Abstract

Purpose

Radium is the most common source of alpha radiation exposure to humans and non-human species in the environment but the dosimetry is complicated by the decay chain which involves gamma exposure due to radon daughters. This paper seeks to determine the separate contributions of alpha and gamma doses to the total dose and total direct and non-targeted effect in a fish and a human cell line.

Materials and methods

This study aimed to isolate the effect of alpha particles following exposure to low doses of radium in cells, and their progeny which received no further exposure. This was initially done by comparing the survival values of a human keratinocyte cell line (HaCaT) and an embryonic Chinook salmon cell line (CHSE-214) exposed to gamma radiation, from survival of the same cell lines exposed to mixed alpha and gamma radiation through exposure to Ra-226 and its decay products. A Monte Carlo simulation was later performed to determine the contributions of radium decay products including radon daughters.

Results

The human cell line showed increased radioresistance when exposed to low doses of alpha particles. In contrast the fish cell line, which demonstrated radioresistance to low dose gamma radiation, showed increased lethality when exposed to low doses of alpha particles. Significant and complex levels of non-targeted effects were induced in progeny of irradiated cells. The simulation showed that gamma and beta decay products did not contribute significant dose and the highest beta dose was below the threshold for inducing non-targeted effects.

Conclusions

The results confirm the need to consider the dose-response relationship when developing radiation weighting factors for low dose exposures, as well as the need to be aware of possible cell line and species differences.

中文翻译：

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从低剂量镭的总影响中分离出 α 相关成分的影响

摘要

目的

镭是环境中人类和非人类物种最常见的 α 辐射照射源，但由于氡子体引起的 γ 照射，剂量测定因衰变链而变得复杂。本文旨在确定 α 和 γ 剂量对鱼和人类细胞系的总剂量以及总直接和非靶向效应的单独贡献。

材料和方法

本研究旨在分离细胞中暴露于低剂量镭后 α 粒子的影响，以及未进一步暴露于其后代的细胞。这最初是通过比较暴露于伽马辐射的人类角质形成细胞系 (HaCaT) 和胚胎奇努克鲑鱼细胞系 (CHSE-214) 的存活值来完成的，从暴露于混合 α 和伽马辐射的相同细胞系的存活到暴露于 Ra-226 及其衰变产物。后来进行了蒙特卡罗模拟以确定包括氡子体在内的镭衰变产物的贡献。

结果

当暴露于低剂量的 α 粒子时，人类细胞系表现出增加的抗辐射性。相比之下，对低剂量 γ 辐射表现出抗辐射性的鱼细胞系在暴露于低剂量 α 粒子时表现出更高的杀伤力。在辐照细胞的后代中诱导了显着和复杂水平的非靶向作用。模拟表明，伽马和贝塔衰变产物没有产生显着的剂量，最高贝塔剂量低于诱导非靶向效应的阈值。

结论

结果证实，在为低剂量暴露制定辐射加权因子时需要考虑剂量-反应关系，以及需要注意可能的细胞系和物种差异。