Passive smoking ‘can harm’ hearing

Hearing loss may be another passive smoking peril faced by teenagers, a study has found.

Inhaling other people’s tobacco smoke almost doubled the risk of impaired hearing among adolescents, scientists discovered.

Levels of hearing loss were mild but potentially enough to affect performance in the classroom.

Exposure to second-hand smoke has already been linked to a range of dangers in both children and adults. Living with a smoker is known to raise the risk of dying from heart disease and lung cancer. In children, it worsens the severity of asthma attacks and can lead to middle ear infections.

The new US study looked at health data on more than 1,500 children and teenagers aged 12 to 19.

Participants were seen at their homes and given extensive hearing tests.

Their blood was also analysed for traces of cotinine, a chemical produced from nicotine in the body. The presence of cotinine in the blood of a non-smoker is evidence of passive smoking.

Youngsters exposed to second-hand smoke were more likely to be suffering from senso-neural hearing loss, caused by problems affecting the inner ear.

“It’s the type of hearing loss that usually tends to occur as one gets older, or among children born with congenital deafness”, said Michael Weitzman, a professor from the New York University (NYU) School of Medicine, who took part in the study.

The findings were published yesterday in the journal Archives of Otolaryngology – Head & Neck Surgery.

Teenagers taking part in the research were assessed for their ability to hear different frequencies of sound.

With every test, those exposed to smoke performed worse than those living in non-smoking environments. They were especially impaired in the mid-to-high frequency range important for understanding speech. Participants with higher cotinine levels were also more likely to have low-frequency hearing loss in one ear.

Overall the researchers concluded that passive smoking was “independently associated with an almost two-fold increase in the risk of hearing loss”.

Anil Lalwani, also professor from NYU School of Medicine, who led the research, said: “More than half of all children in the US are exposed to second-hand smoke, so our finding that it can lead to hearing loss in teenagers 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.”

More than 80 per cent of the affected teenagers were not aware of any problem, said the re-searchers.

The association may be explained by toxic tobacco chemicals damaging the ear’s delicate blood supply, the scientists believe.

Even mild hearing loss can have “subtle yet serious” consequences, said Prof. Weitzman.

Affected children may have difficulty understanding what is being said in the classroom and become distracted. In some cases they could be branded as “troublemakers” or wrongly diagnosed with attention deficit hyperactivity disorder.