The biological effect of radiation on a person consists in the ionization of the cells of the tissues of his body and the appearance of radiation sickness. The course of the disease will depend on many factors: on the area of the lesion, on the dose of ionizing radiation, on the time during which this dose is received.
Ionizing radiation
When high-energy particles, or photons, pass through a substance, they form in their path pairs of charged particles called ions. Therefore, it is ionizing radiation that is considered dangerous. The biological effect of radiation affects living matter to a greater extent. Living tissue is cells that are constantly being updated, it is a dynamic process. And for him, ionizing radiation is doubly painful.
In part, radiation damage is associated with mechanical damage to molecular structures, for example, chromosomes. Partly - with chemical processes occurring with the released radicals. Since a person consists of water at 75%, it is water cells that absorb the first radiation, forming free radicals such as OH, HO2, N. The chain reactions of oxidation of protein molecules by these radicals subsequently occur. Further functional changes appear in the biological laws of cell life.
The following changes occur in the cells:
- the division mechanism and the chromosome apparatus of the damaged cell are damaged;
- the process of cell renewal and differentiation is blocked;
- the proliferation and regeneration of tissues is blocked.
Most of all, the biological effect of radiation affects constantly renewing cells of the bone marrow, spleen, gonads, etc.
Acute radiation sickness
A very high dose of ionizing radiation (more than 600 rad) leads to rapid death of a person (if no treatment is carried out). At a dose of 400-600 rad, about 50% of people die. An acute radiation sickness begins, in which the hematopoietic system (red bone marrow) collapses and dies and the body's defense system ceases to work.
The first week of acute radiation sickness is asymptomatic - this is the so-called latent period of the disease. Then a breakdown occurs, immunity fails, all chronic diseases begin to worsen, and new infections appear. By about the fourth week, anemia develops, the blood stops clotting, and the risk of bleeding increases.
Today's level of medicine can save people who received a dose of ionizing radiation of up to 1000 rad. Previously, the biological effects of radiation in such quantities were not treatable. Radiation sickness is an extreme degree of damage. Smaller doses can cause leukemia and various malignant tumors.
Sources of radiation and types of exposure
A person can receive a dangerous dose of radiation from a passing radiation cloud or from the contaminated surface of buildings, structures, land. This is called external exposure. Internal exposure occurs when a person inhales contaminated aerosols (inhalation hazard) or consumes contaminated food and water. Radioactive substances can come in contact with skin and clothing. Such exposure is called contact.
The biological effects of radiation can cause the following effects:
- Somatic-stochastic. They are difficult to detect and may not appear for decades.
- Somatic. Affect only the irradiated person, the offspring are not affected.
- Genetic. Sexual cellular structures of irradiated people are disrupted, which will affect the offspring that appears with congenital deformities and mutations.
The degree of exposure depends not only on the dose, but also on the time of exposure to radiation. A dose of 300 rad, received over several months, will not lead to illness, but at one time can lead to serious consequences. Acute radiation sickness can develop with a single dose of 100 rad.