Radon Gas & Alpha Radiation 

Radon is a gas that no human sense can detect. It is dangerous as it is unstable and radioactive. As we breath it in, radon will emit alpha particle radiation and precipitate as solid radioactive metals within our lungs.

Harriet Brooks, unsung "collaborator", was actually one of Canada's trailblazing geniuses.

What do we know? 

  1. Radon was discovered in the late 1800’s by Canadian scientists Harriet Brooks and Ernst Rutherford at McGill University. Its ability to cause cancer was discovered in the 1950-1970’s in Canadian uranium miners. Very high residential radon was 1st discovered in the 1980’s.
  2. Radon emits alpha particle radiation, which, as it has mass, is very different to the more commonly known (and less dangerous) x-ray radiation that is made up of photons (light). For a given dose, alpha particle radiation deposits much more energy per unit of distance (what is called higher ‘linear energy transfer’) compared to x-rays, making it more hazardous.
  3. Radon has a half-life of 3.8 days, meaning that, in that period of time, 50% of a given amount of radon will have emitted an alpha particle and transformed into the next element in the chain of radioactive decay – in this case, solid radioactive polonium-210.
What the science says: 

In his 1904 book Radioactivity, Rutherford described the first experiments showing that radon – which he had called the ‘radium emanation’ – arose from the earth and accumulated in caves and cellars with undisturbed air.

Reference: Rutherford, E. Radioactivity of the Atmosphere and Ordinary Materials. Radioactivity. Cambridge University Press. 1904, Chapter 11, Section 212, pages 357-362.

Radon Exposure & DNA Damage 

The alpha particle radiation emitted by radon damages DNA in such a way that it is very difficult (impossible) for our cells to heal without causing genetic mutations. There is no dose of particle radiation that does not cause DNA damage.

  1. Four alpha particles are emitted for every radon atom that decays in our lungs. The first three are emitted quickly, as the radon transforms into longer-lived radioactive lead (210Pb).
  2. As alpha particles pass through lung cells, they cause serious DNA damage – the key ‘instructions’ for life that controls health. This damage is almost always clustered together in a very small space and also contains many different complex damage types.
  3. Our cells can repair DNA damage and, most of the time, this is quick and accurate – meaning few genetic mutations arise. However, our cells are not good at repairing alpha particle-induced DNA damage quickly or accurately. As a result of this, and unlike the more simple DNA damage from other types of radiation (such as x-rays), there is functionally no dose of particle radiation that is “safe” in terms of ‘consequence (mutation)-free’ DNA damage induction and repair.
What the science says: 

The main reason that the DNA damage from particle radiation is so hard-to-repair quickly and accurately is that it contains many different types of damage that are all very tightly clustered together.

Review Article Summarizing Research: Moore et al. The repair of environmentally relevant DNA double strand breaks caused by high linear energy transfer irradiation–no simple task. DNA Repair (Amst) 17, 64-73 (2014). Link to article. 

Radon and Cancer-Causing Mutations 

The genetic mutations caused by chronic exposure of lung cells to alpha particle radiation from radon will drive cancer formation. Depending on dose, it can take 1-3 decades before lung cancer is diagnosed.

  1. Radon is classified as a category 1 carcinogenic (cancer causing agent) by the International Agency for Research on Cancer (IARC). Category 1 is only assigned to carcinogens that research and medicine has established to cause cancer in humans and animals with no doubts whatsoever.
  2. Like many environmental lung carcinogens, such as tobacco or asbestos, it is chronic exposure to radon that is relevant to increasing relative lifetime risk of cancer.
  3. Cancer occurs when genetic mutations impact how a cell grows, divides and/or spreads. When more genetic mutations accumulate over time, the risk of a cell becoming cancer increases.
  4. The chances of getting a radon-induced lung cancer depend on the DOSE and DURATION of exposure, with higher exposures for longer periods meaning more genetic mutations greater cancer risk. Dose-for-dose, particle radiation causes a lot more genetic mutations than simple x-rays.
What the science says: 

The original IARC monograph on radon summarizes the evaluation of the cancer-causing effects of radon in people exposed to radon in uranium mines. The relationship was clear and without any doubt.

Reference: You can download a free copy of the IARC monograph on radon. (IARC Monographs on the Evaluation to Carcinogenic Risks to Humans, Volume 43, published in 1988).

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