Noise and carbon monoxide exposure increases hearing loss, Universite de Montreal study

Main Category: Hearing / Deafness
Article Date: 17 May 2005 - 7:00 PDT

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Researchers have gathered evidence which shows that combined chronic exposure to noise and carbon monoxide in the workplace induces hearing loss. Adriana Lacerda, researcher at the ecole d'orthophonie et d'audiologie of the Universite de Montreal, presents her findings at the annual meeting of the Acoustical Society of America in Vancouver on Wednesday. Those findings are the result of a study conducted with over 8,600 workers exposed to both noise and carbon monoxide in the workplace. Among the riskier professions are welders, firefighters, garage mechanics, truckers, forklift operators and miners.

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 Gagne of the ecole d'orthophonie et d'audiologie at the Universite de Montreal. She is the recipient of the Brazilian government's CAPES bursary (Coordena de Aperfeioamento de Persoal de Nivel Superior), Universidade Tuiuti do Parana bursary and also the recipient of a bursary of excellence from the Universite de Montreal.

About Universite de Montreal

Founded in 1878, the Universite de Montreal counts 13 faculties and, along with its two affiliated schools, HEC Montreal and l'ecole Polytechnique, is Quebec's largest institution of higher learning, second in Canada, and among the most active in North America. With a faculty of 2,400 professors and researchers, the university has a student population of more than 55,000, offers more than 550 undergraduate and graduate programs and awards some 3,000 Master's and PhD degrees each year.

University of Montreal
http://www.umontreal.ca/english/index.htm

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