1. Where does a Pyrolysis method fit into answering the question of the fate of an ingredient in Cigarette combustion? To Be or Not to be, That is the question.

2. Evaluating if ingredient(s) increase risk Determine the fate of the ingredient(s). Determine the fate of the ingredient(s). Do they remain intact? Do they remain intact? Are they changed in the combustion process? Are they changed in the combustion process? Are these changes due to new products not observed previously? Are these changes due to new products not observed previously? Are they just adding to what is already present? Are they just adding to what is already present? Determine if the products or transfer of ingredients affect biological changes that increase risk. Determine if the products or transfer of ingredients affect biological changes that increase risk. Exposure and kinetics of exposure Exposure and kinetics of exposure Test for biological activity Test for biological activity Behavioral changes Behavioral changes

3. Ingredient(s): A simplified view. Single component ingredients Single component ingredients Menthol Menthol Complex mixtures Complex mixtures Cocoa Cocoa Honey Honey Apple juice Apple juice

4. Challenges of determining fate of ingredient(s) Burning process complex Burning process complex Some generalized Reaction pathways taking place: Some generalized Reaction pathways taking place: Transfer Transfer Oxidation Oxidation Reduction Reduction Pyro synthesis Pyro synthesis Particulate formation Particulate formation Complex mixture of chemical products (>4800) Complex mixture of chemical products (>4800) Major products CO 2, CO and H 2 O Major products CO 2, CO and H 2 O A signal-to-noise problem A signal-to-noise problem

5. Challenges of determining fate of ingredient(s) (continued) No single analytical method for everything. No single analytical method for everything. This means techniques mentioned here would not be applicable to all problems. This means techniques mentioned here would not be applicable to all problems. New approaches may need to be developed. New approaches may need to be developed.

6. Approaches to determining fate Comparison to reference Comparison to reference Stable isotope / radioisotope Stable isotope / radioisotope Pyrolysis Pyrolysis Direct measurement Direct measurement

7. Comparison to reference Comparison to reference Reference without ingredient being tested. Reference without ingredient being tested. Reference for evaluating inter- and intra-laboratory methods. Reference for evaluating inter- and intra-laboratory methods. Considered necessary. Considered necessary.

8. Stable isotope / radioisotope - Advantages Reduces chemical noise Reduces chemical noise Allows relative and absolute comparisons Allows relative and absolute comparisons Allows determination of products and possible mechanisms Allows determination of products and possible mechanisms

9. Stable isotope / radioisotope - Limitations Labels may not be available Labels may not be available Only certain position in the component may be labeled making it difficult to determine some of the products Only certain position in the component may be labeled making it difficult to determine some of the products Complex mixtures would be difficult and costly to form labels on each component of the mixture Complex mixtures would be difficult and costly to form labels on each component of the mixture This is an example of why flexibility of experimental design is important. This is an example of why flexibility of experimental design is important.

10. Pyrolysis First, we do not consider pyrolysis to be sufficient by itself. First, we do not consider pyrolysis to be sufficient by itself. Performed under conditions of isolation. Performed under conditions of isolation.

11. Pyrolysis- Advantages Used as a screen to indicate: Used as a screen to indicate: Possible products of the pyro-synthesis process. (New products?) Possible products of the pyro-synthesis process. (New products?) Help predict intact transfer. This could be most helpful in that if this predicted intact transfer, labeling would not be necessary. Analytical methods could be targeted for that intact component (still need mass balance). Help predict intact transfer. This could be most helpful in that if this predicted intact transfer, labeling would not be necessary. Analytical methods could be targeted for that intact component (still need mass balance). Would be useful for complex mixtures. Would be useful for complex mixtures. Possible products Possible products Are they different from what is known to exist? Guidance for targeted analytical methods to determine if increases of these components have occurred. (If yes, what is the risk due to this increase?) Are they different from what is known to exist? Guidance for targeted analytical methods to determine if increases of these components have occurred. (If yes, what is the risk due to this increase?) Are there components that would remain intact thus could isotopic methods or targeted analytical methods be used in comparison of the burning cigarette with and without the ingredient for those compounds? Are there components that would remain intact thus could isotopic methods or targeted analytical methods be used in comparison of the burning cigarette with and without the ingredient for those compounds?

12. Conclusions Overall the determination of the fate of an ingredient(s) under burning conditions is a signal-to-noise problem. Overall the determination of the fate of an ingredient(s) under burning conditions is a signal-to-noise problem. Methods have been demonstrated as to how to undertake this problem but there is not a single approach that would cover all possibilities. Methods have been demonstrated as to how to undertake this problem but there is not a single approach that would cover all possibilities. Thus we have decided that flexibility in experimental design is important. Thus we have decided that flexibility in experimental design is important. Pyrolysis is an important method for screening and giving guidance to the fate of ingredient(s) but pyrolysis is no substitute for comparison of matrix with and without the ingredient. Pyrolysis is an important method for screening and giving guidance to the fate of ingredient(s) but pyrolysis is no substitute for comparison of matrix with and without the ingredient. Isotopic labeling is an important approach to determining the fate of an ingredient but it may not be practical for every ingredient especially for complex mixtures. Isotopic labeling is an important approach to determining the fate of an ingredient but it may not be practical for every ingredient especially for complex mixtures.