Well, a quick Google search shows you wrong - there is well-documented research into the amount of radioactivity in coal plant emissions. As an example, USGS: http://pubs.usgs.gov/fs/1997/fs163-97/FS-163-97.html
Is it an issue? The released radioactivity from a coal plant is up to 100 times that of a nuclear power plant - but those emissions are so ludicrously low that you can treat it as (100 * 0) = 0. There really isn't a health issue from the emissions.
Mercury, Sulfur, Nitrogen, sure - Radioactivity, not so much.