Why public health people are more worried than excited over e-cigarettes

Abstract

The research field on e-cigarettes is characterized by severe methodological problems, severe conflicts of interest, relatively few and often small studies, inconsistencies and contradictions in results, and a lack of long-term follow-up. Therefore, no firm conclusions can be drawn on the harm of e-cigarettes, but they can hardly be called safe. Experimental studies indicate negative health effects and, amongst others, the major ingredient propylene glycol warrants concern. Growing evidence raises doubt about the efficacy of e-cigarettes as a smoking cessation aid. Unfortunately, it seems that many smokers use e-cigarettes with the intention to quit but switch to long-term use of e-cigarettes or dual use. Use is spreading rapidly to minors, ex-smokers, and never-smokers. It is questionable whether the potential health benefits obtained by some smokers outweigh the potential harm by use of non-smokers, of undermining of complete cessation, smokers' dual use, and of eventual re-normalization of smoking. Even if e-cigarettes are significantly less harmful than conventional cigarettes, the product may have a very negative impact on public health if its use is spread to a large part of the population.

Figure 1

The long-term impact of smoking and e-cigarette use on public health – year 2050. The risk models are based on assumptions of prevalence of smoking and prevalence of use and harm of electronic cigarettes (EC). Harm of smoking is known to be extremely high; this is our reference. Maximal harm = 100. In a harm reduction perspective the harm of EC-use is estimated as extremely low/very low = 1 or 5. In a public health perspective the harm of EC-use is estimated low/moderate = 10, 15 or 25. Harm reduction perspective: Smoking scenario 1: the theory assumes that smokers are reluctant to quit and smoking rates will remain high (15% smokers, harm =100). E-cigarette scenarios: the theory assumes that harm of EC-use is extremely low/very low and use will be restricted to smokers only. EC-scenario 1: 10% of the population use ECs, harm = 1. EC-scenario 2 (worst case): 20% of the population (primarily smokers) use ECs, harm = 5. Public health perspective: Smoking scenario 2: the theory is that smokers wish to quit and tobacco control efforts are effective. Smoking rates will reduce steadily over the next decades (5% smokers, harm =100). Smoking scenario 3 (worst case): EC-use might undermine smoking cessation and renormalize conventional smoking, and the smoking rates might increase. The harm indicated as squared is the extra harm indirectly caused by ECs (30% smokers, harm = 100). E-cigarette scenarios: according to the theory we might underestimate long-term harm of ECs, and use of ECs might spread to a large part of the population EC-scenario 3: 20% of the population use ECs, harm = 10. EC-scenario 4: 30% of the population use ECs, harm = 15. EC-scenario 5 (worst case): 40% of the population use ECs, harm = 25.

Figure 2

The difficult balance between the potential pros and cons of e-cigarettes. The public health perspective.