Fanny’s Factcheck: Are we going to turn into luminous little green men?
From the comic book: 'De Kiekeboes: Uranium-235'
In ‘Uranium-235’, Fanny is chasing a smuggler of radioactive waste, and where better to find them than at Nuclean? The fictitious comic strip company specialises in the processing of radioactive waste. During a visit to Nuclean, Fanny meets a man who churns out nothing but clichés and nonsense. He asserts that radiation can turn you into a luminous little green man. Is that right? Of course not! Radiation is a natural phenomenon. While it can damage DNA at high doses, in controlled quantities, it also saves lives!
© In collaboration with De Standaard Uitgeverij. All illustrations and storylines belong to them.
Radioactivity is everywhere
Radioactivity is a natural phenomenon. Our air, our plants, our chairs and even ourselves – literally everything is constructed from atoms. Each atom, in turn, is made up of even smaller particles: protons and neutrons that sit together in a nucleus, and electrons that float in a cloud around the nucleus. If too many particles are crowded together in the nucleus, that nucleus may have too much energy. This is what we mean by an unstable or radioactive nucleus. An unstable nucleus will want to evolve towards a stable state. It will therefore emit its surplus of energy and does so by 'showing a particle the door'. The energy surplus is sent outwards and may occur in the form of particles (alpha, beta or neutron) or radiation (gamma). We call this emission ionising radiation.
‘Radioactive Brazil nuts’
Did you know that you get a dose of 0.001 mSv if you eat 30 grams of Brazil nuts?
This is because ionising radiation has been present since the Earth came to be. It is quite literally everywhere: in the water, in the air, in the soil and … in our Brazil nuts. Living beings are also radioactive. And we as humans are no exception to that!
So everyone is constantly being exposed to ionising radiation. The average Belgian receives an annual dose of 4 millisieverts (mSv) per year. Part of that comes from nature. Consider, for example, radiation from substances in the Earth's crust or cosmic rays. The latter, which in high doses can be deadly in space, are dampened by the Earth's atmosphere and magnetic field. In addition, we breathe in radionuclides – such as radon – or we eat them, just like with our Brazil nuts.
The total exposure to natural radiation is estimated at 2.4 mSv/year. If the total annual dose amounts to 4 mSv, then where does the other part of exposure come from? It might surprise you, but that exposure originates from medical applications. In medicine, ionising radiation is used to make a diagnosis (radiography, CT scan, scintigraphy, etc.), for sterilising medical equipment (needles, razors, etc.) and for therapeutic applications (the various kinds of radiotherapy).
Radioactivity is also used in industry, for example to irradiate food so as to keep it fresh for longer, to check welding seams or to produce electricity. Industrial facilities – including nuclear power stations – are, in contrast, responsible for less than 1% of the dose received every year.
About quantities and units
Activity, dose, sievert … What do they all mean? A brief overview of quantities and units:
- Becquerel (Bq): This is the unit of Activity: in other ways, it says how 'much' something is radiating.
- Gray (Gy): This unit expresses how much radiation a material has absorbed (I.e. how much energy is taken in per kilogram).
- Sievert (Sv): The biological effect that radiation has on a living organism is expressed with the sievert unit. Sievert is the unit of dose: you can understand that as the amount of damage the radiation causes.
Effects of radiation on our bodies
Ionising radiation emitted passes through our bodies. The body can handle a low dose. After all, it is equipped with mechanisms for repairing damaged cells. However, when the exposure to ionising radiation is very intense or persists for a long time, our repair mechanisms are no longer able to handle it. You won't suddenly turn green and luminous, but healthy cells may die off and/or the cells' DNA can be damaged, meaning they can no longer perform their function properly.
The effects of radiation vary and depend upon:
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The higher the dose and the faster you incur the dose, the greater the damage to the body. In the event of high doses – even over a short period – the effects of radiation are immediate and can be serious. In technical jargon, these are known as deterministic effects: they are certain to appear in a tissue from a certain threshold dose.
In the event of long-term exposure to low doses, the effects of radiation will not appear until later on. One of the consequences is an increased chance of cancer or genetic deviations in any offspring. The risk that these delayed effects will occur also depends upon the dose incurred: it steadily declines in line with the dose received. However, no threshold value has been determined here. The science begins with the theoretical notion that any exposure – however small – has an effect.
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Some radionuclides spread out homogeneously in the body, while others are concentrated in one or more organs. Iodine-131 is one example of this – it mounts up in the thyroid gland. Not every radionuclide emits the same type of radiation, and different types of radiation have varying effects. For example, an alpha emitter will cause a great deal of damage locally at a short distance, while a beta emitter is less damaging, but will be able to permeate further into a material, meaning the damage will be more spread out.
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Radiation sensitivity – even with equal doses – varies sharply from person to person. Children and pregnant women are the most sensitive to consequences from ionising radiation. Not all organs are equally sensitive to radiation either: the impact of ionising radiation on lungs, for example, is greater than on skin and bone tissue.
Basic rules for radiological protection
Living and working with ionising radiation requires some precautions. In the sector, we maintain the ALARA principle. ALARA stands for ‘As Low As Reasonably Achievable’. It means that a dose of radiation should always be kept as low as reasonably possible. But how do you limit that exposure, when you come into contact with a radioactive source? To do so, we adhere to the following basic rules:
Three rules
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Limit the time during which you come into contact with the source.
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Maintain as much distance as possible from the radioactive source.
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Shielding fences keep radiation at bay and protect people.
People who come into contact with ionising radiation professionally are specifically trained to handle it carefully. On top of that, they wear adapted clothing, such as overalls, lead aprons, gloves or full-face masks.
Saving lives
And what if … we were to use that same radiation to attack cancer cells? That might sound like science fiction, but it's not! In the past century, we have garnered knowledge on radiation effects at various dose levels. We studied human cells, examined plants and analysed other micro-organisms. With one goal in mind: unravelling the biological mechanisms behind the effects of radiation. Today, we are using that knowledge we have garnered to help cure cancer patients.
Very specifically, at SCK CEN, we are researching and developing Targeted Radionuclide Therapy (TRT). This is where a specially designed molecule navigates to a tumour and any metastases, and attaches to it. It carries a radionuclide along with it. This radionuclide emits its excess energy, thus irradiating cancer cells in a highly localised and precise manner. The cancer cells are damaged, causing them to die off and the tumour eventually shrinks. The healthy tissue remains largely spared. In other words, it is work down to the millimetre and precision medicine.
For patients, this translates into fewer side-effects and a better quality of life. With TRT, then, we are entering a new era in which cancer treatment is not only more targeted, but also more personal. Francis Ligot testifies as such in this video: he has already been through two such treatments.
Would you like to know more about this type of cancer treatment? Click here!
Conclusion – Is radioactivity dangerous?
Ionising radiation is only dangerous when we are exposed to high doses (for a long time) or handle it in an unsafe way. Radiation mainly offers opportunities. Doctors have been using it to help track down cancer, heart conditions and other diseases for many years, and in modern times, more and more to treat cancer too. It is very important, however, that we handle it responsibly.
Safety
SCK CEN sets great store by safety. In order to avoid building up ‘too much radiation’, we closely monitor our exposure. We monitor our own employees' radiation doses and measure radioactivity throughout Belgium to protect the population. We report on this to FANC, the Federal Agency for Nuclear Control. But how do you monitor something you cannot see, smell, hear or feel? You can read that in Fanny’s fact check on ‘Measuring radioactivity’!
Click here to read Fanny's Factcheck about 'measuring radioactivity'