Bad habit of smoking can lead to the formation of oxidants (free radicals). Because in the content of the cigarettes contained H2O2 productivity increases drastically.
One cause of the disease is due to the large pile of oxidants in the body. Overcoming these oxidants usually by administering antioxidants regularly. Even so, this does not mean oxidant is completely gone from the body.
Every human being in his body can contain chemicals. Such as lead, insecticides, and other dangerous without suffering from clinical symptoms.