COMMON RADIOACTIVE ITEMS
Radium dial, glow-in-the-dark watch and clock
faces and compasses, especially those painted in the first
half of the 20th century contain large amounts of alpha and gamma
emitters that can raise count rate by ten to twenty times or more
next to the watch. Rates from a night table alarm clock manufactured
in the fifties emit about 40 counts per minute a foot in front of
the glass cover. Recently, a fad in jewelry has led to the use of
bare watch faces and other parts from broken watches combined as
pins or brooches. Some of these have the radium containing paint
on them and are quite dangerous. The paint could flake or rub off
and be inhaled or eaten.
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.
