Why are cigarettes radioactive?

Question

Or is it just smoking them? How did the radioactive elements come to be?

In: 5

Answer 1

There is trace amounts of everything in the soil – lead, arsenic, uranium… there is plenty of everything in the soil. The exact concentrations of those vary from region to region, but there is nowhere on Earth where you will find soil that is free of harmful elements.

Plants grow in the soil and absorb elements out of it. Some plants are more efficient at absorbing certain elements than others, but all plants will take up some amount of every harmful element. That means that every plant and, by extension, everything you eat, contains trace amounts of things like lead and arsenic.

Tobacco, like all other plants, contains trace amounts of uranium and uranium nuclides (like cesium). Those elements are radioactive. This makes tobacco, and all other plants, weakly radioactive. This is not any different than your body – you have about 22 micrograms of uranium in your body at any given time and can’t help but eat about 3 micrograms of uranium every day. Your body generates a tiny amount of radiation as a result of this uranium.

Your body has a number of other radioactive elements in it as well, such as carbon-14 and potassium-40. Carbon-14 and potassium-40 generate the bulk of your body’s radioactivity – there is so little uranium in your body that its overall level of radioactivity is trivial. The same is true of tobacco.

There was a study that came out in the 1980’s that postulated that if you smoke 20 cigarettes per day for 50 years and *all* of the uranium from those cigarettes deposited in your lungs, that over the course of your life that would add the equivalent of about 6 medical x-rays worth of radiation to you, corresponding to a small, but noticeable increase in your risk of cancer. This study is frequently cited by the CDC, EPA, and anti-smoking groups because it’s a good scare tactic for people who don’t understand what radiation is.

There are a lot of assumptions in that study that are unlikely to be true. Even if they are true, the cancer risk added by uranium in tobacco is trivial and lower than the risk posed to you by eating food – which, again, also contains uranium. Smoking is bad for you because you’re breathing in smoke, which is a highly carcinogenic substance, not because tobacco is radioactive.