Designing a reduced risk cigarette

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Designing a reduced risk cigarette

• Dr M J Taylor
• Director of Scientific Development
• Filtrona Technology Centre

Tabexpo Congress 27 29 November Paris Nord
Villepinte
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Overview

• Reduced risk
• Harmful compounds in smoke
• Harmful Compound Reduction
• Cigarette Construction
• Tobacco
• Cigarette Paper
• Filter Options
• Conclusions

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Toxic Chemicals in Mainstream Smoke

• At our current state of scientific knowledge no
  one will ever be able to claim the development of
  a less hazardous cigarette based solely on the
  reduction of known toxic chemicals in smoke
• The approach of reducing tar yields appears to be
  the most practical way of producing a less
  hazardous cigarette as when tar is reduced both
  known and unknown toxicants are reduced
• Development of more consumer acceptable products
  that reduce gas-phase toxicants appears to be
  another route to a less hazardous cigarette. As
  it is well known that charcoal containing filters
  have a high efficiency for removing carbonyl
  compounds from smoke

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Clearing the Smoke

• For many diseases attributable to tobacco use,
  reducing the risk of disease by reducing exposure
  to tobacco toxicants is feasible
• Products for Reduced Exposure Potential (PREPs)
  have not yet been evaluated comprehensively
  enough (including for a sufficient time) to
  provide a scientific basis for concluding that
  they are associated with a reduced risk of
  disease compared to conventional tobacco use
• Carefully and appropriately conducted clinical
  and epidemiological studies could demonstrate an
  effect on health but this would take many years

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Less Hazardous Cigarettes

• Less hazardous cigarettes are eminently feasible
• A relative scale of inhaled doses of tar from
  different brands is given by the tar to nicotine
  ratio ratios of the smoke from those brands.
  Because gas and tar yields generally correlate,
  the tar/nicotine ratio would be a reasonable
  proxy for the ratio of the whole smoke and
  nicotine and would be a valid index of overall
  risk reduction. The lower the tar/nicotine ratio
  the lower the potential risk
• In theory a 101 ratio of tar to nicotine
  delivers twice the potential harmful substances
  than a 51 ratio of tar to nicotine

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Alternative Views

• A risk free cigarette that involves burning
  tobacco cannot be produced
• Dose response relationships of such a complex
  mixture as cigarette smoke are not fully
  understood
• Great difficulty exists in making reliable
  judgements about the risk associated with any
  tobacco product
• In Vitro and genotoxicity tests
• Biomarkers of harm
• The only guaranteed reduced risk strategy is to
  stop smoking

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Possible Reduced Risk

• For most toxicity studies studying single or
  small numbers of compounds in workplace or other
  exposure reducing the dose does reduce the risk
• Many years of testing would be required to
  confirm the validity of any reduced risk claim
• If reducing the dose does reduce the risk then
  the development of products that can be
  demonstrated by independent validated testing
  procedures to offer the consumer reduced levels
  of harmful compounds is highly desirable

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Smoke Composition
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Potentially Harmful Smoke Compounds
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Potentially Harmful Smoke Compounds
Tar and Nicotine excluded
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Potentially Harmful Smoke Compounds
Tar, Nicotine and CO excluded
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Relative Risks of Some Smoke Compounds
Approved workplace exposure limits short-term
exposure 15 minutes maximum Long-term value no
corresponding short term value given
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Relative Risks of Some Smoke Compounds
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Cigarette Construction

• Three major elements of the cigarette
• Tobacco
• Cigarette Paper
• Filter

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Cigarette Construction

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Tobacco

• Tobacco comprises of a complex mixture of over
  2000 chemicals
• Direct transfer to smoke accounts or about one
  third of smoke constituents including a number of
  harmful compounds
• These include
• Tobacco specific nitrosamines
• Metals
• Small amounts of Aldehydes, Ketones, Pyridines
  and Phenols

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Tobacco

• A number of workers have studied the
  relationships between TSNAs in tobacco and
  mainstream smoke
• Reducing the levels of TSNAs formed during
  tobacco curing is possible by using heat exchange
  curing methods
• Tobaccos with very low levels of pre-formed
  TSNAs give much lower levels of TSNAs in
  mainstream smoke
• It may be possible that tobacco with lower levels
  of metals may also deliver lower levels in
  mainstream smoke

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Cigarette Paper

• Can be used to control
• Static burn rate
• Ventilation
• Puff count
• Draw resistance
• Cigarette paper air permeability is a crucial
  paper specification used to reduce smoke yields

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Cigarette Paper Compound Reduction
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Filters

• Initially used to prevent tobacco from entering
  smokers mouth
• Primary purpose is reduction of particulate smoke
  yields
• Can give taste modification of final product
• Growth in the use of filters using activated
  carbon
• Complex filters increasingly used

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Filter Materials
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Methods of Reducing Various Smoke Fractions
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Selective Filtration

• Most filters work by trapping smoke aerosol
  particles by direct interception and diffusional
  deposition with a minor contribution from
  inertial impaction but this is not a selective
  process
• The capture of particles by the fibres tends to
  be irreversible and all compounds in the particle
  are retained except for small quantities that may
  vaporise from the surface and be released into
  the smoke stream
• Another possible filtration mechanism is the
  removal of material at the surface of a fibre or
  granule by chemical reaction or adsorption
• Adsorption is the mechanism that occurs on porous
  solids such as activated carbon

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Selective Filtration

• To be selectively removed a compound must diffuse
  to the surface of the porous granule and then
  undergo adsorption or reaction to be removed from
  the smoke stream
• Once a compound is removed from the smoke then
  more will diffuse to the surface of the granule
  so that selective removal can be very efficient
• But diffusional mechanisms are critical for the
  occurrence of selective filtration
• Gases and vapours can diffuse quite readily
• Non-volatile compounds with no vapour pressure
  cannot diffuse

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Selective Filtration

• The more volatile the compound the greater the
  chance of selective removal
• No volatility no selectivity
• Selective filtration could be considered as a
  major contributor towards products with reduced
  yields of harmful compounds if filters with
  higher degrees of selectivity towards harmful
  compounds can be developed

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Compound Distribution in Smoke
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Granular Additives

• Granular materials such as carbon are currently
  the most effective materials available for the
  reduction of vapour phase compounds
• A wide range of materials are available that
  could be use in cigarette filters for the
  reduction of harmful compounds
• Different types of granular materials with
  different properties and surface chemistries
  could give a different profile of compound
  removal. That is more selectivity towards harmful
  compounds
• Most current filters use coconut shell based
  carbon which is from a renewable source

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Granular Additives
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Granular Additives
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Cigarettes

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Calculation of Compound Retention

• Retention (Control Cigarette Yield
  Test Cigarette Yield) x 100
• 
  Control Cigarette Yield

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Materials Tested

• Standard coconut shell based carbon
• Coal based carbon
• HCNR carbon - impregnated high surface area
  coconut shell based carbon
• Silica Gel - a typical (60A) silica gel
• Ion Exchange Resin - a weak base anion exchange
  resin

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Material Properties
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Compounds Studied
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Retention of Cyanides and Carbonyls
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Retention of Hydrocarbons
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Retention of Semi-Volatile Bases
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Filters

• Any new materials used will still have to be
  incorporated into a cigarette filter
• However, the final product must be acceptable to
  the consumer in terms of taste and smoking
  satisfaction
• Many filter types are available that allow a
  range of loadings and combinations of additives
  to be included into the filter
• Generally the more complex the filter
  construction the greater the cost of production
• Extremely complex filters may give rise to
  reduced risk products but their cost may mean
  they tend towards low volume niche brands that
  would not make a major contribution to risk for
  the majority of smokers
• Low cost filters that also give reduction in
  harmful compounds are also required

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Active Acetate Dual Filter
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Triple Granular Filter
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Multi-Segment Filter
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Active Patch FilterTM (APFTM)
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Active Patch FilterTM

• Mono-process carbon filter.
• Patch of activated carbon is printed onto the
  inner surface of the plugwrap.
• Patch position is flexible, and ventilation can
  be achieved through either single patch, or split
  patch configuration.
• Clean run filter concept - no machine
  contamination.
• Charcoal loading up to 3mg per linear patch mm.
• Total loading controlled by the length of the
  patch.
• Similar VP and SV performance to other charcoal
  filters with same carbon loading, but with less
  carbon taste".

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Conclusions

• The road to a potentially reduced product could
  follow many routes
• Until the exact nature of a reduced risk product
  is defined the final goal will always be
  difficult
• The design of a reduced risk cigarette needs
  contributions from all aspects of tobacco science
• Tobacco blends adding the minimum amount of
  harmful compounds to the smoke by direct transfer
• Careful selection of cigarette paper to reduce
  yields of harmful compounds
• A highly effective filter giving high degrees of
  selective filtration towards targeted compounds

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Conclusions

• At the moment carbon is still the most effective
  granular filter additive available for the
  reduction of harmful compounds
• Global trends will continue to be a reduction of
  the yields of all compounds in smoke
• Filters will continue to play a major role in
  PREP product development
• Filters will continue to get longer and lower in
  circumference
• Some PREP products will use complex multi-segment
  filters
• Perhaps mono-filter solutions, which allow
  reductions in a range of toxicants that may be
  more readily available to a wider range of
  smokers, may be a route to follow

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Conclusions

• Would changing all brands to carbon filters bring
  about risk reduction to a wider range of smokers
• It should be possible to produce cigarettes with
  lower yields of harmful compounds
• But the degree of consumer acceptability still
  needs to be determined
• Also many years of testing will be required to
  establish if products with reduced yields really
  do represent reduced risk

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• Thank you for your attention
• Filtrona - Delivering Solutions through Innovation