Isolation of the effects of alpha-related components from total effects of radium at low doses

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.

Keywords:

• Low dose radiation
• environmental radiation protection
• uranium mining
• genomic instability
• alpha particles

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This work was supported by the Natural Sciences and Engineering Research Council (NSERC) of Canada in the form of a Collaborative Research and Development Grant [Grant No. CRDPJ 484381-15]. We acknowledge continued support from the National Chronic Fatigue and Immunodeficiency Foundation Inc.

Notes on contributors

Chandula Fernando

Chandula Fernando is a PhD student at the University of Toronto with a background in Radiation Biology and Medical Physics. His research interests include the indirect consequences of exposure to radiation in doses relevant to nuclear incidents and accidents.

Soo Hyun Byun

Soo Hyun Byun is a Professor of Nuclear Physics at McMaster University focusing on advanced radiation detector and nuclear instrumentation developments.

Xiaopei Shi

Xiaopei Shi was a Post-Doctoral Researcher at McMaster University interested in radiobiological effects of environmentally relevant levels of radium-226. She is currently in Shanghai, China.

Colin B. Seymour

Colin B. Seymour is a Professor of Radiation Biology at McMaster University interested in the biological consequences of low-level radiation exposure.

Carmel E. Mothersill

Carmel E. Mothersill is a Professor of Radiation Biology at McMaster University interested in the impacts of low dose and chronic radiation exposures on non-human species and on ecosystems.