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Information Directory

Reference Directory

It’s Everywhere!

Is radioactivity unique?
The earth has always been radioactive. Everyone and everything that has ever lived has been radioactive. In fact, the natural radioactivity in the environment is just about the same today as it was at the beginning of the Neolithic Age, more than 10,000 years ago.

What is radiation?
Radiation is energy in the form of particles or rays given off by atoms as they go from an unstable to a stable state. Some radioactive atoms exist naturally; others are made artificially.

Is there radioactivity in our bodies?
Yes.  During our lifetime, our bodies harbor more than 200 billion billion radioactive atoms. About half of the radioactivity in our bodies comes from Potassium-40, a naturally-occurring radioactive form of potassium. Potassium is a vital nutrient and is especially important for the brain and muscles. Most of the rest of our bodies’ radioactivity is from Carbon-14 and tritium, a radioactive form of hydrogen. These naturally-occurring radioactive substances expose our bodies to about 25 “millirem” per year, abbreviated as “mrem/yr”.

Is there radioactivity in food and water?
Yes.  Most radioactive substances enter our bodies as part of food, water or air. Our bodies use the radioactive as well as the nonradioactive forms of vital nutrients such as iodine and sodium. Radioactivity can be found at every step of the food chain. It is even in our drinking water. In a few areas of the United States, the naturally-occurring radioactivity in the drinking water can result in a dose of more than 1,000 millirem in one year.

What kinds of radioactivity are in food?
In general, the foods we eat contain varying concentrations of radium-226, thorium-232, potassium-40, carbon-14, and hydrogen-3, also known as tritium.

How much of these radionuclides are in foods?
Well, it depends, of course, on the food item.  The U. S. Department of Energy gives the following concentrations as examples:  Salad Oil 4,900 pCi/l; Milk 1,400 pCi/l; Whiskey 1,200 pCi/l; Beer 390 pCi/l; Tap Water 20 pCi/l; Brazil Nuts 14.00 pCi/g; Bananas 3.00 pCi/g; Tea 0.40 pCi/g; Flour 0.14 pCi/g; and Peanuts and Peanut butter 0.12 pCi/g.

Is there radiation in outer space?
Yes.  Another type of natural radiation is cosmic radiation from the sun and outer space. Because the earth’s atmosphere absorbs some of this radiation, locations at higher altitudes receive a greater exposure than those at lower altitudes. In Ohio, for example, the average resident receives a dose of about 40 millirem in one year from cosmic radiation. In Colorado, it is about 180 millirem in one year. Generally, for each 100-foot increase in altitude, there is an increased dose of one millirem per year.

Flying in an airplane increases our exposure to cosmic radiation. A coast-to-coast round trip gives us a dose of about four millirem.

The rocks and soils around us are radioactive.

In Ohio, radiation in soil and rocks contributes about 60 millirem in one year to our exposure. In Colorado, it is about 105 millirem per year. In Kerala, India, this radioactivity from soil and rocks can be 3,000 millirem per year, and at a beach in Guarapari, Brazil, it is over 5 millirem in a single hour — but only a few residents who use that beach receive doses in excess of 500 millirem per year.

Is there radioactivity in our homes?
As a matter of fact, there is.  If you live in a wood house, the natural radioactivity in the building materials gives you a dose of 30 to 50 millirem per year. In a brick house, it is 50 to 100 millirem per year. And, if your home is so tightly sealed that there is little ventilation, natural radioactive gases (radon) can be trapped for a longer period of time and thus increase your dose.

Is it true that we can’t escape from radioactivity?
Yes, its quite true.  Each person with whom we spend eight hours a day gives us a dose of about 0.1 millirem in a year.

Using a gas stove can increase the dose by about two millirem per year because of radioactive materials in the natural gas.

A person who smokes two packs of cigarettes a day receives a radiation dose of about 1,300 millrem per year. This is because polonium (a radioactive element) is part of the smoke and when inhaled, it gets trapped in the lungs.

So, its everywhere, right?
Radiation really is everywhere. We are exposed to a constant stream of radiation from the sun and outer space. Radioactivity is in the ground, the air, the buildings we live in, the food we eat, the water we drink, and the products we use. The average person in the United States receives a dose of about 620 millirem per year from these natural sources of radioactivity and typical medical radiation exposures.

To put these radiation doses into perspective, although theoretically the risk increases with increased exposure to radioactivity, no effects have ever been observed at levels below 5,000 millirem delivered over a one year period. In fact, effects seen when humans are exposed to 100,000 millirem over a short time period are temporary and reversible. It takes a short-term dose of more than 500,000 millirem to cause a fatality.

Is it true that we can’t live without it?
Yes, our bodies are radioactive.  Its a simple fact of nature.  But there is no cause for alarm. These very small but detectable levels of radioactivity are natural . . . as natural as life itself.