@Nomad

Like I said, it's cumulative, as in one more cigarette, one more M&M, one more drink. What matters is total radiation. With human physiology, we need to include other non-radiation cancer risk factors like lifestyle risks, diet and our genetic makeup.

from Camerapedia Wiki:

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.

Most smaller lenses with thorium elements are not very dangerous. However, thorium eyepieces are dangerous. They can give a very large alpha and beta particle dose to the cornea of the eye, causing cataracts and other problems. Normally these particles are stopped by skin, but the surface of the eye is quickly damaged by them, and at close range, the dose can be very high

Really, folks don't get nervous about this. The only lenses to use with care are Kodak Aero.

All others are pure alpha emitters, shielded by your skin or a piece of paper. The only way they could damage you if you grind the glass and inhale or swallow…

My GH2 is still working very well... with 55 1.2 and 35 2.0 About the image quality, aesthetic is not very well mensurable, its up to taste, like ass, each one has its own! The thorium coat dont make the lens "better", but unique.

Is there another, more complete list than the one pointed out on the first page?

Less than a banana, but no way to know if a tiny amount of radiation is dangerous. Anyway, the non radioactive lenses take better photos, so it is kind of a moot point. http://www.bbc.co.uk/news/magazine-15288975

There are many words of wisdom written in this thread. In the last passage, I accomplished some of them, as well corrected few information which were not right- for all those who will read this topic and try to learn something here.

I own myself several radioactive lenses, so naturally I also wanted to know how dangerous using of old radioactive lenses could be. I've found this video which contains at least some reasonable values, as opposite to many videos with panicy noises of the Geiger counter without the facts, like many other videos present:

I am getting slightly upset almost every time when reading in the newspaper some articles about Fukushima, Tchernobyl or about the radioactivity in general: so many journalists seem not to understand the numbers they are writing about. We need to have few facts to get impression of how high the danger for our health could effectively be:
A: how high the radioactivity really is
B: how long time was body exposed to it, or
C: total radiation dose.

Let's check it:
Example lens: Canon FL 58mm f/1.2 (contains radioactive Thorium dioxide)
- Average exposure to the radiation by practical use of this lens is 1 µSv/hour if constantly kept on-body
- Harmless amount of radiation for humans is 3 µSv/day
- Keeping this lens just half of your arm length away from your body reduces the radiation to negligible amount

BTW, we live surrounded by Thorium:
The bones of a human contain 0.002 to 0.012 mg per kg of bone mass. We all are consuming through our food and water about 0.05 to 3 µg of Thorium daily. It would be better for us to avoid any exposure to the radioactivity, but it is not possible- it is all around us.

Among many absolutely correct things what @soundgh2 wrote, it is also true that flying in the airplane exposes our bodies to much higher effective dose of (cosmic) radiation: it varies between roughly 3-7 µSv/hour. Compare it to lenses radiation....so rather avoid here and there some flight and keep your Takumars, @Roberto. I owned some 25 years ago Pentax Spotmatic F with three radioactive Takumars (I didn't even know about their radioactivity), I just loved that camera so much that I kept it often literally close to my bed. I am still perfectly healthy, so the Takumars made no harm me... did you read this, @disastronaut ? Feel supported by my time experience.

Although the outgoing danger is too small to get rid of the radioactive lenses, as @nomad says there is also no particular reason to own some.... BTW, the yellowing of some russian vintage lenses @nomad mentioned comes from aging of Canada balsam they are coated with, they're indeed not radioactive. @nomad has right that many other, non-radioactive vintage lenses give just same optical results- and indeed, the lens radioactivity could indeed mean much higher danger for the camera sensor than for user's health, maybe @ZeCahue could post us here if he still uses most of the time his radioactive lenses and if he noticed any bad effects meanwhile? I still own my radioactive Canons, but I don't find them optically superior like @mee does. As @DrDave wrote, coatings are improved so much meanwhile, and Nokton which was mentioned for instance outpreforms very clearly just any of the radioactive lenses I ever owned: in terms of sharpness, color rendition, CA control and ghosting plus it also has wonderful image with character and lovely bokeh.

And all of radioactive lenses have one common disadvantage: dealing with their yellowing, which is result of radioactive process in the glass. I deal with that nasty problem exposing my radioactive lenses during winter months to direct sunlight, when the weather is really nice and when I can stay home and turn the lenses as the sun position moves. I cut round whole in the paper which has the same size like the front (or back) lens. White paper prevents heating of the lens, aperture blades should be open (both for reason of preventing oil exceeding). Exposing several days to the UV rays brings first results, yellowing starts disapearing.

I totally understand that old lenses have character, I have many, but there is no reason to own one unless you really want to. The simple fact is that the micro coatings are much better now, and the lenses are mostly superior. Doesn't mean I will part with my Vivitar 1:1 90mm macro, but I don't use it so much any more. That said, most lenses probably have the same rads as a banana, but you never know, you might get a "hot" one. If you are worried, don't sleep with it.

For $160 you can get the Panny 14mm which is as sharp as Leica, light as feather, slim as a hockey puck, has fast, silent autofocus and does not glow in the dark. I have never seen an old lens that was really sharp wide open, it was shock to use the 20mm for the very first time and have my wide-open ideas turned upside down. If you like the character of the lens, then keep it and use it! You can buy lead golf tape for $5 on eBay and line a small box for it as well.

@DrDave in my case I use it because it was a free gift, and none of my other lenses can match it's results. I try to use my non thorium 50mm FD lenses whenever possible, and my Panny 14-42 lens for wide shots, but that 35 f2 concave thorium lens just produces such gorgeous results. The focus feels great and is so precise and the bokeh is on par with the Nokton lenses IMHO. It makes everything look very filmic and is actually a very sharp lens, even wide open. I do plan on trying to replace it with the Nokton 25mm .95 lens someday. But that is allot of money for me at the moment.

You use a radioactive lens because it is unique.

You can't get that image from a modern lens.

Just know what you are dealing with, when using and storing the lens.

@roberto fair 'nuf - not saving lives are we :) "Personal View" sort of sums it up - I wasn't entering an argument just re-blah blah blah-ing years of tedious physics which ended up in a piece of paper saying yes - I'd survived years of tedious physics - my daily job is resolving broadcast shit so don't worry some ASCII wibble aint a worry. Still like my faintly yellow lens though I must say.

As a journalist for most of my adult life, I try to balance stories and am judged by my peers according to my ability to do so. But from time to time I am surprised by a non-journalist who assumes I have allegiances one way or another. (They assume both ways).

I find we skip over others' posts in online forums, making assumptions over others' beliefs which were never there, sometimes even implying that the person has a Freudian belief behind what they are saying.

Forums pose a challenge for us to try to understand others when faced with words alone, without facial expressions or vocal inflections. I find it hard to imagine faces behind the words. It's also a challenge to force myself to abandon a false caricature of another which I have built up.

Just as in driving, we often perceive other motorists as a kind of enemy, forums are a good opportunity to seek humanity behind the words, abandon paranoia and presumptions. For me, it's a chance to cultivate the Tao. Sorry for when I offend you.