For the public, radioactivity is a boolean. Something is either not radioactive, or it's radioactive and will melt your face and/or turn you into a cronenberg.
In practice, almost everything is radioactive to some degree. This is always handy to show people who don't get this: https://xkcd.com/radiation/
In practice, almost everything is radioactive to some degree. This is always handy to show people who don't get this: https://xkcd.com/radiation/