Limit values for occupationally exposed persons

In Germany, about 420,000 persons are monitored for reasons of occupational radiation protection. These people work, e.g., with

• X-ray units,
• sealed high-radioactive sources,
• unsealed radioactive substances.

Occupationally exposed persons can as well be exposed to

• an enhanced level of civilian radiation (e.g. at nuclear power stations) or
• an enhanced level of natural radiation (e.g. radon in mines, show caves or drinking water facilities or
• to cosmic radiation during flights

at their workplaces. The permissible occupational radiation exposure for these persons is limited and officially supervised.

Annual dose limits

The limit value of the effective dose for occupationally exposed persons is 20 millisieverts in a calendar year in all European countries (in the USA 50 millisieverts per year). In addition to the limit value of the effective dose different annual limits for organ doses are defined to protect individual parts of the body.

The limit value of the effective dose for occupationally exposed persons under 18 years (e.g. apprentices) is 1 millisievert in a calendar year. The responsible authority can specify an annual dose limit of 6 millisieverts for adolescents aged between 16 and 18, if this is necessary to achieve educational objectives. Lower organ dose limits apply to adolescents as well.

The annual limit values (effective dose and organ dose) for occupationally exposed persons (above and under 18 years) are summarised in the following table:

Radiation protection during pregnancy

For occupationally exposed women the same dose limits apply as for men, provided that they are not pregnant. However, for women within childbearing years the organ dose of the uterus must not exceed 2 millisieverts per month.

With notification of an existing pregnancy the unborn child shall not receive a higher dose than 1 millisievert until its birth.

Limit of the occupational life time dose

Additionally to the dose limits specified in the Euratom Basic Safety Standards an occupational life time dose limit for workers exists in Germany: the sum of all effective doses received during the whole occupational career of a worker shall not exceed 400 millisieverts.

Exceeding of dose limits

If a dose limit is exceeded, the responsible regulatory body examines the cause. Dependent on the cause it can

• set the effective dose limit to be 50 millisieverts in one year, however, 100 millisieverts must not be exceeded in five consecutive years
• impose additional requirements,
• forbid activities,
• set penalties and
• withdraw licences.

Dosimetry

Officially approved dosimeters are used for the measurement of radiation exposure at workplaces. The dosimeters are distributed by officially approved dosimetry services and usually evaluated in a monthly period. The dose fracture resulting from natural ambient radiation is subtracted from the measured value.

If workers handle open radioactive substances the possibility of an up-take of radionuclides into their body cannot be excluded, (e.g. through mouth, nose or skin). These persons are additionally monitored by officially approved laboratories for incorporation monitoring. These laboratories monitor the workers regularly or at special occasions. All dosimetric results are regularly sent to the National Dose Register of the BfS, which, among other things, supervises the keeping of dose limits.

The dose values of the members of the aircraft personnel are calculated by the airlines using certified computer programmes and sent to the Federal Office for Civil Aviation (Luftfahrt-Bundesamt – LBA), which is responsible for the supervision of air crews. The monthly doses of the personnel are sent to the National Dose Register of the BfS by the Federal Office for Civil Aviation.