Health effects at low doses
Most exposure comes from the medical sector
Radioactivity has been around since the origin of the earth. It is literally everywhere: in water, air, soil and living creatures. In other words, radioactivity is a natural phenomenon but is also used in human activities. Every year, the average Belgian citizen is exposed to a dose of 4 millisievert. Almost half of it comes from medical applications in which ionising radiation is used for diagnostic purposes.
Health effects at low doses?
The radiation dose depends on the type of examination and the number of examinations. It could, for instance, take eight months to reach the same radiation dose through natural exposure than with a CT scan of the head. The medical sector keeps the doses as low as possible but does this low dose still have an impact on healthy tissue? Which effect do these low doses have in the short and long term? SCK CEN disentangles the mechanisms to get a better understanding of the health effects. By scientifically substantiating these mechanisms, SCK CEN tries to improve the radiation protection. Both in the medical sector and beyond.
Three systems within the body
The research of SCK CEN focuses on three systems in the human body.
Our cognitive skills or abilities define the extent to which people are able to absorb and process knowledge and information. Irradiation during pregnancy or the treatment of brain cancer at a young age increase the risk that children will experience cognitive problems later in life. Their learning ability and IQ may be affected. SCK CEN examines the underlying mechanisms to be able to develop targeted medication.
Exposure to ionising radiation may lead to more cardiovascular diseases. What is the cause of this? Which mechanisms play a role here? As from which radiation dose are these mechanisms activated? Can countermeasures mitigate these effects? The research of SCK CEN aims to find an answer to these questions.
The immune system is affected by ionising radiation. At low doses, it will become overactive whereas it will be weakened at high doses. With the radiation doses that are found in space, people will age faster. The muscles will be weakened and people will get a cold more easily. Other factors such as psychological stress may increase these effects. SCK CEN performs research into how our body reacts to this combination of factors.
Biomarkers: natural predictors of radiation sensitivity
Radiation sensitivity differs from person to person. It depends on factors such as age, gender and genetics. Women, for instance, run a higher risk of contracting breast cancer than men after radiotherapy. People with certain genetic disorders have an increased risk of cancer, including patients with ataxia telangiectasia, a genetic disorder of the nerves and the immune system. To be able to predict this radiation sensitivity, SCK CEN performs research into so-called biomarkers. Biomarkers are natural molecules, genes or other biological characteristics that tell us more about processes in the body. With this knowledge, SCK CEN can, for instance, predict which patients will suffer from more side effects of radiotherapy so that corresponding measures can be taken in advance.
Accurately establishing the physical dose following a nuclear incident
One of the techniques used for establishing the contracted radiation dose is checking the gene expression. Gene expression gives cells the signal to produce proteins whenever these are needed. Establishing the gene expression results in a general value per gene, but every exon – the coding sequence of a gene – may react differently after radiation. That’s why SCK CEN researchers do not analyse the entire gene but only those elements that are important. Our DNA contains about 50,000 genes. By only studying the expression of pre-determined exons, researchers can – shortly after the exposure – measure the exposure dose as a function of time more accurately. This enables them to respond quicker to nuclear incidents, for instance. Rapid screening, a correct diagnosis and corresponding medical treatment improve the survival rate after having been exposed to high radiation doses. However, this method is still in its infancy.