You’re lucky, it’s not radioactive:
(This is from a review I found)
“IS MY SUPER-TAKUMAR 28MM F3.5 RADIOACTIVE?
That’s quite a question to hit you with, isn’t it?
It stems from the Super-Takumar 55mm f1.8 and 50mm f1.4 being infamously radioactive, along with several other lenses made by various different manufacturers between the 1940s and 1970s.
From the information I can find online, like here for example, the 28mm Takumar is thankfully free of any radioactivity issues.”
(This is from a review I found)
“IS MY SUPER-TAKUMAR 28MM F3.5 RADIOACTIVE?
That’s quite a question to hit you with, isn’t it?
It stems from the Super-Takumar 55mm f1.8 and 50mm f1.4 being infamously radioactive, along with several other lenses made by various different manufacturers between the 1940s and 1970s.
From the information I can find online, like here for example, the 28mm Takumar is thankfully free of any radioactivity issues.”