In 1990 de International Commission on Radiological Protection (ICRP) as recommended the following radiation dose limits to workers and to the general public:
- 100 mSv in 5 years of [effective dose] 1 for workers (maximum 50 mSv in any single year, average 20 mSv per year) of any branch, including medicine, industry, research, etc.
- 1 mSv per year to the general members of the public;
These recommendations have been implemented with minor changes into regulations in most countries, including the US and the European countries.
Radiations workers are obliged to use a personal dosimeter to record the amount of radiation they are exposed to. In my particular experience, most of workers don’t get more that 5 mSv in a single year, unless a radiation incident has occur, that’s why values higher than that used to be investigated. In fact I would investigate any reading in a particular workers dosimeter above the natural background.
The 1990 recommendations of ICRP have been recently updated, [with almost no change to these values] 2.