It is now more than six months since the beginning of the accident on 11 March 2011 at the Fukushima Daiichi Nuclear Power Plant in Japan. The Japanese government and local health authorities have started to collect the information necessary to estimate radiation doses received by those living in the area around the plant, drafted plans for the health care of residents, and started to implement some of them. This paper reviews and discusses the studies necessary for risk evaluation of cancer and non-cancer diseases, including those already planned, mainly from the view point of evaluating health risk using epidemiological approaches. In the long run, it is important to establish a cohort with a control group. Even if the cumulative doses are estimated to be so low that it is difficult to evaluate the risk of cancer and non-cancer diseases, it is necessary to conduct such a study to reassure residents. The health care programme of the Fukushima Prefecture government, including hea...

Se-79 is a long-lived radionuclide of potential radiological significance in relation to the deep geological disposal of solid radioactive wastes. In the context of release to the terrestrial environment, its main radiological impact is delivered through food chain pathways. Therefore, its accumulation in soils and uptake by plants is an important consideration in post-closure safety assessment studies. However, representation of its behaviour in the soil–plant system requires consideration of the multiple valence states that it can exhibit under different redox conditions and its susceptibility to volatilisation. A simple model is described that includes seasonal variations in soil hydrology and their effects on the mobility and root uptake of Se-79. Illustrative calculations are undertaken with the model, to demonstrate its capabilities for interpreting experimental data on the behaviour of Se-79 in soils and plants, and for making projections on the long-term behaviour of Se-7...

The specification of shielding for CT facilities in the UK and many other countries has been based on isodose scatter curves supplied by the manufacturers combined with the scanner's mAs workload. Shielding calculations for radiography and fluoroscopy are linked to a dose measurement of radiation incident on the patient called the kerma–area product (KAP), and a related quantity, the dose-length product (DLP), is now employed for assessment of CT patient doses. In this study the link between scatter air kerma and DLP has been investigated for CT scanners from different manufacturers. Scatter air kerma values have been measured and scatter factors established that can be used to estimate air kerma levels within CT scanning rooms. Factors recommended to derive the scatter air kerma at 1 m from the isocentre are 0.36 µGy (mGy cm) ⁻¹ for the body and 0.14 µGy (mGy cm) ⁻¹ for head scans. The CT scanner gantries only transmit 10% of the scatter air kerma level and t...

Safegrounds is a forum for developing and disseminating good practice guidance on the management of radioactively contaminated land on nuclear and defence sites in the UK. This review has been provided to Safegrounds as a summary of the basis for current radiation risk estimates and the International Commission on Radiological Protection (ICRP) protection system, in a form that will be accessible to a wide range of stakeholders. Safegrounds has also received viewpoint papers from other members who contend that the ICRP methodology results in substantial underestimates of risk, particularly for internal emitters. There is an extensive literature on the risks of radiation exposure, regularly reviewed by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and other expert groups. These data provide a sound basis for the system of protection recommended by ICRP. The available epidemiological and experimental evidence supports the application of cancer...

The aim of this work was to determine the possible occurrence of damage to the immune system during the course of chronic ingestion of ¹³⁷Cs. BALB/C mice were used, with ¹³⁷Cs intake via drinking water at a concentration of 20 kBq l ^{− 1}. Adults received ¹³⁷Cs before mating and offspring were sacrificed at various ages between birth and 20 weeks. Phenotypic analysis of circulating blood cells and thymocytes did not show any significant modification of immune cell populations in animals ingesting ¹³⁷Cs as compared with control animals, with the exception of a slight increase in Treg percentage at the age of 12 weeks. Functional tests, including proliferative response to mitogens such as phytohaemagglutinin, response to alloantigens in mixed lymphocyte reaction and immunoglobulin response to vaccine antigens such as tetanus toxin and keyhole limpet haemocyanin did not show any significant functional modification of the immune sy...

Experimental data from the literature are presented to create a chain which links radiation induced cancer in animals to cell reproductive death and then to chromosomal aberrations and somatic mutations. The cancer data reveal the same peak value of cancer induction following different radiation exposures which leads to an association between cancer induction and cell killing. Other data show a direct correlation between cell survival and chromosomal aberration yield independent of whether a sensitiser is used or not. Data on the induction of somatic mutations in mammalian cultured cells show the same direct relationship between mutation frequency and cell killing following neutron and gamma ray exposures. Taken as a whole, the experimental data provide convincing evidence that radiation induced cancer arises from chromosomal damage.

In order to optimise the monitoring of potentially exposed workers, it is desirable to determine specific values of absorption for the compounds handled. This study derives specific values of absorption rates for different chemical forms of plutonium from in vitro and animal (monkeys, dogs, mice, rats) experiments, and from human contamination cases. Different published experimental data have been reinterpreted here to derive values for the absorption parameters, f _r, s _r and s _s, used in the human respiratory tract model currently adopted by the International Commission on Radiological Protection (ICRP). The consequences of the use of these values were investigated by calculating related committed effective doses per unit intake. Average and median estimates were calculated for f _r, s _r, and s _s for each plutonium compound, that can be used as default values for specific ...

The aetiology of childhood leukaemia remains generally unknown, although exposure to moderate and high levels of ionising radiation, such as was experienced during the atomic bombings of Japan or from radiotherapy, is an established cause. Risk models based primarily upon studies of the Japanese A-bomb survivors imply that low-level exposure to ionising radiation, including to ubiquitous natural background radiation, also raises the risk of childhood leukaemia. In a recent paper (Wakeford et al 2009 Leukaemia 23 770–6) we estimated the proportion of childhood leukaemia incidence in Great Britain attributable to natural background radiation to be about 20%. In this paper we employ the two sets of published leukaemia risk models used previously, but use recently published revised estimates of natural background radiation doses received by the red bone marrow of British children to update the previous results. Using the newer dosimetry we calculate that the best...

The use of mobile head computed tomography (CT) equipment in intensive care is of benefit to unstable patients with brain injury. However, ionising radiation in a ward environment presents difficulties due to the necessity to restrict the exposure to staff and members of the public according to regulation 8(1–2) of the Ionising Radiation Regulations 1999. The methodology for enabling the use of a mobile head CT unit in an open ward area is discussed and a practical solution given. This required the reduction in scatter doses through the installation of extra internal and external shielding, and a further reduction in annual scatter dose by restricting the use of the equipment based on a simulation of the annual ward workload.

Since the end of the Second World War, industrial and medical uses of radiation have been considerably increasing. Accidental overexposures of persons, in either the occupational or public field, have caused deaths and severe injuries and complications. The rate of severe accidents seems to increase with time, especially those involving the public; in addition, accidents are often not immediately recognised, which means that the real number of events remains unknown. Human factors, as well as the lack of elementary rules in the domains of radiological safety and protection, such as inadequate training, play a major role in the occurrence of the accidents which have been reported in the industrial, medical and military arenas.