>>2632904>>oh no. what should I do?you should disregard him, he is a ruseman. It's the same principle as how the smoke detector out in the hall has radioactive americium in it. That shit will kill you very dead indeed if you eat it. So... y'know, don't do that.
The radioactivity in old lenses comes from thorium oxide (
http://camerapedia.wikia.com/wiki/Radioactive_lenses) Thorium is measurably radioactive, and it's bad for you if it gets inside you, but it is not very fierce at all. From the same page,
>Typical radiation levels can approach 10 mR/hr as measured at the lens element's surface, decreasing substantially with distance; at a distance of 3 ft. (.9 m.) the radiation level is difficult to detect over typical background levels. For reference, a typical chest x-ray consists of about about 10 mR, a round-trip cross country airline flight exposes a passenger to 5 mR, and a full set of dental x-rays exposes the patient to 10 mR to 40mR.Very nearly all thorium is thorium-232, which decays by alpha emission (not gamma emission as the other anon claims), with a half-life of about 14 billion years. Alpha particles are the lowest-energy kind of radioactivity, and they're stopped by the layer of dead cells on your skin. This same thing is why they're bad news if eaten, because all the radiation stays in one concentrated area. And thorium is a heavy metal and those just aren't good for you in general, radioactive or no. But if you don't get it inside you it's very difficult to hurt yourself with it.
