I have often wondered about how much of this debate is fueled by the idea that radiation is the one-and-only carcinogen in the world, or at least, the idea that it is by far the strongest carcinogen? There are many carcinogens: smoke is a moderately strong carcinogen: exposure to smoke through smoking is a very clear cause of cancer. Wood smoke contains the same carcinogenic elements as other types of smoke.
We cannot ban carcinogens from our world. They exist. In most cases, we deal with them through setting limits for exposure or release. Only radiation bears this LNT burden, which is the equivalent of saying that "any bit of radiation could kill you! " Yes, and any particle of wood smoke in your lungs could lead to lung cancer, etc. I mean, where will it end? No more woodstoves or fireplaces?
Since zero exposure to carcinogens is not possible, and since we have mechanisms to fight off low exposures (or we would never live to grow up), setting reasonable limits for various toxins is the reasonable approach. Using a non-measurable "rule" (we have to attempt to get to zero exposure for this one) is not reasonable.