Articles in the London's Sunday Telegraph and Monday's Times of London said the seven-year study was an embarrassment to the agency. WHO countered in a statement Monday, saying the study had not been withheld and that its design was the reason it could not conclusively link cancer with secondhand smoke.
Passive smoking does cause cancer.
WHO examined the effects of environmental tobacco smoke in seven European countries, seeking to test results of earlier studies that found increased risks of lung cancer for nonsmokers exposed to smoke. The agency said it found about a 16 percent increased cancer risk in passive smokers. However, WHO acknowledged that this increase was not considered to be meaningful, because too few people were studied. This study compared 650 lung cancer patients with 1,542 healthy people. Studies intended to pinpoint small increases in risk often must study many thousands of people in order to rule out the possibility that the results were a matter of chance.