Preface
Ionising radiation is present at low doses and low dose rates in the natural environment, largely from radioactive atoms in minerals formed during the early history of the planet. The technological developments of the 20th century have resulted in the use of radioactive materials for military, industrial and medical purposes. The peaceful use of radiation includes power generation, industrial testing, bio-medical research, disease diagnosis and cancer therapy ? all an integral part of our modern world.
These benefits to society need, however, to be weighed against the known potential of radiation to cause health effects in exposed people, principally ? tissue injury, cancer and genetic effects that are passed to offspring. Much is known on the likelihood of these health effects after exposure to radiation at high doses and high dose rates. However, the vast majority of man-made radiation exposures to workers and the general public occur at low doses and low dose rates where risks cannot be reliably assessed by direct observation. The majority scientific view is that risks of excess cancer and genetic effects are likely to rise in simple proportion to radiation dose and that even the lowest of doses carries some risk, albeit vanishingly small. However, some suggest that there is a low dose region (the dose threshold) where there is no excess risk of any health effect; conversely, others claim that low dose risks are grossly underestimated. Because of scientific uncertainties, the low dose issue remains an important source of debate in radiation protection and more widely in policy/ standard setting.
In order to weigh the socio-economic benefits of radiation against its potential effects on health, it is essential to gain a better understanding of this low dose and low dose rate issue. For this principal reason the European Commission has supported a programme of epidemiological and basic research on the health effects of radiation.
Fundamental research supported by the Commission over many years has made a substantial contribution to the understanding of the mechanisms that underlie radiation-induced health effects. The overall objective is to provide a sound biological basis for radiation protection. The research areas considered to be of particular importance are DNA damage response processes in cells, the specific mechanisms of cancer induction, heritable susceptibility to induced cancer including individual risk, the modelling of low dose cancer risk, heritable effects, effects on the developing brain and the diagnosis/treatment of cancer and radiation injury (see notes 1, 2 and 3). Research in some of these areas included consideration of the health effects of the Chernobyl reactor accident.
The success of these research programmes has been promoted by involving many of the key European research laboratories and placing emphasis on interdisciplinary collaboration and communication. This success in achieving research objectives is well illustrated by the establishment of strong biological and biophysical links between the dose-dependent appearance of DNA damage in irradiated cells, the recognition and repair of these initial DNA lesions and the contribution made by residual DNA changes to cancer development in tissues. This experimentally derived information is providing an increasingly robust biological foundation for the development of improved judgements on cancer risk after radiation.
However, although much has been learned of radiation mechanisms and their modelling (see notes 4, 5, 6 and 7), it is clear that further research is needed in order to address remaining uncertainties on the risks to health after low dose and low dose rate radiation.
Preface