Natural background radiation and cancer mortality in the Republic of Ireland.

An extensive area of rural Ireland was monitored in detail for natural background radiation (NBR); average background radiation values were derived for all District Electoral Divisions (DEDs) in this area. Cancer mortality rates were calculated for the DEDs aggregated according to average NBR. No association was apparent between cancer mortality rates and levels of natural background radiation.

Indoor natural radiation levels in Ireland.

The principal results of a preliminary study made on indoor radiation levels in Ireland are presented. During the period 1983-84 measurements were made in over 250 houses. Most measurements were made using passive devices: TLDs for penetrating radiation and CR-39 alpha track plastic detectors for radon measurements. The median value of the doses from penetrating radiation was 0.78 milligray/year with a maximum value of 1.47 m Gy/year detected. The radon concentrations showed a large degree of variability with a median value of 43 Bq/m3. About 10% of the houses had radon air concentrations in excess of 100 Bq/m3 with a maximum of 700 Bq/m3 being recorded. A tentative analysis of the data with regard to the geological situation is presented.

Measurements on retention and transfer characteristics of radiocaesium from poor quality upland soils to heather and from heather to sheep.

This paper presents results from initial measurements of Cs-134, Cs-137 and K-40 activities made on poor quality upland soils and associated Calluna vulgaris vegetation. Soil-plant radiocaesium and potassium relationships were investigated. Chernobyl caesium shows a higher concentration ratio from soil to heather compared to the older weapons-test caesium. Significant radiocaesium levels have been measured (both in vivo and in vitro) in sheep grazing four sites. There was a significant correlation found between radiocaesium concentrations in sheep and activity deposited in the soil.

Regulatory control of air crew exposure to cosmic radiation: the European approach.

The current European Directive on radiation protection requires that exposure of air crew to cosmic radiation should be assessed if it is likely to exceed 1 milliSievert per year. The approach to this problem in the European Union is described and the relative merits of experimental measurement and computer based assessment are discussed. The particular importance of protection against cosmic radiation exposure in the case of female air crew during pregnancy is described.

Radiocesium levels in Irish Sea fish and the resulting dose to the population of the Irish Republic.

Discharges of radioactive materials from the nuclear fuel reprocessing plant at Sellafield in the United Kingdom give rise to 137Cs and 134Cs in fish caught in the Irish Sea. Measurements made on fish catches landed in the Irish Republic show average activities of 68 and 3 Bq/kg (wet) of 137Cs and 134Cs, respectively. The estimated population dose to the Irish public is approximately 2 man-Sv y-1 and the possible dose to a member of the critical group is 1.4% of the limit recommended by the International Commission on Radiological Protection.

Dosimetry for occupational exposure to cosmic radiation.

In the course of their work, aircraft crew and frequent flyers are exposed to elevated levels of cosmic radiation of galactic and solar origin and secondary radiation produced in the atmosphere, aircraft structure, etc. This has been recognised for some time and estimates of the exposure of aircraft crew have been made previously and included in, for example, UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) publications. The recent increased interest has been brought about by several factors--the consideration that the relative biological effectiveness of the neutron component as being underestimated; the trend towards higher cruising altitudes for subsonic commercial aircraft and business jet aircraft; and, most importantly, the recommendations of the International Commission on Radiological Protection (ICRP) in Publication 60, and the revision of the Euratom Basic Safety Standards Directive (BSS). In 1992, the European Dosimetry Group (EURADOS) established a Working Group to consider the exposure to cosmic radiation of aircraft crew, and the scientific and technical problems associated with radiation protection dosimetry for this occupational group. The Working Group was composed of fifteen scientists (plus a corresponding member) involved in this field of study and with knowledge of radiation measurement at aviation altitudes. This paper is based on the findings of this Working Group. Where arrangements are made to take account of the exposure of aircraft crew to cosmic radiation, dose estimation procedures will not be necessary for persons for whom total annual doses are not liable to exceed 1 mSv, and therefore, in general, for crew on aircraft not routinely flying above 8 km. Where estimates of effective dose and, in the case of female staff who are pregnant, equivalent dose to the embryo or fetus, are required (for regulatory or other purposes), it was concluded that the preferred procedure was to determine route doses and fold these with data on staff rostering.

ICRP, 123. Assessment of radiation exposure of astronauts in space. ICRP Publication 123.

During their occupational activities in space, astronauts are exposed to ionising radiation from natural radiation sources present in this environment. They are, however, not usually classified as being occupationally exposed in the sense of the general ICRP system for radiation protection of workers applied on Earth. The exposure assessment and risk-related approach described in this report is clearly restricted to the special situation in space, and should not be applied to any other exposure situation on Earth. The report describes the terms and methods used to assess the radiation exposure of astronauts, and provides data for the assessment of organ doses. Chapter 1 describes the specific situation of astronauts in space, and the differences in the radiation fields compared with those on Earth. In Chapter 2, the radiation fields in space are described in detail, including galactic cosmic radiation, radiation from the Sun and its special solar particle events, and the radiation belts surrounding the Earth. Chapter 3 deals with the quantities used in radiological protection, describing the Publication 103 (ICRP, 2007) system of dose quantities, and subsequently presenting the special approach for applications in space; due to the strong contribution of heavy ions in the radiation field, radiation weighting is based on the radiation quality factor, Q, instead of the radiation weighting factor, wR. In Chapter 4, the methods of fluence and dose measurement in space are described, including instrumentation for fluence measurements, radiation spectrometry, and area and individual monitoring. The use of biomarkers for the assessment of mission doses is also described. The methods of determining quantities describing the radiation fields within a spacecraft are given in Chapter 5. Radiation transport calculations are the most important tool. Some physical data used in radiation transport codes are presented, and the various codes used for calculations in high-energy radiation fields in space are described. Results of calculations and measurements of radiation fields in spacecraft are given. Some data for shielding possibilities are also presented. Chapter 6 addresses methods of determining mean absorbed doses and dose equivalents in organs and tissues of the human body. Calculated conversion coefficients of fluence to mean absorbed dose in an organ or tissue are given for heavy ions up to Z=28 for energies from 10 MeV/u to 100 GeV/u. For the same set of ions and ion energies, mean quality factors in organs and tissues are presented using, on the one hand, the Q(L) function defined in Publication 60 (ICRP, 1991), and, on the other hand, a Q function proposed by the National Aeronautics and Space Administration. Doses in the body obtained by measurements are compared with results from calculations, and biodosimetric measurements for the assessment of mission doses are also presented. In Chapter 7, operational measures are considered for assessment of the exposure of astronauts during space missions. This includes preflight mission design, area and individual monitoring during flights in space, and dose recording. The importance of the magnitude of uncertainties in dose assessment is considered. Annex A shows conversion coefficients and mean quality factors for protons, charged pions, neutrons, alpha particles, and heavy ions(2 < Z ≤2 8), and particle energies up to 100 GeV/u.

Relationships between deposition of Chernobyl originating caesium and ruthenium radionuclides and rainfall in Ireland.

Deposition data for caesium and ruthenium radionuclides in Ireland as a result of the Chernobyl accident were obtained by high-resolution gamma-ray spectrometry of soil samples taken at 111 locations throughout the country. Investigation of the relationships between deposition and recorded rainfall in relevant periods enabled an assessment to be made of the activity concentration within the plume during the wash-out phase. Detailed surveys in two regions of the country enabled a comparison to be made of the relative deposition of ruthenium and caesium isotopes. No evidence was found to suggest any difference in wash-out ratios for the two ruthenium isotopes.

The flax industry in Northern Ireland twenty years on.

In 1961-62 a survey of respiratory symptoms in 2528 workers in flax mills in Northern Ireland and of dust levels in the mills was conducted. The workers were followed up in 1978, because recent developments suggested that an upturn in the industry was likely. Flax dust has an acute, reversible effect on the respiratory system, and byssinosis is a prescribed disease under the Industrial Injuries Act (1965). However, the follow-up study found no evidence of an effect on survival of either exposure to dust or byssinosis. The number of applications to compensation panels for assessment and certification of byssinosis has increased greatly in Northern Ireland. Although certification is independent of any subsequent common law claim by a worker for compensation on the grounds of disablement consequent on negligence by his employer, it must weight heavily in such a claim. About 50 common law claims have been settled out of court for large sums in Northern Ireland, and 950 claims are waiting to be heard. The future cost to the industry is estimated to be at least 16 million pounds. Since byssinosis appears not to cause excess mortality, it is unlikely to cause serious long-term morbidity. Although workers should be compensated for disablement due to negligence, in the absence of unequivocal evidence of disablement caused by byssinosis the financial settlements being reached in Northern Ireland seem unreasonable.

Transfer characteristics of radiocaesium from soils to permanent pasture.

Depth profile measurements of 137Cs and 134Cs were carried out in 11 permanent pastures that had been exposed to fallout from the Chernobyl accident. In addition to gamma-ray spectrometric analysis, the selected pastures were characterized by several soil parameters, the influence of which on transfer was investigated. Sampling of soil and pasture grass was undertaken during a period extending from the Spring of 1987 to the Autumn of 1988. The results show that there has been limited downward migration of Chernobyl-derived caesium. In October 1988 more than 88% of the 137Cs attributable to Chernobyl was mainly confined to the top 10 cm of undisturbed soil, with 79% on average in the top 5 cm. The distribution of pre-Chernobyl caesium at the 11 sites was also evaluated. In an investigation of the influence of soil parameters on transfer to grass, a negative correlation with pH was observed in 1987. In April 1987 concentration ratios for 137Cs in grass ranged from 0.03 to 0.49. In general, comparison of the concentration ratio values showed a decreasing trend over the 18 months.