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:
- 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.
- 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.
- 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.
- 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.
- 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.
For more information: