Workers exposed to both chemicals and noise should wear both respiratory protection and hearing protection.

In a study published in the journal "Anales del Sistema Sanitario de Navarra," a team of researchers analysed the way in which various physical and chemical contaminants interact and the impact that this has on hearing alteration in 558 metal workers.

"Workers exposed to noise in the presence of metalworking fluids exhibit a delay in hearing alteration in comparison with those exposed only to noise at the same intensity," said Juan Carlos Conte, lead author of the study and a researcher at the University of Zaragoza.

"However," he said, "those exposed to noise in the presence of welding fumes experience increased hearing alteration."

"A problem we detected with respect to welding fumes in the presence of noise was that the protection used is effective for reducing the intensity of noise, but not for reducing the effects of the chemical contaminant," Conte explained.

Cellulose masks or others made of similar compounds had little effect in this case, since their capacity to filter particles such as charcoal had no effect on toxic gas molecules such as carbon monoxide.

In noisy atmospheres with metalworking fluids, people have the advantage of being able to use masks for respiratory protection, the researchers found. However, ear protection must be used in the same way to ensure that workers are comprehensively protected from noise.

Noise-related hearing loss is the most common occupational disease in Europe and is increasingly common among young people.

10 million workers in the US

The National Institute for Occupational Safety and Health in the US, NIOSH, estimates that almost 10 million American workers are exposed to occupational combinations of noise and chemicals that pose a hazard to their hearing.

These chemicals include metals, solvents, insecticides, herbicides and asphyxiant gasses. Some studies have indicated, that the combined effects of noise and chemicals on hearing are higher than what would be observed for exposure to either noise or the chemicals alone.

Source: www.ens-newswire.com