Hearing loss associated with xylene exposure in a laboratory worker

Abstract

BACKGROUND: Xylene is an organic solvent, widely used in histology laboratories and other occupational settings. Research in animals has demonstrated that xylene induces outer hair cell damage. Evidence regarding the effects of xylene in humans is only available from studies investigating workers exposed to mixtures of solvents containing xylene. These data indicate that mixtures of solvents containing xylene may induce hearing loss and central auditory dysfunction. PURPOSE: To comprehensively evaluate the peripheral and central auditory system of a histology laboratory worker exposed to xylene, who had presented with bilateral mild sensorineural hearing loss at an initial assessment. RESEARCH DESIGN: A case report of a male histology laboratory worker who has been exposed to xylene for over 20 yr. RESULTS: A diagnosis of bilateral mild sensorineural hearing loss of cochlear origin was made on the basis of otological, neuroimaging, and audiological examinations. Results indicating the absence of transient-evoked otoacoustic emissions, and auditory brainstem responses as expected for a mild cochlear hearing loss, were obtained. CONCLUSIONS: The observed bilateral mild sensorineural hearing loss was considered to have been induced by xylene exposure, due to the absence of any other etiological factors related to the onset of hearing loss. The results found in this patient are in agreement with animal data indicating xylene-induced ototoxicity. Xylene-exposed individuals should be audiologically monitored on a regular basis.