When
plants and animals absorb radioactivity, it stays stored in their cells. So
although radioactivity in a stream of water may be
very slight, plants in the stream may be more radioactive than the surrounding
water. They have absorbed a little
radioactivity every day and stored it in their cells. When fish and animals eat these plants, they
take in this radiation and store it in their own
cells, where it can build up to dangerous levels. It is the alpha particles, beta particles,
and gamma rays emitted by radioactive
atoms that enter and damage living cells. Alpha particles are made up of protons and neutrons and
are too weak to penetrate, or go into, human skin. They can be stopped by a
sheet of paper. But they are not harmless to living things. If alpha particles
are breathed in or come in through food, they can hurt lungs and other body
organs and do the kind of damage that leads to cancer.
Beta particles are electrons. They can go through the
skin but are stopped inside the body. They damage and kill cell, as can gamma
rays.
Gamma rays are electromagnetic waves that can go right
through our bodies and keep on going. In fact, they can go through concrete up
to six and one-half feet (two meters) thick. It takes very thick walls to
protect living things from gamma rays. If
they hit reproductive cells (sperm or egg cells), they can cause birth defects.
Now there are strict laws and guidelines for using all radioactive
materials.
Special shields are used to protect people who get and
give x-rays, and the number of x-rays allowed per year for a person is limited. Animals and people can’t breathe radiation
out, sweat it out, or get rid of radioactivity in any way once it is in their
system except by letting it age or decay.
Radioactivity ‘lives’ for many thousands of
years. But it can hurt life much more quickly.
Nuclear energy seems economical in day-to-day operation.
However, until a way is found to safely dispose of the radioactive waste, its
total cost is hard to measure. If the
money needed for safe transportation of nuclear waste and the creation of
permanent storage is added to the cost, it may be quite expensive. Health
problems related to increased environmental radiation might also raise the
price people pay for nuclear energy.
For now, nuclear energy is one source of energy we use
to meet some of our energy needs, while we try to find ways to harness energy
without dangerously polluting our planet.
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