Maximum permissible dose

Maximum permissible dose (MPD) - radiation dose, which at systematic influence over the indefinitely long period of time does not cause a running any pathological changes or diseases that can be detected by means of modern methods of research. In the USSR approved the SDA under irradiation of the whole body of 0.1 REM per week, which corresponds to 0,017 REM per working day and 5 REM per year. The maximum permissible total dose of irradiation (D) for the entire work period is calculated by the formula: D=5 (N -18) REM, where N is the person's age, 18 is the age at which usually begins professional activities.
Cm. also Doses of ionizing radiation.

Maximum permissible dose (MPD) - radiation dose, which at systematic influence over the indefinitely long period of time does not cause a running any pathological changes or diseases to be detected by modern means of research.
Proposed in 1925, the amount of traffic rules of 0.1-0.2 p (x-ray) per working day is periodically revised, and in 1959, the international Commission on radiation protection has adopted the SDA under irradiation of the whole body of 0.1 REM per week, which corresponds to 0,017 REM per working day and 5 REM per year.
Under non-uniform irradiation of the body is usually considered the impact on the so-called critical organs (see). Dose of 0.1 REM/week adopted for irradiation groups critical of the authorities - the sex glands, bone marrow, the lens of the eye, the impact of which is equal to the irradiation of the whole body. For skin and thyroid gland, with comparatively less radiosensitivity, adopted SDA 0,6 REM/week or 30 REM per year. For irradiation of other organs of traffic rules is 0.3 REM per week, or 15 REM per year. The irradiation of the hands and feet of traffic rules in 5 times more, than at the irradiation of the whole body (0.5 REM per week). In the USSR these doses are approved as the traffic rules. It is accepted that the total dose of occupational exposure D for all time of operation shall not exceed D=5 (N - 18) REM, where N is the person's age, 18 is the age for occupational exposure.
When carrying out emergency works allowed to exceed the total annual external exposure dose to 12 REM. This value is added to the received (to date) dose, and if the total dose exceeds this value, the excess is compensated by reducing the radiation therapy for 5 years. For people who are in the sanitary-protective zone or working in areas adjacent to those that work with radioactive substances and sources of ionizing radiation, the SDA is 0.5 REM per year. The annual amount of traffic rules for the population of all age groups living outside the sanitary protection zone, is 0.05 REM, i.e. close to the level of natural background. In terms of the possible exposure of the bone marrow dose is 10 times more than the natural background, which by today's standards is safe. Irradiation of the gonads comparable with the level of exposure to natural background, the total dose to the gonads doubling.
In accordance with the established values of the relative biological efficiency (see) for different types of radiation adopted the following traffic rules (see table).

Type of ionizing radiation RBE SDA happy/week
Gamma rays and x-ray
Beta particles, and the electron flows
Streams of protons and alpha-particles
Multiply charged ions and recoil
Thermal neutrons
Fast neutrons
1
1
10
20
3
10
0,1
0,1
0,01
0,005
0,033
0,01

Cm. also Doses of ionizing radiation.