Abstract

Noise exposure has traditionally been considered the primary risk factor for hearing loss. However, ototoxicants commonly found in occupational settings could affect hearing loss independently, additively, or synergistically when combined with noise exposures. The purpose of this investigation was to determine the combined effect of metal and solvent ototoxicants, continuous noise, and impulse noise on hearing loss. Noise and ototoxicant exposure and pure-tone audiometry results were analyzed for U.S. Air Force personnel (n = 2,372) at a depot-level aircraft maintenance activity at Tinker Air Force Base, Oklahoma. Eight similar exposure groups based on combinations of ototoxicant and noise exposure were created including: (1) Continuous noise (reference group); (2) Continuous noise + Impulse noise; (3) Metal exposures + Continuous noise; (4) Metal exposures + Continuous noise + Impulse noise; (5) Solvent exposure + Continuous noise; (6) Solvent exposures + Continuous noise + Impulse noise; (7) Metal exposure + Solvent exposures + Continuous noise; and (8) Metal exposure + Solvent exposures + Continuous noise + Impulse noise. Hearing loss was assessed at center octave band frequencies of 500–6,000 Hz and using National Institute for Occupational Safety and Health Standard Threshold Shift (STS) criteria. Hearing changes were significantly worse at 2,000 Hz in the Metal exposure + Solvent exposure + Continuous noise group compared to the Continuous noise only reference group (p = 0.023). The Metal exposure + Solvent exposure + Continuous noise group had a significantly greater relative risk (RR) of 2.44; 95% CI [1.24, 4.83] for developing an STS at 2,000 Hz. While not statistically significant, the Solvent exposure + Continuous noise group had a RR of 2.32; 95%CI [1.00, 5.34] for developing an STS at 1,000 Hz. These results indicate that noise exposure may dominate hearing loss at ≥3,000 Hz while combined effects of concomitant exposure to ototoxic substances and noise are only noticeable at ≤2,000 Hz. These results also suggest combined exposures to ototoxicants and noise presents a greater hearing loss risk than just noise.

摘要

传统上，噪音暴露被认为是听力损失的主要危险因素。然而，职业环境中常见的耳毒物与噪声暴露相结合时可能会独立、相加或协同地影响听力损失。本研究的目的是确定金属和溶剂耳毒物、连续噪声和脉冲噪声对听力损失的综合影响。对俄克拉荷马州廷克空军基地基地级飞机维护活动中的美国空军人员 (n = 2,372) 的噪音和耳毒性暴露以及纯音听力测试结果进行了分析。根据耳毒剂和噪声暴露的组合创建了八个类似的暴露组，包括： (1) 连续噪声（参考组）；(2)连续噪声+脉冲噪声；(3)金属暴露+持续噪音；(4)金属暴露+连续噪声+脉冲噪声；(5)溶剂暴露+持续噪音；(6) 溶剂暴露+连续噪声+脉冲噪声；(7)金属暴露+溶剂暴露+持续噪音；(8) 金属暴露+溶剂暴露+连续噪声+脉冲噪声。听力损失在 500-6,000 Hz 的中心倍频程频率下进行评估，并使用国家职业安全与健康研究所标准阈值偏移 (STS) 标准。与仅连续噪声参考组相比，金属暴露 + 溶剂暴露 + 连续噪声组在 2,000 Hz 时的听力变化明显更差 (p = 0.023)。金属暴露+溶剂暴露+连续噪音组的相对风险（RR）显着更高，为2.44；开发 2,000 Hz 的 STS 的 95% CI [1.24, 4.83]。虽然不具有统计显着性，但溶剂暴露 + 连续噪声组的 RR 为 2.32；95%CI [1.00, 5.34] 用于开发 1,000 Hz 的 STS。这些结果表明，噪声暴露可能在 ≥3,000 Hz 时主导听力损失，而同时暴露于耳毒性物质和噪声的综合影响仅在 ≤2,000 Hz 时才明显。这些结果还表明，与仅接触噪音相比，同时接触耳毒性物质和噪音会带来更大的听力损失风险。