Approximately 42.1 million adults in the US smoke cigarettes, and more than 16 million Americans suffer a disease caused by the habit, such as heart or lung disease. Now, new research from the University of Manchester in the UK finds that smoking and passive smoking may also increase the risk of hearing loss.
The research team, led by Dr. Piers Dawes of the Centre for Human Communication and Deafness at the university, recently published their findings in the Journal of the Association for Research in Otolaryngology.
For their study, the team assessed 164,770 adults from the UK between the ages of 40 and 69. All participants were a part of UK Biobank - a health project involving more than 500,000 individuals - and underwent hearing tests between 2007 and 2010.
The researchers calculated that smokers were 15.1% more likely to develop hearing loss, compared with passive smokers and non-smokers, while passive smokers were 28% more likely to develop hearing loss than non-smokers.
For smokers, the team found that the more packets participants smoked each week and the longer they smoked, the higher their risk of hearing loss.
Ex-smokers were found to have a slightly reduced risk of hearing loss, which the researchers say could be a result of an overall healthier lifestyle once they quit the habit.
How could smoking affect hearing loss?
The researchers are unable to determine the exact reasons why smoking and passive smoking increases the risk of hearing loss. But they point out that many smokers had heart disease, which could have impacted hearing.
Researchers found that smokers were 15.1% more likely to develop hearing loss, compared with passive smokers and non-smokers, while passive smokers were 28% more likely to develop hearing loss than non-smokers.
"We are not sure if toxins in tobacco smoke affect hearing directly, or whether smoking-related cardiovascular disease causes microvascular changes that impact on hearing, or both," says Dr. Dawes.
Explaining why passive smokers appear to have a higher risk of hearing loss than smokers, the researchers note that passive smokers were only compared with non-smokers in the study, while smokers were compared with both passive smokers and non-smokers. Therefore, the results could have "underestimated" smokers' hearing loss risk.
In the US, approximately 36 million adults report some form of hearing loss. The condition is typically associated with older adults, as exposure to sounds over the years can cause damage to the inner ear over time.
But Dr. Ralph Holme, head of biomedical research at Action on Hearing Loss in the UK - which helped fund the study - believes these latest findings indicate that smoking is also a risk factor for later-life hearing loss. He says:
"Hearing loss is often viewed as an inevitable consequence of aging, but as the research published today shows, this may not always be the case. Giving up smoking and protecting your ears from loud noise are two practical steps people can take today to prevent hearing loss later in life."
This is not the only study to associate smoking with hearing loss. A 2011 study from NYU Langone Medical Center in New York, NY, found that children exposed to secondhand smoke have a higher risk of developing hearing loss in their teens.