Swift Current presentation highlights health impacts of ionizing radiation

Posted on 26 October 2026 by Ryan Dahlman

By Matthew Liebenberg

mliebenberg@prairiepost.com

Retired family physician Dr. Dale Dewar continues to raise awareness about the adverse effects of ionizing radiation on human health.

She is a former executive director of International Physicians for the Prevention of Nuclear War Canada and co-authored the 2014 book From Hiroshima to Fukushima to You: A Primer on Radiation and Health.

She was the guest speaker at a weekly lunch meeting of the Swift Current Kiwanis Club on Sept. 18 and also made an afternoon presentation at an event hosted by the First United Church Earthcare Partners, an interest group in the congregation that promotes discussion and awareness about the environment.

Ionizing radiation can come from natural sources, such as cosmic rays from the sun and the radioactive gas radon, or from human-made sources such as medical imaging equipment (X-rays, CT and PET scans) and nuclear power use (generation, accidents or nuclear weapons).

“No matter who I have as an audience when I speak about ionizing radiation or health effects studies, there will be somebody who reminds me that doctors cause the greatest radiation burden that people carry,” she said during her afternoon presentation. “Every X-ray that we have leaves marks in our body. In terms of damage done, X-rays are cumulative. We see this especially in children.”

She also referred to the impact that ionizing radiation from natural sources can have on human health.

“We know that cosmic rays from the sun can cause skin cancer,” she said. “We also know that radon, one of the gases found in the decay chain of uranium, causes 20 per cent of the lung cancers in non-smokers in Canada. That’s 20 per cent from a gas that we get that may be in the ground around us.”

The focus of her presentation was mostly on the ionizing radiation from human-made sources and the long history of radiation safety claims.

“I’d like to speak to the topic of ionizing radiation with using the terms fraudulent forever, because from the very beginning of the use of ionizing radiation in health and in humans, there were lies and more lies and information was withheld at various points in development,” she stated.

Dewar has been critical of the nuclear industry over the years and she noted that proponents of the industry continue to question the effect of ionizing radiation.

“There’s been this quarrel going on and we still see it today over whether or not ionizing radiation is bad for humans,” she said. “I think that we still see that in some of the news, especially by people who want to further the nuclear industry.”

She mentioned that it took a long time for the scientific community to make a clear statement about the effects of ionizing radiation. A landmark declaration by the Committee on the Biological Effects of Ionizing Radiation (BEIR), a committee of the American National Research Council, was issued in 2006.

“It had taken them 30 years to come to this,” she said. “Each one of the preceding BEIR reports had come close to saying we don’t see any way around it and we do have to say that it looks like ionizing radiation is harmful, but they wouldn’t come right out and say it. The BEIR VII [report] said there was no level at which there is a zero effect on biological systems.”

The dose of ionizing radiation, which is measured in millisieverts (mSv), will vary between different types of medical imaging scans. Dewar’s presentation indicated that a chest X-ray will result in 0.1 mSv per view and a chest CT scan will cause about 10 mSv of radiation. A bitewing dental X-ray has a reading of 0.005 mSv and a panoramic dental X-ray of the entire mouth will result in a reading of 0.15 mSv.

While medical practitioners rely on diagnostic imaging to detect injuries and illnesses, Dewar cautioned that X-rays and CT scans are often ordered far too routinely. She has done presentations at medical conferences to share the recommendations of the Choosing Wisely Canada radiology guide that advises against the overuse of diagnostic imaging.

Choosing Wisely Canada is a national, clinician-led initiative for reducing unnecessary tests and treatments when there is strong scientific evidence that they are not helpful to patients or may expose them to harm. The radiology guide suggests that routine or early diagnostic imaging should be avoided unless there are specific red flags or clinical indications present.

She believes it is important for patients to take ownership of their medical decisions by directly questioning physicians before consenting to diagnostic procedures. She cautioned against accepting vague diagnostic “fishing expeditions” and she has advised people to inquire whether a proposed scan will yield actionable clinical information.

“I really don’t think people should treat their doctors if they’re sort of a god walking on the ground,” she said. “Step back and examine what you’re going to go for. Are you going to learn something useful? If you’re not going to learn something useful, why would you go and have it?”