Smoking tied to higher risk of hearing loss: study

TOKYO: Smokers may be more likely to develop hearing loss than nonsmokers, and the risk increases with each additional cigarette people smoke on a typical day, a Japanese study suggests.

Researchers examined data on almost 50,000 Japanese workers, ages 20 to 64, who didn’t have hearing loss. After a maximum follow-up of eight years, more than 5,100 people developed hearing loss.

Compared to nonsmokers, people who currently smoked were 60 percent more likely to develop high-frequency hearing loss that makes it hard to understand speech in noisy environments. Current smokers were also 20 percent more likely to develop low frequency hearing loss that makes difficult to detect deep voices.

“The more one smokes, the higher the risk of hearing loss,” said lead study author Huanhuan Hu of the Department of Epidemiology and Prevention at the National Center for Global Health and Medicine in Tokyo.

“Quitting smoking virtually eliminates the excess risk of hearing loss, even among quitters with short duration of cessation,” Hu said by email. “Because the risk of hearing loss increases with the number of cigarettes smoked per day, if quitting is impossible people should still smoke as little as possible.”

At the start of the study, participants were typically in their 40s, and about 19,000 of them were current smokers. About 9,800 were former smokers and 21,000 had never smoked.

Current smokers were more likely to be overweight or obese, have chronic health problems like high blood pressure and diabetes, and work in jobs with higher levels of occupational noise.

Each year during the study, participants had comprehensive hearing tests.

Compared to nonsmokers, people who currently smoked up to 10 cigarettes a day were 40 percent more likely to develop high frequency hearing loss and 10 percent more likely to develop low frequency hearing loss, the study found.

When smokers went through 11 to 20 cigarettes a day, they were 60 percent more likely to develop high frequency hearing loss and 20 percent more likely to develop low frequency hearing loss.

With more than 20 cigarettes a day, people were 70 percent more likely to develop high frequency hearing loss and 40 percent more likely to develop low frequency hearing loss.

While the study wasn’t a controlled experiment designed to prove whether or how smoking might cause hearing loss, it’s possible that nicotine exposure may damage the ears, Hu said.

Other limitations of the study include the reliance on participants to accurately report on their smoking habits, researchers note in Nicotine and Tobacco Research. The study also lacked on occupational noise exposure for all of the people in the study.

Still, the findings add to a growing body of evidence suggesting that smoking can contribute to hearing loss, said Dr. Matteo Pezzoli, a hearing specialist at San Lazzaro Hospital in Alba, Italy, who wasn’t involved in the study.

“The study showed clearly that there is a direct link between the number of cigarettes smoked and the damage suffered,” Pezzoli said by email.

“To maintain the hearing we have when we’re young, in addition to quitting smoking it is also important to lead a healthier lifestyle and increase sporting activities,” Pezzoli added. “It is also very important to protect your ears from prolonged exposure to loud noise.”