Smoking damages the body 'in minutes rather than years'

Chemicals inhaled by smokers enter the blood stream as quickly as if they had been injected, say experts

Smoking a single cigarette causes genetic damage to the body within minutes rather than years, researchers say.

In a report - described as 'a stark warning' to those tempted to start smoking - scientists found that cancer-causing chemicals in tobacco form rapidly after the first inhalation from a cigarette.

One in five adults smoke in England and the habit causes more than 80,000 deaths a year. Half of long-term smokers will die prematurely due to cigarettes.

Dr Stephen Hecht from the University of Minnesota led a team that studied the level of harmful substances known as polycyclic aromatic hydrocarbons in 12 smokers.

Scientists have long believed that PAHs are one of the main causes of lung cancer, but until now it was not known how the chemicals caused DNA damage in humans.

Dr Hecht and colleagues added a labelled PAH, phenanthrene, to cigarettes and tracked its fate in 12 volunteers who smoked the cigarettes.

They found that phenanthrene quickly forms a toxic substance in the blood known to trash DNA, causing mutations that can cause cancer.

The smokers developed maximum levels of the substance in a time frame that surprised even the researchers: just 15 to 30 minutes after the volunteers finished smoking.

The researchers said the effect is so fast that it's equivalent to injecting the substance directly into the bloodstream.

Dr Hecht, an internationally recognized expert on cancer-causing substances found in cigarette smoke and smokeless tobacco, said: 'This study is unique. It is the first to investigate human metabolism of a PAH specifically delivered by inhalation in cigarette smoke, without interference by other sources of exposure such as air pollution or the diet.

'The results reported here should serve as a stark warning to those who are considering starting to smoke cigarettes.'

The findings were published in Chemical Research in Toxicology, one of 38 peer-reviewed scientific journals published by the American Chemical Society.