The manufacturing process of cigarettes these days is very complex. Cigarettes produced abroad contain, besides tobacco, a range of raw materials designed to prolong shelf life, preserve the flavor, increase addiction, including starches, glues and other contents, besides which the tobacco itself is rinsed in alcohol, all of which serve as the basic filling of all cigarettes.
These facts were clarified in a very thorough examination which took place before Pesach of 5774 by the famous chemist Rabbi Dr. Eliyahu Licht, upon whom Torah leaders rely for all that involves halachic questions regarding raw material.
Some things in a cigarette
Following a lively discussion carried on by leading poskim regarding the Pesach kashrus of cigarettes, it was Rabbi Licht who assumed the main role of authority. He examined the list of the contents of cigarettes from various companies from abroad, analyzed them professionally, and discovered to his amazement that a significant part of the contents of the most popular brands of cigarettes do require a special kashrus supervision for Pesach since they are suitable for canine consumption and constitute a very serious threat of their being actual chometz, so that refraining from smoking on Pesach is no longer a chumra severity but an actual prohibition of chometz.
The problem of smoking on Pesach has concerned the gamut of eminent poskim over past centuries. Many are the rabbonim who have discussed the issue on both the halachic and the practical plane, reaching a decision according to the ruling of the Mogen Avrohom, the Maharam Schick and the Mishna Berurah: smoking on Pesach is forbidden because of the probability of chometz included alongside the components of the tobacco.
Heading the poskim opposed to smoking on Pesach in latter times was HaRav Yosef Shalom Eliashiv whose opinion was to absolutely forbid it unless it was completely determined that there were no other ingredients in the cigarettes themselves besides the tobacco. His disciples, HaRav Efrati, HaRav Kook and HaRav Derzi duly testified to this. HaRav Eliashiv also said that in general, one should refrain from smoking those cigarettes whose contents were not clarified, adding that from the time that one is forbidden to eat chometz on Erev Pesach, one must also not smoke. One should sell the cigarettes in his possession to a goy since the argument that they are not suitable consumption for a dog is not sufficient.
In a responsa written recently, the head of the Beis Ho'roa Haklali of Yerushalayim, HaRav Ben Zion HaKohen Kook, quotes what he heard from his master-teacher HaRav Eliashiv regarding the severity of abstaining from smoking on Pesach. "Maran was concerned about smoking on Pesach since the chometz contained in the cigarettes were not consumed by the fire but were mingled with other ingredients, it was therefore not invalidated for canine consumption. Therefore," concludes HaRav Kook in his letter, "it is advisable not to smoke on Pesach unless there is halachic supervision that none of the components in the cigarettes have suspicion of chometz, and may one who warns and the one who heeds be... [duly blessed]"
In light of the proliferation of electronic cigarettes, a halachic ruling was recently issued by HaRav Moshe Sternbuch that these cigarettes also require a hechsher since the evaporating liquid contains a flavoring which turns into vapor, leaving a pleasant taste in the mouth, and that according to halachic ruling, this is considered as if one is truly tasting the body of those ingredients, which is regarded like actual consumption.
We have seen that Torah leaders of the past generation refrained from smoking on Pesach. It is quoted in "Orchos Rabbenu" that the Steipler was very stringent in this, as was HaRav Soloveitchik, Rosh Yeshivas Brisk, who did not smoke on Pesach and made a strong point of this. His talmid said, "I entered his study chamber on Pesach holding a cigarette in my hand. He was very taken aback and said: `How do you dare bring something here on Pesach whose contents are altogether questionable?'"
The author of "Palgei Tzvi" wrote that he asked HaRav Wosner about smoking on Pesach. He said that those who are altogether stringent in general never smoked on Pesach since they contained chometz."
According to the American Lung Association, "There are approximately 600 ingredients in cigarettes. When burned, cigarettes create more than 7,000 chemicals. At least 69 of these chemicals are known to cause cancer, and many are toxic. Many of these chemicals also are found in consumer products, but these products have warning labels—such as rat poison packaging. While the public is warned about the danger of the poisons in these products, there is no such warning for the toxins in tobacco smoke."
This about a quarter of all the possible additives. Click to see the entire list on Wikipedia. Note that the last-listed ingredient is YEAST! 
