High levels of secondhand smoke on the job can double nonsmokers' risk of developing lung cancer, and those who inhale it at work long-term face a 50 percent higher risk, researchers said on Wednesday.
Scientists led by epidemiologist Leslie Stayner of the University of Illinois at Chicago combined the results of 22 studies on secondhand smoke conducted in the United States, Canada, Europe, India, Japan and China.
Writing in the American Journal of Public Health, they said that for nonsmokers who were highly exposed to secondhand smoke at work, there was approximately a 100 percent increase in lung cancer risk.
The researchers adopted the previous studies' definitions of high exposure, based on factors like the numbers of smokers present in the workplace and actual amounts of smoke exposure.
Lung cancer risk for nonsmokers exposed for 30 years to secondhand smoke on the job jumped by 50 percent. Nonsmokers exposed to any secondhand smoke in the workplace experienced a 24 percent increased risk that rose based on level and duration of exposure, they said.
"We believe that our study provides the strongest evidence to date that smoking in the workplace does present a substantial risk to workers -- and particularly to workers who are working in highly exposed areas such as bar workers or restaurant workers," Stayner said in an interview.
The researchers said a lot of the evidence for an increased lung cancer risk caused by secondhand smoke has come from studies of nonsmokers married to a smoker. Previous studies also had not broken down the increased risk caused by secondhand smoke by level of Secondhand smoke, also called passive smoke and environmental tobacco smoke, is smoke from a cigarette, pipe or cigar and smoke exhaled from the lungs of smokers that is inhaled by nonsmokers.
In addition to cancer, it has been linked to respiratory problems and asthma in nonsmokers.
Stayner said the findings lend further credence to efforts in many communities in the United States and throughout the world to ban or limit smoking in the workplace.
For example, tighter smoking restrictions take effect this week in France, with bans in offices, stores, schools and hospitals.
Cafes, bars and restaurants will have until January 2008 to comply. In cafes and restaurants, smoking will still be permitted in hermetically sealed rooms without any services
exposure, they said.
