Re: Skin dose from enriched uranium

[mcnaught@lanl.gov (Mike McNaughton)]

The paragraph below discusses the effects of uranium on the skin, and
concludes that even pure uranium would not cause erythema. However, I have
read that Henri Bequerel received mild erythema as a result of keeping
radioactive samples in his front pocket. I don't think Bequerel ever
extracted radium, so his samples must have been uranium or thorium.
Therefore, I wonder if this story about Bequerel is really accurate. Does
anyone know the source of the story?

>The skin dose rate from unirradiated uranium, not uranium ore, of any
>enrichment is about 200 mrem/hr.  The dose to cause skin "burns",
>depending on the area irradiated, is greater than 1500 rem.  The mass of
>uranium is not a factor unless it is very small.  If it is very small,
>e.g. a gram or so, there is no effect even if the person were to hold it
>for a very long time.  Therefore, a person would need to hold the
>uranium in his hand for 1500000/200 = 7500 hours (a little less than a
>year) to get a dose that might cause a burn, if the dose were given all
>at once.  Because the dose is spread out over so long a time, it would
>take longer (e.g. a higher dose) to produce an effect, because the skin
>has a repair mechanism. I don't think the author will have a person
>holding uranium continuously for such a long time.

"Shlala gashle" (Zulu greeting, meaning "Stay safe")
mike (mcnaught@LANL.GOV)