I've read that good isotopes emitting alpha and beta are slowly decaying and transforming into isotopes emitting gamma radiation. This is why old lenses can become dangerous after 40-50 years.
It's not. The XKCD is pretty solid, but if you like napkin-math, here's some. This is napkin-math quality only. I take no responsibility for personal irradiation choices.
Someone studied this back in 1988 and, if I read this right, if you're using a radioactive lens as an eyepiece (say, for a telescope) then the exposure limit for the eye back then was a cumulative 15 mSv per year.
This camera emits (rounding up) 0.003 mSv/h, so you must only use it for 5000 hours per year. There's 8760 hours per year, so in order to reach the 15 mSv annual exposure limit, you'd need to hold this camera up to a single eye for ~13 hours a day for 365 days in order to reach annual exposure limits.
TLDR: If you tape this camera to your skull in front of one eye for a year including while sleeping, you'd receive 26 mSv of exposure in that eye, exceeding the 1988 annual safe exposure limit of 15 mSv cited in a random paper from 1988. Most people will hold the camera up to their eye for less than this amount of time per year.
TLDRTLDR: Do not use this camera as a cyborg attachment and you'll be fine.