The biological effects of radiation on humans can be divided into two groups, somatic effects, and genetic effects.
(1) Somatic effects:
A dose of 600 to 700 roentgen is invariably fatal in humans and a dose of 400 to 500 roentgen can kill up to 50% of people.
Those who are not killed, also suffer from severe damage and radiation sickness. If a person is exposed to 25 to 50 roentgen of radiation it affects white blood cells (corpuscles) and produces lassitude and softening of the muscles.
The somatic effects of radiation can be immediate and delayed. Immediate effects are radiation sickness and acute radiation syndrome.
Delayed effects take time to develop and can take from a few weeks to a few years to develop.
Delayed effects of radiation are mainly leukemia (blood cancer), malignant tumors ( cancer) shortening of life, and fetal developmental abnormalities.
(2) Genetic effects:
Somatic effects are seen during one’s lifetime of the person exposed to ionizing radiation genetic effects generally manifest in the life of off-spring.
Genetic effects of radiation are mainly due to point mutation and chromosomal mutation.
Chromosomal mutation generally is involved with sterility and point mutation affects the genes.
Protection from Radiation:
The amount of radiation received from outer space is about 0.1rad per year and at present, it is not considered a hazard.
The additional permissible dose from man-made sources is about 5rad per year. Out of all the man-made sources, x-ray constitutes the greatest hazard.
In routine fluoroscopy, a dose of 4rad is delivered to a part in one minute, which means unnecessary x-ray examination should be avoided, mainly in pregnant women and children.
There is the requirement of adequate control & surveillance of x-ray installations, protection of workers, improvement of techniques to reduce the dose of radiation.
Effective protective measures include the use of lead shields and lead rubber aprons by radiographers.
Lead aprons of 0.5mm thickness of lead reduce the intensity of scattered x-rays up to 90% and all workers should use them who are associated with x-rays.
Workers also should wear a dosimeter or a film badge that shows accumulated exposure to radiation.
Besides all the above periodic medical cheek up, regular working hours & recreation should be provided to the health workers who are exposed to x-rays.
Radiation hygiene is one of the latest branches of hygiene. International agencies like WHO(World Health Organization), IAEA(International Atomic Energy Agency), and the International Commission on Radiological Protection (ICRP) are active in the field of radiation hygiene.
The ICRP has recommended that the genetic dose to the whole population from man-made sources (other than natural sources) should not exceed 5rems per year over a period of 30 years.
Many countries in the world have adopted the ICRP recommendation. The main concern is to promote the peaceful use of atomic energy without any problem with health.
There is a growing concern throughout the world in recent times for codes of practice for the safe operation of nuclear power plants and safe disposals of nuclear waste.