Why Smoking Can Cause Hearing Loss
According to the Centers for Disease Control and Prevention (CDC), tobacco use is the single most significant preventable cause of death and disease in the US, responsible for the demise of over 480,000 Americans every year.
The research shaking its finger at Uncle Bob puffing on his pipe is not new – even from decades ago clinical trials established an association between smoking and hearing loss, discovering that the prevalence of hearing loss is higher in current smokers than non-smokers across all age groups.
Unsurprisingly, there also appears to be a link between the amount of smoking and degree of hearing loss. This is measured in a unit known as pack-years, where one pack-year means smoking an equivalent of one pack (20 cigarettes) per day for one year (or 40 cigarettes a day over half a year, etc). The greater the number of pack-years, the greater the prevalence of hearing loss with those with over 40 pack-years being 1.30 times more likely to have hearing loss than those with no smoking exposure. Unfortunately for Uncle Bob’s non-smoking wife, Aunt Jean, exposure to secondhand smoke also contributes a higher likelihood of hearing loss compared to those who don’t live with a smoker.
Smoking During Pregnancy
Maternal smoking during pregnancy is also a problem, reported in around 12% of pregnancies in the US (though at least this is better than 40% of maternal smokers back in 1967). In addition to being responsible for about 10% of premature births and 5% of infant deaths, maternal smoking has been found to be associated with an almost 3-times increase in the odds of low-frequency sensorineural hearing loss (SNHL) among young teenagers. Knowing that teenagers have selective hearing at the best of times, exacerbating this by exposing them to cigarette smoke in the womb is perhaps not the best idea. A study investigating the effects of secondhand smoke exposure to infants also found a 4.9x increased prevalence of hearing deficits in babies as young as 10 months old.
Research has noted that children with even mild degrees of hearing loss are more likely to be held back in school or drop out early as these children are negatively affected in their ability to learn and communicate. The hearing loss in children exposed to maternal smoking is thought to be at risk of further progression into adolescence if the child continues to be exposed to secondhand smoke or, God forbid, take up pipe-puffing themselves. Interestingly, it is thought that school-aged students who are more likely to engage in smoking during these years are those from working-class or lower to middle-income class families, and are more likely to consider schooling unnecessary, a social group of students one 1983 research paper delicately termed “burnouts.”
How Does Smoking Cause Hearing Loss?
It’s well known that smoking causes all sorts of problems, not just hearing loss. The tar and various chemicals contained in a cigarette have been linked to causing:
- Lung damage
- Heart disease
- A weakened immune system
- Eye disease
Good hearing is dependent on a number of anatomical structures working as they should. The contents of cigarette smoke are thought to be ototoxic (poisonous to the ear’s structures). It has been suggested that the increased exposure to carbon monoxide from cigarette smoke reduces the oxygen available to the sensory hair cells of the inner ear, causing damage and a decrease to hearing sensitivity.
Overall blood supply to the auditory system is reduced due to the effects of nicotine, causing narrowing and blockages of blood vessels. Nicotine is also known to affect the neurotransmitters involved in the signaling of the auditory nerve required for processing of sound information.
In the uterus, unborn babies exposed to maternal smoking are thought to undergo permanent changes to their metabolism due to chronic fetal malnourishment from cigarette-related dysfunction of the placenta. Another proposed idea is that nicotine and the other chemicals in cigarette smoke directly damage the fetus’s inner ear structures while in the womb.
Unfortunately, sensorineural hearing loss as a result of smoking is irreversible but there is evidence that quitting can prevent further loss; the heightened risk of hearing loss has been found to decrease within 5 years of quitting. All in all, there is very little benefit to smoking, Uncle Bob, and you should stop.