Causes and risk factors of acute lymphoblastic leukaemia

The cause of ALL is not known, but research is going on all the time to find out more about it. Like other cancers, ALL isn’t infectious and can’t be passed on to other people.

There are a number of factors that may increase a person’s risk of developing ALL. Having a particular risk factor doesn’t mean you will definitely get ALL. And people without any known risk factors can still develop it. The known risk factors of ALL are:

Radiation exposure

Exposure to very high radiation levels increases the risk of developing ALL. However, very few people in the UK will be exposed to radiation levels high enough to increase their risk. For example, these might be the high levels of radiation following a nuclear accident.

In recent years there has been publicity about a possible increase in risk of leukaemia in children living close to nuclear power plants. A large study found that there is very little evidence of an increase in risk.

Research has shown that a person’s risk of developing ALL is not significantly increased by exposure to radon gas. Radon is a naturally occurring gas that can pass from the soil into the foundations of some buildings in parts of the UK.

Genetic conditions

ALL is not caused by an inherited faulty gene, so members of your family don’t have an increased risk of developing ALL just because you have it. However, people with certain genetic disorders, including Down’s syndrome and Fanconi’s anaemia, are known to have a higher risk of developing leukaemia.

Exposure to chemicals

In very rare cases, leukaemia may occur in people who have been exposed to chemicals used in industry, such as benzene and other solvents.


It is thought that ALL develops because of changes to a certain type of immature blood cell. What causes the changes is not fully understood, but infection may be involved. However, no specific infections have been found to cause leukaemia.