Secondhand Smoke Said to Kill 600,000 a Year

You don't have to light up yourself in order to be exposed to an alarmingly high lung cancer risk. A new international study says as many as 600,000 people die each year from exposure to passive, or so-called "secondhand smoke from someone else's cigarettes.

The major study, based on subjects in 192 countries, is published in the latest issue of the British medical journal Lancet.

Worldwide, 40 percent of children, 33 percent of male non-smokers, and 35 percent of female non-smokers were exposed to secondhand smoke in 2004, the study found.

This exposure was estimated to have caused 379 000 deaths from ischaemic heart disease, 165 000 from lower respiratory infections, 36 900 from asthma, and 21 400 from lung cancer.

 Women especially vulnerable

603 000 deaths were attributable to secondhand smoke in 2004, which was about one percent of worldwide mortality. The researchers concluded that 47 percent of deaths from second-hand smoke occurred in women, 28 percent in children, and 26 percent in men.

Disability-adjusted life years (DALYs) lost because of exposure to secondhand smoke amounted to 10.9 million, which was about 0.7 percent of total worldwide burden of diseases in DALYs in 2004. In children, DALYs amounted to 61 percent.

The largest disease burdens were from lower respiratory infections in children younger than five years, ischaemic heart disease in adults, and asthma in adults and children.

"These estimates of worldwide burden of disease attributable to secondhand smoke suggest that substantial health gains could be made by extending effective public health and clinical interventions to reduce passive smoking worldwide, the authors wrote.

 Known carcinogen

Since the 1990s, secondhand smoke has been classified as a "known human carcinogen" by the U.S. Environmental Protection Agency (EPA), the U.S. National Toxicology Program, and the International Agency for Research on Cancer (IARC), a branch of the World Health Organization.

Tobacco smoke contains over 4,000 chemical compounds, according to the American Cancer Society. More than 60 of these are known or suspected to cause cancer.

The Society says secondhand smoke is estimated to cause 46,000 deaths from heart disease and 3,400 from lung cancer among non-smokers in the U.S. each year.

The researchers said they undertook this latest study because, while exposure to secondhand smoke is common in many countries, the magnitude of the problem has, until now, been poorly understood.