Assessing the exposure situations with naturally occurring radioactive materials across European countries by means of the e-NORM survey

Despite the EU states being under the umbrella of the European Directive 2013/59/Euratom, a certain degree of heterogeneity may be noticed in the implementation of EU recommendations concerning regulation and handling of NORM into national legislation and practice. This is mainly a result of the still existing incomplete international knowledge about different phenomena related to NORM. Therefore, the attempt to advance the understanding of the behaviour and exposure of NORM is at the core of the European RadoNorm project. Within this context, an international survey on NORM has been prepared. The goals of the survey were to gather information and data from European countries that will contribute making an updated and/or new (a) systematic overview of NORM exposure situations and their analysis with respect to different radiation protection aspects, (b) knowledge about applied radioecological models in a variety of NORM exposure situations to improve evaluation of possible exposure doses and risk for population and workers, as well as of environmental risk, and (c) overview of overall mitigation measures applied in NORM involving industries, and possible remediation activities applied at NORM affected legacy sites. The survey is built upon an extended list of NORM-involving industries and processes, covers general aspects of NORM, presence of multi-stressors, as well as practical procedures applied in management and regulation, also in the context of a circular economy. The survey responses were obtained from 19 countries. An analysis of survey responses proved that NORM control is still a complex issue for many countries, and the recently-introduced regulatory solutions require further interpretation for developing procedures and good practices. The present work provides a detailed analysis of the survey responses with respect to regulation, management and investigation of NORM.

A methodology for the systematic identification of naturally occurring radioactive materials (NORM)

Naturally occurring radioactive materials (NORM) are present worldwide and under certain circumstances (e.g., human activities) may give radiation exposure to workers, local public or occasional visitors and non-human biota (NHB) of the surrounding ecosystems. This may occur during planned or existing exposure situations which, under current radiation protection standards, require identification, management, and regulatory control as for other practices associated with man-made radionuclides that may result in the exposure of people and NHB. However, knowledge gaps exist with respect to the extent of global and European NORM exposure situations and their exposure scenario characteristics, including information on the presence of other physical hazards, such as chemical and biological ones. One of the main reasons for this is the wide variety of industries, practices and situations that may utilise NORM. Additionally, the lack of a comprehensive methodology for identification of NORM exposure situations and the absence of tools to support a systematic characterisation and data collection at identified sites may also lead to a gap in knowledge. Within the EURATOM Horizon 2020 RadoNorm project, a methodology for systematic NORM exposure identification has been developed. The methodology, containing consecutive tiers, comprehensively covers situations where NORM may occur (i.e., minerals and raw materials deposits, industrial activities, industrial products and residues and their applications, waste, legacies), and thus, allows detailed investigation and complete identification of situations where NORM may present a radiation protection concern in a country. Details of the tiered methodology, with practical examples on harmonised data collection using a variety of existing sources of information to establish NORM inventories, are presented in this paper. This methodology is flexible and thus applicable to a diversity of situations. It is intended to be used to make NORM inventory starting from the scratch, however it can be used also to systematise and complete existing data.

Experience with NORM waste disposal in different European countries

Industrial processes generate various quantities of waste that can be contaminated with radionuclides of natural origin (naturally occurring radioactive material ('NORM waste')). The efficient management of this waste is essential for any industries affected by NORM waste generation. To obtain an overview of current practices and approaches in Europe, the IRPA Task Group on NORM conducted a survey among task group members and other experts from European countries. The results revealed significant differences in methods and approaches in the European countries. In many countries, landfills are used to dispose of small- and medium-sized quantities of NORM waste with limited activity concentration. But our survey indicated that despite a uniform reference basis for national legislation in Europe, there are different framework conditions for the disposal of NORM waste in practice. In some countries, the disposal is hampered because the interface between the radiation protection system and the waste regime is not yet clearly regulated. Particular practical problems include the lack of acceptance of waste because of the 'radioactivity' stigma and only vague specifications by the legislators on acceptance obligations of the waste management sector.

Tools for harmonized data collection at exposure situations with naturally occurring radioactive materials (NORM)

Naturally occurring radioactive materials (NORM) contribute to the dose arising from radiation exposure for workers, public and non-human biota in different working and environmental conditions. Within the EURATOM Horizon 2020 RadoNorm project, work is ongoing to identify NORM exposure situations and scenarios in European countries and to collect qualitative and quantitative data of relevance for radiation protection. The data obtained will contribute to improved understanding of the extent of activities involving NORM, radionuclide behaviours and the associated radiation exposure, and will provide an insight into related scientific, practical and regulatory challenges. The development of a tiered methodology for identification of NORM exposure situations and complementary tools to support uniform data collection were the first activities in the mentioned project NORM work. While NORM identification methodology is given in Michalik et al., 2023, in this paper, the main details of tools for NORM data collection are presented and they are made publicly available. The tools are a series of NORM registers in Microsoft Excel form, that have been comprehensively designed to help (a) identify the main NORM issues of radiation protection concern at given exposure situations, (b) gain an overview of materials involved (i.e., raw materials, products, by-products, residues, effluents), c) collect qualitative and quantitative data on NORM, and (d) characterise multiple hazards exposure scenarios and make further steps towards development of an integrated risk and exposure dose assessment for workers, public and non-human biota. Furthermore, the NORM registers ensure standardised and unified characterisation of NORM situations in a manner that supports and complements the effective management and regulatory control of NORM processes, products and wastes, and related exposures to natural radiation worldwide.

The self-absorption correction factors for 210Pb concentration in mining waste and influence on environmental radiation risk assessment

The radioactive lead isotope ²¹⁰Pb occurs in waste originating from metal smelting and refining industry, gas and oil extraction and sometimes from underground coal mines, which are deposited in natural environment very often. Radiation risk assessment requires accurate knowledge about the concentration of ²¹⁰Pb in such materials. Laboratory measurements seem to be the only reliable method applicable in environmental ²¹⁰Pb monitoring. One of the methods is gamma-ray spectrometry, which is a very fast and cost-effective method to determine ²¹⁰Pb concentration. On the other hand, the self-attenuation of gamma ray from ²¹⁰Pb (46.5 keV) in a sample is significant as it does not depend only on sample density but also on sample chemical composition (sample matrix). This phenomenon is responsible for the under-estimation of the ²¹⁰Pb activity concentration level often when gamma spectrometry is applied with no regard to relevant corrections. Finally, the corresponding radiation risk can be also improperly evaluated. Sixty samples of coal mining solid tailings (sediments created from underground mining water) were analysed. Slightly modified and adapted to the existing laboratory condition, a transmission method has been applied for the accurate measurement of ²¹⁰Pb concentration . The observed concentrations of ²¹⁰Pb range between 42.2 ÷ 11,700 Bq·kg^-1 of dry mass. Experimentally obtained correction factors related to a sample density and elemental composition range between 1.11 and 6.97. Neglecting this factor can cause a significant error or underestimations in radiological risk assessment. The obtained results have been used for environmental radiation risk assessment performed by use of the ERICA tool assuming exposure conditions typical for the final destination of such kind of waste.

Chemical composition and biological value of proteins of the yeast Yarrowia lipolytica growing on industrial glycerol

Michalik, B., Biel, W., Lubowicki, R. and Jacyno, E. 2014. Chemical composition and biological value of proteins of the yeast Yarrowia lipolytica growing on industrial glycerol. Can. J. Anim. Sci. 94: 99–104. The aim of this study was to evaluate the chemical composition and biological value of proteins from the yeast, Yarrowia lipolytica, after cultivation on glycerol, a waste product obtained in the production of biofuel from rapeseed. In the tested material we determined moisture, crude protein, ether extract, nitrogen-free extract (NFE), ash, calcium, phosphorus, cadmium, mercury, arsenic, amino acids and fatty acids. The biological value of Y. lipolytica and Saccharomyces cerevisiae proteins was determined with laboratory rats by two methods: the growth method (protein efficiency ratio standardized for casein, PERstand; net protein retention, NPR) and the Thomas–Mitchell method (biological value, BV; true digestibility, TD). The protein content of Y. lipolytica [467 g kg−1 dry matter (DM)] was similar to that of S. cerevisiae (479 g kg−1 DM). Of particular interest was the almost 30-times higher crude fat content in Y. lipolytica (200 g kg−1 DM) than in S. cerevisiae (6.7 g kg−1 DM). Yarrowica lipolytica cells accumulated substantial amount of fat in which more than 90% of fatty acids were unsaturated fatty acids with a considerable share of polyunsaturated fatty acids (34%). The low share of sulfur amino acid of Y. lipolytica (2.05 g 16g−1 N) and S. cerevisiae (2.32 g 16g−1 N) limited the nutritional value of the protein of the studied yeast. The biological value of proteins as assessed by the growth method (PER, NPR) did not differ between the two yeast species. Finally, Y. lipolytica was a rich source of highly digestible ether extract (over 57%).

Geno-toxicity assay of sediment and water samples from the Upper Silesia post-mining areas, Poland by means of Allium-test

Genotoxic potential of two environmental compartments (water and sediment) from the Upper Silesia Coal Basin (USCB), Poland were evaluated and compared by employing root meristem cells of Allium cepa. The clear genotoxic effect of water and sediment sampled was shown, with an important contribution of severe types of cytogenetic abnormalities. The most biologically relevant pollutants were revealed through multivariate statistical analysis of relationships between biological effects registered and the environment contamination. Overall, results of simultaneous use of conventional monitoring methods and biological tests suggested that contemporary levels of persistent pollutants in post-mining areas of the USCB may enhance the risk both for human health and biological components of natural ecosystems.

Availability of radium isotopes and heavy metals from scales and tailings of Polish hard coal mining

Radium and heavy metal contaminated tailings and scales resulting from Polish hard coal mining were investigated for their mobilisation potential by using leaching methods. The main focus is set on a three-step extraction procedure proposed by BCR (Bureau Communautaire de Référence, now Standards Measurements and Testing Programme) of the European Union, which was used for investigating the availability of radium isotopes. In addition, the results of a Polish extraction procedure for the heavy metals' water solubility are presented for rough comparison. After a special treatment, the BCR-reagents were measured by gamma-spectrometry to define their radium activity concentrations; the heavy metal content in the water soluble fractions was determined by ICP-AES. The samples were collected at two different sites influenced by the discharge of pit water from hard coal mining. The tailings were taken from a former tailing pond, which now is no longer in use, but the settled material is still present. At another abandoned and meanwhile flooded tailing pond, the scales were scraped from the inside of a discharge tube. The results obtained show that there is different leaching behaviour between the radium isotopes. The tailings being characterised by surface adsorbed radium provide up to 25% of the initial (226)Ra content, (228)Ra is altogether leached up to 15%. The scales comprise stable radiobaryte (Ba[Ra]SO(4)) and can be considered as being unable to provide radium isotopes, since no trace of radium dissolution was observed. The leaching behaviour of heavy metals is similar to that of radium. Mn, Ni and Zn are dissolved by water from the tailings; the scales do not provide any.

Effects on non-human species inhabiting areas with enhanced level of natural radioactivity in the north of Russia: a review

Results of long-term radioecological investigations in areas with an enhanced level of natural radioactivity in the north of Russia are summarized. Deleterious changes within animal and plant populations inhabiting areas with an enhanced level of natural radioactivity in the Komi Republic were revealed. These changes are expressed in enhanced levels of mutagenesis, destructive processes in the tissues of animals, disturbances of reproductive functions and reduced offspring viability. Compensatory processes, resulting in animal and plant survival under extremely adverse conditions of radium and uranium-radium contamination, were observed as well. However, obvious signs of adaptation failed to be detected. The findings suggest that adverse somatic and genetic effects are possible in plants and animals in the dose range observed at sites with an enhanced level of natural radioactivity. In contrast, different plant species inhabiting an area with an enhanced level of natural radioactivity in the taiga zone of the Sakha Republic (Yakutia) reveal a stimulation of growth processes, photosynthesis, endogenous low molecular weight antioxidant synthesis as well as adaptive response. It is apparent from the data presented that naturally occurring differences in terrestrial radiation level could be of genetic and ecological consequence.

Carrot infection by Alternaria radicina in field conditions and results of laboratory tests

Carrot black rot caused by the fungus Alternaria radicina (Meier) Drechsler et Eddy, the economically important disease of carrot (Daucus carota L.). Research was carried out in 2004 and 2005 in order to establish correlation between plant infestation in the field and laboratory experiments. To determine the incidence and severity of the disease in mature crop, a 5-degree scale was used, where 1 meant no visible disease symptoms and 5 meant total foliage infestation. Plants were rated individually and the disease index was calculated. Fungus pathogenicity in laboratory conditions was determined using a petiole assay and a root disc assay. The petiole assay was conducted during the vegetation period; basal parts of petioles detached from fully developed carrot leaves were put in contact with the growing A. radicina mycelium. The root disc assay was conducted during storage of carrot roots; root discs were inoculated with toothpicks overgrown by A. radicina mycelium. The isolate of A. radicina was pathogenic to petioles and carrot discs. Differences in the reaction of the examined cultivars in the field and laboratory experiments were revealed. However, no significant correlation between plant infestation in the field and the results of laboratory experiments were observed.

Differences in editing of mitochondrial nad3 transcripts from CMS and fertile carrots

A high level of the nucleotide sequence conservation was found for mitochondrial nad3 gene of carrot. Three silent nucleotide substitutions differentiate nad3 open reading frames from cytoplasmic male sterile and male fertile carrots. All these differences are preserved on the RNA level. Partial and silent editing also distinguished both carrots. Three of the C to U conversions were specific to the fertile line. In the two examined carrot lines editing did not affect the mode of alteration of encoded amino acids.

Differences in editing of mitochondrial nad3 transcripts from CMS and fertile carrots

A high level of the nucleotide sequence conservation was found for mitochondrial nad3 gene of carrot. Three silent nucleotide substitutions differentiate nad3 open reading frames from cytoplasmic male sterile and male fertile carrots. All these differences are preserved on the RNA level. Partial and silent editing also distinguished both carrots. Three of the C to U conversions were specific to the fertile line. In the two examined carrot lines editing did not affect the mode of alteration of encoded amino acids.

Contamination of settling ponds and rivers as a result of discharge of radium-bearing waters from Polish coal mines

Saline waters from underground coal mines in Poland often contain natural radioactive isotopes, mainly 226Ra from the uranium decay series and 228Ra from the thorium series. Approximately 40% of the total amount of radium remains underground as radioactive deposits, but 225 MBq of 226Ra and 400 MBq of 228Ra are released daily into the rivers along with the other mine effluents from all Polish coal mines. Technical measures such as inducing the precipitation of radium in gobs, decreasing the amount of meteoric inflow water into underground workings, etc. have been undertaken in several coal mines, and as a result of these measures, the total amount of radium released to the surface waters has diminished by about 60% during the last 5-6 years. Mine water can have a severe impact on the natural environment, mainly due to its salinity. However, associated high levels of radium concentration in river waters, bottom sediments and vegetation have also been observed. Sometimes radium concentrations in rivers exceed 0.7 kBq/m3, which is the permitted level for waste waters under Polish law. The extensive investigations described here were carried out for all coal mines and on this basis the total radium balance in the effluents has been calculated. Measurements in the vicinity of mine settling ponds and in rivers have given us an opportunity to study radium behaviour in river waters and to assess the degree of contamination. Solid waste materials with enhanced natural radioactivity have been produced in huge amounts in the power and coal industries in Poland. As a result of the combustion of coal in power plants, low-radioactive waste materials are produced, with 226Ra concentration seldom exceeding a few hundreds of Bq/kg. A different situation is observed in coal mines, where, as a result of precipitation of radium from radium-bearing waters, highly radioactive deposits are formed. Sometimes the radioactivity of such materials is extremely high; precipitates from coal mines may have radium concentrations of 400,000 Bq/kg--equivalent to 3% uranium ore. Usually, such deposition takes place underground, but sometimes co-precipitation of radium with barium takes place on the surface, in settling ponds and in rivers. Therefore management of solid waste with technologically enhanced natural radioactivity (TENR) is a very important subject.