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Radiation, Water Quality and the
Fukushima Disaster
http://www.emfnews.org
Philip A. Candela, Ph.D.
July 11, 2011
On March 11, 2011, Japan’s Fukushima No. 1 Nuclear Power
Plant withstood shaking from the fourth largest earthquake
recorded worldwide in over one hundred years. However, the
19 foot-high seawall separating the facility from potential
oceanic onslaughts could not withstand the tsunami that
followed. The plant flooded, electrical power to the cooling
system was lost, and the reactors overheated, triggering a
release of radioactive material into the environment. In the
wake of the accident, there has been much discussion
regarding the contamination of air, soil, food, the oceans
and drinking water. Some concerns related to drinking water
are addressed in this communication.
Radiation in Perspective
Accidents involving radiation elicit emotional responses
worldwide. Such reactions are understandable, given the
devastation wreaked by nuclear weapons at Hiroshima and
Nagasaki, and the simple fact that radioactive phenomena are
undetectable by our five senses. However, much of the angst
concerning very low levels of radiation is unfounded, and
the nuclear accident in Japan, and the ensuing exposures,
should be considered in light of dosages, the power of
dilution, and our natural radiation environment.
Radiation is a general process by which particles or
waves move through matter or space, and describes phenomena
such as visible light, radio waves, the radiation from
radioactive materials, and X-rays. Radiation can be
classified as ionizing or non-ionizing: examples include
X-rays, and radio waves, respectively. Ionizing radiation,
such as that produced as a consequence of radioactivity, is
energetic enough to knock electrons from atoms, making them
more reactive, and capable, therefore, of doing biological
damage.
Although radiation sounds frightening, life on Earth has
been bathed in a natural ionizing radiation environment for
billions of years; uranium, thorium, potassium, and other
radioactive elements are natural parts of the Earth’s crust.
Our food, the soil in our backyards, and the masonry of our
houses are naturally radioactive. Carrying a banana in your
lunch bag exposes you to ionizing radiation by virtue of its
potassium content: approximately one in every 10,000
potassium atoms in the banana is naturally radioactive.
All the sources of natural radiation contribute to our
“natural radiation background” and in some places on Earth,
the natural background is on the order of one hundred times
higher than average, without ill effects to humans. A major
principle of environmental science states that “the dose
makes the poison.” Ionizing radiation is not intrinsically
dangerous: the danger lies in our being exposed to a
sufficient dose to cause biological damage. Our bodies are
continually damaged by the action of oxygen and other
outside agents, including very low levels of ionizing
radiation, and our bodies possess the ability to repair some
of this damage.
Fukushima and Surrounding Areas
Two of the dominant radioactive substances released from
the Fukushima reactor, iodine-131 and cesium-137 (I-131 and
Cs-137, respectively), commonly form water-soluble compounds
that can find their way into drinking water supplies. I-131
can be transported long distances in the atmosphere as a
gas, and can be transferred from the air to water supplies
by the action of rainwater. I-131 has a half-life of 8 days:
that means a capped bottle of water containing I-131 will
have only half the concentration of I-131 after 8 days, a
quarter after 16 days, and so on. Cs-137 forms solid
particles that can fall out of the atmosphere more easily
than the gaseous forms of I-131. With a half-life of 30
years, Cs-137 persists in the environment for much longer
than I-131.
Following the tsunami, drinking water in Tokyo had
measurable I-131 (e.g., 200 Becquerels [i]/liter
of water). What was the risk to human health from drinking
that water? Let’s say that two liters of the water were
consumed by an individual each day for two months. Assuming
no further iodine is added to the water, the concentration
of I-131 decreases with time due to its half-life. The
effective dose, then, would amount to only about
one-thirtieth of a yearly dose of the natural radiation
background. Dilution, another important factor, can lower
the radioactivity of I-131 in a water supply. Cs-137
persists longer, but dilution and dispersal of Cs-137 can
reduce exposure. For a snapshot in time of the relative
radioactivity of Cs-137 to I-131, in Ibaraki Prefecture,
south of Fukushima, the relative radioactivity of Cs-137 in
drinking water in late March was approximately 10 percent of
that of I-131.
Outside of Japan, the effect of dilution and dispersal
was apparent: I-131 in rain water from Berkeley, California
in late March was 40-50 times lower than the concentrations
found in Tokyo tap water. Compared to the natural radiation
background in the U.S., these values were quite
insignificant. By mid-April, both I-131 and Cs-137 were
below detectable levels in the Berkeley rainwater.
The fact that we can analyze for a substance in water
does not necessarily mean that substance will damage
health. This is another important environmental corollary
of “the dose makes the poison.” Finally, the most commonly
overlooked problem regarding water quality in the wake of
the unfortunate events in Fukushima is the unwarranted fear
of very low level radiation.
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