ABSTRACT
Industrial hearing loss has generally been associated with noise exposure, but there is a growing awareness that industrial solvents can have an adverse effect on the auditory and vestibular systems in man. Both animal experiments and human studies point to an ototoxic effect of industrial solvents, as well as some central auditory and vestibular disturbances. This review examines the research from the last four decades in an attempt to get an overview of the available evidence. Research shows that industrial solvents are ototoxic in rats. The majority of the solvents studied cause a loss of auditory sensitivity in the mid-frequencies in rats, affecting outer hair cells in the order OHC 3 > OHC 2 > OHC 1 . Inner hair cells are generally unaffected. Spiral ganglion cells are most vulnerable to trichloroethylene. Simultaneous exposure to solvents and noise results in a synergistic effect; the pattern of trauma mirrors that due to solvent exposure rather than noise, but is more enhanced. There is a critical level when synergy occurs. The effects of solvents on the vestibular system are neurotoxic and influence the vestibulo-oculomotor system in both animals and humans; humans also present with problems in postural sway. There is a strong suggestion from human studies that solvents are ototoxic in man, but findings show that both the peripheral and central auditory pathways can be affected. Hearing losses can be in the high frequency region or can affect a wider range of frequencies. Hearing loss and balance disturbances can occur at levels below permitted levels of exposure. The synergistic effect of combined exposure to solvents and noise has also been noted in humans, resulting in greater hearing losses than would be expected from exposure to noise and solvents alone. The findings from both human and animal studies indicate that exposure to industrial solvents or to industrial solvents and noise can have an adverse effect on hearing and balance. The implications for industry and hearing conservation are far reaching.
Subject(s)
Animals , Auditory Pathways/drug effects , Benzene Derivatives/toxicity , Carbon Disulfide/toxicity , Hair Cells, Auditory, Outer/drug effects , Hearing Loss/chemically induced , Humans , Noise, Occupational/adverse effects , Occupational Exposure/adverse effects , Postural Balance/drug effects , Rats , Solvents/toxicity , Trichloroethylene/toxicity , Vestibule, Labyrinth/drug effectsABSTRACT
Os autores apresentam a influência de agentes químicos na audiçäo de trabalhadores. Foi realizado um levantamento objetivando-se as possíveis substâncias químicas ototóxicas, demonstrando-se onde säo encontradas e seus efeitos nocivos para a audiçäo humana. Os dados encontrados neste trabalho demonstram a existência de substâncias químicas causadoras de prejuízo no sistema auditivo, tanto na sua porçäo periférica quanto central. Salienta-se a importância de um trabalho aprofundado nesta área, dadas as novas substâncias químicas que surgem a cada ano, nos ambientes de trabalho
Subject(s)
Humans , Arsenic/toxicity , Carbon Disulfide/toxicity , Occupational Diseases , Hearing Disorders/chemically induced , Lead/toxicity , Mercury/toxicity , Trichloroethylene/toxicityABSTRACT
A teoria da inibiçäo da piridoxamina pelo CS2 e a conseqüência interferência no metabolismo do triptofano, tem sido estudada por alguns autores e se apresenta como muito promissora para a elucidaçäo de um dos mecanismos de açäo tóxica desse solvente industrial. A funçäo da Vitamina B6 no organismo humano, principalmente sobre o metabolismo do triptofano e a excreçäo do seu principal metabilito, o ácido xanturenico, é estudada no presente trabalho, correlacioando-se a exposiçäo ocupacional ao sulfeto de carbono