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A highly publicised study by Public Health England (PHE) that claimed that e-cigarettes are 95 percent less harmful than tobacco has been attacked by medical journal The Lancet for relying on weak evidence.

The PHE report, written by researchers at King's College London and Queen Mary University of London, argued that vaping is substantially less harmful than smoking tobacco, and that the use of e-cigarettes could help to reduce smoking-related disease and deaths in the UK, as well as lowering public health costs.


The report's '95 percent safer' claim was reported widely by the media -- but an editorial in The Lancet has now called that statistic into question, saying it was based on weak statistics from researchers who had conflicting interests.

PHE took its statistics from a paper in the journal European Addiction Research, led by addiction researcher David Nutt. The research explored the harmfulness of tobacco and other nicotine products, "scoring" them in terms of their effects on users and non-users alike.

But while cigarettes were given a score of 99.6 score out of 100, and e-cigarettes just a lowly 4, Nutt and his co-authors also urged that there was a "lack of hard evidence for the harms of most of the products on most of the criteria" -- meaning the evidence is far from watertight.


Raising further caution around the statistics, The Lancet notes that there were relevant conflicts of interest highlighted between three of the paper's 11 authors. "The reliance by PHE on work that the authors themselves accept as methodologically weak raises serious questions not only about the conclusions of the PHE report, but also about the quality of the agency's peer review process," the editorial argues.

The authors of the PHE report have since responded, countering that the statistics called into question were part of a much larger body of evidence, delving into how effective e-cigarettes are at helping people to quit smoking, amongst other potential benefits.

The rejoinder also argues that the "95 percent" statistic remains justified, given public misinformation about the harms of vaping and its potential for weaning smokers off tobacco products.