There’s radiation and there’s radiation. I expect you’re correct about general exposures from various sources, like, say microwaves from phones and stuff. But as a tiny data point I started regularly checking background airborne at my shop after the Big Fukushima. My shop is about five days downwind of the thing and, sure enough, about five days later background jumped 200-300 times normal and stayed there for about two months. But now it’s back to historic 2-3 counts p/m.
But there will be industrial areas, for example, where levels will be up for various forms. Somebody is always finding an old dump left over from the Manhattan Project, for instance. Unaware folks absolutely have to be seeing long term effects from these things. Abandoned radiographic equipment is another sleeper source of exposure. I guess you sort of “had to be there” to even think about these kinds of effects?