While noisy jobs have long been associated with hearing
difficulties, the current study offers fresh evidence that louder
work conditions might contribute to risk factors for heart disease
as well.
"A significant percentage of the workers we studied have hearing
difficulty, high blood pressure and high cholesterol that could be
attributed to noise at work," said study coauthor Elizabeth
Masterson of the National Institute for Occupational Safety and
Health in Cincinnati, Ohio.
About 22 million U.S. workers are exposed to loud noise on the job,
Masterson said by email.
"If noise could be reduced to safer levels in the workplace, more
than 5 million cases of hearing difficulty among noise-exposed
workers could be prevented," Masterson added. "This study also
provides further evidence of an association between occupational
noise exposure and high blood pressure and high cholesterol, and the
potential to prevent these conditions if noise is reduced."
Noise is thought to increase heart risks by causing stress, which in
turn triggers release of stress hormones like cortisol, and changes
in blood vessels and heart rate, the study team notes in the
American Journal of Industrial Medicine.
For the study, researchers examined nationally-representative survey
data from 22,906 adults who were employed in 2014.
One in four workers reported exposure to occupational noise at some
point in the past, and 14 percent had experienced loud work
conditions in the previous year.
Industries with the most noise exposure included mining,
construction and manufacturing.
Overall, 12 percent of participants had hearing difficulties, 24
percent had high blood pressure, 28 percent had high cholesterol and
4 percent had experienced a major cardiovascular problem like a
heart attack or stroke.
After accounting for participants' other risk factors, the
researchers attributed 58 percent of the cases of hearing
difficulty, 14 percent of the instances of high blood pressure and 9
percent of the elevated cholesterol cases to exposure to
occupational noise.
The study did not, however, find a clear link between noisy work
conditions and heart disease, heart attacks or strokes. It's
possible there were too few people with these medical issues to
determine whether the conditions might be associated with
occupational noise, Masterson said.
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Hearing difficulty was linked to all three heart conditions, and
it's possible that both occupational noise exposure and hearing loss
might independently influence the risk of heart problems, she added.
The study wasn't a controlled experiment designed to prove whether
or how occupational noise exposure might directly cause risk factors
for heart disease like high blood pressure or elevated cholesterol
or lead to heart attacks and strokes.
Another drawback is that researchers lacked data on the intensity or
duration of noise exposure, the study team notes.
"The study itself does not establish a cause and effect relationship
between noise exposure and the coronary heart disease outcomes,"
said John Dement, an occupational health researcher and professor
emeritus at Duke University in Durham, North Carolina.
It's unclear, for example, whether noise exposure might cause high
blood pressure or if high blood pressure might be a risk factor for
hearing loss with or without occupational noise exposure, Dement,
who wasn't involved in the study, said by email.
"I think it's premature to draw too many conclusions about
implications for patients beyond what we already know about
preventing noise exposures and managing cardiovascular disease risk
factors," Dement added.
Still, workers can take steps to reduce noise exposure by using
quieter equipment when possible, keeping machinery well maintained
and lubricated, and erecting barriers between noise sources and work
areas, Masterson advised. Workers can also wear hearing protection
in noisy areas, and keep any music at a safe volume.
Routine hearing tests are also key.
"Hearing loss is a permanent condition," Masterson said. "However,
workers with even mild hearing impairment can benefit from clinical
rehabilitation, which includes learning lip-reading, fitting hearing
aids and adopting other compensation strategies to optimize
hearing."
SOURCE: https://bit.ly/2pzpPtJ American Journal of Industrial
Medicine, online March 14, 2018.
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