Potentiation of Chemical Ototoxicity by Noise

Abstract

High-intensity and/or prolonged exposure to noise causes temporary or permanent threshold shifts in auditory perception. Occupational exposure to solvents or administration of clinically important drugs, such as aminoglycoside antibiotics and cisplatin, also can induce permanent hearing loss. The mechanisms by which these ototoxic insults cause auditory dysfunction are still being unraveled, yet they share common sequelae, particularly generation of reactive oxygen species, that ultimately lead to hearing loss and deafness. Individuals are frequently exposed to ototoxic chemical contaminants (e.g., fuel) and noise simultaneously in a variety of work and recreational environments. Does simultaneous exposure to chemical ototoxins and noise potentiate auditory dysfunction? Exposure to solvent vapor in noisy environments potentiates the permanent threshold shifts induced by noise alone. Moderate noise levels potentiate both aminoglycoside- and cisplatin-induced ototoxicity in both rate of onset and in severity of auditory dysfunction. Thus, simultaneous exposure to chemical ototoxins and moderate levels of noise can potentiate auditory dysfunction. Preventing the ototoxic synergy of noise and chemical ototoxins requires removing exposure to ototoxins and/or attenuating noise exposure levels when chemical ototoxins are present.

Chronic lead exposure induces cochlear oxidative stress and potentiates noise-induced hearing loss

“…Moreover, simultaneous exposure to lead enhanced the noise-induced hearing loss, suggesting an additive effect. This is consistent with other reports which indicated that chronic exposure to low levels of lead may be a risk factor for acquired hearing loss from complex exposures (Hwang et al, 2009; Park et al, 2010; Wu et al, 2000) and simultaneous exposure to ototoxicants that induce oxidative stress may have an additive or synergistic effect (Boettcher et al, 1987; Steyger, 2009). …”

“…For example, simultaneous exposure to even low levels of ototoxic drugs such as cisplatin and noise caused a greater shift in hearing thresholds and histological damage than that caused by isolated exposures (Boettcher et al, 1987). Similarly, simultaneous exposure to organic solvents and noise potentiated the noise-induced permanent threshold shifts (Steyger, 2009). …”

Ototoxic Substances at the Workplace: a Brief Update

“…Again, IRSST's assessment seems to be rather conservative and refers to selected agents exclusively. There is further evidence, for instance, that a broad range of volatile lipophilic solvents can exacerbate noiseinduced hearing impairment to a certain extent (4,11).…”

Hearing loss in a pediatric patient following cisplatin chemotherapy and subsequent exposure to excessive noise

“…While causality between the exposure to chemotherapy and the delayed ototoxicity post noise exposure cannot be guaranteed, our service has encountered other patients post platinum-based chemotherapy that developed hearing loss following noise exposure. The synergistic effects between ototoxic compounds and noise on hearing loss have also been demonstrated in animal models, and there is evidence of a common pathway (involving oxidative stress) between noise-induced and platinum-induced ototoxicity [15,16]. The hearing loss and tinnitus experienced by this patient and its subsequent recovery could be described as temporary threshold shift (TTS).…”