This had been surmised because previous research has indicated that smokers are at much greater risk of some degree of hearing loss.
Researchers examined data on 3,307 adults aged 20-69 who were classified as passive smokers based on blood levels of the chemical cotinine, a breakdown product of nicotine.
Smoking Can Increase Risk of Hearing Loss in Nonsmokers
In the study, 14% of former smokers who had been exposed to tobacco smoke by others were more likely to have impaired hearing in low to mid frequencies.
The study also found that more than 46% of these former smokers who had been exposed to secondhand smoke had high-frequency hearing loss, which can make speech sound muffled. Researchers say although the risk of hearing loss was not as strong among people who had never smoked, nearly one in 10 people in that group, or 8.6%, had low- to mid-frequency hearing loss, and 26% had high-frequency hearing loss.
The findings suggest that continued exposure to smoke by former smokers could continue the progression of high-frequency hearing loss that started when the former smokers were still smoking.
Hearing Loss May Be Another Consequence of Exposure to Tobacco Smoke
“Further research is required to determine whether [passive smoking] potentiates the effect of noise exposure and aging on hearing,” the researchers say. “If this finding is independently confirmed, then hearing loss can be added to the growing list of health consequences associated with exposure to secondhand tobacco smoke.”
The data examined came from the National Health and Nutrition Examination Survey, a yearly household survey combined with a physical examination including hearing testing of a representative sample of the U.S. population. “Although previous studies have reported the link between active smoking and increased risk of hearing loss, this study found significantly increased adjusted odds for hearing loss by former smokers for both low-mid and high-frequency hearing loss,” the authors write. “Furthermore, never smokers exposed to SMS [secondhand smoke] had increased risk of low-frequency hearing loss.”
The study is published in the bimonthly journal Tobacco Control, owned by the BMJ Group.