 What
is Radium?
Radium is a naturally-occurring,
silvery-white, radioactive material that can exist in several
forms called isotopes. Radium is formed when uranium and thorium
(two other natural radioactive substances) decay (break down)
in the environment. Radium is almost everywhere: in soil, water,
rocks, plants, and foods at low levels.
Radium only degrades
by radioactive decay. Each isotope of radium releases radiation
at its own rate. The concentrations of radium-226 and radium-228
in drinking water are generally low, but there are some areas
where high concentrations of radium occur due to geologic sources.
In the U.S., radioactivity
is usually measured in units called "curies". The level
of radioactivity in water is usually very low and is measured
in picocuries (one picocurie equals one-trillionth of a curie)
per liter (pCi/l).
What Levels of Radium
are Safe?
The EPA's maximum
contaminant level (MCL) for radium (Radium-226 and Radium-228
combined) in public water supplies is 5 picocuries per liter (pCi/l).
The MCL has been set well below levels for which health effects
have been observed. It is therefore assumed to be protective of
public health. EPA estimates the additional lifetime risks associated
with drinking water containing 5 pCi/l is about 1 in 10,000. Public
water supplies whose radium levels exceed 5 pCi/l are not inherently
"unsafe" but are required to notify the public that
the water exceeded the MCL. Water containing elevated levels of
radium may carry a correspondingly higher level of risk to health.
Is Radium harmful
to my health?
Radium in water may
pose a hazard to human health when the water is used for drinking
or cooking. Only a small portion of ingested radium is absorbed
from the digestive tract and distributed throughout the body.
The rest is passed unchanged from the body. Some absorbed radium
is excreted in urine. Absorbed radium behaves similarly to calcium
and is deposited in the tissues of the body, especially bone.
Any radiation received externally through showering, washing,
or other uses is not a hazard since alpha particles do not travel
through your skin.
Internally deposited
radium emits alpha particles that may then damage surrounding
tissue. Studies of workers exposed to high levels of radium and
other sources of alpha radiation for extended periods show that
high levels of radium may cause depression of the immune system,
anemia, cataracts, and fractured teeth. Exposure to high levels
of radium also has shown an increased incidence of bone, liver
and breast cancer.
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