It seems a dead easy way to make tobacco healthier would be to stop using polonium containing fertilizer when growing it. and or not grow tobacco in polonium containing soils.
So why is this just viewed as a given?
Here’s some background information on the subject.
As to your specific question of why they don’t use different fertilizer, the answer, not surprisingly, is that it’s too expensive, as stated in the Philip Morris internal memo on the subject.
nm
dataguy’s got it covered.
It seems that (1) natural phosphate deposits contain polonium, (2) tobacco growth requires tons of phosphates. And (3) smoking would be plenty carcinogenic even if all polonium was magically removed. To extrapolate from numbers in the review that dataguy linked: 160,000 people die each year from lung cancer in the US (~80% from smoking IIRC), and if you removed all polonium from tobacco, 158,400 people would die from lung cancer. Removing polonium would make smoking only a tiny bit less extremely unhealthy.
How much extra would you pay for cigarettes that are 1% less likely to give you lung cancer?
Many smokers would take more polonium in exchange for a lower price.