Aspects of harmonisation of individual monitoring for external radiation in Europe: conclusions of a EURADOS action.

Following the publication of the EU Council Directive 96/29, EURADOS coordinated two working groups (WGs) for promoting the process of harmonisation on individual monitoring of occupationally exposed persons in Europe. An overview of the major findings of the second WG is presented. Information on the technical and quality standards and on the accreditation and approval procedures has been compiled. The catalogue of dosimetric services has been updated and extended. An overview of national regulations and standards for protection from radon and other natural sources in workplaces has been made, attempting to combine the results from individual monitoring for external, internal and workplace monitoring. A first status description of the active personal dosemeters, including legislative and technical information, and their implementation has been made. The importance of practical factors on the uncertainty in the dose measurement has been estimated. Even if a big progress has been made towards harmonisation, there is still work to be done.

Film badges for personal dosimetry of roentgen radiation.

The paper describes the calibration procedure for and data obtained from routine X-ray dosimetry service in Poland. In 1998 the number of readouts amounted to 152,000. The dosimetry concerned 31,281 workers in 3,113 enterprises. The annual collective dose was assessed to be 16.7 man.Sv. The analysis of the calibration quality is discussed as well. Only 2.9% of all points lay outside the quality curve while the number of the acceptable outliers was 5%.

Track counting and the blots.

Track detectors are very useful devices for alpha particle dosimetry. Alpha particle tracks are registered on the detector's surface. The registered track density is proportional to the dose. When the dose is low the greatest effect on the total error of dose assessment has a Poisson distribution (random error). When the dose is high, the greatest contribution to the total error is the effect of track overlapping (systemic error). This paper describes how to solve the problem of overlapping tracks when a computer aided image analyser is used. The formulae presented in this paper were proven in the international calibration programme run by NRPB and EU.

Quality control and reliability of reported doses.

Results of performance tests verifying the dosimetric properties of dosimetric systems are published in various reports (e.g. IAEA and EURADOS). However, there is hardly any information in the open literature relating to the uncertainty in a dose measurement or in the annual dose, which is increased by failure of the evaluation or data management system, damage of the dosemeter itself or by the loss of dosemeter. In this article, an attempt is made to estimate the importance of the above-mentioned conditions. This is achieved by sending questionnaires to about 200 approved dosimetric services in Europe. In total 88 questionnaires were returned and analysed. In the questionnaires, the frequency of occurrence of the various error conditions were investigated. Participants were also asked to evaluate the impact of the error condition from a dosimetric point of view and what countermeasures are taken. The article summarises all responses and compares different sources of errors according to their impact on the uncertainty of the resulting dose and gives a comprehensive overview on quality control actions and reliability on reported doses from European dosimetric services.

[Classification of mines in Poland by group radiation exposure of miners]. / Klasyfikacja kopaln w Polsce pod wzgledem grupowego narazenia radiacyjnego górników.

The computer data base on individual occupational exposure to ionizing radiation among miners (established at the Nofer Institute of Occupational Medicine, Lodz) was used to classify all Polish non-uranium mines (coal, copper, lead-zinc and chemical raw material mines) according to values of the so-called group radiation exposure (in man-sivert units). In total 72 coal mines, 13 chemical raw material mines and 10 metal ore mines employing 246,580, 3,080, 17,820 miners, respectively, were assessed. The analysis of individual annual miners exposures indicated the highest exposure to ionizing radiation in this group of workers in comparison with other occupational groups in Poland. An equivalent occupational group dose in Poland amounts to 1,480 man-siverts. Out of this dose 96.4% is received by miners, 2.5% by X-ray workers, 0.7% by workers of isotope laboratories and 0.1% by physiotherapeutists working in health resorts.

[Occupational problems from exposure to roentgen rays]. / Problemy zawodowej ekspozycji na promieniowanie rentgenowskie.

The authors analysed methodological problems concerning the use of film dosimetry in the evaluation of annual doses received by workers exposed to X-radiation. This is mainly related to nonlinearity of the optical density of films dependent on the dose and the photon energy. The set of four filters solved these problems. The evaluation of occupational exposure among workers being in contract with X-radiation sources in 1996 as well as the analysis of data on occupational exposure followed since 1966 are presented.

[Exposure to chemical carcinogens in Poland in 1999]. / Narazenie na rakotwórcze substancje chemiczne w Polsce w 1999 R.

Occupational exposure to chemical carcinogens in Poland, based on the data provided by the Central Register of Carcinogenic Agents, is presented. More than 220,000 employees in 2376 enterprises were exposed to chemical substances, mixtures and technological processes recognized as carcinogenic. The majority of them were present in the three regions (voivodships) of Poland: slaskim, dolnoslaskim and malopolskim.

Transformation of field monitoring results into miners' annual exposures to radon progeny.

This paper presents the theory of estimating miners' radiation hazard, using the values of radon daughters' concentration in the work-environment. All measurement results can be obtained with any technique beginning with instant measurement and ending with long-term dosimetry. The measurements carried out in metal ore mines show that the seasonal changes in radon daughters' concentration have their main influence in the estimation of the miners' hazard. The estimation of the hazard which was obtained from equations, was compared with the results given from the computer simulation.

Authorized limits of radon daughter products in Polish underground metal-ore mines in the light of experience.

The paper presents the results of measurements of individual exposures of miners to radioactive radon daughter products, naturally existing in air of metal-ore mines. Results concern the three year period between 1985 and 1987, during which the observed annual average concentrations were stable and have been recognised as values corresponding to the steady state. They are presented and analysed assuming several possible values of the Authorized Limit of the exposure of miners to radon daughter products. The values: 1 WLM, 2.5 WLM, 3.5 WLM (Working Level Month) were considered and compared with the value of 5 WLM, which is currently the basic limit recommended by the International Commission on Radiological Protection (ICRP), and approved by the WHO, ILO and IAEA. Though the value of 3.5 WLM is presently adopted and officially authorized in Poland as the Authorized Limit of annual individual miners' exposure, the results presented in this paper lead to the conclusion that the value of 2.5 WML could be adopted instead of the current one. This means that the present limit could be decreased by about 30% and without causing any social, technological and economic problems in Polish metal-ore mines.

Radiological classification of Polish underground mines and recommendations of surveillance.

The paper presents the most recent data, collected 1987-1989, on concentrations of 222Rn products in the air of all Polish underground non-uranium mines, and data on the exposure of the miners employed there. The concentrations and exposure of miners were evaluated by using 'passive' dosimeters, based on the track-etch solid state nuclear track detector, worn as small individual cassettes on helmets of representative groups in every mine for one month, four times a year (once in each season of the year). The paper contains the average annual exposure of miners in coal-, metal-ore-, and chemical raw materials oremines. The paper, also presents expected 'frequency' distributions of individual miners' exposure in particular types of mines, as well as the computer simulations of 'relative frequency' distributions of expected miner's exposure when the Annual Limit of Exposure would be adopted at the level 17, 12, 8.6, 6.9 and 3.4.10(-3) Jhm-3 (5.0, 3.5, 2.5, 2 and 1 WLM). The concept and criteria of classification of mines according to the radiation hazards are presented and discussed. According to that concept, all mines in Poland have been considered and classified into four classes of mines with a different level of radiation hazard. The appropriate radiological surveillance to the respective class of mine is proposed and discussed.

Field monitoring versus individual miner dosimetry of radon daughter products in mines.

The paper presents the results realised simultaneously by two different and independent systems of measurement of an assessment of miners' exposure to radon daughter products which naturally occur in the air of mines. The first one, called the Air Sampling System (ASS), was based on the field monitoring of radon progeny in air, the second one, called the Individual Dosimetry System (IDS), was based on the individual dosimeters worn by miners. Experimental comparison of these two systems has been conducted for six years in eleven Polish underground metal-ore mines. This study reveals that no correlation exists between the concentration and annual miners' exposures evaluated by the ASS and IDS. The ratio ASS/IDS for mine population varies from 11.0 to 0.14 in respect of annual concentration means, and in respect to annual exposures, this ratio varies from 4.5 to 0.14. The conclusion to be drawn from six years' observation and comparison of both systems is that correct and true evaluation of miners' exposure to radon progeny can be made only by the use of the Individual Dosimetry System, since the Air Sampling System is too sensitive and too dependent on the Strategy of sampling and its radiation.

Computer-aided methods for evaluating cancer risk in miners due to radiation exposure.

The paper presents some aspects of radiation hazard which occurs in a non-nuclear sector of industry, namely radiation hazard in non-uranium underground mines. The radiation hazard is caused in each type of underground mine by the naturally occurring noble radioactive gas-radon (222Rn) and radioactive products of its decay 218Po, 214Pb, 214Bi/214Po the so-called 'radon daughters' occurring in the mines' air. The paper presents the concept of how to provide a reliable system of assessment of miners' exposure by application of representative individual dosimetry, and also presents principles of computer-aided methods for interpretation of the results of miner's dosimetry useful for conversion of dosimetry data to the term of expected risk of cancer caused by exposure at miner's workplaces. The representative Individual Dosimetry system strengthened by computer-aided methods of analysis of results provided essential information on radiation cancer risk for miners employed in coal mines, metal-ore mines, chemical raw material mines in Poland. The coefficient of annual cancer risk induction is 1.5 x 10(-4) year-1 for coal mines, 1.40 x 10(-4) year-1 for metal ore mines and 1.5 x 10(-4) year-1 for chemical raw material mines. The radiation risk appears to be of the same magnitude as the conventional risk of life loss at work-related accidents. The average Lost Life Expectancy coefficient for both the radiation risk and conventional risk are 0.5 and 0.3 year per each miner, respectively.