Oxidative stress biomarkers and otoacoustic emissions in humans exposed to styrene and noise

Abstract

Exposure-induced damage of the cochlear amplifier is shown in the mid-frequency range, confirming animal experiments, in which hair cells in the cochlear middle turn were damaged. Hearing damage is consistent with the outer hair cell apoptosis pathway associated with oxidative stress.

Evaluation of potential health effects associated with occupational and environmental exposure to styrene – an update

“…A relationship between styrene metabolites and oxidation products was only observed for the RNA oxidation product oxoGuo in non-smokers. However, a significant negative relationship was reported for oxoGuo and DPOAE components at specific frequencies (Sisto et al 2016). The authors interpreted this study as supporting the mechanistic hypothesis of styrene-induced damage of the cochlear amplifier in the mid-frequency range, consistent with OHC apoptosis associated with oxidative stress.…”

“…Oxidative stress biomarkers have recently been associated with sensitive indices of hearing impairment in solventexposed workers. As discussed previously, workers in an FRP facility exposed to mean styrene concentrations of about 26.5 ppm (and noise levels of 82 dB) exhibited reduced amplitude of total DPOAEs in the mid-frequency range compared to age-and sexmatched controls said to have no exposure to solvents, noise, or other ototoxic agents (Sisto et al 2016). Urinary concentrations of MA + PGA and the DNA and RNA oxidation products 8-oxo-7,8-dihydroguanine (oxoGua), 8-oxo-7,8-dihydro-20-deoxyguanosine (oxodGuo), and 8-oxo-7,8-dihydroguanosine (oxoGuo) were measured in the exposed workers.…”

“…Noise is the most frequent cause of irreversible sensorineural hearing loss in the workplace. Styrene and other simple aromatic chemicals such as toluene, ethylbenzene, and xylenes have been linked to hearing loss in the workplace, particularly in conjunction with exposure to noise (Fechter 1999;Hormozi et al 2017;Johnson 2007;Johnson et al 2006;Lawton, Hoffmann, and Triebig 2006;Metwally et al 2012;Morata et al 2011;Sisto et al 2016Sisto et al , 2013Śliwińska-Kowalska et al 2005;Tognola et al 2015;Triebig, Bruckner, and Seeber 2009;Triebig et al 2001). The evidence base is reasonably robust for this effect, and supported by a number of high-quality toxicological and mechanistic animal studies (Campo et al 1999(Campo et al , 2001(Campo et al , 2003(Campo et al , 2011(Campo et al , 2014Chen et al 2007;Chen, Tanaka, and Henderson 2008;Chen and Henderson 2009;Loquet, Campo, and Lataye 1999;Fetoni et al 2016;Gagnaire and Langlais 2005;Gagnaire et al 2006;Lataye, Campo, and Loquet 2000;Lataye et al 2001Lataye et al , 2003Lataye et al , 2004Mäkitie et al 2002;Pouyatos et al 2004;Pouyatos, Campo, and Lataye 2005;Venet et al 2015;Wang et al 2...…”

“…The small sample size, the absence of information on inclusion, exclusion criteria and considerations of hearing risk factors, the poor descriptions of styrene and noise exposure characterization, and the absence of evaluations for dose-response relationships are among the limitations of this study. Sisto et al (2016) recently repeated the DPOAE tests in a group of styrene-exposed molders from the same Italian FRP facility using a new technique. The mean styrene exposure of the exposed group (n = 9 women) was higher than previously reported (26.5 ppm), with a concurrent noise exposure level of 82 dBA.…”

The Influence of Occupational Noise Exposure on Cardiovascular and Hearing Conditions among Industrial Workers

“…It should be emphasized that aging is the most common reason for sensorineural and noise-induced hearing abnormalities, and both related closely with the formation of ROS (reactive oxygen species). Researchers suggested that hearing damage is associated with the outer hair cell apoptosis pathway which due to oxidative stress involving oxidative damage to biological molecular (such as nucleic acids, lipids, proteins and so on) and accompanies progression of several physical conditions, including neurodegenerative, cardiovascular, eproductive and kidney diseases, and also different cancers 32 .…”