THURSDAY, Aug. 17, 2006 (HealthDay News) -- All types of tobacco use or exposure -- smoking, chewing, or secondhand smoke -- boost a person's risk for heart attack, Canadian researchers say.
Researchers at McMaster University in Ontario analyzed data from more than 27,000 people in 52 countries and factored in other lifestyle traits -- such as diet and age -- that could affect heart attack risk. They found that any form of tobacco use or exposure was harmful.
Publishing in the Aug. 19 issue of The Lancet, they found that moderate and heavy smokers had a three-fold increased risk of a heart attack and light smokers (8-10 cigarettes a day) had a two-fold risk.
The risk decreased with time after a person stopped smoking, the study said. Among light smokers, there was no excess risk 3 to 5 years after they quit smoking. Moderate and heavy smokers still had an excess risk of about 22 percent even 20 years after they kicked the habit.
The researchers also concluded that exposure to secondhand smoke increased the risk of heart attack in both former smokers and nonsmokers. People with the highest levels of secondhand smoke exposure (22 hours or more per week) have about a 45 percent increased risk of heart attack, the study said.
Chewing tobacco doubled the risk of heart attack, the researchers found.
The U.S. National Library of Medicine has more about smoking and smokeless tobacco.