Dear Triin,
I tried posting some articles for but hidden HTML codes really messed up the entire thread. I'm going to try a little different approach this time. The three studies I was referencing were the 1988 U.S. Surgeon General's Report by Dr. Koop, and two articles I've cited in "Nicodemon's Lies. I doubt we'll locate full texts of the studies online but abstracts are available. Here are a few of good links that contain brief abstracts of most of the work in drug comparison over the past decade. If you run into any other good materials please share the link.
Be careful in searching as Phillip Morris and other drug manufacturers have funded lots of "scientific" research with findings to the contrary and now NRT drug manufactures have found scientists who'll say that nicotine may be addictive but our nicotine is wonderful! A couple of these are not very detailed but still reinforce the fact that the findings around the world are producing similar results. The last Turkey article was very early, May 1991, but very telling in regard to NRT. Nicotine marketing has improved tremendously in just a decade. I'm off to class!