Multivariate-adjusted effect estimates (95% CI) of hearing thresholds (dBHL) with IQR increment in occupational noise exposure (dBA), stratified according to participant status.

<p>Models were adjusted for age, age², sex, BMI, and hypertension, defined in Model C, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097538#pone-0097538-t003" target="_blank">Table 3</a>.</p><p>CI, confidence interval.</p><p>^<i>a</i>PTA (dBHL) change per interquartile range (IQR) of occupational noise, 94.26 dBA - 84.74 dBA: 9.52 dBA.</p><p><i>*p<0.05.</i></p

General characteristics of study participants (N = 30,072^a).

<p>^<i>a</i>Participants (N = 33,072) are the individuals having all interest variables in this study: advanced audiometric measurements, age, occupational noise, sex, BMI, and hypertension.</p><p>^<i>b</i>Age-adjusted means were presented.</p><p>^<i>c</i>Occupational noise (a daily 8-hour time weighted average level in each industry).</p><p>^<i>d</i>PTA (pure tone average) of standard threshold at 2, 3, 4 kHz frequencies.</p><p>^<i>e</i>Hearing thresholds at 1 kHz were obtained from primary audiometric tests.</p><p>^<i>f</i>Hearing Loss (PTA at 2, 3, 4 KHz frequencies > 25 dBHL).</p><p>SD, standard deviation.</p

Multivariate-adjusted effect estimates (95% CI) of hearing thresholds (dBHL) with IQR increment in occupational noise exposure (dBA), stratified according to occupational exposure to ototoxic chemicals.

<p>Models were adjusted for age, age², sex, BMI, and hypertension, defined in Model C, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097538#pone-0097538-t003" target="_blank">Table 3</a>.</p><p>CI, confidence interval.</p><p>^<i>a</i>PTA (dBHL) change per interquartile range (IQR) of occupational noise, 94.26 dBA - 84.74 dBA: 9.52 dBA.</p><p><i>*p<0.05.</i></p

Noise-Induced Hearing Loss in Korean Workers: Co-Exposure to Organic Solvents and Heavy Metals in Nationwide Industries

<div><p>Background</p><p>Noise exposure is a well-known contributor to work-related hearing loss. Recent biological evidence suggests that exposure to ototoxic chemicals such as organic solvents and heavy metals may be additional contributors to hearing loss. However, in industrial settings, it is difficult to determine the risks of hearing loss due to these chemicals in workplaces accompanied by excessive noise exposure. A few studies suggest that the effect of noise may be enhanced by ototoxic chemicals. Therefore, this study investigated whether co-exposure to organic solvents and/or heavy metals in the workplace modifies the risk of noise exposure on hearing loss in a background of excessive noise.</p><p>Methods</p><p>We examined 30,072 workers nationwide in a wide range of industries from the Korea National Occupational Health Surveillance 2009. Data on industry-based exposure (e.g., occupational noise, heavy metals, and organic solvents) and subject-specific health outcomes (e.g., audiometric examination) were collected. Noise was measured as the daily 8-h time-weighted average level. Air conduction hearing thresholds were measured from 0.5 to 6 kHz, and pure-tone averages (PTA) (i.e., means of 2, 3, and 4 kHz) were computed.</p><p>Results</p><p>In the multivariate linear model, PTA increment with occupational noise were 1.64-fold and 2.15-fold higher in individuals exposed to heavy metals and organic solvents than in unexposed individuals, respectively.</p><p>Conclusion</p><p>This study provides nationwide evidence that co-exposure to heavy metals and/or organic solvents may exacerbate the effect of noise exposure on hearing loss in workplaces. These findings suggest that workers in industries dealing with heavy metals or organic solvents are susceptible to such risks.</p></div

Additional file 1: Table S1. of Factors associated with secondhand smoke incursion into the homes of non-smoking residents in a multi-unit housing complex: a cross-sectional study in Seoul, Korea

Fourteen items of socio-demographic information. Table S2. Two items of smoking status. Table S3. Two items of secondhand smoke incursion at home. Table S4. Seven items of built environmental information. (DOCX 26 kb