Tuesday, July 19, 2011

Second Hand Smoke Causes Hearing Loss

Who would have thought that second hand smoke could cause hearing loss? ABC reports that a study found connection in teens between second hand smoke and hearing loss:




The researchers noted that the link of secondhand smoke exposure with elevated thresholds ranging from 0.5 kHz to 8 kHz suggests "that the injury to the inner ear is global."
In addition, the unilateral hearing loss is probably an early phase of ocular damage that is likely to progress in severity, they cautioned.
The elevated thresholds at 2, 3, and 4 kHz were particularly important, according to Lalwani and colleagues.
"These mid-to-high frequencies are critical for hearing in humans and are responsible for the clarity of hearing that allows us to discriminate between similar sounding words," they observed.
Possible mechanisms by which secondhand smoke could result in auditory damage include effects on the vasculature of the inner ear and injury from nicotine or other components of the smoke.
Hearing loss in young children has been shown to interfere with not only speech and language development, but also cognitive function, academic progress, and social interaction.
But newborns and young children are routinely screened for hearing difficulties, while adolescents are not.
The findings of this study suggest that teens who are exposed to secondhand smoke should have their hearing tested, and parents and caretakers should be made aware of the auditory hazards of their smoking.
Limitations of the study include its use of cross-sectional data which doesn't allow assignment of causation, lack of information on duration and sources of secondhand smoke exposure -- including prenatal exposure -- and absence of data on other factors such as exposure to loud noises.
The researchers also were unable to rule out the possibility that some of the participants had conductive, rather than sensorineural, hearing loss.
They concluded, "Future studies need to investigate the adverse consequences of this early hearing loss on social development, academic performance, behavioral and cognitive function, and public health costs."

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