Radon Called United States’ Worst Radiation Hazard
Radiation. Few words in any language generate more anxiety.
Used with names such as Hiroshima, Three Mile Island or Chernobyl, it produces an even more frightening fallout.
Yet, applied with human ingenuity, radiation can destroy malignant cells in a tumor, sterilize medical products and foodstuffs, track the progress of a medicine through the body with radioisotopes, date archeological and geologic events and turn water into steam for electric power. Soon, radiation may be used to detect plastic explosives in suitcases.
“To live with radiation is indeed to constantly weigh its risks against its benefits,” Charles E. Cobb Jr. wrote recently in National Geographic. “Everywhere I traveled, I heard this debated. I found that definite answers were elusive, scientific knowledge worryingly incomplete and opinion often contradictory.”
Humans can’t avoid living in a sea of radiation. Almost all this exposure--some 82% of it in the United States--comes from natural sources. Cosmic and solar rays keep up a steady drizzle of gamma rays and heavy particles, but the atmosphere shields us from most celestial radiation.
More than half of natural radiation comes from radon, a gas given off by the decaying of the common radioactive element, radium, in the soil. Inhaled radon continues to decay and produces alpha radiation, which can cause lung cancer.
A federal survey of 20,000 houses in 17 states found that more than 25% of them harbored potentially hazardous amounts of radon. It is “the largest environmental radiation health problem affecting Americans,” Richard Guimond of the Environmental Protection Agency said.
Anthony Nero of the Lawrence Berkeley Laboratory added: “You’re talking about huge doses, in comparison with all other background radiation. Radon is like having two or three Chernobyls every year.”
Man-made radiation, which accounts for the other 18% of exposure in the United States, comes from many everyday sources such as medical X-rays and nuclear medicines. Radioactive sensors are in 26 million household smoke detectors, and uranium gives a gleam to dentures.
Just what is radiation? Although the term is broad enough to include sunlight and heat, radio waves and microwaves, it is most often used to mean ionizing radiation.
Every radioactive substance contains unstable atoms, or radionuclides. These atoms want to become something else--something stable--so they change, or decay. With each change energy is released. A radionuclide may transform itself many times before it becomes stable, in sequences known as decay chains. That energy--or radiation--produces charged particles, or ions, from once-neutral particles.
Ionizing radiation is the atomic equivalent of a bull in a china shop. When it penetrates living tissue, it wreaks havoc on the atoms and molecules in its path and sets off events that can destroy living cells or make them function abnormally.
More than a million Americans, from military veterans and weapons-building workers to hospital technicians and uranium miners, have been exposed to greater-than-normal amounts of radiation.
