In a nationwide study of more than 1,500 teenagers aged 12 to 19, NYU School of Medicine researchers found that teenagers exposed to smoke, as determined by tests that showed cotinine (a metabolite of nicotine) in their blood, performed worse across every sound frequency tested. Most notably, their ability to detect mid-to-high frequencies, which is important for understanding speech, was compromised. In addition, teenagers with higher cotinine levels were more likely to have unilateral low-frequency hearing loss.
The teens exposed to secondhand smoke were more likely to have sensorineural hearing loss, which is most often caused by problems with the cochlea, the snail-shaped hearing organ of the inner ear. Researchers explained that this kind of hearing loss usually tends to occur as one ages, or in children who are born with congenital deafness.
Overall, the researchers conclude that their findings indicate that “tobacco smoke is independently associated with an almost 2-fold increase in the risk of hearing loss among adolescents.”
Subtle Yet Serious
The consequences of mild hearing loss, which researchers suspect may be due to damage to the ear’s delicate blood supply, are “subtle yet serious” researchers said. Affected children can have difficulty understanding what is being said in the classroom and become distracted. As a result, they may be labeled as troublemakers or misdiagnosed with ADHD (attention deficit hyperactivity disorder).
Because mild hearing loss is not always noticeable, over 80 percent of the affected teenagers in the study were not aware of any problem, the researchers reported.
“Those children who are exposed to secondhand smoke … need to be regularly screened,” said the study’s lead author Anil Lalwani, M.D., professor of professor of otolaryngology, physiology, neuroscience and pediatrics at NYU School of Medicine.
While this is the first study to link secondhand smoke with hearing loss, other health hazards are associated with secondhand smoke. Living with a smoker raises the risk of dying from heart disease and lung cancer, and in children exposure to smoke exacerbates the severity of asthma attacks and causes more than 750,000 middle ear infections, according to the American Cancer Society.
The researchers pointed out that more than half of American children are exposed to secondhand smoke, and this new link to potential hearing loss “has huge public health implications.”
“We need to evaluate how we deal with smoking in public places and at home, as well as how often and when we screen children for hearing loss,” said Lalwani.
The study is published in the July issue of Archives of Otolaryngology – Head & Neck Surgery.