Correlation between acoustic parameters and Voice Handicap Index in dysphonic teachers.

OBJECTIVE: The aim of this study was to investigate the relationship between acoustic analysis and biopsychosocial implications of voice problems, evaluated by the Voice Handicap Index (VHI). MATERIALS AND METHODS: The study comprised 120 female teachers with voice disorders, evaluated by videolaryngostroboscopy. 60.8% of this group were diagnosed as having functional dysphonia and 39.2% had dysphonia with benign vocal fold masses (nodules and polyps). The controls consisted of 30 euphonic women. The correlations between VHI and acoustic analysis were assessed in both groups using the Pearson correlation coefficient and regression analysis. RESULTS: In teachers, the total VHI score was over 5 times as high as in controls (p < 0.001). Moreover, in teachers, significant positive correlations were found between the total VHI score and the frequency perturbation parameters and amplitude perturbation parameters when both statistical methods were used. These acoustic parameters also significantly correlated with the score on the functional and emotional subscales, but rarely with the physical subscale of the VHI. CONCLUSIONS: The study revealed a significant relationship between the objective voice measurements and the VHI. The results confirmed that VHI can be a valuable tool for assessing biopsychosocial implications of occupational dysphonia and should be incorporated in multidimensional voice evaluation.

Hearing loss among workers exposed to moderate concentrations of solvents.

OBJECTIVES: It is known that some industrial organic solvents are ototoxic. This study was aimed at evaluating the hearing effects of a mixture of organic solvents alone or in combination with noise on employees in paint and lacquer enterprises. The concentration of solvents was below the occupational exposure limits (OEL) for most of the subjects. METHODS: Altogether 517 subjects were divided into the following three groups: persons with no risk due to noise or organic solvent exposure at the workplace, workers exposed to organic solvents only, and workers exposed to both organic solvents and noise. RESULTS: The relative risk (RR) of hearing loss in the solvent-only exposure group was significantly increased (RR 4.4 and RR 2.8 for noise exposure of < 80 dB-A and < 85 dB-A, respectively) in a wide range of frequencies (2-8 kHz). No additional risk in the solvent + noise exposure group was found (RR 2.8). Hearing thresholds were significantly poorer in a wide range of frequencies (1-8 kHz) for both groups exposed to solvents, when compared with the reference group. The mean hearing thresholds at frequencies of 2-4 kHz were poorer for workers exposed to solvents + noise than for the solvent-only group; this finding suggests an additional effect for noise. However, there was no correlation between hearing loss and the extent of solvent exposure. CONCLUSIONS: The results indicate that occupational organic solvent exposure at moderate concentrations increases the risk of hearing loss, and the ototoxic effects should be considered when the health effects of exposed workers are monitored.

[Hearing impairment in the plastics industry workers exposed to styrene and noise]. / Ocena uszkodzen sluchu u pracowników narazonych na styren i halas w przemysle tworzyw sztucznych.

Styrene exerts ototoxic effect in animals, and the combined exposure to this solvent and noise produces a synergistic effect relative to the isolated exposure to noise. However, there is a lack of reliable evidence that chronic occupational exposure to styrene is ototoxic to humans. Neither has been documented its additive effect with noise. The present study was aimed to assess hearing impairment and the risk of hearing loss in workers exposed to both styrene and noise. The study group included 72 male workers occupationally exposed to styrene in the plastics industry. The results were compared with two control groups, matched by age, gender and personal traits: one group composed of 82 male workers employed in a printing house and exposed only to noise at the levels almost twice as high as those observed in the group exposed to styrene and noise, and the other consisted of 65 male workers exposed neither to solvents nor to noise at workplace. In the group exposed to styrene and noise, significantly increased average hearing loss, as compared to both control groups, was found at all frequencies (1-8 kHz). The risk of hearing loss in the group exposed to styrene and noise was seven times higher (RR: 6.6; 3.0-15.9) than in the non-exposed group, and four times higher (RR: 4.0; 1.8-9.1) than in when workers exposed only to noise. However, no relationship could be observed between the amount of styrene exposure and hearing impairment, taking account of the confounding effect of noise and age. The results of the study suggest that the exposure to solvent mixtures with styrene as a basic component may exert additional, to noise, adverse effect on the auditory organ.

[Standardized new method for measuring vibration perception]. / Standaryzacja nowej metodyki badania czucia wibracji.

The examination of the vibration perception is one of the basic measurements applied in the evaluation of the peripheral neuropathies in hand-arm vibration syndrome (HAVS) The detailed guidelines on how this kind of examinations should be performed, presented in the 1998 ISO standard, differ substantially from those currently binding in Poland. The aim of this study was to standardize the method of vibration perception measurements, taking account of the parameters consistent with the ISO recommendations, such as algorithm (stimulus presentation method), vibration frequency, the size and contact force of vibrating probe, as well as the comparison of the results obtained by means of both methods (ISO-recommended method and standard Polish method). It was found that the algorithm change (ascending method replaced by Bekesy's technique, recommended by ISO) did not affect the of the vibration perception thresholds values within the wide range of frequencies (32-500 Hz), whereas the decreased size of probe, pressed with smaller contact force, resulted in significantly higher values of perception thresholds within the frequency range of 125-400 Hz. The comparison of the outcomes of the ISO-recommended and Polish standard methods revealed that the perception thresholds did not differ at the frequency of 125 Hz, but at the frequencies of 250 and 400 Hz, the ISO-recommended method produced higher values. Moreover, at the frequencies ranging from 125 to 400 Hz, the results of the perception threshold measurements, taken several times in the same persons (intrasubject variability) by means of both methods, were more scattered. It was revealed that the measurements at the frequency range of 4-125 Hz should be included in the vibration perception examinations, and the certification of the ability to work in the conditions of exposure to hand-arm vibration should be based on their results. It is also essential that in the standard examination, a smaller vibratory probe (phi = 5 mm) and lighter contact force (0.1 N) than those currently used, should be applied.

[Assessment of hearing impairment in workers exposed to mixtures of organic solvents in the paint and lacquer industry]. / Ocena uszkodzen sluchu u pracowników narazonych na mieszaniny rozpuszczalników organicznych w przemysle farb i lakierów.

Clinical and experimental studies indicate a possible harmful effect of chemicals, especially organic solvents, on the hearing system. In combined exposure to noise and solvents, very common in industry, it is most likely that a synergetic action of these factors enhances the traumatising effect of exposure to noise. The aim of this study was to assess the incidence and the risk of hearing impairment in 117 paint and lacquer factory workers exposed to a mixture of organic solvents. An analysis of organic solvent mixtures reveals that xylene and ethyl acetate are their major components whose concentrations depend on individual workposts. The control group consisted of 76 workers exposed to noise exceeding, Threshold Limit Value and 125 healthy subjects exposed neither to noise nor to solvents in their occupational setting. Pure tone audiometry revealed the highest hearing thresholds in workers exposed to solvents, lower thresholds in those exposed to noise, and the lowest ones in the non-exposed individuals. Hearing loss was found in 30% of workers exposed to organic solvents, in 20% of noise-exposed subjects, and in only 6% of non-exposed subjects. The comparison of relative risk values also indicated significantly enhanced probability of hearing impairment in workers of the paint and lacquer factory (9.6; 3.2-25.6), which is even more strongly pronounced than in the group of subjects exposed to noise (4.2; 1.2-13.2). An analysis of hearing impairment risk in particular frequencies suggests that organic solvents may damage the inner ear in much greater extent than noise. The results of the study show that exposure to organic solvents may create a significant risk of hearing impairment. Therefore, further steps should be taken to include the exposed population into effective preventive programmes.

Efficacy of vibration, electric current and thermal perception tests in diagnosis of hand-arm vibration syndrome.

Vibration perception test is usually proposed as a useful tool for quantitative assessment of neurological disturbances induced by hand-arm vibration syndrome (HAVS). The increased mean vibration perception threshold (VPT) is an early manifestation of this syndrome. However, we have identified a group of exposed subjects with normal VPT who showed electric current and/or thermal sensitivity impairment. The use of three tests instead of a single vibration test increased by 27% the number of persons with detected quantitative skin sensory disorders. The intensity of quantitative disorders of vibration and electric current sensitivity was closely related to the duration of vibration exposure. The thermal perception was diminished in subjects working for a longer period of time, but there was no relationship between intensity of disorders and the duration of exposure. In an early stage of hand-arm vibration syndrome (prevention of HAVS) the use of three tests helps to identify a larger number of workers at risk who should undergo thorough diagnostic examinations. In our study the proportion of identified workers increased from 27% (32 subjects with vibration sensory impairment) to 45% (53 persons with disorders detected in one, two or even three tests).

[Vibration syndrome and occupational exposure in Poland]. / Zespól wibracyjny w Polsce na tle narazenia zawodowego na wibracje.

The objective of the study was to analyse the data on the exposure to vibration, and the incidence of vibration syndrome in individual branches of the national economy and voivodships. The data were obtained from the records of The Nofer Institute of Occupational Medicine in Lódz, containing reports submitted to the Institute every three years, and the literature on fragmentary analyses of this kind of exposure. Although, the number of persons exposed to vibration, and the incidence of occupational diseases induced by vibration have decreased, the material collected provide evidence that vibration syndrome still plays an essential role in occupational pathology. The decrease in the vibration syndrome incidence observed during the years 1982-97 was lower than the decline in the number of persons exposed to vibration, but the ratio of the number of cases to the number of those exposed remained unchanged (2.1). In 1994-97, forestry workers constituted the largest working population exposed to vibration, and the number of persons with diagnosed vibration syndrome significantly increased, however, exposure to vibration in this branch of economy considerably declined. In the mining industry, a significant decrease in the number of persons exposed to vibration, as well as in the incidence of vibration syndrome was observed at that time. The worse situation in forestry might result from the past negligence of hygiene norms or less effective diagnosis in early stages of the disease development. The lack of measuring and monitoring of vibration intensity in the working environment is an alarming observation in view of the fact that both the number of persons exposed, and the incidence of occupational diseases caused by this kind of exposure are still high.

[Test of electric current perception thresholds at the fingertips--repeatability of the results]. / Badania progu czuci pradu elektrycznego na opuszkach palców osób zdrowych--sprawdzenie powtarzalnosci wyników.

The main aim of present study was to estimate the repeatability of measurements of electric current thresholds performed ten times in the same person. The study covered five persons. Variation in values was connected with individual differences in perception of the stimuli. Coefficients of variation were used as a relative measure of dispersion. Coefficients of variation calculated for individual frequencies were as follows: 7-37% for direct current, 4-19% for alternating current at frequency of 50 Hz, 3-23% for 100 Hz, 5-26% for 400 Hz, 5-23% for 1000 Hz and 4-19% for transient current. Current at frequency of 50 Hz showed the lowest perception threshold and the highest repeatability of values. At frequencies 100, 400 and 1000 Hz values of perception thresholds were higher and more variable. Transient current was sensed at high intensity but it showed small differences in consecutive examinations.