Ionising radiation: should we be concerned?

All humans experience ionising radiation constantly and it is all around us. Your first time thinking about radiation and its effects were likely to be at the dentist’s office when the dentist stepped outside to take an X-ray of your teeth. Although many people worry about the dose of radiation they receive on a regular basis, this article should explain why radiation should not be a concern for most people around the world.

Radiation is a form of energy that travels through a medium. There are many different types of radiation and only some of them are ionising. Ionising radiation is radiation that has enough energy to remove electrons from an atom, which causes it to become ionised, and form an ion. Only the high-frequency part of the electromagnetic spectrum, ultraviolet, X rays and gamma rays are ionising.

Although ionising radiation can come from artificial sources like X-ray machines, there are many natural sources of ionising radiation. Buildings, soil, food, and drink are just some of the things that naturally produce low levels of ionising radiation. One of the most famous examples of radioactive food are bananas. Bananas have radioactive 40K, but you would have to eat 100 million bananas in one go for the dose to be fatal! This is why the dentist steps outside when you are getting an X-ray because they take an awful lot of those X-rays, and they would be receiving a huge dose of ionising radiation every year if they did not try to minimise their exposure.

Ionising radiation is harmful in high doses because it can heat your DNA and cause damage to the DNA inside your cells. It can cause single-strand or double-strand breaks which are not harmful if they can be repaired. However, if the damage causes errors in the DNA code, it can cause mutations that could make a cell cancerous. If there is no way for the damage to be repaired, then the cell will be killed. Not all cells are equally sensitive to the effects of radiation. Cells that are dividing like skin and intestinal cells are the most sensitive to damage while neurons are quite radioresistant.

Although radiation sounds very dangerous it is safe in low doses. It is used in a wide variety of medical treatments such as tracers or in radiotherapy. Radioactive iodine is often used to help detect thyroid cancer as it has a short half-life and decays fast enough that it does not cause the body damage. Ionising radiation is also used in radiotherapy as a treatment for cancer because the correct dose of radiation can kill tumour cells and help immune cells get to the cancerous cells.

If someone does receive too large of a dose of radiation, some treatments can help as long as the dose is not too high. One possible treatment is the salt potassium iodide (KI), which helps to treat poisoning by radioactive iodine. This salt can block the radioactive iodine from being absorbed by the thyroid gland which protects it from damage by radiation and can prevent thyroid cancers from developing. Although KI is an effective treatment for iodine poisoning, if the dose of any form of ionising radiation is too high, there are no treatments available. If someone receives a dose of radiation higher than 10.0Gy, they will experience severe gastrointestinal damage and cardiovascular collapse, with most cases ending with death in about two weeks.

Even though most organisms cannot withstand regular high doses of radiation the bacteria Deinococcus radiodurans can actually withstand very high levels. This is because it has a very efficient DNA repair system that can quickly and accurately repair any damage or breaks in the DNA that occur as a result of radiation. Also, the bacteria have high levels of antioxidants which prevent damage to cells caused by free radicals which can be produced from radiation exposure. This allows the bacteria to avoid the damage radiation usually causes which allows them to be exposed to large amounts of it.

Ionising radiation might sound very dangerous, and in high doses, it can certainly cause a lot of damage. However, it is important to bear in mind that the very low doses the average person experiences daily should not be a concern of the general population, and the improvements humans get from being able to use radiation are immeasurable. Whether ionising radiation is being used to detect cancers, gamma rays are being used to carefully clean medical equipment, or you receive some radiation from your post-lunch banana, it is certainly not something to be afraid of.

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