Intended effects | What the THR approach aims to achieve | Reduce smoking, reduce toxic exposure from smoking | Toxicological—assessments of products and/or human exposures; behavioural—reduced smoking |
Mechanism | How the approach is thought to accomplish the intended effects | Reduce smoking by reducing nicotine need due to providing nicotine; reduce toxin production by reducing burning temperature | Toxicological—(reduced production); behavioural—(reduced smoking) |
Potency | Power of the mechanism, if it works, to yield reduced harm | Cessation almost completely eliminates harm | Medical—biological impact of use; epidemiological—resulting disease impact |
Toxicology known | Current state of knowledge about the toxicology of the approach or product | Epidemiology of smokeless tobacco is characterised; newly engineered products have barely been characterised toxicologically, and not at all epidemiologically | Toxicological, medical, behavioural, and epidemiological |
Toxicology complex | Complexity of the toxicology, due in part to complexity or novelty of engineering in the product/approach | Reduction in smoking is simple, because the toxic exposures are qualitatively unchanged, but quantity is reduced. Newly-engineered products, in contrast, may introduce new toxins or interactions | Toxicology—characterisation of new product, including potentially new toxins and interactions |
Toxicity | Remaining potential for toxicity, even if harm is reduced | Smokeless tobacco, even if less harmful than smoking, is still harmful | Toxicology, medical, epidemiology |
Population risk | Total population hazard, when changes in adoption and cessation of smoking are considered | Increased adoption of smoking if cigarettes are perceived as “safe” may lead to increased total harm | Behavioural and epidemiological study of impact on initiation and cessation, along with toxicological evaluation of exposures |
Appeal | Appeal to smokers, leading to adoption | Taste or inconvenience of some products may deter adoption | Behavioural and marketing studies of preference; epidemiology of adoption |
Behaviour change | The amount of behaviour change smokers must make to adopt the approach | Smoking cigarette with different tobacco requires little change; changing to smokeless tobacco requires substantial change | Behavioural analysis |
Risk to others | The risk (or change in risk) to people other than the user | Smokeless tobacco produces no sidestream smoke, thus reducing environmental tobacco smoke exposure | Toxicological analysis of byproducts |
Dependence | Effect of the approach on nicotine dependence | Changing to smokeless tobacco likely to leave dependence unchanged; no-nicotine cigarettes unlikely to support dependence | Pharmacological analysis of nicotine exposures; behavioural and epidemiological assessment of dependence |