Many people are afraid of radiation. They think of it as an invisible, man-made, deadly force, and this fear often underpins opposition to nuclear power.
In fact, most of the radiation is natural and life on Earth would not be possible without it.
In nuclear energy and nuclear medicine, we have simply harnessed radiation for our own use, just as we harness fire or the medicinal properties of plants, which also have the power to do harm.
Unlike some toxins found in nature, humans have evolved to live with low doses of radiation, and only relatively high doses are harmful.
A good analogy for this is paracetamol: one tablet can cure your headache, but if you take a whole box at once, it can kill you.
The Big Bang, which occurred almost 14 billion years ago, generated radiation in the form of atoms known as primordial radionuclides (in this case primordial refers to the beginning of time).
These are now part of everything in the universe. Some have very long physical half-lives.
The half-life is the measure of how long it takes for half of its radioactivity to disintegrate: for a radioactive form of thorium it is 14,000 million years, for one of uranium 4,500 million and one of potassium 1,300 million.
Primordial radionuclides are still present today in rocks, minerals, and soil .
Its decomposition provides a source of heat inside the Earth, turning its molten iron core into a convection dynamo that maintains a magnetic field strong enough to protect us from cosmic radiation that would otherwise wipe out life on Earth. the planet.
Without this radioactivity, the Earth would have gradually cooled down to a dead rocky globe with a ball of cold iron in the center, and life would not exist.
Radiation from space interacts with elements in the Earth’s upper atmosphere and some surface minerals to produce new “cosmogenic” radionuclides, which include well-known forms of hydrogen, carbon, aluminum, and other elements.
Most decay quickly, except for a radioactive form of carbon whose half-life of 5,700 years allows archaeologists to use it for radiocarbon dating.
Primordial and cosmogenic radionuclides are the source of most of the radiation that surrounds us.
Plants absorb radiation from the ground, and it is found in foods such as bananas, beans, carrots, potatoes, peanuts, and Brazil nuts.
Beer, for example, contains a radioactive form of potassium, but only about a tenth of that is found in carrot juice.
Most of the radionuclides in food pass through our body and are eliminated, but some remain for some time (their biological half-life is the time it takes for our body to eliminate them).
That same radioactive form of potassium emits high-energy gamma rays as it decays and escapes the human body, ensuring that we are all slightly radioactive.
Living with radioactivity
Historically, we have not been aware of the presence of radioactivity in our environment, but our bodies naturally evolved to live with it.
Our cells have developed protective mechanisms that stimulate DNA repair in response to radiation damage.
Natural radioactivity was first discovered by French scientist Henri Becquerel in 1896.
The first man-made radioactive materials were produced by Marie and Pierre Curie in the 1930s and have been used in science, industry, agriculture, and medicine ever since.
For example, radiation therapy remains one of the most important methods of treating cancer.
To increase the potency of therapeutic radiation, researchers are currently trying to modify cancer cells so they are less able to repair themselves.
We use radioactive material for both diagnosis and treatment in “nuclear medicine”.
Patients are injected with specific radionuclides depending on the part of the body where treatment or diagnosis is needed.
Radioactive iodine, for example, accumulates in the thyroid gland, while radium accumulates mainly in the bones.
The emitted radiation is used to diagnose cancerous tumors. Radionuclides are also used to treat cancer by directing emitted radiation at a tumor.
The most common medical radioisotope is 99mTc (technetium), which is used in 30 million procedures each year worldwide.
Like many other medical isotopes, it is artificial, derived from a parent radionuclide that is itself created from the fission of uranium in a nuclear reactor.
Radiation fear could boost fossil fuels
Despite the benefits that nuclear reactors offer us, people fear the radiation they generate, either from nuclear waste or from accidents such as Chernobyl or Fukushima.
But very few people have died from nuclear power generation or accidents compared to other primary energy sources.
We are concerned that fear of radiation is harming climate mitigation strategies.
For example, Germany currently generates about a quarter of its electricity from coal, but considers nuclear power dangerous and is shutting down the remaining nuclear power plants.
But modern reactors generate minimal waste.
This waste, along with legacy waste from old reactors, can be immobilized in cement and glass and disposed of underground.
Radioactive waste also does not generate carbon dioxide, unlike coal, gas or oil.
We now have the understanding to safely harness radiation and use it for our benefit and that of our planet.
By fearing it so much and rejecting nuclear energy as a primary energy source, we risk being dependent on fossil fuels for longer.
This not radiation is what puts us and the planet in the greatest danger.