Originally posted by vyoufinder Thoriated glass was used and allowed up through the late 80's. My K mount 50mm 1:1.4 is radioactive. I also have an M 50mm 1:2 which was yellowed and cleared using UV light, so I'm pretty sure it is too (it's early, all metal version.)
https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1717/nureg-1717.pdf (see: 3-285)
There is definitely a risk. According to U.S. Nuclear Division's Office of Nuclear Regulatory research, the risk may even be "substantial."
So, looking at your source material, that states that, if you were to spend a thousand hours per year looking through your camera lens (that's 2.73 hours per day, every day of the year, or, 19.23 hours per week) you would be exposed to a total of 0.2 mSv/yr. That is the equivalent of about 5 or 6 intercontinental flights a year or 2 chest x-rays. One CT-scan is 20mSv, so you'd have to look through your lens for 10,000 hours (There's 8,760 hours in a year) to get the equivalent exposure as to one CT-scan.
If you were a normal user, and lets assume you have 5 or more lenses, one of which is radioactive, and lets assume you're not a commercial video camera operator, then lets assume you may spend, at most, 2 hours a day looking through your various lenses. Possibly therefore, you may look through your radioactive lens 0.4 hours per day. (24 minutes) That would give you 0.03 mSv/yr which is the same radiation you would receive if you flew from Seattle to Portland (a 55 minute flight) roughly 100 times a year.
Your normal background radiation exposure, in the USA, averages 6.24 mSv per year. If you use your lens for 24 minutes every day, your annual exposure would increase by about 0.5%.
Put another way: If you have granite benches in your kitchen, your annual exposure will be somewhere between 0.005 to 0.18 mSv depending on the type of granite, if you spend 4 hours a day in the Kitchen. It could be argued that going outside and taking photos will be safer for you than spending time in your kitchen.
While there may be a risk, the risk is infinitesimally small and most certainly not "substantial".
Last edited by MarkJerling; 11-29-2017 at 03:33 AM.