Watches manufactured since the mid 1960's use tritium, H3, a radioactive form of heavy hydrogen, with a half-life of 12.26 years or Promethium-147, a totally man-made radioactive element with a half-life of 2.64 years. Both of these elements are weak beta and gamma emitters and cannot send many particles beyond the cover glass of the watch. However, greater quantities of these elements must be used to make the same amount of light from luminous paint.
Thorium oxide coated gas lamp mantles used in ornamental gas lanterns and gas burning camping lamps are radioactive. The thorium oxide is chosen because it can be raised to white heat without decomposing. However, the mantle does become extremely fragile and will powder into a fine ash which can potentially be inhaled or ingested. Thorium is a natural alpha emitter with the potential for increasing lung tumors. Thorium disintegrates to produce radon-220, an alpha particle emitting radioactive gas. Other uses of thorium include improving alloys of tungsten and magnesium. Thoriated tungsten welding rods are partly vaporized in the arc welding process. Filaments in electronic tubes and television picture tubes have be coated in thorium oxides to produce electrons more easily.
Cerium oxide, a powdery pink glass and jewelry polishing compound, while not radioactive in itself, is extracted from monazite sands containing thorium oxide. Trace amounts of thorium oxide remain with the extracted cerium oxide. Thorium oxide is a potent alpha particle emitter that poses a serious threat to internal organs if inhaled or ingested.
Most smoke detectors contain about 1 microcurie of Americium 241, an alpha emitter deposited on a thin piece of metal foil surrounded by a metal shield. The alpha particles cannot escape unless the smoke detector is taken apart or vaporized in a fire, but some gamma rays are emitted. The Rad*Scanner reads about 30 counts per minute higher than the background average when place on top off a smoke alarm. The half-life of Am-241 is 458 years and certainly will outlast the useful life of the smoke detector.
Antistatic brushes for photographic use in removing dust from film negatives contain Polonium 210, an alpha emitter that will vaporize appreciably at 55 degrees C (130 degrees F), a temperature that is reached easily on the dashboard of an automobile on a hot summer day. This could be another inhalation danger, if the manufacturing method does not adequately contain the Polonium.
The fluorescent lamp starters, the small cylindrical package mounted in some types of lighting fixtures, contains a glass, gas-filled bulb with less than 15 nanocuries of krypton 85, a beta and gamma emitting radioactive gas with a 10.4 year half life. The purpose of the krypton is to ionize the other gases in the starter tube to assist the lamp starting on a cold morning. Actual amounts must be smaller. The Rad*Scanner has not detected any increase in count levels around these devices.
Pottery glazes and art glass, some ceramic glazed jewelry and cloisonné enameled jewelry contain high percentages of uranium oxides to produce bright yellows and oranges. Fiesta Red china dishes by Fiestaware produced through 1971 emit gamma and beta. Acidic foods left in contact with this chinaware will dissolve small amounts of these radioactive elements which will be ingested. Enameled jewelry made with these glazes and worn next to the skin is hazardous.
Some gemstones, notably natural zircons, are radioactive. Additionally, some topaz, beryl and tourmaline stones were treated with neutrons from atomic reactors to deepen or change their color. This treatment left some stones hot enough to be of concern, about 0.2 milliroentgens per hour. Some artificial diamonds are made from metal oxides, such as yttrium oxide stabilized with thorium oxide, a radioactive compound.
Some porcelain teeth, artificially colored with uranium containing metal oxides to improve the reflective appearance, can expose the mouth to 1000 millirem per year for each cap. This is two and a half times the average whole body yearly exposure from all natural sources and medical X-rays.
Radon, a gaseous breakdown product of radium, can build up in enclosed spaces such as basements. A potent alpha emitter, radon is believed to cause as many as 30,000 lung cancer deaths each year in the United States, alone. The United States Environmental Protection Agency has mandated some very sophisticated procedures for measuring trace amounts of radon gas at the levels likely to be found in enclosed spaces. A known volume of air is forced through a filter and the filter is checked for radioactive radon breakdown products. If above average count level within enclosed interior spaces such as basements and ground floor level closets are detected by the Rad*Scanner, additional approved tests for radon should be done.
Potassium-40, a strong beta emitter with a long half life of over 1.3 billion years, makes up only a small proportion (less than 0.02%) of naturally occurring potassium salts. The long half-life means relatively few atoms of potassium-40 decay at a time. The total radioactivity is about 1/1000 of an equal weight of uranium salts. Potassium salt deposits in some places has a higher concentration of potassium-40. Since potassium is indispensable for life of plants and animals, we will find it in almost all foods. Some brands of "salt substitute" made mainly from potassium salts might be marginally more radioactive than others, depending on the source of the ingredients.
During normal operation, nuclear power reactor losses from buildup of gasses and easily vaporized elements are continuously released in small amounts: tritium, iodine, cesium, krypton and xenon. Of these, the tritium can oxidize to form radioactive water and organic compounds. Radioactive iodine concentrates in the thyroid gland and contributes to thyroid malfunctions and tumors. Cesium compounds settle in the bones. Radioactive krypton and xenon are inert gases that do not readily form compounds, but are slightly soluble in body fat and decay to form elements that settle in bone tissue.
During airplane flights, at crusing altitude, passengers and crew are exposed to elevated levels of cosmic rays, 20 to 40 times those experienced at sea level.
PROGRESSIVE SYSTEMS COMPANY
1620 WEST MAIN STREET
HOUSTON, TEXAS 77006-4712
TEL: 713 523-0515
Back to Table of Contents