Chronic exposure to noise at work has been shown to increase the risk of high blood pressure, and new research suggests people working noisy jobs may have a higher chance of heart attack, as well.

Researchers at the University of British Columbia in Vancouver found that people who were exposed to the most noise as part of their job at lumber mills were 50 percent more likely to have a heart attack over a 45-year period, relative to the general population of British Columbia.

“I hope that this study illustrates this significant weakness in our current approach to reducing the risk of adverse health effects from noise, and that more effort is placed in reducing noise levels in the workplace,” study author Dr. Hugh W. Davies told AMN Health.

He explained that the workers in this study were exposed to noise from saw blades, machinery and other equipment. Davies added that the U.S. government estimates that millions of workers are routinely exposed to levels of noise that can damage hearing at work, mostly from jobs in manufacturing, transportation and the military.

Indeed, in a similar study, also published in the journal Epidemiology, Wolfgang Babisch of the Federal Environmental Agency in Germany and his colleagues found that men who lived by noisy road traffic for at least 10 years were 80 percent more likely to experience a heart attack.

Davies explained that noise tells our body that we are in a stressful situation. “Humans, like most animals, are hardwired to react to loud noise as a ‘warning’ of something about to happen - that’s why we jump when we hear something loud and unexpected,” he said.

So when people are around loud noises, their bodies react, perhaps by increasing heart rate and blood pressure, or inducing hormonal changes, Davies explained. These changes “are all geared to getting us ready to respond to a threat, and are perfectly normal.”

However, over time, chronic noise can cause those changes to become permanent, keeping a worker’s blood pressure constantly high, or inducing them to gain weight - both of which can increase the risk of heart problems, Davies noted.

To protect workers, Davies suggested that employers implement changes in the workplace that cut back on noise, rotate workers between noisy and quieter shifts, and offer them earplugs or other devices to protect their hearing.

However, he noted that it’s not clear whether hearing protection will save people’s hearts from the long-term effect of noise. “We do not know if this is an appropriate intervention to reduce the risk of heart attack mediated by stress,” he said.

In the lumber mill study, Davies and his colleagues followed 27,464 people who had worked at a lumber mill for at least one year from 1950 to 1995, noting who had a heart attack.

They found that workers were overall more likely to have a heart attack, and the risk was higher in people exposed to the most noise, and in those without hearing protection.

In the traffic noise study, Babisch and his team compared exposures to traffic noise in 1881 heart attack patients and 2234 people who had not experienced heart attack. They found that men exposed to noisy street traffic for at least 10 years were significantly more likely to experience heart attack.

SOURCE: Epidemiology, January 2005.