Exposure to ionising radiation results in a health detriment. In normal situations doses are very low so that there is no clinically observable tissue effect, but there still is a possible late effect, cancer in particular. It is assumed that there is no dose threshold for this effect: any exposure, however small, can be the cause of cancer later in life. It is further assumed that the probability of occurrence of a late effect is proportional to the dose. This calls for a specific approach in radiation protection based on the three principles of justification, optimisation and dose limitation, which are the cornerstones of the system of protection established many decades ago by the International Commission on Radiological Protection (ICRP).
Euratom legislation has always followed the recommendations of the ICRP. This highly respected scientific organisation has recently issued new guidance on the system of radiation protection (Publication 103, 2007). While preserving the three pillars of the system, the ICRP sets out in more detail the application of the principles throughout any exposure situation and irrespective whether the source of radiation is man-made or natural.
You can read the proposal here.