When I was a medical doctor in the hospital system, every now and then I needed to get a chest x-ray on a patient who was also a cigarette smoker.
Quite often, they would get nervous about the potential radiation damage from a chest x-ray. But when I told them that two packets of cigarettes gave them the same radiation dose as a chest x-ray, they would not believe me.
This raises two questions. First, how did a radioactive metal get into their cigarettes? And second, why did they not believe me?
Every year, we humans smoke about six trillion cigarettes, enough to make a chain that would easily reach from the Earth to the Sun, and back, and then do the whole trip again, just for good measure.
By 2020, cigarettes will be killing about 10 million people each year. They have already knocked off 100 million people in the 20th century, and if we don't come to our senses, they could kill one billion in the 21st century.
The radioactive metal in cigarettes is polonium-210. It was discovered in 1898 by Marie and Pierre Curie. It is extremely toxic (about 250-million-times more toxic than cyanide) and is naturally present in uranium.
Developed countries use fertiliser that is manufactured from apatite rock, and this rock naturally contains uranium which then decays to radioactive polonium-210, which enters the tobacco plant through both the leaves and roots.
When the cigarette burns, it reaches temperatures of 600–800°C, hotter than the melting point of polonium.
The liquefied polonium sticks to tiny particles in the cigarette smoke, and then preferentially lands at locations in your airways and lungs, where one pipe splits into two pipes.
Polonium-210 has a very short half-life of 138 days. It is intensely radioactive, and sprays alpha particles on to the surrounding tissues.
Now, most people would be definitely worried if you suggested that they have a chest x-ray every day for the rest of their lives. But some of these people quite happily smoke, sometimes up to two packets of cigarettes every day.
Cigarette smoke is already loaded with various chemicals that are well-known to cause cancer. It's estimated that the radiation dose from the polonium-210 in cigarettes accounts for about two per cent of cigarette deaths. That is several thousand deaths each year in the USA alone.
It was first discovered that cigarettes contained radioactive polonium about half a century ago. So how come it's not general knowledge?
The answer is simple. Big Tobacco has done an excellent cover-up job for the last half century.
Once they realised that there was radioactive polonium in tobacco, they started their own internal — and very secret — research program. They even came up with ways to drastically reduce the amount of polonium in cigarette smoke.
At one giant tobacco company, RJ Reynolds, a memo was sent, and it read, referring to the radioactive polonium, "removal of these materials would have no commercial advantage".
But there was another reason why they wanted to keep their research secret. At the Phillip Morris tobacco company in 1978, a scientist, Paul Eichorn, wrote a memo to his boss, Robert Seligman, the then vice-president of research and development at Philip Morris.
Eichorn wrote, referring to research on polonium, "it has the potential of waking and sleeping giant. The subject is rumbling, and I doubt we should provide facts."
But the big tobacco companies had yet another reason for not publishing their research. They were following their infamous motto of 'doubt is our product'.
So any tiny variation in the research done by scientists outside the tobacco industry was spun into the spurious claim that even the experts don't really know what makes smoking harmful.
Big Tobacco's internal research showed that polonium was harmful, but to quote an internal Philip Morris document from 1982, so long as they kept their research quiet, any suggestion of a link between polonium-210 and lung cancers is "spurious and unsubstantiated".
Perhaps Big Tobacco should get some of their own internal research x-rayed, so they can see through their own smoke screen.
http://www.abc.net.au/science/articles/2012/03/13/3451931.htm
