Radioactivity is not the driver of lung cancer in cigarettes.
So you're saying the EPA and CDC are making it up?
No, I'm saying it's well known that carcinogenic compounds like tar are what causes the lung cancer. It's not radioactivity. https://en.wikipedia.org/wiki/Tar_(tobacco_residue)
The radioactive materials are just a bonus you get for free.
I mean smoking shouldn't really cause cancer to begin with. It really depends on how much radioactive material is in ecigs, which afaik we don't know yet.