Causes Of Cancer

The cause of many cancers is still unknown but there are many factors known as carcinogens, which can increase the risk of developing the disease. Cancer usually develops after a long term, low level exposure to the carcinogen.

There are many different types of carcinogen. Chemical carcinogens are chemicals that cause cancer. A notorious example is cigarette smoke which contains tar rich in polycyclic aromatic hydrocarbons. Benzene vapor, present in unleaded petrol, is also known as carcinogen. Physical carcinogens include such things as asbestos dust, ultraviolet rays from sunlight, X-rays and other forms od radiation. Some viruses have been linked to cancer. These are rare and are called biological carcinogens.

Many chemicals are cancer suspects which means that animal experiments may have resulted in cancer but the evidense linking the cancer to that chemical is currently uncertain.