Chalansonnet Monique, Carreres-Pons Maria, Venet Thomas, Thomas Aurélie, Merlen Lise, Boucard Stéphane, Cosnier Frédéric, Nunge Hervé, Bonfanti Elodie, Llorens Jordi, Campo Pierre, Pouyatos Benoît
1Institut National de Recherche et de Sécurité, Rue du Morvan, CS 60027, Cedex, 54519 Vandœuvre, France.
2Departament de Ciències Fisiològiques and Institute of Neurosciences, Universitat de Barcelona, 08907 L'Hospitalet de Llobregat, Catalonia Spain.
J Occup Med Toxicol. 2020 May 11;15:9. doi: 10.1186/s12995-020-00260-5. eCollection 2020.
Carbon disulfide (CS) exacerbates the effect of noise on hearing, and disrupts the vestibular system. The goal of this study was to determine whether these effects are also observed with intermittent CS exposure.
Rats were exposed for 4 weeks (5 days/week, 6 h/day) to a band noise at 106 dB SPL either alone or combined with continuous (63 ppm or 250 ppm) or intermittent (15 min/h or 2 × 15 min/h at 250 ppm) CS. Hearing function was assessed by measuring distortion product otoacoustic emissions (DPOAEs); balance was monitored based on the vestibulo-ocular reflex (VOR). Functional measurements were performed before, at the end of exposure and 4 weeks later. Histological analyses of the inner ear were also performed following exposure and after the 4-week recovery period.
The results obtained here confirmed that CS exposure exerts two differential temporary effects on hearing: (1) it attenuates the noise-induced DPOAE decrease below 6 kHz probably through action on the middle ear reflex when exposure lasts 15 min per hour, and (2) continuous exposure to 250 ppm for 6 h extends the frequency range affected by noise up to 9.6 kHz (instead of 6 kHz with noise alone). With regard to balance, the VOR was reversibly disrupted at the two highest doses of CS (2 × 15 min/h and continuous 250 ppm). No morphological alterations to the inner ear were observed.
These results reveal that short periods of CS exposure can alter the sensitivity of the cochlea to noise at a dose equivalent to only 10 times the short-term occupational limit value, and intermittent exposure to CS (2 × 15 min/h) can alter the function of the vestibular system.
二硫化碳（CS）会加剧噪声对听力的影响，并扰乱前庭系统。本研究的目的是确定间歇性接触CS是否也会产生这些影响。
将大鼠暴露于106 dB SPL的带噪环境中4周（每周5天，每天6小时），单独暴露或与连续（63 ppm或250 ppm）或间歇性（250 ppm时每小时15分钟或每小时2×15分钟）的CS联合暴露。通过测量畸变产物耳声发射（DPOAE）评估听力功能；基于前庭眼反射（VOR）监测平衡。在暴露前、暴露结束时和4周后进行功能测量。暴露后和4周恢复期后也对内耳进行了组织学分析。
此处获得的结果证实，CS暴露对听力产生两种不同的暂时影响：（1）当暴露持续时间为每小时15分钟时，它可能通过作用于中耳反射减弱低于6 kHz的噪声诱导的DPOAE降低，（2）连续6小时暴露于250 ppm可将受噪声影响的频率范围扩展至9.6 kHz（单独噪声时为6 kHz）。关于平衡，在两种最高剂量的CS（每小时2×15分钟和连续250 ppm）下，VOR可逆性中断。未观察到内耳的形态学改变。
这些结果表明，短时间接触CS可在仅相当于短期职业限值10倍的剂量下改变耳蜗对噪声的敏感性，间歇性接触CS（每小时2×15分钟）可改变前庭系统的功能。
