Leading article: No escaping the dangers of tobacco

Given the history of half-truths and special pleading which characterise the public pronouncements of tobacco companies, many people will find it unsurprising that the latest analysis casts doubt on previous industry-backed studies into the safety of cigarette additives. Indeed, independent scientists now claim that research published by Philip Morris a decade ago actually "obscured findings of toxicity".

No doubt Philip Morris, the world's second-biggest cigarette company, will explain why its original gloss on the research was correct. Yet many will find it odd to be arguing over details when the harm done by smoking is undisputed. But politics, business and law are different than science. That is why the firm is engaged in a lawsuit with the state of Oregon over a smoking-related wrongful-death claim worth up to $48m (£30m). It is also why Philip Morris is challenging the Australian government over legislation that will next year ban logos and brand imagery on cigarette packs, replacing them with the firm's name in a standard font on a drab packet covered in graphic health warnings.

The move could set an expensive precedent for the tobacco industry in important emerging markets like Brazil, Russia and Indonesia, which are the places where growth in sales is to be found. Four-fifths of the world's one billion smokers live in poor countries and the World Health Organisation is urging governments to adopt plain packaging strategies. For the tobacco companies, protecting such markets is not the rearguard action it might appear in the developed world.

Which comes back to the issue of additives. There are some 599 substances approved by the US government for use in cigarettes, including menthol, glycerol and beeswax. All have different properties when burned. In fact, more than 4,000 chemical compounds are created by lighting a cigarette, 43 of them known carcinogens. Putting additives in tobacco also increases the amount of fine particles inhaled, which adds to inflammation in the lungs. Were this data newly discovered, there would be calls for a ban on additives. As it is, moves to tighten public health rules are the best available course.