Page 156 - Health, Population and Environment Education 10

Causes of Cancer
About 90-95% of cancer cases occur due to environmental factors and the remaining
5-10% are due to inherited genetics. Common environmental causes that contribute to
cancer death include tobacco (25-30%), unhealthy diet and obesity (30-35%), infections
(15-20%) stress, lack of physical activity and pollution.

The major causes of cancer are classified as follows:
1. Physical Factors Do You Know
Physical factors that cause cancer include exposure
to harmful radiation like UV-rays, x-rays, etc. • Tobacco smoke causes 90%
of lung cancer. It contains
2. Chemical Factors over fifty carcinogens.
Chemical factors that cause cancer include • Tobacco is responsible for
consumption of tobacco, tobacco products, alcohol about one in five cancer
and long term exposure to smoke, harmful colours, deaths worldwide.
etc.

3. Biological Factors
Biological factors that cause cancer include infection of bacteria and viruses. For example,
human papilloma virus causes cervical cancer in females. Hepatitis B virus causes liver
cancer. Similarly, Helicobacter pylori causes cancer of intestine.

Fig: 14
Human papilloma virus Hepatitis B virus Helicobacter pylori

Major Symptoms of Cancer
1. Sore does not get better for a long time.

2. The size of wart or mole increases gradually.
3. Painless lumps in breast can be noticed.
4. Blood is seen in the stool in intestinal cancer.
5. Persistent cough

6. Hoarseness of voice
7. Bleeding from nose, mouth, anus, vagina, etc.

156 GREEN Health, Population and Environment Education Book-10