Radiation

Radiation is a part of man's environment. The sources of radiation to which man is exposed are divided into two groups:

1.Natural

• cosmic rays
• environmental (terrestrial, atmospheric)
• internal (potassium-40, carbon-14)

2.Man-made

• medical and dental (x-rays, radioisotopes)
• occupational exposure
• nuclear (radioactive fallout)
• miscellaneous (television sets, radioactive dial watches, isotope tagged products, luminious markers)

The term "ionizing radiation" is applied to radiation which has the ability to penetrate tissues and deposit its energy within them. The amount of radiation received from outer space and background radiation has been estimated to be 0.1 rad a year. Apparently, this doesnot at present constitute a hazard. The additional permissible dose from man-made sources should not exceed 5 rad a year. Of the man made sources, the X-rays constitute the greatest hazard . In routine fluoroscopy, a dose of 4 rad is delivered to a part of the body in about one minute.This implies that unnecessary x-ray examinators should be avoided, especially in the case of children and pregnant women .Radiation protection is the youngest branch of hygiene, and is called radiation-hygience. The International Commission on Radiological Protection (ICRP), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) have been active in this field.