Radiation is energy given off by atoms in the form of particles
or electromagnetic rays. There are actually many different
types of electromagnetic radiation that have a range of
energy levels. They form the electromagnetic spectrum and
include radio and micro waves, heat, light, and x-rays.
However, when you see the word 'radiation' on this Website,
we refer to 'ionizing radiation,' (radiation that has enough
energy to break chemical bonds).
What is radioactivity?
The radioactivity of a material is the property of emitting
radiation.
Is all ionizing radiation the same?
No. Ionizing radiation can be in the form of particles
or rays, and each form behaves differently. The kind of
radiation given off by a nucleus depends on the nature of
the imbalance in the nuclear forces.
Where am I likely to encounter radioactive
materials?
We encounter radiation from numerous sources: the
atmosphere, soil and water, food, and even our own bodies.
Many of the sources we encounter are shielded to prevent exposure.
For example, a small amount of radioactive material is used
in ionizing technology smoke detectors. It is sealed in a
chamber and surrounded by a housing to prevent contact. However,
we may encounter other sources, such as naturally occurring
radon or uranium mill tailings which are not shielded and
require us to take protective measures
How can people be exposed to radiation?
Each of the different routes, or pathways, by which people
can be exposed to radiation result in exposure to different
parts of the body. When calculating exposures or estimating
the effects of exposures, health physicists analyze the
three exposure pathways: inhalation,
ingestion,
and direct (external)
exposure
Living tissue in the human body can be damaged by ionizing
radiation. The body attempts to repair the damage, but sometimes
the damage is too severe or widespread, or mistakes are
made in the natural repair process.
How do we know radiation causes cancer?
At first it was learned through observation. As early as
1910-1912, radiation was known to cause skin cancer. As
the uses of radiation became more widespread, and their
apparent effects better documented, scientists conducted
careful studies of people exposed to radiation. Among the
best known long-term studies are those of Japanese atomic
bomb blast survivors, other populations exposed to nuclear
testing fallout (for example, natives of the Marshall Islands),
and uranium miners.
Is any amount of radiation safe?
The effects of very low levels of ionizing radiation are
very difficult to study. They are well below the levels
of normal background radiation that people receive from
natural sources. In fact, the conclusions about the effects
of low levels of radiation come from what we learned about
the effects of higher levels of radiation exposure. As a
result, there is no firm basis for setting a "safe"
level of exposure above background.
Most regulatory and advisory bodies around the world (including
EPA) assume that any exposure carries some risk and that
the risk increases as the exposure increases.
EPA carries out its radiation protection program responsibilities
with several key, complementary activities:
setting protective limits on radioactive emissions and
associated risks to public health and the environment
assessing radiation risk
responding to emergencies involving radioactive materials
communicating providing information and inviting
participation in radiation exposure protection programs
working cooperatively with industry, the states, other
federal agencies, and national and international organizations
that have radiation protection responsibilities.
Why does EPA have a radiation protection program?
Congress gave EPA the responsibility and authority to develop
and issue standards, regulations, and guidance to protect
people and the environment from harmful exposure to radiation
EPA is the primary Federal agency charged with protecting
people and the environment from harmful and avoidable exposure
to radiation.
Do other organizations have radiation protection
responsibilities?
Yes, federal, state, and local governments, as well as
tribal organizations play important roles in radiation protection.
International organizations, such as the International Atomic
Energy Agency also play a role.