Low Dose Radiation
The goal of the Low Dose Radiation Research Program is to support research that will help determine health risks from exposures to low levels of radiation. This information is critical to adequately and appropriately protect people while making the most effective use of our national resources.
Extensive research on the health effects of radiation using standard epidemiological and toxicological approaches has been used for decades to characterize responses of populations and individuals to high radiation doses, and to set exposure standards to protect both the public and the workforce. These standards were set by using modeling approaches to extrapolate from the cancers observed following exposure to high doses of radiation to predicted, but not measurable, changes in cancer frequency at low radiation doses. The use of models was necessary because of our inability to detect changes in cancer incidence following low doses of radiation. Historically, the predominant approach has been the Linear-no-Threshold model and collective dose concept that assumes each unit of radiation, no matter how small, can cause cancer. As a result, radiation-induced cancers are predicted from low doses of radiation for which it has not been possible to directly demonstrate cancer induction.
Over the next 100 years, radiation exposures associated with human activity are expected to be low dose and low dose-rate radiation from medical tests, waste clean up, terrorism events and environmental isolation of materials associated with nuclear weapons and nuclear power production. The major type of radiation exposures will be low Linear Energy Transfer (LET) ionizing radiation (primarily X- and gamma-radiation) from fission products. The DOE Low Dose Radiation Research Program will thus concentrate on studies of low-LET exposures delivered at low total doses and low dose-rates.
The research program is building on advances in modern molecular biology and instrumentation, not available during the previous 50 years of radiation biology research. These techniques will allow the program to examine the relationship between normal oxidative damage and radiation-induced damage, using studies conducted at very low doses and dose-rates. The radiation-induced perturbation of normal physiological processes, along with the biological system’s homeostatic responses will eventually be characterized at all levels of biological organization - from genes to cells to tissues to organisms.
Research is supported in five interrelated areas:
  1. Low dose radiation vs. endogenous oxidative damage - the same or different?
    A key element of this research program will be to understand the similarities and differences between endogenous oxidative damage, damage induced by low levels of ionizing radiation, and the health risks from both.
  2. Understanding biological responses to radiation and endogenous damage.
    Molecular, cellular, and tissue responses modify the processing of radiation induced damage and/or determine whether or not damaged cells are eliminated, inhibited, or expressed as cancers. Three biological responses of particular interest are bystander effects, induction of genomic instability, and the radio-adaptive response. These responses impact cancer risks from radiation.
  3. Thresholds for low dose radiation - fact or fiction?
    We do not know if there are radiation doses or energies below which there is no significant biological change or below which normal cellular processes can effectively deal with the damage induced. If there are, then there should be no regulatory concern for exposures below these thresholds since there will be no increase in risk.
  4. Genetic factors that affect individual susceptibility to low dose radiation.
    Do genetic differences exist making some individuals more sensitive to radiation-induced damage? Such genetic differences could result in sensitive individuals or sub-populations that are at increased risk for radiation-induced cancer.
  5. Communication of research results.
    This research program will only be a success if the science it generates is useful to policy makers, standard setters, and the public. Research results must be effectively communicated so that current thinking reflects sound science.
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