FAQ's about Exposure and Health

What is radiation?

Radiation is energy that is transmitted in the form of waves or particles. Scientists divide radiation into two broad categories – ionising radiation, and non-ionising radiation.

Ionising radiation is a proven hazard because it has enough energy to break apart molecules such as DNA which may in time lead to cancer. Non-ionising radiation does not have enough energy to cause such damage.

Where are we likely to come across ionising radiation?

We encounter ionising radiation constantly.  It occurs naturally in the rocks and soil, in the food and water we eat and drink, and bombards the earth’s atmosphere from outer space.  It is produced artificially, and widely used in medicine, industry and research.  It is used in X-rays, in radiotherapy to treat cancers, in smoke detectors, and in many industrial processes.  The production of electricity from nuclear power generates ionising radiation as a by-product.

Where do we come across non-ionising radiation?

Non-ionising radiation is generated by everyday energy sources, including light, heat, TV and radio signals, mobile phone signals, microwaves, and electro-magnetic fields associated with power lines.  The Department of the Environment, Community and Local Government is currently responsible for the health effects of non-ionising radiation including electromagnetic fields.

Can ionising radiation be avoided?

Ionising radiation has been with us since the birth of the universe.  Even if we could avoid artificially created radiation, we would still be exposed continuously to natural sources of ionising radiation.  Because it is present in the soil, we consume it in our food and water.  One type of natural radionuclide is radon gas that rises up through the ground into the atmosphere and we inhale it from the air when we breathe.  We cannot avoid exposure to ionising radiation – but we can minimise it.

How does ionising radiation affect the human body?

The effects of ionising radiation on the human body depend on the quantities of ionising radiation received.  In general, when ionising radiation enters the body it deposits some of its energy in human tissue typically by ionising atoms or possibly breaking the bonds of a molecule.  These chemical changes may damage the tissue which may not be repaired properly.  In time, the damaged tissue may become a cancer.

What are the effects of very high doses?

In big enough quantities - i.e. those encountered by being very close to the site of a severe nuclear accident or explosion, such as the fire-fighters in the Chernobyl accident - ionising radiation can destroy human cells at a faster rate than they can be replaced by the natural regeneration of cells that occurs continually in the body.  There is a high risk that this can cause serious illness and even death.


What are the effects of medium doses?

At medium doses, that is, those encountered by being exposed to a large source of radiation for a long period i.e. high radon concentrations in your home for a number of years, there is a medium risk that this may eventually lead to cancer several to forty years later.

What are the effects of low doses?

At low doses, that is, those typically encountered if you have low concentrations of radon in your home, there is a small risk that the damage caused to human cells will lead to cancer.

Is there a proven link between ionising radiation and cancer?

Yes, there is a general scientific consensus that ionising radiation can trigger changes in human tissue that can, in some circumstances, mutate into cancer.  The risk rises in line with increased exposure to ionising radiation, in the same way that the risk of skin cancer grows with increased exposure to the sun’s rays.

Is natural radiation less harmful than radiation from artificial sources?

No.  For a given amount of radiation, there is no difference between the harm caused by natural or artificial radiation.

What are the health risks from radon?

Radon is the second biggest cause of lung cancer in Ireland and worldwide after tobacco smoking.  Radon is responsible for up to 250 lung cancer cases in Ireland every year.

Does smoking increase the risk from radon-linked lung cancer?

Yes.  Like tobacco smoke, radon is classified as a Class A carcinogen.  The combination of tobacco and radon magnifies the risk of lung cancer. Smokers account for more than nine out of ten radon-linked lung cancer deaths in Ireland.  The radon risk to an active smoker is 25 times greater than to a lifelong non-smoker.

Are X-rays dangerous?

X-rays are a vital tool in medicine, ensuring the precise diagnosis of certain illnesses.  The radiation dose from a simple X-ray is extremely small and therefore the risk is correspondingly small.

How many X-rays is it safe to receive?

During a chest X-ray, the radiation dose received is comparable to two days normal background radiation exposure.  Therefore the risk is very small and can be justified on the basis that an illness may go undiagnosed without the X-ray and may have a higher risk.

What about more complex X-rays, such as CT scans?

The radiation dose from a chest CT scan is roughly the equivalent of that received from 250 chest X-rays.  Although substantially higher than the dose from a simple X-ray, the dose from a CT scan is still within acceptable risk limits.  The procedure will only be carried out if your consultant judges that the benefits outweigh any risk.

Should I try to avoid X-rays?

If the procedure is justified on medical grounds, the simple answer is no.  Pregnant women should be especially cautious, and should discuss the procedure in advance with a medical practitioner to ensure that any risk to the pregnancy is minimised.

Is it dangerous to swim in the Irish Sea?

Radioactivity has been monitored in the Irish Sea since 1982.  While radioactive discharges from Sellafield remain the main source of artificial radioactivity in the Irish sea, on-going monitoring has shown that these discharges have no significant health effect on the Irish public whether sailing, swimming or diving in the Irish Sea.

Is it safe to eat seafood from the Irish Sea?

The consumption of fish and shellfish is the main way the Irish public are exposed to radiation from Sellafield.  Radioactivity in seafood from the Irish Sea is constantly monitored.  Radiation doses to those who consume very large quantities of fish and shellfish have been calculated and represent less than four thousandth of the total annual average dose received by the Irish public.

Does air travel pose any radiation risk?

The earth is permanently exposed to a stream of atomic particles, which originate from the solar system and beyond.  Frequent flyers, particularly airline crew on long-haul routes, can receive radiation doses comparable with those who work directly with ionising radiation.  Air operators are legally obliged to evaluate the risk to air crew. For casual flyers, any health risk from air travel is likely to be low.

After Chernobyl, is it safe to visit Belarus or the Ukraine?

Based on available dose assessments, it is generally safe to visit these countries.  In the area around Chernobyl itself, the more heavily contaminated areas have been sealed off to the public.  If you are in these countries for a prolonged stay it may be wise, as a precautionary measure, to avoid eating mushrooms, berries, fresh-water fish and game.

Can children visiting Ireland from Chernobyl pass on radioactivity?

Children coming to Ireland as guests from the Chernobyl region may contain trace amounts of radioactivity as a result of contamination in their country.  However, the amount is likely to be very small in comparison with the amount of naturally occurring radioactivity in their body.  It certainly would not pose a radiation hazard to any other person.