The study, published in this week's issue of the British Medical Journal, is the first to examine smoking trends in a developing nation and involved 1.25 million Chinese, making it the world's largest investigation of smoking deaths.
The survey found that not only was the rate of deaths from smoking higher than expected, but that the types of diseases caused by smoking also varied widely from the West.
If current smoking patterns persist in China (where two-thirds of the men become smokers before the age of 25), tobacco will kill about 100 million of the 300 million males now under 30, according to the researchers.
Surprisingly, smoking was found to be decreasing among Chinese women, having dropped from 10 percent before 1950 to 1 percent today, say the researchers, affiliated with England's Oxford University, Cornell University in the United States, and the Chinese Academies of Preventive Medicine and of Medical Sciences.
China now logs the highest number of deaths from smoking of any country, having recently overtaken the United States.
And the trends seem to be mirroring what occurred in the West years ago as smoking spread across the globe, with deaths increasing several decades after the main rise in smoking.
"If we don't have action right now, we will suffer after 20 or 30 years. Then it's too late. So we have to let all of society know these results," said one researcher, Wang Kean, president of the Beijing-based Chinese Academy of Preventive Medicine.
Smoking already is causing about 750,000 deaths a year in China, and that will rise to 3 million people a year by the middle of the next century, when the young smokers of today reach middle and old age, the study said.
Worldwide, cigarettes will cause about 4 million deaths a year by 2000, split between rich and poor countries, it said.
But if current smoking trends persist, the total will be 10 million deaths a year by 2030, with 70 percent of them coming from developing nations, said Dr. Alan Lopez, chief of the World Health Organization's Division of Epidemiology and Burden of Disease, writing in a separate editorial published in the same journal.
"The hazards are already substantial and they cannot be limited to China," Lopez said. While the Chinese make up 20 percent of the world's population, they smoke 30 percent of the world's cigarettes, said Richard Peto, who led the research team from Oxford. Chinese adults severely underestimate smoking risks, he said.
"A 1996 nationwide survey showed that two-thirds believe smoking does little or no harm," he said. "The truth is that half of all persistent smokers get killed by tobacco. As two out of every three young men in China smoke, tobacco will eventually kill about a third of all the young men in China."
Analthough the overall risk of death may become about as big for Chinese as for Western smokers, the way in which smoking kills in China is surprisingly different, the researchers found.
In China, smoking causes many more deaths from chronic lung disease than lung cancer, the reverse of what happens in the West. Smoking also was not strongly linked to heart disease in China, as it is in the West, but instead was linked to tuberculosis.
The researchers attributed the differences to the fact that smoking exacerbates diseases already common in a country, and noted that Chinese and Western disease patterns differ.