"Menthols are rumored to contain fiberglass. According to this canard, the evil cigarette companies secrete the substance in the product in an effort to better transmit that menthol sensation and nicotine kick by way of causing tiny cuts in the smoker's throat and mouth. This same rumor also attaches to smokeless (chewing) tobacco, especially to the Kodiak brand.
There's no fiberglass in cigarettes. Granted RJR did try using a fiberglass shell on its flopped smokeless cigarettes in 1994, but that part of the contraption wasn't ingested by the smoker -- it was more of a housing, if you will. Other than that, no fiberglass.
The fiberglass rumor parallels similar falsities about Carmex lip balm and tampons. But of course if consumers overuse lip balm, they will come to rely on it and afterwards have to continue using the product. That little detail of life isn't in dispute, but rather than accept it, some Carmex users prefer to believe the evil manufacturer secretes ground glass in the product to roughen users' lips and thus enslave them to the little jars with the yellow lids. Likewise, a cyber-rumor that swept the Internet in 1999 claimed evil tampon manufacturers were putting asbestos in that product to promote bleeding and thus ensure women went through more tampons per period. The common sense realization that if the government had deemed asbestos far too dangerous to have in the walls of homes, it certainly wouldn't passively watch from the sidelines as consumers stuck the same substance inside themselves failed to occur to as many people as one would hope, and this rumor about asbestos flew from one inbox to another. "
http://www.snopes.com/business/alliance/menthol.htm has the whole article....they have lots of other info on most urban legends youve heard...