Hearing Whether you smoke yourself or are around smokers, you’re inhaling more than 4,000 different substances, 50 of which are known carcinogens. This puts you at risk of respiratory infection, asthma, heart disease and lung cancer. Previous studies have shown that smokers are more likely to suffer hearing loss, and now new research from the University of Miami, Florida, USA shows that people who live or work in environments where they are exposed to smoke are also more likely to become hard of hearing.
This new research, published in Tobacco Control (a peer-reviewed journal of the BMJ), looked at data from the US National Health and Nutrition Examination Survey, for which people undergo an annual physical exam and complete a survey. From the survey, 3307 people aged between 20 and 69 were classed as passive smokers – an assessment based on a blood sample, checking cotinine levels. (Cotinine is biomarker for exposure to tobacco smoke.) Hearing loss was identified by testing the study participants’ abilities to hear different frequencies, ranging from low, 500 Hz, to 8000 Hz. Age-related hearing loss often begins with a loss of hearing in the high frequencies, but difficulties in picking up on low-frequency sounds is more problematic as it can make it more difficult to follow speech.
The researchers found that several factors seem to increase the likelihood of hearing loss – age (being older made it more likely), gender (men were more at risk of hearing loss than women), and having diabetes. But even when they took these factors into account, they also found a raised likelihood of hearing loss if a person had been or continued to be in a passive smoking environment.
Of those passive smokers who had previously smoked themselves, 14% suffered low-to-mid frequency hearing loss; 46% had high frequency hearing loss. Those passive smokers who had never smoked themselves were also more likely to suffer hearing loss than those who’d never been in a passive smoking environment. One in ten non-smokers who were exposed to second-hand smoke had low-to-mid hearing loss, and 27% had high frequency hearing loss.
In a separate study, researchers from University of Ibadan in Nigeria found that age-related hearing loss is associated with low levels of folic acid. Hearing impairment is very common in people over 70 – 71% of over-70s in the UK have mild to profound hearing loss – but its actual cause is unknown. The researchers interviewed 126 men and women over 60 who had been examined and were not found to have any underlying medical conditions – anyone who had a history of disease or ear-related problems was excluded from the study. When the researchers checked the data they found that those who had high-frequency hearing loss also had low levels of folic acid (32% lower), indicating that vitamin supplements might be useful in helping to prevent hearing impairment, especially if malnutrition is possible.
First published December 14, 2010