ABSTRACT
Some clinical and laboratory studies indicate that industrial solvents such as toluene, styrene, xylene, trichloroethylene and carbon disulfide or their mixtures may affect the inner ear, although the mechanism of this process is still not well understood. The aim of this investigation was to assess the incidence of hearing and vestibular disorders (using modem audiological and vestibular tests) in 61 workers exposed to a mixture of organic solvents at the production of paints and varnishes; the control group included 40 age-matched non-exposed subjects. Environmental and biological monitoring revealed that the most significant exposure can be attributed to the following mixture constituents: ethylbenzene, xylene and trimethylbenzene isomers such as pseudocumene, mesitylene and hemimellitene. Electronystagmographic examinations showed the symptoms of vestibular dysfunction, as well as the decreased duration, amplitude and slow phase angular velocity of induced nystagmus in 47.5% of the subjects exposed versus 5% of controls. This was accompanied by sensorineural high frequency hearing loss, identified by means of pure tone audiometry in 42% of those exposed versus 5% controls, and reduced amplitudes of transiently evoked and distortion-product otoacoustic emissions. The findings closely correspond with the rate of the total exposure to the solvent mixture. A possible mechanism responsible for ototoxicity of solvents is discussed.
Subject(s)
Ear, Inner/drug effects , Hearing Disorders/chemically induced , Occupational Diseases/chemically induced , Occupational Exposure/adverse effects , Solvents/adverse effects , Vestibular Diseases/chemically induced , Adult , Case-Control Studies , Ear, Inner/physiopathology , Electronystagmography , Hearing Disorders/physiopathology , Humans , Male , Middle Aged , Occupational Diseases/physiopathology , Vestibular Diseases/physiopathologyABSTRACT
Noise-induced hearing loss together with presbyacusis are the most frequent causes of the disorders of the inner ear among adults. The authors present briefly epidemiological, diagnostic and certification aspects of this issue. Their attention was mainly focused on the role of objective methods of hearing examinations (impedance audiometry, brainstem electric response audiometry, recording of otoacoustic emissions) in diagnostic procedures. A growing significance of these methods, especially in frequent cases of the aggravation and simulation among persons who claim for certification of occupational noise-induced hearing loss, was highlighted.
