Smokers are being tricked into smoking low-tar cigarettes by the tobacco industry, which has known for two decades that they offer no significant health benefits over other cigarettes, ASH, the anti-smoking lobby, has said.
The group said yesterday that new research has revealed that the marketing of low-tar cigarettes was just "propagation of a falsehood by the tobacco industry".
ASH UK and the Imperial Cancer Research Fund say documents released in the US show that tobacco companies have been aware of the discrepancy for years, but have continued to market their "light" brands as a healthier alternative.
Although low-tar cigarettes register tar levels of just one to five milligrams on testing machines, compared to the standard of around 12mg, researchers said the way they were smoked meant users took in far more tar.
Dr Luke Clancy, chairman of ASH Ireland, said yesterday he was disappointed but not surprised by the findings.
"In the US in particular there is definite evidence on record of the tobacco industry telling people blatant lies in relation to their products and the damage being done to people's health."
He said the tobacco industry was one of the wealthiest in the world and could afford to spend billions on marketing internationally.
"This is another example of an innocent public being conned by a marketing strategy of a product that kills people."
The Minister for Health, Mr Cowen, told The Irish Times yesterday this was another indication that the public had to be very sceptical of cigarette marketing. It was a difficult battle, he said, for those involved in public health to counteract the "serious advertising muscle" of the tobacco industry.
The report says that, consciously or otherwise, smokers change the way they smoke when they switch to low-tar cigarettes, in an attempt to inhale enough to satisfy their craving for nicotine. Changes include taking more or deeper puffs or blocking the ventilation holes in filters, designed to draw in air to reduce nicotine and tar levels, with their fingers, lips or saliva.
Tests commissioned showed that when the ventilation holes were blocked, tar intake rose from 1mg displayed on the packet of Silk Cut Ultra to 12mg, similar to a standard Benson and Hedges cigarette, and from 6mg displayed on packets of Marlboro Lights to 10.5mg.
The report claimed that drawing smoke more deeply into the lungs could be responsible for a rise in adenocarcinomas, a previously rare form of lung cancer linked recently to increased smoking of light cigarettes.
Documents published in the report, released during litigation in the US, showed that tobacco companies have been aware of changes smokers made to satisfy their craving for nicotine.
But the authors said they continued to develop products which made it easy for smokers to "compensate" and marketed them as healthier options.
The report called for all tar and nicotine figures to be removed from packets and replaced with a warning that cigarettes were addictive. Branding such as low, light or mild should be withdrawn, it said.