Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia.
University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, HR-10000, Zagreb, Croatia.
J Environ Radioact. 2019 Nov;208-209:106018. doi: 10.1016/j.jenvrad.2019.106018. Epub 2019 Jul 20.
The aim of this study was to assess the environmental radiological risk of coal ash and slag to terrestrial wildlife. The research site used in this study was a disposal site of coal ash and slag with enhaced content of uranium decay chain radionuclides. With the use of the ERICA Tool, total dose rates to wildlife and risk of resultant radiobiological effects were estimated. As input data for the assessment, experimental activity concentrations of U, Ra and Pb in coal ash and slag and best estimates of activity concentrations for related daughter radionuclides and U decay chain were used. Where possible, the experimental data for activity concentrations of U, Ra and Pb in plants and related concentration ratios were used. Results were compared to background dose rates, also estimated by the Tool. The Tool's assessment data indicated internal exposure as the prevalent exposure pathway with Ra and Po as the main dose contributors. Also, the contribution of U decay chain to the total dose rate was not negligible since for some organisms it represented up to 11% of the total dose rate. The risk of an occurrence of radiobiological effects in plants on the coal ash and slag disposal site can be considered negligible since the estimated total dose rates were below the screening dose of 10 μGyh and near the dose rates estimated for plants in the control area. However, the estimated dose rates for reference animals and Lichen & Bryophytes were above the screening dose rate for most organisms and on average 13 times higher than the estimated background dose rates. At the given dose rates, an occurrence of different radiobiological effects could not be excluded for animals in close contact with coal ash and slag such as earthworms and small burrowing mammals. A separate assessment performed on an example of reference plants showed that the use of activity concentrations in organisms as input data can result in an order of magnitude smaller estimates of dose rates in comparison to activity concentration in coal and ash as input data. Our study highlighted the need for experimental data in radiological risk assessments to mitigate the conservatism of the ERICA Tool and its tendency to overestimate dose rates.
本研究旨在评估煤灰和炉渣对陆生野生动物的环境放射性风险。本研究使用的研究地点是一个煤灰和炉渣处置场，其中铀衰变链放射性核素的含量增加。使用 ERICA 工具估算了野生动物的总剂量率和由此产生的放射性生物效应风险。作为评估的输入数据，使用了煤灰和炉渣中 U、Ra 和 Pb 的实验活度浓度以及相关子体放射性核素和 U 衰变链的最佳估计活度浓度。在可能的情况下，还使用了植物中 U、Ra 和 Pb 的实验活度浓度数据以及相关的浓度比。将结果与工具估算的背景剂量率进行了比较。工具的评估数据表明，内部暴露是主要的暴露途径，Ra 和 Po 是主要的剂量贡献者。此外，U 衰变链对总剂量率的贡献也不容忽视，因为对于一些生物体，它占总剂量率的 11%。煤灰和炉渣处置场植物发生放射性生物效应的风险可以认为是微不足道的，因为估计的总剂量率低于 10µGyh 的筛选剂量，接近对照区植物估计的剂量率。然而，对于参考动物和地衣和苔藓，估计的剂量率在大多数生物体中高于筛选剂量率，平均比估计的背景剂量率高 13 倍。在给定的剂量率下，与煤灰和炉渣密切接触的动物（如蚯蚓和小型穴居哺乳动物）可能会发生不同的放射性生物效应。对参考植物的单独评估表明，与将煤灰和炉渣中的活度浓度作为输入数据相比，使用生物体中的活度浓度作为输入数据可以使剂量率的估计值小一个数量级。我们的研究强调了在放射性风险评估中需要实验数据，以减轻 ERICA 工具的保守性及其高估剂量率的趋势。
