April 05, 2018
Hypertension and hyperlipidemia are more common among workers exposed to loud noise in the workplace, suggests new research from the National Institute for Occupational Safety and Health (NIOSH), part of the Centers for Disease Control and Prevention (CDC).
It's estimated that noise on the job affects 41 million US workers, the researchers say.
"Reducing workplace noise levels is critical not just for hearing loss prevention — it may also impact blood pressure and cholesterol," NIOSH Director John Howard, MD, said in a news release. "Worksite health and wellness programs that include screenings for high blood pressure and cholesterol should also target noise-exposed workers."
The study was published online March 14 in the American Journal of Industrial Medicine.
The researchers analyzed data from the 2014 National Health Interview Survey to estimate the prevalence of occupational noise exposure, hearing difficulty, and heart conditions within US industries and occupations. They also looked at ties between workplace noise and heart disease.
The survey assessed workplace noise exposure by asking respondents if they ever had a job where they were exposed to loud or very loud sounds or noise for 4 or more hours a day, several days a week. Loud was defined as so loud that they had to speak in a raised voice to be heard and very loud as having to shout in order to be understood by someone standing an arm's length away, the survey explained.
Among the cohort of 22,906 current workers, 49% were male, 62% were white, and 55% had a college degree.
In the analysis, 25% of current workers reported a history of work-related noise exposure, with 14% exposed in the prior year. In addition, 12% of workers experienced hearing difficulty, 24% had hypertension, and 28% had elevated cholesterol.
A history of workplace noise exposure was associated with a significantly elevated risk for hypertension (prevalence ratio [PR], 1.16; 95% confidence interval [CI], 1.09 - 1.23) and elevated cholesterol (PR, 1.10; 95% CI, 1.01 - 1.19), but not with coronary heart disease or stroke.
On the basis of these data, 58% of hearing difficulty cases, 14% of hypertension cases, and 9% of elevated cholesterol cases among US workers can be attributed to occupational noise exposure, the researchers say.
Industries with the highest prevalence of occupational noise exposure were mining (61%), construction (51%), manufacturing (47%), utilities (43%), and transportation and warehousing (40%).
Occupations with the highest prevalence of noise exposure were production (55%); construction and extraction (54%); installation, maintenance, and repair (54%); transportation and material moving (44%); and protective service (36%).
Noise and the Stress Response
"We can't determine if noise causes these conditions in a cross-sectional study. We can't say that noise leads to these conditions," Elizabeth Masterson, PhD, coauthor and epidemiologist at NIOSH, told theheart.org | Medscape Cardiology.
"We don't know the mechanism, but it has been theorized to work through both the autonomic nervous system and endocrine system via a stress response that elevates key biological risk factors for cardiovascular disease such as blood pressure and cholesterol," she added.
"There are some biologic reasons why loud noise would raise blood pressure," said Maryann McLaughlin, MD, associate professor, cardiology, Icahn School of Medicine at Mount Sinai in New York City, who wasn't involved in the study.
"Any kind of stress, even though the patient may not consider a loud-noise environment particularly stressful, it definitely can raise adrenaline levels, which then can raise blood pressure. Even if they have become accustomed to that background level of noise, their body can still be affected in that way," McLaughlin said in an interview.
"There are many environmental risks, such as air pollution, that can affect cardiovascular disease, and loud noise is an added factor that we should start to pay attention to," she added. "For anyone in an environment with increased noise levels, it's not just hearing loss that we have to think about, but there may in fact be some risk for high blood pressure and high cholesterol."
Masterson said, "It is important that workers be screened regularly for these conditions in the workplace or through a healthcare provider, so interventions can occur. As these conditions are more common among noise-exposed workers, they could especially benefit from these screenings."
The study supports an evidence review published in the Journal of the American College of Cardiology in February, which found a link between environmental noise from road traffic and aircraft and increased risk for heart disease, as reported by theheart.org | Medscape Cardiology.
On the basis of their review, the authors concluded that it's becoming clear that transportation noise is associated with oxidative stress, vascular dysfunction, autonomic imbalance, and metabolic abnormalities — potentially contributing to the development of cardiovascular risk factors, such as arterial hypertension and diabetes, as well as progression of atherosclerosis and increased susceptibility to cardiovascular events.
The study had no commercial funding. The authors have disclosed no relevant financial relationships.