@Chris. Thanks for the links. After reading some of the primary papers in Science from 40 years ago, I am convinced that there is probably some merit to the idea that heavy smokers (1–2 packs per day) may ingest/inhale enough polonium to cause some damage and possibly contribute to the development of lung cancer.
I’m not in agriculture or environmental sciences, but I would speculate that this fertilizer is cheaper than the alternatives. It seems to me that on the one hand, tobacco companies want to avoid bad publicity (so don’t want to admit there is a problem), but no the other hand, might benefit by having smokers around longer if they switch fertilizers.
I would add however, that even if the fertilizer is changed, I believe that there would still be lung cancer, (and mouth, throat, esophageal, stomach and other cancers) and fertilizer/polonium has nothing to do with emphysema (another major killer) and heart disease (yet another major killer).