information

URN: urn:nbn:de:101:1-201604043407
URN: urn:nbn:de:101:1-201604254267

Abstract

The International Commission on Radiological Protection (ICRP) assumes that a linear relationship between radiation dose and tumor risk results in an overestimate of the risk for low doses and low dose-rates.
In recommendation 103 (ICRP 2007) the ICRP confirmed its previous argumentation and recommends retaining a dose- and dose-rate-effectiveness factor (DDREF) of 2 for solid tumours in the case of photon and electron exposures (sparsely ionising radiation). Risk values largely determined using epidemiological studies on the survivors of the Hiroshima and Nagasaki atomic bombings are divided by this DDREF for low-dose and low-dose-rate radiation protection applications.
In its statements regarding ICRP 103, the German Commission on Radiological Protection (Strahlenschutzkommission, SSK) rejected this argumentation and called for a DDREF of 1, i.e. for the use of a pure linear no-threshold relationship (SSK 2006).
In recent times, the scientific basis for justifying DDREF has increasingly become subject of controversial debate all the way up to expert committees. Given these circumstances, the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) commissioned the German Commission on Radiological Protection (SSK) with reviewing the current state of science and preparing a recommendation regarding DDREF.
The SSK points out:
With its many facets, the DDREF is an extremely subtle concept and should not strictly be seen as a single "factor" since it contains several influencing factors that have only been bundled into a single factor for practical radiation protection purposes.
As was the case several times in the past, an assessment to determine whether or not the DDREF value currently generally used in radiation protection to estimate radiation risk should be changed is not solely based on specified scientific findings in a narrow sense as it also includes other criteria pertaining to other key aspects of radiation protection and practical implementation. Assessment solely on the basis of scientific principles and criteria is not commensurate to the importance and function of DDREF.
The SSK recommends:

• Based on current scientific findings, the SSK no longer considers justifications for the DDREF used in radiation protection as being sufficient.
• In view of the assessments set out in this report, the SSK therefore recommends abolishing the DDREF or adjusting it to bring it into line with more recent findings.
• Due to its importance to risk evaluation and impact on radiation protection, in the case of adjusting the DDREF, the SSK recommends in parallel that all of the other parameters pertaining to the detriment be adapted to the latest scientific findings.
• The SSK means that an international agreement in these issues is urgently necessary and recommends that its assessment be used as a basis for international discussions on these issues.