NavList:

Gary,

I really wouldn't worry at all about the radiation from your sextant,

....or the 1950's alarm clock next to your head at the side of the bed which glows so brightly with its radium paint you can read by it - you are being exposed to radiation all the time from natural sources which amount to far greater levels of radiation exposure. The gamma radiation from the sextant is so small it is negligible.

Radiation exposure and potential deleterious effects is all about _relative_ risks of exposure - in quantity and time. A high dose of ionising radiation in short timescale is dangerous: same dose over a long time not so dangerous as cell repair occurs.

The radium ladies case is interesting. They were ingesting huge amounts of radioactive material but the main manifestation of physical ill health was the serious deterioration of bone structure due to calcium replacement and anaemia. There were of course an increased number of cancer cases - but not as many as you might expect: about twenty per thousand and that over some years.
For a toxicological report on radium see:
http://www.bvsde.paho.org/bvstox/i/fulltext/toxprofiles/radium.pdf

Your recent flight across the pond from Paris to the US of A will have given you more of a dose with cosmic gamma rays than your sextant: probably equivalent to twenty years worth of sextant radiation.
And if you have a single X-ray at your dentist or hospital you will have had a lifetimes worth of your sextant radiation.

And if you live in a granite area (like Cornwall or Aberdeen here in the UK) -move - because you are constantly exposed to quite high levels of radiation from the granite directly, and from the radon gas that seeps out of the rock from under your house and into your living rooms. The latter is a problem in most rocky areas incidentally, and is actually serious enough to merit special consideration of good ventilation in the floor/roof/wall spaces to make sure it dissipates. Oh! and sleep with your bedroom window open too is a good idea.

It used to be thought that ionising radiation has no lower limit of damage effect - especially to DNA and hence to biological systems; but this has now been challenged with evidence that small low levels of constant ionising radiation (as actually occurs in nature) actually stimulates cell and DNA repair
mechanisms - so that sextant might actually be helping you to better health...!! But as you are a lawyer..I can't guarantee that :-) .

Park your sextant with the box open next your favourite chair so you can look at it, or pick it up if you like.. and enjoy !

Douglas Denny.
Chichester. England.
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