We know which chemicals in cigarettes are carcinogens so why cant we isolate and eliminate them from cigarettes? creating a safer cig for smokers

I wish we could: Many of them are heterocyclic hydrocarbons with odd atoms (oxygens, nitrogens) in the ring. They intercalate into the DNA and mutate the base pairs. We simply won't be able to eliminate the bunch -- that would be science fantasy. If you're addicted to nicotine, get a smokeless form instead, or break the addiction by whatever means.