International Archives of
Int Arch Occup Environ Health 42, 251-256 (1979)
Occulmakmal and Elinnnmlnial HMealth © Springer-Verlag 1979
Noise-Induced Hearing Loss and Blood Pressure O Manninen and S Aro Department of Public Health, Faculty of Medicine, University of Tampere, Vuolteenkatu 11, SF-33100 Tampere 10, Finland
Summary A sample of 188 male and 92 female engineering industry workers was investigated Pure-tone audiometric measurements were used as an estimator of prolonged noise exposure Using the air conductance thresholds at frequencies of 3,4 and 6 kHz, subjects were classified into three hearing classes Their systolic (SBP) and diastolic blood pressure (DBP) was measured. In the older age group (41-64 years), the mean SBP of subjects with moderate hearing loss was 12 mmHg higher among men (n=35) and 18 mmHg higher among women (n= 7) than among subjects with normal hearing (n= 27) The mean DBP levels of subjects with moderate hearing loss were 5 mmHg and 4 mm Hg higher, respectively However, in the class of severe hearing loss (n=38 ; only male workers) the mean SBP was only 2 mm Hg and the mean DBP only 1 mm Hg higher than among subjects with normal hearing In the younger age group ( 26-40 years) no differences in either SBP or DBP between the hearing classes were found. Key words: Industrial noise
Hearing loss
Blood pressure
Findings related to the effects of noise on blood pressure (BP) are somewhat controversial As a consequence of immediate noise exposure, diastolic blood pressure (DBP) has usually risen, whereas systolic blood pressure (SBP) has either increased (Steinmann et al , 1955) or decreased (Floss, 1964 ; Ponomarenko, 1966 ; Mosskov and Ettema, 1977 a, 1977 b) slightly In all these cases the pulse pressure has diminished. When exposing subjects to intensive broad-band noise in a laboratory setting no significant change in either SBP or DBP was found (Cartwright and Thompson, 1975). Many epidemiological studies have demonstrated an association between prolonged exposure to occupational noise and elevated BP or increased prevalence of hypertension (Anticaglia and Cohen, 1970 ; Craff et al , 1968; Jonsson and Hansson, 1977 ; Meinhart and Renker, 1970; Parvizpoor, 1976 ; Satalov et al , 1969) In one study (Satalov et al., 1962) no hypertension was found, but some cases of hypotension were A number of animal experiments have shown that exposure to noise and other stress factors has been followed by an immediate or prolonged rise in BP (Andriukin, 1961 ; Anticaglia and Cohen, 1970; Hudak and Buckley, 1961 ; Kreher et al , 1977 ; Medoff and Bongiovanni, 1945 ; Smookler et al , 1973).
0304-0131/79/0042/0251/$ 1 20
252
O Manninen and S Aro
The purpose of this study was to investigate the association between exposure to long-term occupational noise and SBP and DBP among workers in the Finnish engineering industry Audiometric tests were used as the basis for appraisal of individual long-term noise exposure. Material and Methods The present data were collected during the so-called METELI' project The sample (233 men and 119 women) was selected from among the workers of three engineering factories of the same company in central Finland A systematic stratified sampling was used. In the factories the nature of work on the production lines varied greatly with a range of products from huge paper machines and marine Diesel engines through tractors, outboard motors and shotguns to delicate electric meters Distributions of noise levels as well as other characters of working conditions in these factories have been described in detail elsewhere (Manninen, 1977). Measurements of hearing ability, BP and relative weight were performed during a detailed health examination Hearing levels were determined with a clinical Maico-audiometer using the so called combined technique (combined descending and ascending progressions) in an audiometric examination chamber where the ambient noise level ranged between 20 and 25 d B The hearing thresholds of both ears were tested at frequencies of 125-8000 Hz with air-conducted pure tones. Using the frequencies 3, 4, and 6 kHz in particular, the subjects were classified as having mild hearing loss (class I, loss of hearing no more than 40 d B at any of the three frequencies), moderate hearing loss (class II, loss of hearing 45-60 dB) and severe hearing loss (class III, loss of hearing 60 dB or more). All BP measurements were taken with a mercury sphygmomanometer A trained nurse took all the measurements (casual BP) BP was recorded from the right upper extremity in a sitting position after the subject had rested for a few minutes SBP was recorded at the second sound and DBP at the point of disappearance of the sounds BP values were read to an accuracy of 2 mm Hg. Relative weight, which is the percentage of the subject's ideal weight (D 6beln, 1959), was determined in order to eliminate the influence of weight on the variations in BP (Chiang et al , 1969) Subjects who used antihypertensive drugs or had chronic urinary infection or who had hearing impairment not attributable to noise damage (estimated by otoscopy, audiograms, and history of diseases and traumas of the ear) were excluded The final sample size was 280 persons (188 male and 92 female workers).
Results Table 1 shows the mean SBP and DBP among men and women in the two age groups in different hearing classes. In the group of young males there seems to be no change in SBP in different hearing classes DBP is slightly higher in hearing class II than in either of the other classes The number of cases in hearing classes II and III is relatively small for further interpretations, however No such comparisons are possible for the younger female group, because all the women but one belong to hearing class I. In the older male group the mean SBP is 12 mm Hg higher in hearing class II than in hearing class I, and 10 mm Hg higher than in hearing class III The same biphasic phenomenon also appears to some extent in the mean DBP of this group. In the female group the mean SBP is as much as 18 mm Hg higher, and the mean DBP 4 mm Hg higher than in hearing class I However, the number of cases in class II METELI was a collaborative project of a multidisciplinary research team carried out in 19711976 The project was financed by the Social Science Research Council of the Academy of Finland and by the Ministry of Education
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Int Arch Occup Environ Health 42, 251-256 (1979)
Occulmakmal and Elinnnmlnial HMealth © Springer-Verlag 1979
Noise-Induced Hearing Loss and Blood Pressure O Manninen and S Aro Department of Public Health, Faculty of Medicine, University of Tampere, Vuolteenkatu 11, SF-33100 Tampere 10, Finland
Summary A sample of 188 male and 92 female engineering industry workers was investigated Pure-tone audiometric measurements were used as an estimator of prolonged noise exposure Using the air conductance thresholds at frequencies of 3,4 and 6 kHz, subjects were classified into three hearing classes Their systolic (SBP) and diastolic blood pressure (DBP) was measured. In the older age group (41-64 years), the mean SBP of subjects with moderate hearing loss was 12 mmHg higher among men (n=35) and 18 mmHg higher among women (n= 7) than among subjects with normal hearing (n= 27) The mean DBP levels of subjects with moderate hearing loss were 5 mmHg and 4 mm Hg higher, respectively However, in the class of severe hearing loss (n=38 ; only male workers) the mean SBP was only 2 mm Hg and the mean DBP only 1 mm Hg higher than among subjects with normal hearing In the younger age group ( 26-40 years) no differences in either SBP or DBP between the hearing classes were found. Key words: Industrial noise
Hearing loss
Blood pressure
Findings related to the effects of noise on blood pressure (BP) are somewhat controversial As a consequence of immediate noise exposure, diastolic blood pressure (DBP) has usually risen, whereas systolic blood pressure (SBP) has either increased (Steinmann et al , 1955) or decreased (Floss, 1964 ; Ponomarenko, 1966 ; Mosskov and Ettema, 1977 a, 1977 b) slightly In all these cases the pulse pressure has diminished. When exposing subjects to intensive broad-band noise in a laboratory setting no significant change in either SBP or DBP was found (Cartwright and Thompson, 1975). Many epidemiological studies have demonstrated an association between prolonged exposure to occupational noise and elevated BP or increased prevalence of hypertension (Anticaglia and Cohen, 1970 ; Craff et al , 1968; Jonsson and Hansson, 1977 ; Meinhart and Renker, 1970; Parvizpoor, 1976 ; Satalov et al , 1969) In one study (Satalov et al., 1962) no hypertension was found, but some cases of hypotension were A number of animal experiments have shown that exposure to noise and other stress factors has been followed by an immediate or prolonged rise in BP (Andriukin, 1961 ; Anticaglia and Cohen, 1970; Hudak and Buckley, 1961 ; Kreher et al , 1977 ; Medoff and Bongiovanni, 1945 ; Smookler et al , 1973).
0304-0131/79/0042/0251/$ 1 20
252
O Manninen and S Aro
The purpose of this study was to investigate the association between exposure to long-term occupational noise and SBP and DBP among workers in the Finnish engineering industry Audiometric tests were used as the basis for appraisal of individual long-term noise exposure. Material and Methods The present data were collected during the so-called METELI' project The sample (233 men and 119 women) was selected from among the workers of three engineering factories of the same company in central Finland A systematic stratified sampling was used. In the factories the nature of work on the production lines varied greatly with a range of products from huge paper machines and marine Diesel engines through tractors, outboard motors and shotguns to delicate electric meters Distributions of noise levels as well as other characters of working conditions in these factories have been described in detail elsewhere (Manninen, 1977). Measurements of hearing ability, BP and relative weight were performed during a detailed health examination Hearing levels were determined with a clinical Maico-audiometer using the so called combined technique (combined descending and ascending progressions) in an audiometric examination chamber where the ambient noise level ranged between 20 and 25 d B The hearing thresholds of both ears were tested at frequencies of 125-8000 Hz with air-conducted pure tones. Using the frequencies 3, 4, and 6 kHz in particular, the subjects were classified as having mild hearing loss (class I, loss of hearing no more than 40 d B at any of the three frequencies), moderate hearing loss (class II, loss of hearing 45-60 dB) and severe hearing loss (class III, loss of hearing 60 dB or more). All BP measurements were taken with a mercury sphygmomanometer A trained nurse took all the measurements (casual BP) BP was recorded from the right upper extremity in a sitting position after the subject had rested for a few minutes SBP was recorded at the second sound and DBP at the point of disappearance of the sounds BP values were read to an accuracy of 2 mm Hg. Relative weight, which is the percentage of the subject's ideal weight (D 6beln, 1959), was determined in order to eliminate the influence of weight on the variations in BP (Chiang et al , 1969) Subjects who used antihypertensive drugs or had chronic urinary infection or who had hearing impairment not attributable to noise damage (estimated by otoscopy, audiograms, and history of diseases and traumas of the ear) were excluded The final sample size was 280 persons (188 male and 92 female workers).
Results Table 1 shows the mean SBP and DBP among men and women in the two age groups in different hearing classes. In the group of young males there seems to be no change in SBP in different hearing classes DBP is slightly higher in hearing class II than in either of the other classes The number of cases in hearing classes II and III is relatively small for further interpretations, however No such comparisons are possible for the younger female group, because all the women but one belong to hearing class I. In the older male group the mean SBP is 12 mm Hg higher in hearing class II than in hearing class I, and 10 mm Hg higher than in hearing class III The same biphasic phenomenon also appears to some extent in the mean DBP of this group. In the female group the mean SBP is as much as 18 mm Hg higher, and the mean DBP 4 mm Hg higher than in hearing class I However, the number of cases in class II METELI was a collaborative project of a multidisciplinary research team carried out in 19711976 The project was financed by the Social Science Research Council of the Academy of Finland and by the Ministry of Education
Noise-Induced Hearing Loss and Blood Pressure Io
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.0 00-ooo U C -C Q + 1 +
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