Frequently
Asked Questions about the DOE Low Dose Radiation
Research Program
What
is the DOE Low Dose Radiation Research Program?
The
Department of Energy is funding the Low Dose Radiation Research
Program to understand the biological responses of molecules,
cells, tissues, organs, and organisms to low doses of radiation.
The program will ensure that research results are communicated
openly to scientists, decision makers, and the public. Results
will be used in at least two ways: (1) evaluate models that
predict human health risks from exposure to low doses of
radiation, and (2) help determine whether current radiation
protection standards reflect the most recent scientific
data. If not, then results may be used in developing more
appropriate standards.
What
is a low dose of radiation?
Dose
is the amount of radiation energy deposited per unit of
mass. A low dose can be classified according to its health
impact or in comparison to natural background radiation.
Background radiation, over which we have no control, comes
from such sources as cosmic rays, radon, radium, and other
radioactive materials in the earth and has not been shown
to cause adverse health effects. This dose of radiation
is considered to be low. For the Low Dose Radiation Research
Program, a low dose of acute low-LET (Linear Energy Transfer)
radiation such as X rays, gamma rays, or beta particles
is defined as being less than 10 rem or 0.1 Sv. This level
of exposure (less than 10 rem) has been at or below the
limit of detection for most biological changes observed
in past research and is twice the yearly occupation exposure
limit.
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Why
was the Low Dose Radiation Research Program started at this
time?
Using
traditional toxicological and epidemiological approaches,
scientists have not been able to demonstrate an increase
in disease incidence at levels of exposure close to the
background. Over the past 10 years, however, there has been
an explosion of new techniques and instrumentation to measure
biological and genetic changes following low doses of radiation.
These new tools allow studies to be done that were not possible
in the past. Such research helps define radiation's effect
on cells and molecules and provide scientific input for
decisions about the adequacy of current radiation standards.
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How
long will the Low Dose Radiation Research Program last and
how large is the program?
The
research program is projected to last 10 years at a funding
level of about $20 million dollars a year. As of FY 202,
54 projects initiated by investigators and covering a wide
range of research topics were funded. DOE anticipates funding
new projects each year. Projects are selected only after
undergoing rigorous peer review by independent scientists;
once selected, the projects will be reviewed regularly by
independent review groups. DOE anticipates that research
in the Low Dose Radiation Research Program will produce
data that will help improve our understanding of the health
impact from exposure to low level radiation.
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What
major areas of research are being funded by this program?
The
DOE Low Dose Radiation Research Program centers on the following
five major research areas:
-
Develop new techniques and equipment that will make
it possible to measure and characterize damage induced
after exposure to low doses of radiation.
-
Compare DNA damage and repair induced by normal physiological
processes with that produced by ionizing radiation (radiation
capable of displacing electrons from atoms).
-
Discover mechanistic links between early biological
changes induced by low doses of radiation and changes
in disease frequency or risk.
-
Characterize the role of genetics in the sensitivity
of individuals and populations to radiation-induced
disease.
-
Synthesize and combine research results to determine
if there are dose thresholds below which no biological
responses or increases in radiation risk occur.
What
are some of the new techniques and equipment this program
is using and developing?
The
program is using advances in gene sequencing (the order
of the genetic makeup), rapid detection of changes in gene
expression (the process by which a gene's coded information
is converted into proteins which alter cell function), and
characterization of human genotypes (human genetic makeup)
as well as research results derived from the use of these
techniques. The program is novel in its ability to link
these biological advances with new equipment such as the
microbeam machine. The microbeam directs microscopic beams
of different types of radiation to individual living cells
and organelles such as the nucleus. Researchers now have
the ability to known amounts of direct radiation to specific
individual cells and to detect damage in cells traversed
by radiation as well as in neighboring cells not traversed.
Until recently, this kind of precision was not possible.
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Why
is DOE committed to providing the public with information
about this research program?
DOE
and its predecessor agencies have an uneven track record
in communicating about radiation and its health consequences.
As part of the agency's commitment to significantly improving
that record, this program will communicate openly the results
of its funded research.
Further,
future policy decisions about such issues as exposure limits
and cleanup standards will be based, in part, on the results
of research in this program. These policies are aimed at
protecting human health and the environment, so DOE will
provide any interested individuals or groups with the scientific
information that influences these policies. For example,
risk calculations may be important components of policy
decisions, so DOE will communicate the methods used to calculate
risk and the elements considered within risk assessments.
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How
can understanding cellular and molecular mechanisms for radiation-induced
changes affect risk assessment?
Understanding
cellular and molecular mechanisms involved in radiation-induced
changes can help improve the accuracy of risk assessments
in three interrelated ways. First, this understanding can
strengthen models used to predict the risks of low radiation
exposures by supporting and bolstering the scientific underpinnings
of existing models and prompting the development of new,
more accurate models. Second, risk assessments will improve
as scientists learn whether biological mechanisms linking
radiation exposure with diseases such as cancer operate
the same way for high and low doses of radiation. Third,
program research on these mechanisms can reduce the uncertainties
of estimated cancer incidence through a better understanding
of the processes that lead to cancer.
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Why
is it important to discover the mechanistic links between
radiation-induced cellular and molecular damage and diseases
such as cancer?
Knowing
how radiation-induced cellular and molecular damage is linked
to diseases such as cancer may help identify early biological
changes that predict an increased risk of disease for an
exposed population. This information may lead to interventions
to minimize or block disease incidence associated with damaged
or altered cells. Because low dose radiation exposure may
be neither a one-time event nor recent in its occurrence,
it also is important to understand the role that previous
exposures play in producing biological changes and, subsequently,
disease. Therefore, this program seeks to develop more sensitive
indicators of past radiation exposures.
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Why
does the program seek to distinguish the effects of high and
low doses of radiation?
The
question of whether high and low doses of radiation affect
living systems differently has been at the center of a continuing
scientific controversy. Technological and scientific advances
now make it possible to address this question in a much
more direct way. Now scientists can learn directly about
the types and amounts of damage from low level radiation
exposures instead of estimating the low level effects by
observing damage from high levels of radiation. As scientific
understanding of the specific effects of low radiation doses
improves, risk estimates can become increasingly robust.
Further,
conducting low dose radiation research should help to resolve
the scientific debate over the existence of a radiation
threshold, that is, a radiation dose below which there either
are no significant biological changes or the induced damage
is managed effectively by normal cellular processes. Although
some researchers interpret scientific evidence to mean that
no dose of radiation is safe, others interpret the evidence
to mean that there are low doses of radiation that are not
harmful. Resolving this debate would have tremendous implications
within the scientific community and could significantly
affect radiation-related policy and regulatory decisions.
(See the related Frequently Asked Question, "What
are the implications of radiation thresholds?")
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Why
is it important to be able to differentiate between DNA damage
induced by normal processes and that caused by radiation?
Researchers
know that damage to DNA is caused by free radicals (charged
molecules). Free radicals are produced by normal physiological
processes as well as by radiation exposure at both high
and low doses. "Normal" DNA damage caused by free radicals
typically is repaired with very few errors through cellular
and molecular processes. Nevertheless, this "normal" damage
may still contribute to the aging process and to diseases
associated with aging, including cancer.
Large
amounts of DNA damage undoubtedly are caused by free radicals
shortly after single, acute exposures to high radiation
doses, and this damage occurs in multiple sites in individual
cells. It is not repaired easily, may be misrepaired, and
can induce mutations and cancer.
What
is not known is how successfully DNA is repaired when free
radicals are produced by low levels of ionizing radiation--a
concern for public and occupational radiation protection.
Scientists do know that free radicals resulting from low
doses of ionizing radiation are a fraction of those produced
by normal body processes.
This
program, therefore, seeks to distinguish between radiation-induced
DNA damage and that caused by natural processes. This will
be accomplished by understanding how the damage is repaired
and the relationship between nonrepaired DNA damage and
the induction of disease.
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What
are the implications of radiation thresholds?
Radiation
thresholds are important to policy decisions about setting
exposure standards. Such standards now are based on an underlying
model called linear-no-threshold (LNT), which maintains
that any exposure to radiation may be harmful and extrapolates
low dose effects from known high dose effects.
Scientists
disagree about the validity of this LNT model. Some support
an alternative model in which thresholds do exist; this
view maintains that some doses of radiation produce no harmful
health effects. Other scientists suggest that small doses
of radiation may even be beneficial. Determining the existence
of thresholds and the levels at which they might occur will
provide valuable scientific data for deciding whether new
radiation protection standards are needed and what those
standards should be.
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What
can be learned from studying human subpopulations that are
resistant or sensitive to radiation-induced damage?
Researchers
know that individuals and subpopulations (cultural groups
defined by geography or occupation) vary in their patterns
of exposure to potential environmental insults and in their
responses to environmental conditions. Studying these differences
with respect to low doses of radiation can lead to an enhanced
understanding of the mechanisms involved both in radiation-induced
biological changes and in resistance to those changes. This
information, in turn, can be used to develop interventions
and treatments. It also can be used as a basis for policy
decisions aimed at controlling exposure to and reducing
risks to sensitive subpopulations from low dose radiation
exposure.
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What
are the expected benefits of research conducted in this program?
DOE
anticipates several benefits from low dose radiation research.
First, research results should produce a greater understanding
of genetic repair and misrepair mechanisms within cells;
this is expected to benefit cancer research, treatment,
and prevention. Second, research should decrease uncertainty
associated with the potential health effects of low doses
of radiation. Third, the program will provide information
necessary for determining whether current radiation protection
standards reflect the latest scientific understandings.
Fourth, research results will be applicable to the realm
of radiation cleanup, influencing decisions about levels
required to protect public health, radiation workers, and
the environment. Fifth, this program will provide information
to all interested parties, including members of the public,
about the latest scientific developments regarding low dose
radiation health effects.
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What
potential beneficial "spin-offs" may result from this program?
Major
spin-offs probably will derive from a better understanding
of cancer, whether induced by radiation or not. For example,
this program may make possible the identification of individual
phenotypes (the physical expression of one's genetic makeup)
and genotypes (the genetic makeup itself) for cell cycle
control, cell death and DNA-repair genes. This information
may be useful in predicting which individuals or groups
are likely to resist or to show particular sensitivity to
adverse health effects from environmental stress and occupational
exposures. In addition, these kinds of research results
may be used to develop cancer-prevention strategies and
to design improved radiation or other chemical therapies
for cancer treatment.
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