radiation

[P3D Elliott Swanson <elliott@xxxxxxxxxxxxxxxxxxxx>]

A friend of mine, Bill Kolb, ARINC Research Corporation (with Paul Frame, 
Oak Ridge Associated Universities) just published a paper "Living With 
Radiation: The First Hundred Years." (c 1996)

You'd be surprised at the sources of radiation (past and present). In 
Germany, radium laced toothpaste was manufactured for awhile. There were 
radium suppositories for treating piles made by Radium Health Products of 
Royal Oak, Michigan.

The antistatic devices in the photo-3d thread are cited in the report: 
(quoted by permission) "The only source material currently used for static
eliminators in the United States is Polonium-210, an alpha emitter with a
relatively short 138 day half-life. At the time of manufacture a typical
activity is approximately 0.5 mCi. From 1969 to 1988, the Polonium-210 was
incorporated into ceramic microspheres (approximately 40 um in diameter)
affixed to an aluminum backing with epoxy cement. //material skipped//
Nevertheless, it was possible for these microspheres to come loose if the
device were dropped and subsequent license restrictions led the 3M Co. to
end production in the late 1980s. Antistatic devices produced since then
use Polonium-210 sealed between a base of silver and a layer of gold. A
final gold plating provides additional integrity and results in a foil
that is insoluble and inert in most materials. //material skipped// In the
case of the Staticmaster (r) brush, each metal element initially contains
0.25 mCi. When it is no longer effective as a static neutralizer, most of
the polonium will have decayed to non-radioactive lead, but the Nuclear
Regulatory Commission does not want these devices to be discarded as
scrap. the old source should be returned to the manufacturer where the
gold and silver can be recovered. The estimated dose to users of these
devices is about 0.01 mrem/yr." 

Also of interest to photographers is the presence of thorium elements in 
camera lenses. "the Aero-Ektar f 2.5, 7 inch lens was one of the best 
known. Up to 30 percent by weight of thorium oxide was permitted in 
optical glass and lenses containing as much as 28 percent thorium oxide 
were produced for many years. In high thorium content lenses, the glass 
visibly darkens over time due to self-irradiation. //material skipped// 
Many 35mm cameras made by Kodak and Pentax in the 1950s and 1960s, and 
some enlarger lenses, contained thorium elements. These elements were 
often positioned next to the film, which was a good reason not to leave 
film in the camera."

Radiation can also be found in eyeglasses and photographic filters. 
"Camera filters, particularly those manufactured before 1970, may be 
slightly radioactive due to trace amounts of uranium and thorium in the 
materials used to tint such glass."

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I'd be curious to know the results of a radiation reading on a Kodak 
stereo if anyone has the equipment to do this.

Glowingly yours,

Elliott


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