Noise And Carbon Monoxide Exposure Increases Hearing Loss In Workers According To Université De Montréal Study

The correlation between carbon monoxide exposure and hearing loss had been established in previous animal studies but never in humans. Based on data gathered by the National Institute of Occupational Safety and Health, Lacerda compared the hearing of workers exposed to noise levels lower than 90 decibels for 8 hours to another group of workers exposed to noise levels above 90 decibels. In both groups, a sample of workers was also exposed to carbon monoxide.

The results revealed that the workers who were exposed to carbon monoxide and to noise levels above 90 decibels displayed significantly poorer hearing thresholds at high frequencies (from 3 to 6 kiloHertz). A larger shift was observed among workers with 25-29 years of noise exposure in the workplace.

"Based on these results, we recommend that such risks as chronic exposure to carbon monoxide be considered when assessing the risk of developing a noise-induced hearing loss," said Lacerda. One of several hypotheses to explain this phenomenon is that the reduction of oxygen in the blood stream accelerates the deterioration of the sensory cells of the inner ear.

Adriana Lacerda is currently finishing her doctoral thesis under the supervision of Professor Tony Leroux and Jean-Pierre Gagné of the École d'orthophonie et d'audiologie at the Université de Montréal. She is the recipient of the Brazilian government's CAPES bursary (Coordenaçaõ de Aperfeiçoamento de Persoal de Nivel Superior), Universidade Tuiuti do Paraná bursary and also the recipient of a bursary of excellence from the Université de Montréal.