Passive smoking 'doubles hearing loss risk among teens'

Investigators say the findings, from a study of over 1,500 US teens aged 12 to 19, suggest that secondhand tobacco smoke directly damages young ears.

And the greater the exposure the greater the damage.

Often it was enough to impair a teen's ability to understand speech,Archives of Otolaryngol - Head & Neck Surgery reports.

It is still unclear how much exposure could be harmful and when the damage might occur.

Experts already know that smoke increases the risk of middle ear infections.

And they believe it may also harm the delicate blood supply to the ear causing "subtle yet serious" changes.

For these reasons, as well as other smoke-related health risks, they say the best advice is to avoid any exposure to tobacco smoke as far as is feasible.

Lead researcher Professor Anil Lalwani, from the New York University School of Medicine, said: "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."

In the study, around 40% of the 800 teens who had been exposed to secondhand smoke had detectable hearing problems, compared to about 25% of the 750 teens who had not had this exposure.

Yet very few - less than a fifth - of the affected teenagers were aware that they had a problem with their hearing. This is because mild hearing loss is not necessarily noticeable to the individual.

But hearing tests revealed that they struggled with high and low frequency sounds.

Co-researcher Dr Michael Weitzman said: "It's the type of hearing loss that usually tends to occur as one gets older, or among children born with congenital deafness." Kazinform cites BBC. See www.bbc.co.uk for full version