Teens who are exposed to secondhand smoke may be at a higher risk of hearing loss, researchers have found.
"We need to increase focus on this population at risk (for hearing loss) during adolescence who now have risk factors such as noise factors or secondhand smoke," said Dr. Anil Lalwani, who worked on the study.
Secondhand smoke has been tied to a range of health problems in kids, from respiratory infections to behavioural problems, although there is still no ironclad proof that smoke is at the root of all of these problems.
Lalwani and his colleagues from New York University Langone Medical Center thought tobacco smoke might have an effect on the blood flow in kids' inner ear, which is important for hearing.
They analysed data from a U.S. national health survey involving about 1,500 adolescents age 12 to 19. All of those kids had hearing tests in both ears to see if they had any trouble picking up on sounds at different pitches. Researchers also tested their blood for levels of cotinine -- which forms when the nicotine from cigarette smoke breaks down.
A very high level of cotinine suggests that a teen is a smoker, while a lower level means that kid is probably exposed to secondhand smoke.
Teens whose cotinine levels told researchers they spent a lot of time around smokers were more likely to have hearing loss at the lower frequencies of human speech than those without exposure to cigarette smoke.
About 12 per cent of the exposed kids had mild to severe hearing loss in one ear, compared to less than eight percent of kids without smoke exposure.