Secondhand smoke exposure significantly increases risk of developing mouth cancer

LONDON — When most people think about the dangers of smoking, they probably consider the risks of cancer for the smoker. Although it’s common knowledge secondhand smoke is also dangerous, a new study is revealing just how devastating that exposure can be. Researchers say exposure to secondhand smoke can increase the risk of oral cancer by a staggering 51 percent.

Oral cancer, or cancers of the mouth, include those affecting the lip, oral cavity, and throat. These cancers account for almost 450,000 new disease cases and more than 228,000 deaths every year globally.

Scientists say that significant risk factors for these forms of cancer include tobacco smoking and use of smokeless tobacco products. Drinking alcohol can also increase the risk of oral cancer. Tobacco smoke represents the largest amount of human exposure to chemical carcinogens and causes a fifth of cancer-related deaths worldwide.

However, active smokers are not the only people who suffer from these chemicals. Researchers examining data from 192 countries find 33 percent of male non-smokers, 35 percent of female non-smokers, and 40 percent of children have experienced exposure to involuntary smoking through inhaling secondhand tobacco smoke.

Previous research also shows that inhaling secondhand smoke can cause several other diseases, including lung cancer. Although tobacco smoking can cause oral cancer, there is less evidence proving whether or not secondhand smoke also leads to the disease.

Long-term smoke exposure doubles cancer risks

A team from Britain, Portugal, Spain, and the United States evaluated the potential association between secondhand smoke exposure and the risk of oral cancer. Their review analyzed five existing studies involving more than 6,900 people. Among those participants — from Asia, Europe, North America, and Latin America — 3,452 had been exposed to secondhand smoke and 3,525 had not.

Their analysis, appearing in the journal Tobacco Control, reveals the more than 50-percent greater risk of mouth cancer due to secondhand smoke exposure. Additionally, exposure lasting more than 10 to 15 years increases the risk of oral cancers by more than twice the rate in comparison to people with no exposure to tobacco smoke.

“This systematic review and meta-analysis supports a causal association between secondhand smoke exposure and oral cancer,” researchers write in a media release. “Moreover, the analyses of exposure response, including by duration of exposure (more than 10 or 15 years) to secondhand smoke, further supports causal inference.”

“The identification of the harmful effects of secondhand smoke exposure provides guidance to public health professionals, researchers, and policymakers as they develop and deliver effective secondhand smoke exposure prevention programs and adopt appropriate measures to implement guidelines in Article 8 of the World Health Organization’s Framework Convention on Tobacco Control,” the team concludes.

SWNS writer Stephen Beech contributed to this report.