an impact on the next edition of the Canada Food Guide and the next revision of U.S. diet guidelines, cutting back the recommended amounts of some meats.
The documents also show that Agriculture staff considered approaching Health Canada with a pro-meat message:
“Since Health Canada is likely to be the recipient of any letters or comments on this issue, AAFC would need to reach out to Health Canada to contribute to any responses or to to help shape any resulting policy changes.”
The Agriculture Canada critique has drawn praise from Gordon Guyatt of McMaster University, a clinical epidemiologist and prominent health-policy analyst who invented the term “evidence-based medicine.”
Guyatt doesn’t eat meat, but he says he’s not worried about the cancer risk as presented by the IARC.
“There was what one might characterize as hysteria over this WHO thing,” he said on Thursday.
“The way things were presented to the public (by the IARC) was that red meat causes cancer the way smoking causes cancer,” he said. “And that was extremely misleading.”
In the case of smoking, he said, there is a massive number of studies showing “a very large magnitude of risk.” But he said the evidence against red meat and processed meat is weaker, and if there is a risk, “the effect appears to be quite small.”
“The evidence against red meat is so much weaker that it could easily be explained by confounding,” meaning other factors that also influence a person’s health, he said.
“It is quite challenging to communicate risk,” he noted.