Comparative Chemistry of Cigarettes &
Smokeless Tobacco
Objectives of discussion
n
Overview of Chemistry
n
Tobacco – Dark Tobacco chemical composition
n
Smoked Tobacco – Cigarette smoke chemistry
n
Routes of Exposure for smokeless compared to
smoke tobacco
Dark Tobaccos: fire cured, air/sun
cured.
n
n
Fire cures
n Hardwoods – hickory
n Smoke curing adds flavors (phenolics)
n Wood smoke condensate
n Leaf undergoes chemical changes
Air Cured
Smokeless Products
n
Manufacturing process*
n
Grinding followed by sieving
n
High moisture > 50% - oral and nasal
n
n
n
n
Snuff placed in mouth - pinch or wrapped in porous
paper (Snus)
Dry -Sniffed into nasal cavity
Grating and Cutting
n
Moist – Oral or chewing tobacco
n
Dry – chewing tobacco
Stripping and Threshing
n
Plug – chewing
n
Loose leaf - chewing
*Taken from Inger Wahlberg and Tommy Ringberger Chapter 14 :Tobacco Production,
Chemistry and Technology Edited by D.L Davis and M.T, Nielsen, Blackwell
Blackwell Science LTD, 1999
Smokeless Product Categories
stfact_sheet_combined10-23-02.pdf
n
Product Categories
n Chewing Tobacco -Twist, plug and scrap
n Twist braided tobacco leaves
n Plug – pressed leaves in syrup
n Scrap – loose leaf
n Snuff finely ground tobacco
n Sniffed
n Dipping (placing between gum and cheek)
n Swedish Snus (air cured)
n Ground and sieved.
n Mixed with H2O, NaCl , Na2CO3 and flavors
n Heated with steam
n Can be refrigerated (prevents fermentation)
n Nicotine Lozenge
Chemical Composition leaf
n
n
Over 3000 chemicals identified in leaf
n Nicotine 1 to 4% DM
n Starches 29%
n Crude fiber
n Proteins
n Reducing sugars
n Inorganic
Composition changes with curing
n
n
n
n
n
n
Starches decrease to <6%
Reducing sugars increase from 7 to 16%
Insoluble proteins decrease
Soluble proteins increase
Ammonia plus amide increases
Carotenoids decrease ( precursor to flavors )
Chemical Composition leaf
Continued
n
Volatile components
n
n
>150 (impart flavors) Routes of Exposure
n
Fatty acid derived compounds
n
Terpenoids
n
Degraded carotenoids
Additional components if fire cured with hardwoods
>140 (Smoke condensates)
n
Maillard products – pyrroles and furans
n
Naphthalenes and biphenyls
n
phenolics
Components of interest in leaf for
Smokeless and Smoke Products
n
n
n
n
n
Nicotine and pH
Nitrate
TSNA (Tobacco specific nitrosamines)
n Highly variable – ppm levels –decreased with
process changes
PAH’s (polycyclic aromatic hydrocarbons)
Heavy metals (210Po, Cd, Se, Cr etc.)
Comparison of select Smokeless Products
A McNeill, R Bedi, S Islam, M N Alkhatib and R West Tob. Control 2006;15;64
2006;15;64--67
Brand
Moisture %w/w
pH
Copenhagen (USA)
48
7.39
Snus (Sweden)
45.84
7.86
Baba 120 (chewingIndia)
13.18
4.88
BABA Zarda
(chewing - UK)
7.88
5.32
Ariva Lozenge
2.4
7.56
TSNA=NNN+NNK+NAB
ND=nondetect
TSN Benzpyr
Nicotine A
ene
NDMA Nitrite Cr
Ni Pb As
mg/g ug/g
ng/g
ng/g ug/g ug/g ug/g ug/g ug/g
25.8
15.2
3.5
0.48
19.3
1.99
ND
ND
6.7
ND
1.69 2.64 0.45 0.23
1.54 2.59 0.5 0.3
55
2.36
2.83
ND
ND
2.08 2.94 1.56 0.4
48.4
9.2
0.72
ND
2.04
0.4
ND
ND
ND
ND
2.34 5.88 1.18 0.24
1.4 2.19 0.28 0.12
Smoked Tobacco Products
n
Cigarettes
n
Cigars
n
Pipes
Composition of Tobacco Column
n
Tobacco
n
Tobacco ingredients
n
n
Flavors
n
n
Humectants
Preservatives
n
Binders
n
Fillers
Chemical examples of Added ingredients
n
NaCl and NH3Cl
n
n
Sweeteners – sugars or saccharin
Glycerol and propylene glycol
n
Flavors – menthol, licorice, isoamyl isovalerate
Burning cigarette: Taken from Dr. Baker
presentation to LSRO June 8/9, 2004
Chemistry of Burning Cigarette
n
n
Combustion Zone
n
Complete oxidation
n
Incomplete oxidation
Distillation/Pyrolysis zone
n
n
Pyrolysis
n
Combustion-sensitized pyrolysis
n
Thermal decomposition - pyrosynthetic reactions occur
Microexplosions
Combustion Process
n
n
Complete - Oxidation of organic molecules
to carbon, water and CO2
n CxH y + O2 -à X CO2 + Y H2O
n Requires sufficient heat and oxygen
Incomplete
n
- Oxidation and reduction of organic
molecules to carbon, water, CO and
oxides of organic molecules
Pyrolysis Zone
n
n
Thermal degradation of a chemical, usually to a
smaller fragment:
n C2H4 + Heat à CH4 (Methane) + C
• Pyrosynthesis - Recombination of fragments
resulting from incomplete combustion and pyrolysis
to form new smoke components and reform
components observed in tobacco leaf:
n
3 C2H 6 + Heat à C6H6 (Benzene)
Smoke Formation
n
Temperature decreases – Two phases form
n
n
n
n
n
Particulate phase – <0.1 to 1.0 µm-10% water
Vapor phase – gas phase
Deposition and transfer ( Distillation )
Filtration
Composition changes as the length decreases
Possible Pyrolysis products
gas phase
n
n
n
n
Formaldehyde
Proprionaldehyde
CO
Benzene
Possible Pyrosynthesis products
n
n
n
n
n
Benzene
Toluene
Benzaldehyde
Phenol
Polycyclic Aromatic hydrocarbons
(PAH's)
Sidestream smoke: Taken from Dr. Baker
presentation to LSRO June 8/9, 2004
Mainstream Smoke and Sidestream
Smoke differences
n
Natural convection drives the combustion and
smoke formation process
n
Burning zone temperature < 800 C
n
The particles are formed above the burning zone
Smoke composition
n
Vapor phase-81-99% nitrogen, oxygen, carbon
dioxide, carbon monoxide, water and argon.
n
n
>4000 other components identified.
Tar – Total particulate weight collected on
Cambridge filter minus the weight of alkaloids as
nicotine and water (FTC) - 7% nicotine, 10% water
and 83% Tar.
Major compounds in the vapor phase of mainstream smoke of nonfilter cigarettes
Compound
Nitrogen
Oxygen
Carbon Dioxide
Carbon Monoxide
Water
Argon
Hydrogen
Ammonia
Nitrogen oxides (NO x)
Hydrogen cyanide
Hydrogen sulfide
Methane
b
Other volatile alkanes (20)
Volatile alkenes (16)
Isoprene
Butadiene
Acetylene
Benzene
Toluene
Styrene
Other volatile aromatic hydrocarbons (29)
Formic acid
Acetic acid
Propionic acid
Methyl formate
Other volatile acids (6)
Formaldehyde
Acetaldehyde
Acrolein
Other volatile ketones (3)
Methanol
Other volatile ketones (3)
Methanol
Other volatile alcohols (7)
Acetonitrile
Other volatile nitriles (10)
Furan
Other volatile furans (4)
Pyridine
Picolines (3)
3-vinylpyridine
Other volatile pyridines (25)
Pyrrole
Pyrrolidine
N-methlypyrrolidine
a
b
c
Quantity/cigarette smoked a
(% weight of mainstream smoke)
280-320 mg (56 - 64%)
50-70 mg (11-14%)
45-65 mg (9-13%)
14-23 mg (2.8 – 4.6%)
7-12 mg (1.4-2.4%)
5 mg (1.0%)
0.5 – 1.0mg
10-130 µg
100-600 µg
400-500 µg
20-90 µg
1.0 –2.0 mg
c
1.0-1.6 mg
0.4-0.5 mg
0.2-0.4 mg
25-40 µg
20-35 µg
6-70 µg
5-90 µg
10 µg
15 – 30 µg
200-600 µg
300-1700 µg
100-300 µg
20-30 µg
5-10 µg d
20-100 µg
400-1400 µg
60-240 µg
80-140 µg
100-650 µg
50-100 µg
80-180 µg
10-30 µg
100-150 µg
50-80 µg d
20-40 µg
d
45-125 µg
20-200 µg
15-80 µg
7-30 µg
20-50 µg d
0.1-10 µg
10-18 µg
2.0-3.0 µg
Quantity that passes through a Cambridge glass fiber filter.
Parentheses show the number of individual compounds identified in a given group.
Estimate.
Tar Correlates with
n
n
n
n
Nicotine
Carbon monoxide
Ammonia
Benzopyrene
Table 3-2. Numbers of substances in different chemical classes identified in Tobacco
leaf and for cigarette smoke. (Phase one: the Feasibility of Testing ingredients added to cigarettes)
Chemical category
•Functional Groups
Carboxylic acids
Amino acids
Lactones
Esters
Amides and imides
Anhydrides
Aldehydes
Carbohydrates
Nitriles
Ketones
Alcohols
Phenols
Amines
N-nitrosamines 1
Sulfur compounds
N-Heterocyclics
Pyridines
Pyrroles and indoles
Pyrazines
Non-aromatics
Polycyclic aromatics
Other heterocyclics
Ethers
Hydrocarbons
Saturated aliphatics
Unsaturated aliphatics
Monocyclic aromatics
Polycyclicjmnatics
Pesticides
•Miscellaneous
•Inorganic and metallic
# in both leaf
and smoke
Additional #
in leaf
Additional # in
smoke
Total # . detected
140
16
39
314
32
4
48
12
4
122
69
40
37
19
2
450
95:
129
529
205
10
111
138
4
348
334
58
65
23
3
69
18
135
456
227
10
106
30
101
461
157
188
150
18
37
659
129
303
1299
464
24
265
174
109
931
560
286
252
60
42
46
3
18
7
0
2
15
63
9
21
13
1
4
53
324
88
55
43
36
50
88
433
100
94
63
37
56
156
44
10
25
35
25
19
69
58
38
33
55
28
112
105
113
178
138
317
25
110
111
215
226
196
407
78
241
28
Routes of Exposure
n
Smoke chemistry drives the delivery of nicotine
through inhalation. (Nicotine rapidly absorbed)
n
n
Along with other products
Smokeless delivers nicotine through extraction and
absorption at mucosal membranes of mouth and
nose. (pH and free nicotine content important to
delivery)
Routes of Exposure
Route
Smokeless
Smoke
Nasal
A Primary Route
Snuff
x
Liquid extraction of tobacco
and volatiles Chemical
Composition leaf Continued
Gastrointestinal
Primary Route
x
Digestion of Liquid extraction
of tobacco
Inhalation
(MS, ETS)
Primary Route
Absorption directly of vapor phase,
evaporative gas from particle
deposition, diffusion from particle
Conclusions
n
n
n
n
Smokeless Tobacco
n Complex mixture and variable mixture
n Data sparse compared to cigarettes
Cigarettes
n Highly studied
n Complex and variable
n Data mainly from Mechanical smoking machines
n Mechanical smoking does not equal human
smoking
Aerosol composition very complex in smoke tobacco.
Route of exposure inhalation (delivered through lungs)
Smokeless exposure is to extractable and volatile
components in mouth and gastrointestinal (nicotine
delivered orally)