The following article, excerpted here, was published in the Wall Street Journal. You can read the entire article at the WSJ website but you may need a subscription.

What’s Really in Your Cigarette? by Robert N. Proctor
August 31, 2012 / Wall Street Journal / — There are lots of myths about cigarettes: that “lights” offer protection, for one, or that filters actually filter.
Yet another myth is that cigarettes are just tobacco rolled in paper. Nothing could be further from the truth. The cigarette is a surprisingly complex artifact, as we now know from the treasure trove of documents released in the course of litigation. The tobacco archives online at legacy.library.ucsf.edu contain some 80 million pages of formerly secret industry documents, almost all of which were unavailable before the Big Tobacco trials of recent years. Access to these archives has improved over time, and all are now full-text searchable, meaning that anyone with an Internet connection can pull up all documents containing expressions such as “doubt is our product” or “friends in Congress.”
What the documents also reveal is a witches’ brew of ingredients used in cigarettes. A 1992 document drawn up by Covington & Burling, a leading tobacco law firm, lists 614 different additives in cigarettes. Here are some of the choicer items, along with poundages added to cigarettes in 1991: