Health effects

The human body is made up of cells that are able to reproduce. Reproduction is a continual process in all living organisms. Ionising radiation that penetrates a cell can affect this process of reproduction by causing abnormal chemical reactions. Some of these reactions can lead to the death of the cell and others to its survival in a modified form (mutation).

The effects of ionising radiation vary depending on the dose received and the source, method and target of the exposure.

Depending on the dose received during exposure to ionising radiation, there are two types of biological effects: acute or deterministic effects and long-term or probabilistic/stochastic effects.

The acute effects are the direct/immediate effects that appear after a certain exposure threshold (> 1 Sv), in particular when there are very high levels of irradiation for a short period of time. They immediately cause the death of a large number of cells.

They entail nausea, vomiting, skin burns, diarrhoea, convulsions, a drop in lymphocytes and other symptoms that can lead to death.

These effects appear after several hours or days following irradiation. This is also called radiation sickness.

Medical treatment in a specialised centre is required.

Radiation can cause health consequences known as 'late' or 'delayed' effects. These appear in a random manner.

These effects include serious illnesses such as leukaemia and various cancers (of the lungs, thyroid, digestive and urinary tracts, etc.).

Radiation can alter the genome/gene pool and cause genetic anomalies in subsequent generations.

The level of radiation in the event of a nuclear accident is much higher the closer you are to the site of the accident. As far as Grand Duchy of Luxembourg and its population are concerned, the exposure threshold in the event of a nuclear accident at a nearby nuclear power station would most probably not be of sufficient scale to cause acute effects.

The emergency response plan (PIU) in the event of a nuclear accident sets reference levels which, when exceeded, trigger protective measures to avoid or reduce the health risk to the Luxembourg population.

Any damage caused by low levels of radioactivity can potentially be repaired by the body's normal metabolic mechanisms.

Following an accident at a nuclear power station, some categories of people (personnel from the emergency services, the police and the Radiation Protection Department, etc.) may be required to carry out emergency response work within a contaminated zone.

The response personnel who are required to intervene and carry out rescue work in the event of a nuclear accident are more likely to be exposed to the effects of the accident.

They are not sent into regions that have been evacuated or where the population have been advised to take shelter during the release phase unless their task is to save lives, prevent serious radiation-induced health problems or avert catastrophic situations.

They are subjected to specific monitoring to ensure they are not exposed to a higher dose than that set for such an intervention.

Depending on the location and level of exposure, response staff will be required to wear specific protective clothing, rubber boots, single-use gloves, protective breathing masks and even protective goggles for the eyes.

The first response workers, namely rescue workers and the employees at the nuclear power station, are the most susceptible to exposure to high doses of radiation: The level of radiation in a nuclear accident is much higher the closer you are to the site of the accident. The response staff may therefore be exposed to radiation that could cause acute effects.

The probability of developing cancer or genetic anomalies is proportional to the radiation dose received. The higher the dose, the higher the risk of developing cancer.

However, in the same way as we all react differently to atmospheric pollution, we do not all have the same levels of sensitivity to radiation exposure. The youngest cells (those of babies or small children) and those that renew very quickly (intestinal villi) are the most sensitive to radiation. Therefore, for example, the risk of developing a cancer of the thyroid gland (the organ to which iodine-131 attaches) after exposure to radioactive iodine is higher in children and teenagers than adults.

Several types of symptoms can appear following exposure to a radiation dose exceeding 1 sievert (1000 millisieverts). These symptoms include nausea, vomiting, burns on the skin, diarrhoea, convulsions and a drop in lymphocytes.

Doses above 4 sieverts (4,000 millisieverts) are potentially deadly. The length of time it takes for these effects to appear can vary, from several hours to several days following irradiation or contamination.

Acute radiation syndrome (radiation sickness) is a series of effects caused by exposure to a radiation dose above 1 sievert (1000 millisieverts, or around 300 times the natural exposure a person experiences annually).

This syndrome, which causes headaches, nausea and vomiting, manifests itself more and more severely as the radiation dose increases and can lead to death in the event of higher doses (>8 Sv).

Between 4 and 5 Sv, the death rate without medical treatment is 50%.

The level of radiation in the event of a nuclear accident is much higher the closer you are to the site of the accident. As far as the Grand Duchy of Luxembourg and its population are concerned, the exposure threshold in the event of a nuclear accident at a nearby nuclear power station would most probably not be of sufficient scale to cause acute effects.

In the event of a nuclear accident at Cattenom, the protective measures set by the emergency plan are designed to avoid any exposure to doses of acute levels.

The impact of exposure to ionising radiation on biological tissues is expressed as an 'effective dose'. The unit used for the effective dose is the Sievert (Sv). The Sievert is a large unit, which is why millisieverts (1 mSv = 0.001 Sv), or even microsieverts (1 Sv = 0.000001 Sv), are often used.

Below is a list of examples of effective doses of radiation received in different situations and the three reference levels in Luxembourg that lead to the different protective measures for nuclear accidents being triggered.