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1Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bldg 37 Rm 5050A MSC 4255, Bethesda, MD 20892, USA. bonnerw@mail.nih.gov
Mutation Research
|November 9, 2004
Summary
The traditional target model for radiation effects is challenged by new findings. Low-dose ionizing radiation (IR) induces complex cellular responses like hypersensitivity and adaptive responses, impacting health.
Area of Science:
- Radiobiology
- Cellular and Molecular Biology
- Radiation Health Effects
Background:
- The established target model assumed radiation damage is proportional to absorbed energy and cell sensitivity.
- This model posits that only directly hit cells are affected by ionizing radiation (IR).
- Recent evidence suggests cellular responses at low IR doses deviate from these assumptions.
Purpose of the Study:
- To explore phenomena observed at low ionizing radiation (IR) exposures that challenge the traditional target model.
- To investigate the cellular and molecular mechanisms underlying these non-traditional radiation responses.
- To understand the implications of these effects, including hormesis, for human health.
Main Methods:
- Review and synthesis of accumulated evidence on cellular responses to low-dose ionizing radiation (IR).
- Focus on phenomena such as low-dose hypersensitivity (HRS), increased radiation radioresistance (IRR), adaptive response (AR), bystander effect (BE), and death-inducing factor (DIE).
- Analysis of potential interactions between these effects, leading to phenomena like hormesis.
Main Results:
- Evidence indicates that cells exhibit complex responses to low-dose ionizing radiation (IR) that contradict the target model's assumptions.
- Observed phenomena include low-dose hypersensitivity (HRS), increased radiation radioresistance (IRR), adaptive response (AR), and bystander effects (BE).
- These effects may interact, potentially leading to beneficial outcomes at very low exposure levels (hormesis).
Conclusions:
- The traditional target model is insufficient to explain all observed effects of ionizing radiation (IR) on living systems.
- Understanding novel low-dose radiation responses is crucial for accurate risk assessment and potential therapeutic applications.
- Further research into the cellular and molecular bases of these phenomena will enhance our knowledge of radiation biology and hormesis in human health.