Smoking could eventually kill a third of all young Chinese men if nothing is done to get them to drop the habit, according to the largest ever survey of tobacco use.

Two landmark studies involving 1.25m Chinese people show that China has the largest number of smoking-related deaths in the world.

Because of a sharp increase in cigarette sales in the last 30 years, around 2,000 people a day are currently dying of smoking in China.

By 2050, the researchers expect this number could rise to 8,000 a day - some three million people a year.

The research - compiled by Chinese, British and American scientists - is the first nationwide research into the effects of tobacco in a developing country.

Different ways of dying

In the West, smoking causes a high number of heart-related deaths, but in China, the majority of deaths are due to respiratory diseases, including tuberculosis.

Dr Alan Lopez of the World Health Organisation, told a news conference in London: "In the West, cigarettes cause lots of heart attack deaths, while in China smoking causes unexpectedly large numbers of deaths from tuberculosis, emphysema, stomach cancer and liver cancer.

"Worldwide, the only really big causes of premature death that are growing rapidly are HIV and tobacco."

Nearly three-quarters of all Chinese men are smokers.

Average daily consumption rose from one cigarette in 1952 to 10 in 1992, but appears to have stabilised now.

Half die of smoking

The two studies are the result of a long-term international collaboration between Oxford University, the Chinese Academies of Preventive Medicine and of Medical Sciences in Beijing and Cornell University in the US.

For the first, researchers interviewed the families of one million people who had died in 24 cities and 74 rural counties to establish if the dead person had smoked.

The second study is ongoing and is looking at quarter of a million men aged over 40.

It is recording the mortality and causes of death of these men over a 30-year period through annual monitoring, taking into account diet, blood pressure, drinking and other factors.

Five years of the study have so far been completed, but the findings fit with those in the retrospective study - that tobacco kills half of all smokers.

The researchers say men aged 35 to 69 were

51% more likely to die from cancer than average,

31% more likely to die from respiratory deaths

at a 15% higher risk of dying from vascular diseases.

In older men, there was a greater danger of dying from respiratory disease.

Few women smoke in China and, unlike with men, the number is falling. No-one knows why, but Dr Zhengming Chen of Oxford University suggested it could be due to China's recent history and social development.

Causes of death

Smokers who got hooked young were most likely to die prematurely.

The researchers say 12% of all adult male deaths and 3% of all adult female deaths in China are now caused by smoking.

But they say this reflects past smoking habits.

"On present smoking patterns, the death rates of smokers will become double those of non-smokers of the same age, suggesting that about half of today's young smokers will eventually be killed by tobacco," say the studies, which are published in the British Medical Journal.

Jeffrey Koplan, director of the US Centers for Disease Control and Prevention, said the tragedy was that the deaths were "entirely preventable".

Speaking in London, Professor Richard Peto of Oxford University said if cigarette consumption could be halved by 2020, 25 million deaths could be prevented in the first quarter of the 21st century.

He said: "People thought that smoking was not going to cause very many deaths in poor countries like China.

"In retrospect it is just that they have not been smoking long enough. If they start smoking young and keep on smoking then about half the smokers are going to be killed by it.

"I spent ages in the 1980s saying that smoking is really dangerous. People thought I was exaggerating, but in fact it is about twice as bad as I was saying it was going to be."

Ignorance

Surveys showed two-thirds of Chinese people think smoking does little or no harm, 60% think it does not cause lung cancer and 96% do not know that it causes heart disease.

Dr Zhengming said the increase in tobacco consumption did not seem to be due to promotion by tobacco companies since it had been rising since the 1970s - in much the same way as US rates rose between 1910 and 1950.

Only around 10% of cigarettes sold in China are imported.

Chairman Mao is said to have promised Chinese people food, shelter and cigarettes as part of the communist revolution.

Dr Zhengming said smokers were also switching more to cigarettes from traditional methods of smoking such as pipes which have lower death rates.

"China still has a long way to go to educate the public about the risks of smoking," he said.

But he added that, despite Chinese health officials' backing for efforts to reduce tobacco consumption, treasury officials might find it difficult to say no to the huge revenue they can reap from the cigarette industry.

Gro Harlem Brundtland, head of the World Health Organisation is meeting Chinese ministers this weekend to talk about the tobacco problem.

The full text of the research is published on the BMJ's internet site - www.bmj.com - from midnight on 19 November.