Ammonium and pH Manipulation

3.4 Tobacco Additives

In฀ the฀ EU,฀ more฀ than฀ 600฀ additives฀ are฀ used฀ in฀ the฀ manufacture฀ of฀ tobacco฀ products฀ Table฀ 3.7 .฀Although฀these฀additives฀are฀subjected฀to฀toxicological฀testing,฀it฀is฀unclear฀ what฀effects฀they฀have฀on฀smoking฀behaviour:฀if฀such฀products฀when฀added฀to฀tobacco฀ lead฀to฀accelerated฀dependence,฀hasten฀the฀craving฀to฀smoke฀or฀initiate฀an฀increased฀crav- ing,฀then฀this฀is฀a฀major฀problem฀ [79] .฀With฀more฀than฀1฀million฀people฀dying฀annually฀ from฀smoking-related฀causes,฀a฀mere฀1฀increase฀due฀to฀the฀addition฀of฀a฀chemical฀to฀ tobacco฀may฀result฀in฀the฀premature฀death฀of฀hundreds฀or฀thousands฀of฀smokers.฀For฀this฀ reason,฀additives฀in฀tobacco฀products฀are฀a฀major฀public฀health฀issue฀in฀their฀own฀right. Some฀600฀additives฀have฀been฀approved฀as฀admixtures฀to฀tobacco฀products.฀However,฀ only฀the฀tobacco฀companies฀can฀disclose฀which฀additives฀appear฀in฀which฀cigarette฀brands.฀ Not฀even฀the฀European฀Commission,฀which฀is฀responsible฀for฀the฀regulation฀of฀tobacco฀ products,฀can฀provide฀this฀information฀or฀has฀the฀power฀to฀demand฀it. Additives฀are฀put฀into฀tobacco฀see฀Table฀ 3.7 ;฀ [80] ฀for฀the฀following฀reasons: • ฀ To฀increase฀the฀free฀nicotine฀portion฀because฀this฀boosts฀the฀“kick”.฀Ammonium฀com- pounds฀have฀been฀found฀to฀fulfil฀this฀role฀because฀they฀increase฀the฀alkalinity฀of฀the฀ smoke. • ฀ To฀improve฀the฀lavour฀of฀tobacco฀and฀to฀make฀the฀product฀more฀desirable. • ฀ Sweeteners฀and฀chocolate฀are฀used฀as฀additives฀to฀make฀the฀lavour฀of฀tobacco฀more฀ appealing฀to฀children฀and฀irst-time฀users.฀Eugenol฀and฀menthol฀are฀added฀to฀“mask”฀the฀ harmful฀effects฀on฀the฀respiratory฀tract. • ฀ Cocoa฀is฀added฀as฀a฀bronchodilator฀with฀the฀goal฀of฀achieving฀deeper฀inhalation฀so฀that฀ more฀nicotine฀and฀tar฀reaches฀the฀alveoli฀in฀the฀lower฀pulmonary฀segments. • ฀ Additives฀are฀used฀to฀make฀the฀smell฀and฀visibility฀of฀side-stream฀smoke฀less฀annoying฀ and฀mask฀its฀dangerous฀nature฀and฀thus,฀to฀make฀it฀more฀difficult฀for฀passive฀smokers฀ to฀protect฀themselves฀from฀smoking. Various฀additives฀are฀already฀toxic฀alone฀or฀in฀combination฀with฀other฀additives฀and฀phar- macologically฀active฀or฀toxic฀products฀are฀also฀formed฀during฀the฀combustion฀process. Substances฀intended฀to฀keep฀the฀tobacco฀moist฀see฀above฀may฀account฀for฀up฀to฀5฀ of฀the฀tobacco฀weight฀in฀a฀cigarette:฀one฀such฀example฀is฀glycerol฀which฀undergoes฀trans- formation฀to฀the฀ciliatoxic฀substances฀acrolein฀and฀propylene฀glycol฀ [81] .฀Propylene฀oxide฀ has฀been฀detected฀in฀the฀tobacco฀smoke฀of฀cigarettes฀treated฀with฀propylene฀glycol฀ [82] .฀ Ethylene฀glycol฀has฀also฀been฀used฀to฀moisten฀cigarette฀tobacco;฀however,฀this฀practice฀has฀ been฀banned฀because฀of฀the฀formation฀of฀carcinogenic฀ethylene฀oxide฀following฀combus- tion฀ [83] .฀In฀addition,฀traces฀of฀N-hydroxyethylvaline฀haemoglobin฀217–690฀pmolg฀hae- moglobin฀have฀been฀detected฀in฀the฀blood฀of฀smokers฀ [84] ,฀whereas฀non-smokers฀have฀ only฀about฀15฀of฀such฀levels. Tobacco฀ aroma฀ is฀ intensiied฀ by฀ tobacco-speciic฀ terpenoids,฀ pyrroles฀ and฀ pyrazines฀ [85,฀86] ,฀but฀this฀effect฀is฀attenuated฀in฀turn฀by฀ilter฀tips.฀Tobacco฀aroma฀has฀been฀modiied฀ by฀the฀addition฀of฀mint,฀wood,฀spices,฀fruits฀and฀lower฀essences฀coumarins,฀but฀also฀of฀ Principles Substance Effects Additives฀with฀a฀ pharma-cologi- cal฀effect Free฀nicotine฀base Ammonium Ammonium฀technology฀increases฀release฀in฀ smoke฀ [110] Dissociation฀of฀increasing฀nicotine฀effect฀and฀ tar฀yield฀reduction฀ [14] Additives฀that฀ enhance฀the฀ effect฀of฀ nicotine Acetaldehyde฀produced฀by฀ the฀burning฀of฀sugars Laevulinic฀acid฀degradation฀ product฀of฀starch,฀cane฀ sugar฀and฀cellulose Cocoa฀and฀theobromine Glycyrrhizin฀an฀ingredient฀of฀ liquorice Pyridine฀from฀tobacco Increases฀the฀addictive฀effects฀of฀nicotine฀ [110,฀ 111] ,฀optimised฀sugar฀content฀of฀the฀ cigarette฀provides฀the฀basis฀for฀optimal฀ formation฀of฀acetaldehyde฀and฀thus฀for฀an฀ optimal฀nicotineacetaldehyde฀ratio฀ [110] Nicotine฀laevulinate฀removes฀the฀harshness฀ from฀the฀tobacco฀lavour฀while฀preserving฀ the฀aroma,฀the฀salt฀also฀intensiies฀binding฀ to฀the฀high-afinity฀nicotine฀receptors฀by฀ about฀30฀ [112] Cocoa฀contains฀alkaloids฀which฀modify฀the฀ effects฀of฀nicotine:฀one฀such฀alkaloid฀is฀ theobromine฀1,฀which฀has฀bronchodila- tor฀activity฀and฀thus฀improves฀absorption฀ on฀inhalation฀ [113] Possesses฀bronchodilator฀activity,฀to฀date฀this฀ effect฀is฀suspected฀during฀smoking Acts฀like฀nicotine฀but฀is฀less฀reliable.฀Has฀a฀ central฀calming฀action.฀Like฀nicotine,฀ pyri฀dine฀is฀formed฀on฀pyrolysis.฀Both฀ sub฀stances฀have฀CNS-antagonist฀activity฀ [114] Flavour฀modiiers฀ required฀to฀ improve฀the฀ taste฀of฀ nicotine Sugar Liquorice Chocolate Cocoa฀butter Improves฀lavour,฀particularly฀due฀to฀the฀ sugar-ammonium฀reaction฀ [115] ฀by฀giving฀ smoke฀a฀mild฀and฀natural฀lavour Added฀to฀sugar฀to฀improve฀the฀lavour฀of฀the฀ smoke฀more฀mellow,฀woody฀ [116] Harsh฀tobacco฀lavour฀is฀rounded฀off฀by฀traces฀ of฀chocolate Makes฀tobacco฀smoke฀less฀harsh฀ [117] Additional฀toxins Coumarins Acetaldehyde Powerful฀aromatic฀agents,฀but฀hepatotoxic,฀ use฀now฀mostly฀abandoned Mutagenic,฀embryotoxic,฀causes฀tumours฀in฀ the฀respiratory฀tract Additional฀toxins Furfural฀acetate Maltol Eugenol Mutagenic,฀has฀a฀synergistic฀carcinogenic฀ effect฀in฀conjunction฀with฀benzo[a]pyrene Mutagenic฀only฀in฀vitro As฀a฀phenol,฀its฀carcinogenic฀activity฀is฀ uncertain฀ [118] ;฀tests฀required Substances฀that฀ alter฀ side-stream฀ smoke Sodium฀acetate Calcium฀hydroxide Used฀in฀cigarette฀paper฀instead฀of฀tripotassium฀ citrate,฀hence฀less฀visible฀side-stream฀ smoke฀through฀the฀paper฀ [119] Less฀irritating฀for฀non-smokers฀after฀ impregnation฀of฀cigarette฀paper฀ [120] ,฀ milder฀aroma Table 3.7 ฀฀฀Select฀list฀of฀tobacco฀constituents฀used฀in฀cigarette฀production฀and฀their฀effects฀on฀the฀ smoker฀ [80]