Limit values in radiation protection

The Radiation Protection Act and the Radiation Protection Ordinance specify dose limits for the general population and for occupationally exposed persons. In general, any application of ionising radiation must be justified and the radiation exposure must be kept as low as possible even when below the limit values.

Limit values and health risks

Dose limits do not constitute a dividing line between hazardous and harmless radiation exposure. Rather, exceeding a limit value means that the probability of health effects (in particular cancer) exceeds a value that is defined as acceptable. The limit values are laid down by the legislative or regulatory authority.

As there is no dose value below which it is possible to rule out a health risk due to ionising radiation, a certain – albeit minor – risk also exists below the limit values which increases with increasing dose. Therefore, any radiation exposure, even at levels below the specified limit values, should be avoided if possible and, failing this, kept to a minimum (principle of optimisation). In practice, this principle means that in the vast majority of cases radiation exposure is far below the legally specified limit values.

Limit values for exposure of the general public

The limit value for the effective dose aimed at protecting members of the public is 1 millisievert in a calendar year (§ 80(1), Radiation Protection Act).

This value refers to all radiation exposures to which members of the public may be exposed due to nuclear and other facilities for the generation of ionising radiation, as well as the handling of radioactive substances. This means that the limit value applies to the sum of radiation exposure from direct radiation and radiation exposure due to discharges from nuclear facilities. At the same time, the radiation exposure from an individual facility via the exposure pathways of waste water and exhaust air must not exceed 0.3 millisievert per year for either pathway (§ 99(1), Radiation Protection Ordinance).

Medical applications of radiation are excluded from these limitations. There is currently no legal dose limit for radiation from natural sources.

The limit values for the organ equivalent dose ("organ dose") for the general public are specified in § 80(2) of the Radiation Protection Act. They are equal to 15 millisieverts in a calendar year for the lens of the eye and 50 millisieverts in a calendar year for the skin.

In addition, limit values for radiation exposure resulting from the release of radioactive substances into the environment must be taken into account in the planning of protective measures against incidents at a nuclear power plant (see § 104 of the Radiation Protection Ordinance).

Limit values for occupationally exposed persons

The limit value for the effective dose in order to protect occupationally exposed persons is 20 millisieverts in a calendar year (§ 78(1), Radiation Protection Act).

In individual cases, the competent authority can allow a value of 50 millisieverts for a single year, but a value of 100 millisieverts must not be exceeded for five subsequent years. Lifetime occupational exposure must not exceed 400 millisieverts (§ 77, Radiation Protection Act).

These dose limits apply equally to women and men. However, for women of childbearing age, the organ equivalent dose (organ dose) for the uterus must not exceed 2 millisieverts per month. For pregnant women, the limit value for the unborn child is 1 millisievert from the time of declaration until the end of pregnancy (§ 78(4), Radiation Protection Act).

For apprentices under the age of 18, the limit value is 1 millisievert per calendar year (§ 78(3), Radiation Protection Act). For educational purposes, the competent authority may specify a limit value of 6 millisieverts for 16- to 18-year-olds if necessary.

The Radiation Protection Act additionally sets limit values for individual organs for protective measures relating to the radiation exposure of specific parts of the body (§ 78(2), Radiation Protection Act).

For further information and details on this topic, please refer to the article “Limit values for occupationally exposed persons”.

Important limit values and typical dose values in comparison

To allow better classification of the limit values, the following table lists some important limit values and typical dose values (effective dose in each case) for comparison purposes.

Important thresholds for deterministic radiation effects

The table below contains lists some threshold values for acute radiation damage (deterministic radiation effects) in order to facilitate the classification of dose and limit values.