Albedo neutron dosimetry in Germany: regulations and performance.

Personal neutron dosimetry has been performed in Germany using albedo dosemeters for >20 y. This paper describes the main principles, the national standards, regulations and recommendations, the quality management and the overall performance, giving some examples.

Dose registry in Europe: national databases and international statistics.

This paper describes the approach used in ESOREX to compare national dose statistics of occupational radiation exposure at a European level. As every country uses its own scheme to characterise radiation work, the 'best common denominator' has to be found in order to compare dose statistics. The same problem has to be solved for the dose bands used in each country in order to scale dose distributions.

European Study of Occupational Radiation Exposure (ESOREX).

The European Study of Occupational Radiation Exposure (ESOREX) project was initiated by the general directive EC DG XI and carried out by the Bundesamt für Strahlenschutz, Germany (BfS). It consists of surveys carried out in the 28 European states. The study provides comparable descriptions of the national administrative structures used to monitor and register individual occupational radiation exposure and the national dose statistics. It will establish the basis for identifying differences between the states and assessing the possibilities for European harmonisation.

Damage pattern as a function of radiation quality and other factors.

An understanding of damage pattern in critical cellular structures such as DNA is an important prerequisite for a mechanistic assessment of primary radiation damage, its possible repair, and the propagation of residual changes in somatic and germ cells as potential contributors to disease or ageing. Important quantitative insights have been made recently on the distribution in time and space of critical lesions from direct and indirect action of ionizing radiation on mammalian cells. When compared to damage from chemicals or from spontaneous degradation, e.g. depurination or base deamination in DNA, the potential of even low-LET radiation to create local hot spots of damage from single particle tracks is of utmost importance. This has important repercussions on inferences from critical biological effects at high dose and dose rate exposure situations to health risks at chronic, low-level exposures as experienced in environmental and controlled occupational settings. About 10,000 DNA lesions per human cell nucleus and day from spontaneous degradation and chemical attack cause no apparent effect, but a dose of 4 Gy translating into a similar number of direct and indirect DNA breaks induces acute lethality. Therefore, single lesions cannot explain the high efficiency of ionizing radiation in the induction of mutation, transformation and loss of proliferative capacity. Clustered damage leading to poorly repairable double-strand breaks or even more complex local DNA degradation, correlates better with fixed damage and critical biological endpoints. A comparison with other physical, chemical and biological agents indicates that ionizing radiation is indeed set apart from these by its unique micro- and nano-dosimetric traits. Only a few other agents such as bleomycin have a similar potential to cause complex damage from single events. However, in view of the multi-stage mechanism of carcinogenesis, it is still an open question whether dose-effect linearity for complex primary DNA damage and resulting fixed critical cellular lesions translate into linearity for radiation-induced cancer. To solve this enigma, a quantitative assessment of all genotoxic and harmful non-genotoxic agents affecting the human body would be needed.