Objective: Occupational voice disorders in Poland account for over 25% of all occupational diseases. The aim of the study was to assess the prevalence of voice problems in the general population of Polish teachers, and identify risk factors for developing voice pathology. Patients and Methods: The study group comprised 425 female full-time teachers (most of them primary and secondary school, age ranging from 23 to 61 years) and 83 non-teacher women (control) whose jobs did not involve vocal effort, matched for age to the study group. All participants were subjected to a survey using an extensive questionnaire, and to laryngological, phoniatric and videostroboscopic examinations. Results: The overall lifetime vocal symptoms were more frequent in the teachers than in the non-teachers (69 vs. 36%), and in particular it related to permanent and recurrent hoarseness, and dryness in the throat. Mean number of the voice symptoms was 3.21 in teachers and 1.98 in controls (p < 0.001). Abnormal (non-euphonic) voice, neck muscle hypertension during phonation and incorrect resonator function were also significantly more frequent in the teachers. Mean maximum phonation time was shorter in teachers than in the controls (14.3 vs. 15.9 s, p < 0.01). Occupational voice disorders and hyperfunctional dysphonia (that is thought to predispose to such pathology) were found in 32.7% of teachers and 9.6% of control subjects. The probability of developing incomplete glottal closure (odds ratio 13.2x; 95% CI: 1.8–96.8) and hyperfunctional dysphonia (odds ratio 2.7; 95% CI: 1.14–6.44) were significantly higher in the teacher group versus non-teachers. A significant positive relationship was found in teachers between the prevalence of hyperfunctional dysphonia and strained phonation, neck muscle hypertension, instability of voice, self-assessed hyperarousal, and lifetime vocal effort index (years of employment as a teacher × hours of professional activity/week). The prevalence of vocal nodules and incomplete glottal closure were correlated with incorrect phonation technique parameters, but not with psychological factors. No correlation was found with environmental variables, such as classroom temperature, humidity, airborne dust. Conclusion: The prevalence of self-reported symptoms and clinical signs of voice disorders is around 2–3 times more frequent in Polish female teachers than in non-teachers. Lifetime vocal effort, incorrect technique of phonation and psychological predisposition seem to constitute major risk factors for developing occupational voice disorders.

Ototoxicity of styrene and the synergistic action of styrene and noise have been shown in rats. The respective data in humans are scarce and equivocal. This study evaluated the effects of occupational exposure to styrene and combined exposures to styrene and noise on hearing. The study group, comprised of 290-yacht yard and plastic factory workers, was exposed to a mixture of organic solvents, having styrene as its main compound. The reference group, totaling 223 subjects, included (1) white-collar workers, exposed neither to solvents nor noise and (2) metal factory workers, exposed exclusively to noise. All subjects were assessed by means of a detailed questionnaire and underwent otorhinolaryngological and audiometric examinations. Multiple logistic regression analysis revealed almost a 4-fold (or 3.9; 95% CI = 2.4-6.2) increase in the odds of developing hearing loss related to styrene exposure. The factors adjusted for were: age, gender, current occupational exposure to noise, and exposure to noise in the past. In cases of the combined exposures to styrene and noise, the odds ratios were two to three times higher than the respective values for styrene-only and noise-only exposed subjects. The mean hearing thresholds--adjusted for age, gender, and exposure to noise--were significantly higher in the solvent-exposed group than in the unexposed reference group at all frequencies tested. A positive linear relationship existed between an averaged working life exposure to styrene concentration and a hearing threshold at the frequencies of 6 and 8 kHz. This study provides the epidemiological evidence that occupational exposure to styrene is related to an increased risk of hearing loss. Combined exposures to noise and styrene seem to be more ototoxic than exposure to noise alone.

Objective: An incorrect voice emission is a risk factor for developing occupational voice disorders. The study aimed at assessing the effectiveness of voice therapy in female teachers with dysphonia. Methods: The study comprised 133 subjects with voice disorders, taking part in a vocal training programme. A reference group for the present study included 53 teachers with dysphonia. Questionnaire surveys, phoniatric examination and videostroboscopic evaluation were conducted at initial and control examination. Results: In the study group, an improvement after the vocal training was noted in most of the reported symptoms and also in some quantitative parameters of phoniatric examinations compared to the findings for the reference group. The number of patients who assessed their voice as normal increased significantly after the vocal training (2.3 vs. 46.6%). A significant increase in the mean maximum phonation time, from 13.3 to 16.6 s, was observed. The same applied to voice frequency range (increase from 171 to 226.8 Hz). Conclusions: The outcomes of vocal training, such as a subjective improvement of voice quality and an increase in the quantitative parameters (prolonged maximum phonation time, extended voice range) seem to be important parameters for monitoring the effectiveness of training in correct voice emission.

Questionnaire and audiometric data of 701 dockyard workers (517 noise and organic solvent mixture-exposed and 184 noise-only-exposed) were referred to 205 control subjects not exposed to either noise or solvents. The odds ratio (OR) of hearing loss was significantly increased by approximately 3 times in the noise-only group and by almost 5 times in the noise and solvent group. A moderate effect of solvent ototoxicity, in addition to noise, was observed on hearing threshold at a frequency 8 kHz. ORs for hearing loss were 1.12 for each increment of 1 year of age, 1.07 for every decibel of lifetime noise exposure (dB-A), and 1.004 for each increment of the index of lifetime exposure to solvents. The results suggest an additive damaging effect of coexposure to noise and organic solvents to the auditory organ.