Principles Substance
Effects Additiveswitha
pharma-cologi- caleffect
Freenicotinebase Ammonium
Ammoniumtechnologyincreasesreleasein smoke
[110] Dissociationofincreasingnicotineeffectand
taryieldreduction [14]
Additivesthat enhancethe
effectof nicotine
Acetaldehydeproducedby theburningofsugars
Laevulinicaciddegradation productofstarch,cane
sugarandcellulose Cocoaandtheobromine
Glycyrrhizinaningredientof liquorice
Pyridinefromtobacco Increasestheaddictiveeffectsofnicotine
[110, 111]
,optimisedsugarcontentofthe cigaretteprovidesthebasisforoptimal
formationofacetaldehydeandthusforan optimalnicotineacetaldehyderatio
[110] Nicotinelaevulinateremovestheharshness
fromthetobaccolavourwhilepreserving thearoma,thesaltalsointensiiesbinding
tothehigh-afinitynicotinereceptorsby about30
[112] Cocoacontainsalkaloidswhichmodifythe
effectsofnicotine:onesuchalkaloidis theobromine1,whichhasbronchodila-
toractivityandthusimprovesabsorption oninhalation
[113] Possessesbronchodilatoractivity,todatethis
effectissuspectedduringsmoking Actslikenicotinebutislessreliable.Hasa
centralcalmingaction.Likenicotine, pyridineisformedonpyrolysis.Both
substanceshaveCNS-antagonistactivity [114]
Flavourmodiiers requiredto
improvethe tasteof
nicotine Sugar
Liquorice Chocolate
Cocoabutter Improveslavour,particularlyduetothe
sugar-ammoniumreaction [115]
bygiving smokeamildandnaturallavour
Addedtosugartoimprovethelavourofthe smokemoremellow,woody
[116] Harshtobaccolavourisroundedoffbytraces
ofchocolate Makestobaccosmokelessharsh
[117] Additionaltoxins
Coumarins Acetaldehyde
Powerfularomaticagents,buthepatotoxic, usenowmostlyabandoned
Mutagenic,embryotoxic,causestumoursin therespiratorytract
Additionaltoxins Furfuralacetate
Maltol Eugenol
Mutagenic,hasasynergisticcarcinogenic effectinconjunctionwithbenzo[a]pyrene
Mutageniconlyinvitro Asaphenol,itscarcinogenicactivityis
uncertain [118]
;testsrequired Substancesthat
alter side-stream
smoke Sodiumacetate
Calciumhydroxide Usedincigarettepaperinsteadoftripotassium
citrate,hencelessvisibleside-stream smokethroughthepaper
[119] Lessirritatingfornon-smokersafter
impregnationofcigarettepaper [120]
, milderaroma
Table 3.7
Selectlistoftobaccoconstituentsusedincigaretteproductionandtheireffectsonthe smoker
[80]
syntheticsubstances [87,88]
.Cigaretteadditiveshavealsobeenfoundtoreducetheper- ceptionofenvironmentaltobaccosmokeETS;
[87] .
Legislatorsandconsumersfalselyassumethatadditivesmakeiteasierfortheconsumer toacceptcigaretteswithalowtaryieldandthatthehealthrisksare,thus,alsoreduced.
Thesecigaretteshaveperforatediltersinordertodilutetheinhaledair.However,smokers veryquicklylearntocovertheseperforationswiththeirhandsinordereithertoregulate
nicotinedeliveryortoachievedeeperinhalation. ThemodernUScigarettecontains10additivescalculatedwithreferencetoweight,
mostlyintheformofsugar,aromaticagentsandmoisteningagents.Theycontainfurther additivesthatmodifytheeffectsofnicotineandmaketheinhaledmainstreamandevap-
oratingside-streamsmokeappearmorepleasantandlessannoying.Inthiscontext,itis importanttorememberthatside-streamsmokesometimescontainshigherlevelsoftoxic
substances than mainstream smoke; CO levels in side-stream smoke, for example, are 4–14timeshigherthanthoseinmainstreamsmokeseeFig.
3.2 .
3.5 Cigarettes with Reduced Tar Yield
Ifcigarettesarelabelled“Light”and“Ultralight”,smokersimaginethatthereareanumber ofadvantages:reducedtarandnicotineyields,lesserrisktohealthandmilderlavour.A
considerableproportionofsmokersbelievethatlower-tarcigarettesarelessdangerousthan regular cigarettes. According to the representative judgement of smokers of ultralight
45.7,light32.2andregularcigarettes22,ultralightcigarettesreducetheriskof cancer
[88] .Inasurveyof12,371Canadians,thelabel“Light”wasassociatedwith“lesstar”
20.1, “less nicotine” 36.2, “greater safety” or “induces less dependence” 3.2, “mildertaste”6.7and“nothing”or“marketingtrick”14.1.Thetermdidnotconvey
anythingatalltoalargeproportionofsurveyrespondents [89]
.Forthemostpart,smokers areunawareofthetarandnicotineyieldsofthecigarettestheysmokeandbelievethatthey
arereducingtherisktotheirhealthbysmokinglight40andultralightcigarettes60 [87,89]
.Inthecontextofothersurveys,lowerscoreswerereportedforthesequestionssee also
[88] .AccordingtotheCanadiansurvey,infact,moresmokerscomplainedofhealth
problemsemphysema,asthma,lungcancer,strokeafterswitchingfromregulartolight cigarettescomparedwithsmokerswhostayedwithregularcigarettes2.13vs.1.94
[89] .
Smokersfrequentlyignoretheexistenceofcigaretteswithareducedtaryield,despite thedeclarationonthepacks.Consumersinterprettheseiguresasarelectionofvarying
levelsofdamagetohealth.Table 3.5
presentsdetailsofthetarandnicotineyieldsofdif- ferentcigarettebrands.Variousstudiesindicatethattherearenoreliabledatatoshowthat
switchingfromregulartolightcigarettesreducescigaretteconsumptionorthedesireto smoke
[89] .Also,switchingfromregulartolightcigarettesasadeliberateinterimstrategy
doesnotultimatelyimprovesuccessratesforsmokingcessation. FromthelawsuitsagainstthetobaccoindustryintheUSA,ithasemergedthatthe
tobaccocompaniesknewfordecadesaboutthediscrepantanddistortedresultsobtained withsmokingmachinesbasedoncriteriadeinedbytheISOInternationalOrganization
for Standardization, founded in 1946 to promote worldwide trade and collaboration. AgenciesintheUSAincludingtheFederalTradeCommission,theFDAandtheNational
CancerInstitutearenowworkingtowardsausefulsolutiontotheproblem.TheEuropean Commissionisalsopreparingproposalsforthecorrectmeasurementoftarandnicotine
yieldsincigarettes. Afewsmokersmayactuallybeneitminimallyfromlow-tarcigarettes,butthehealth
consequencesinapositivesensehavenotyetbeendemonstrated.However,ithasbeen shownthatdeeperinhalationisassociatedwithanincreaseinadenocarcinomas,atypeof
cancerrarelyseeninthepastandaffectingthedeepsectionsoflungtissue.Onestudy publishedin1997presentedsummarydataonsmokerswhohadsmokedlightandultra-
lightcigarettesovertheperiodfrom1959to1991andwhowerefoundtohaveanincreased incidenceofadenocarcinomas;thesetumourswerefoundtooccur17timesmorecom-
monlyinwomenand10timesmorecommonlyinmen [90,91]
. In2003,Kabatpublishedareviewon50years’experienceofreduced-tarcigarettesand
posedthequestionabouttheknownhealtheffects [92]
.Itwasstatedthatsince1950s,ciga- rettessoldintheUnitedStateshaveundergoneaprogressivemodiication,includingthe
additionofiltersandareductionintheaveragemachine-measuredtarandnicotineyield percigarettebyover60.Theseandothertemporalchangesinmanufacturedcigarettes,
coupledwiththecomplexityofsmokingbehaviour,makeitdificulttoassesstheimpact ofthenewercigarettesonhealth.Someresearchershavesuggestedthatthenewerprod-
ucts,marketedasbeinglessharmful,mayinfactprovidenobeneitcomparedtotheolder, highertarcigarettes.Kabatcriticallyevaluatedtheavailableepidemiologicevidenceon
thehealtheffectsoflow-tarcigarettes.Afteridentifyingimportantmethodologicalprob- lems confronting research in this area, studies of lung cancer, coronary heart disease,
chronicobstructivepulmonarydiseaseandtotalmortalitywereexaminedintermsoftheir strengthsandweaknessesandtheirresults.Thirty-ivestudiesoflungcancerwerefound
tobesuggestivethatsmokersoflowtarcigaretteshavealowerriskby20–30com- paredtosmokersofhighertarcigarettes.Onlyaminorityofstudiesofheartdiseasepro-
videdevidenceofareductioninrisk,ontheorderof10.Studiesconcerningchronic obstructive pulmonary disease COPD were inconsistent, but the majority suggest
decreasedriskinsmokersoflowertarcigarettes.Finally,studiesthatincludedtotalmor- talityindicatedwithahighdegreeofconsistencythatthetotaldeathrateisreducedin
smokersoflowertarcigarettes,ontheorderof10–20 [92]
. However,therearealsostudiesthatindicatethattherearenomajorchangesandaddi-
tionalanalysesofexistingdatasetscouldfurtherclarifytheimpactoflow-tarcigarettes. Inthisrespect,afurtheranalysisbyThunandBurnsalsoexaminedtheepidemiological
evidencerelevanttothehealthconsequencesof“reducedyield”cigarettes [93]
.Theycon- cludethatsomeepidemiologicalstudieshavefoundattenuatedriskoflungcancer,butnot
otherdiseases,amongpeoplewhosmoke“reducedyield”cigarettescomparedtosmokers ofuniltered,highyieldproducts.Thesestudiesprobablyoverestimatedthemagnitudeof
anyassociationwithlungcancerbyoveradjustingforthenumberofcigarettessmokedper dayoneaspectofcompensatorysmokingandbynotfullyconsideringotherdifferences
betweensmokersof“highyield”and“lowyield”cigarettes.Selectedcohortstudiesinthe USAandUKwerefoundthatshowedthatlungcancerriskcontinuedtoincreaseamong
oldersmokersfromthe1950stothe1980s,despitethewidespreadadoptionofloweryield