Contact with certain harmful substances in the environment or workplace can cause cancer. Substances that are known to cause cancer are called carcinogens.

We know, for example, that 9 out of 10 people who develop mesothelioma (a rare type of cancer affecting the linings of the lung and abdomen) have had contact with asbestos. People who have worked in industries such as ship-building and construction may have come into contact with asbestos. Its use is now banned in the UK.

Certain chemicals used in dye factories, rubber production, gas works and other chemical industries have all been linked to bladder cancer. Fortunately these chemicals have now been banned.

Environmental causes include natural radiation, for example, from the sun. We know that most skin cancers, including melanoma, are caused because of prolonged exposure to the sun. Naturally occurring radon gas has also been linked to some types of cancer, namely lung cancer.

It is important to remember that we don't know the cause of many cancers and that there is often more than one cause. Also, although cancer can occur at any age, one of the biggest risks of it developing is increasing age.

There are a number of questions and answers about the causes of cancer that you may find helpful to read.