It is quite true that environment has a direct impact on those living in it and many diseases are the outcome of man’s maladjustment to his environment. The factors, which affect human health and cause disease, can be dividing into two categories:
- Intrinsic or Internal Factors.
- Extrinsic or External Factors.
The factors such as malfunctioning of the body parts, hormonal imbalances, malfunctioning of immune system and genetic disorders, which exist within the human body, are called Intrinsic Factors. The disease caused by intrinsic factors is called organic diseases or metabolic diseases. Some examples of diseases caused by extrinsic factors are: Heart attack, Kidney failure, Cataract, Diabetes etc. The disease caused by intrinsic factors can be cured by proper medical treatment.
The factors, such as malnutrition, disease causing microorganisms, environmental pollutants use of tobacco, alcohol and narcotics, which exist outside the human body, are called Extrinsic Factors. Some examples of disease caused by extrinsic factors are Kwashiorkor, Goitre, Malaria, Cholera, Tetanus etc. The diseases caused by extrinsic factors can be cured
- by providing wholesome food,
- by providing clean environment,
- by social remedies which encourage good habits.
There are some ailments caused by less common extrinsic factors, for example bone fracture after falling from height, frost-bite (prolonged exposure to extreme cold weather), heat-stroke(prolonged exposure to intense hot sun light). These ailments are caused by accidents and are considered as emergencies.
Now let us discuss some common intrinsic and extrinsic factors and the disease caused by them.
Some of the factors, which increase the risk of cancer, are:
Smoking: Tobacco smoke is a proven cause of lung cancer.
Exposure to high energy radiations such as X-rays, Gamma rays can cause skin cancer and leukaemia.
Some viruses are also believed to cause cancer.
Many chemicals applied to skin, inhaled or taken by mouth are also known to cause cancer. These chemicals, which can cause cancer, are known as carcinogenic. Carcinogenic agents in foods may be natural substances or they can be chemicals (food additives) which are deliberately added to food as flavouring agent, as colouring agent, as sweetener as a preservative.
Cancerous growths or tumors can be treated only at early stages. Cancerous growths in advanced stages often result in death.