[davidmanze]

   I think we have to put things in proportion when it come to Thorium and radioactivity, yes it was used in many lenses including Pentax, Minolta and others as well as Kodak, they have been tested by many people, the fact is not in doubt.

 

  It was also used in glass production as well as medical apparatus, eg.  shoe fitting machines and a host of other dangerous medications devices which were finally made illegal in the thirties. Many radioactive glass products still sell in the antique trade (auctions) and are a lime green colour and not considered dangerous and are still legal to sell.

 

  The bottom line:

 

  If you drink heavily and smoke (whatever???),  fly in airplanes, drive on the roads, walk the streets at night, bicycle in large cities and sleep with very loose woman,.... all of which I do..

 

 ............the additional danger of popping a Pentax thorium impregnated lens into your weekend shooting bag.........

 

    ......is likely to be of very little consequence!