Biomedical subjects

S M Mirbod

Publications and source records attributed to S M Mirbod.

31 records · Page 2Linked to original sources

PubMed1994

Prevalence of Raynaud's phenomenon in different groups of workers operating hand-held vibrating tools.

In eight groups of subjects operating various hand-held vibrating tools and aged from 30 to 59 years, the prevalence rates of vibration-induced white finger (VWF) and numbness, pain, or stiffness in the upper and lower extremities were investigated. Hand-transmitted vibration levels (HTVLs) were measured on the back of the hand, by means of unidirectional (x-axis) vibration dosimeters, and the frequency-weighted acceleration levels [(Lh,w)eq,t] were determined as the vibration levels. The prevalence rates of VWF and numbness of the hands in these subjects were compared to the prevalence rates of Raynaud's phenomenon (RP) and numbness of the hands in 1027 males and 1301 females not occupationally exposed to vibration (age range: 30-59 years). It was observed that in subjects exposed to HTVLs of between 1.1 and 2.5 m/s2, the prevalence of VWF was between 0.0% and 4.8%. The prevalence of VWF reached 9.6% in a group of workers exposed to HTVLs of 2.7-5.1 m/s2. The latter group showed a significant difference (P < 0.05) in the prevalence of VWF compared to the 2.7% prevalence of RP in male subjects of the general population. The prevalence of VWF in female subjects exposed to vibration (4.3%) was not significantly different from the prevalence of RP in females of the general population (3.4%). The prevalence rates of numbness of the hands were in the range of 6.5%-30.4% in the exposed groups and in the range of 13.4%-29.5% in the general population. Among the subjective symptoms, only VWF showed a significant positive correlation with HTVLs (R2 = 0.5, P < 0.05). It was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be employed. With a view to decreasing the risk of developing VWF, estimated vibration safety values for 4 h and 2 h daily exposures are discussed.

Adult↗

PubMed1994

Noise in aerobic facilities.

Noise levels were evaluated before and during aerobic sessions in 3 aerobic studios. In addition, hearing threshold levels (HTLs) of 10 female aerobic instructors with the mean (+/- SD) ages of 25.4 (+/- 2.4) years were measured before and 2 min after an aerobic session. The mean (+/- SD) of total instruction time of these subjects was 1274.0 (+/- 704.9) h. Before the aerobic session, noise level was 63 dB(A) and increased to 87 dB(A) during a warm-up period. The highest noise levels of 93-96 dB(A) were recorded during a peak exercise period and decreased to 73 dB(A) during a cool-down period. The dominant spectra of sound pressure levels (SPLs) during the aerobic session were in the frequency range of 1-2 kHz at levels of 75-88 dB(C). The mean values of HTL obtained for each ear of these subjects were between 5 and 15 dB in the frequency range of 1-8 kHz. No significant differences in the mean HTLs of pre- and post-aerobic sessions could be obtained. The mean values of HTL of two groups of subjects divided by their total instruction time (n = 5 in each group, and p < 0.01 in their total instruction time) were quite comparable.

Adult↗

PubMed1994

Operating hand-held vibrating tools and prevalence of white fingers.

Hand-transmitted vibration levels (HTVLs) and the prevalence of vibration-induced white finger (VWF) and numbness of the hands were investigated in eight groups of subjects operating various hand-held vibrating tools. The prevalence rates of Raynaud's phenomenon (RP) and numbness of the hands in 1,027 males and 1,301 females not occupationally exposed to vibration were compared to those of the exposed subjects. The prevalence of VWF was in the range of 0.0-4.8% in subjects exposed to HTLVs of between 1.1 to 2.5 m/s2 and reached 9.6% in a group of workers exposed to HTLVs of 2.7-5.1 m/s2. The latter group showed a significant difference (P < 0.05) in the prevalence of VWF compared to the 2.7% prevalence of RP in male subjects of the general population. The prevalence of VWF in female subjects exposed to vibration (4.3%) was not significant compared to the prevalence of RP in females of the general population (3.4%). The prevalence rates of numbness of the hands were between 6.5% and 30.4% in the exposed groups and in the range of 13.4-29.5% in the general population. It was concluded that in decisions concerning quantitative recommendations for vibration exposure, the prevalence of VWF should be employed. To decrease the risk of developing VWF, estimated vibration safety values for 4 h and 2 h daily exposures are discussed.

Adult↗

PubMed1993

Cutaneous signs (Raynaud's phenomenon, sclerodactylia, and edema of the hands) and hand-arm vibration exposure.

Dermatological tests and examinations of the hand(s) were carried out in vibration-exposed and unexposed males. The subjects were 179 chain-saw workers in private forestry companies and 205 local inhabitants who had never used vibrating tools. The prevalences of Raynaud's phenomenon (RP), sclerodactylia, and edema of the hands were estimated in both groups, and associations between these cutaneous signs and vibration exposure were evaluated. The prevalences of RP and edema in the exposed group were 9.5% and 1.7%, respectively, and in the unexposed group, 2.9% and 1.5%, respectively. Sclerodactylia was seen in 31.8% of the chain-saw workers but in only 6.4% of the unexposed individuals. In statistical analyses based on unconditional logistic regression models with adjustment for age, RP was associated with long-term (> or = 20 years) vibration exposure [odds ratio (OR) = 7.06; 95% confidence interval (CI) = 2.51-19.87]. Sclerodactylia was associated with both short- and long-term vibration exposure (OR = 6.54, CI = 3.30-13.36; OR = 7.05; CI = 3.41-14.60, respectively). There were significant dose-response relationships between RP and duration of exposure and between sclerodactylia and duration of exposure. Results of function tests indicated a longer recovery time and a higher vibration threshold for the workers with RP. The presence of sclerodactylia, however, did not have any significant influence on function test results. It is possible to conclude that not only RP but also sclerodactylia could be induced by vibration exposure. However, most cases of sclerodactylia were not so serious as to involve disturbances of peripheral circulatory and nerve function.

Adult↗

PubMed1993

Prevalence of Raynaud's phenomenon and specific clinical signs related to progressive systemic sclerosis in the general population of Japan.

BACKGROUND: In order to evaluate the prevalence rates of Raynaud's phenomenon (RP) and specific clinical signs related to progressive systemic sclerosis (PSS) in the general population of Japan, inquiries were made concerning RP in the hands and dermatologic examinations were also conducted. METHODS: One thousand and sixty-three subjects (332 men and 731 women) over 30 years of age who underwent inhabitants' health examinations in 1990 were considered for this study. RESULTS: The prevalence of RP was 3.0% in men and 3.4% in women. In 8 men and 17 women with RP who received the blood tests, the positive rates of antinuclear antibody (ANA) were 12.5% and 35.3% in men and women, respectively. The prevalence rates of all five specific clinical signs related to PSS, sclerodactyly, pitting scars of the fingers, brown pigmentation of the body, shortened frenulum of the tongue, and flexion contracture of fingers, were under 2% in men and 3% in women. In women with RP the prevalence rates of sclerodactyly, pitting scars of the fingertips, brown pigmentation of the body, and shortened frenulum of the tongue were 16.0, 4.0, 4.0, and 16.0%, respectively. These values were significantly higher than those of persons without RP. CONCLUSIONS: Because some persons with primary RP may become typical cases of PSS within several years, a followup study, particularly for women who have positive titers of ANA with RP, should be carried out to find out whether the persons suffer from PSS or not.

Adult↗

PubMed1993

A survey on noise exposure level in an aluminum can production plant.

The present investigation was designed to quantify noise exposure of laborers at various sections of an aluminum can production plant. The acoustic environment in each area was described by sound pressure level (SPL). Decibel (dB) readings were taken for a range of individual frequencies and weighting scales (A and C). Speech interference level (SIL) values for laborers in different production sections were also determined. Moreover, by means of a personal noise dosimetry technique, the equivalent continuous noise exposure level (dB(A)) during an 8-h shift (Leq, 8) was computed. The results obtained were as follows. Spectral analysis of the noise indicated that high SPL associated with high frequency noise exceeded the permissible limit against hearing damage, and it generally amounted to levels higher than 90 dB(A), whereas those inside the control rooms were in the range of 54-60.5 dB(A). Assessment of the results obtained from personal noise dosimeters also revealed that the Leq,8 values were higher than the prescribed limit (85 dB(A)). By preliminary audiometric examinations on the right ears of workers, hearing threshold shifts (HTS) were noticed in the range of 7-11 dB at 1 kHz and 12-16 dB at 4 kHz. With regards to the SIL values (93.2-96.5 dB(A)) which were more than the maximum vocal effort, communication between workers and/or with supervisor were appraised to be very difficult (shouting) or impossible. It was concluded that (a) the dB readings observed in this survey indicate a potentially serious possibility of hearing disability, even though high level of HTS could not be noticed in the preliminary audiometric test, and (b) the risk of accidents should also be taken into account regarding the nonauditory effects of such a high level of noise. We suggest that (1) minimizing the transmission of noise through acoustical countermeasures need to be considered, and (2) introducing a schedule comprising on-time and off-time could be beneficial in a workers' health conservation program.

Aluminum↗

PubMed1993

Exposure to segmental vibration and noise in orthopaedists.

The results of several field visits to orthopaedic clinics and the data obtained from a postal questionnaire were used to evaluate the segmental vibration and noise exposure levels in orthopaedists. The analysis of 54 (85.7%) complete questionnaires showed that hand-held plaster saws were used (Mean +/- SE, 12.3 +/- 1.7 min/week) more often than other tools. The mean frequency-weighted acceleration levels while using these tools were in the range of 2.3-2.4 m/s2. The A-weighted sound pressure levels in orthopaedic clinics while using the same instruments were in the range of 88.7-93.4 dB(A). Regarding the vibration magnitude and exposure time, segmental vibration seems not to be a serious problem in orthopaedists. However, the noise level produced from operating orthopaedic tools may have deleterious effects such as masking of speech communication among staff members. Patients' sleep or rest was thought to be disturbed by such noise levels.

Adult↗

PubMed1992

Hand-arm vibration syndrome and its prevalence in the present status of private forestry enterprises in Japan.

Currently there are no limitations on age of employment on private forestries in Japan. Hence, it was hypothesized that in these kind of enterprises, elderly chain saw operators, or those with long-term exposure, might be at higher risk of developing hand-arm vibration syndrome (HAVS). We consequently investigated the prevalence of HAVS in 447 chain saw workers on private forestries in Gifu Prefecture, Japan, with particular reference to age and exposure period. Of this population, 43 (9.6%) had signs and symptoms of vibration-induced white finger (VWF), and among these workers the severity of finger blanching was significantly correlated (P less than 0.01) with the exposure period. Classification of all subjects by exposure period showed that workers with greater than or equal to 30 years' exposure had higher prevalences of VWF (20.9%) and numbness of the hands (25.4%) compared to other groups. Significant differences (P less than 0.01) were found between the functional capacities of workers with VWF and those of control subjects. We concluded that (a) the elderly chain saw operators and those with longer exposure should be moved to other jobs with a lower or no risk of exposure to vibration, and (b) the results of screening tests, even without cold water immersion (which we did not employ, in order to protect workers' hands), could be helpful for the identification of workers with VWF.

Forestry↗

PubMed1992

[Health condition of female aerobic dance instructors. Subjective symptoms and related factors].

Aerobic dance has recently become popular in all age groups, but the injuries among full-time and part-time aerobic dance instructors have rarely been pointed out in Japan. In this study the subjective symptoms of 63 female instructors in Gifu area were evaluated through health questionnaire. As a control group, 94 female students of the same age group were also included to compare the prevalence of subjective symptoms. Multiple logistic regression analysis was applied to observe the relation between instructors' symptoms and working conditions. The following results were obtained: 1) Complaints of leg and foot pain and laryngeal discomfort were significantly greater in instructors than in students even after adjusting for age and participation in other sports. 2) A significant positive relation was found in instructors between the frequency of dance lessons (times/wk) and various symptoms (calf pain, foot pain, sore throat, and hoarse voice) after adjusting for age and participation in other sports. These results suggest that leg and foot pain and laryngeal discomfort are characteristic symptoms of aerobic dance instructors. Consideration should be made to adjust the frequency of dance lessons in order to reduce these symptoms.

Adolescent↗

PubMed1992

A study on the vibration-dose limit for Japanese workers exposed to hand-arm vibration.

To obtain a vibration-dose limit for Japanese workers exposed to hand-arm vibration, the prevalences of vibration-induced white finger (VWF) and numbness of the hand were studied in 5 different groups of workers exposed to segmental vibration. In addition, the prevalence of primary Raynaud's phenomenon (PRP) in the general population without occupational vibration exposure was computed. The vibration levels in the exposed groups (except chain saw operators) ranged from 124.1-129.2 dB (reference value, 10(-6) m/s2). The prevalence of VWF in these groups was 2.2-4.8%. This value was not statistically significant (p greater than 0.05) when compared to the prevalence of PRP in the general Japanese population (2.7-2.9% in our study and 0.5-4.6% in other surveys in Japan). Although the prevalence of numbness of the hands fluctuated among the groups, no significant differences could be demonstrated. Our results were then compared to those of previous reports by literature study [319 papers on hand-arm vibration syndrome (HAVS) and 25 reports on PRP]. At a glance the Japanese population showed a lower prevalence for PRP compared to other countries, which suggested that exposure to cold and biological abilities should also be considered to assess vibration syndrome. A comparison of the vibration characteristics of different tools and the occurrence of VWF in the hands of workers in the literature with those of our data suggested that a daily hand-arm vibration exposure at a level lower than 2.5 m/s2 (128 dB, reference value 10(-6) m/s2) could possibly decrease the risk of VWF among workers exposed to segmental vibration.

Adult↗

PubMed1992

Noise exposure level while operating electronic arcade games as a leisure time activity.

In order to study noise levels associated with electronic arcade games, noise measurements were made in 3 selected game centers and 192 samples were taken in each location. The background noise was recorded at a level of 61 dB(A) and 64 dB(C). When the electronic games were performed these levels of noise reached to 88 approximately 90 dB(A). The 1/3 octave bands analyzing sound pressure levels showed that more intense noise levels arose in a frequency range between 0.5 and 2.0 kHz. The computed values for noise pollution levels (LNP) and L90 (fast response A-weighted sound level exceeded 90% of the measurement time) ranged from 93.3 to 96.6 and from 85.1 to 87.3 dB(A), respectively. Concerning our results and according to Melnic (1979), it was estimated that these levels of noise might cause 4-8 dB temporary threshold shift (TTS) at 4.0 kHz in an individual with less than one hour of exposure to such a level of noise. As for the employees of the 3 game centers, the 8-hr equivalent continuous sound levels (Leq,8) were in the range of 80.3 approximately 87.5 dB(A), although their exposure time could not be exactly determined. It was suggested that: 1) The maximum levels should be limited to a reasonable level, either by the manufacturers or by the game center owners; 2) Education programs in industry should inform the employees about other factors outside the work that may affect their hearing; and 3) For policy-making on hearing conservation, recreational warning and standards should be established.

Auditory Threshold↗

PubMed1992

[Differences in the prevalences of Raynaud's phenomenon in general populations living in a mountain area and in a plain area].

Raynaud's phenomenon (RP) which is the episodic and reversible vascular spasm of the extremities can be elicited by cold or emotional changes. RP has been classified into two groups. One is primary Raynaud's phenomenon (PRP) with no identifiable underlying disease and/or cause, and the other is the secondary form of RP (Raynaud's syndrome) with underlying disease and/or cause, e.g., collagen disease, trauma, vibration from vibrating tools, etc. In the present study using this definition of RP the prevalences of RP were studied in general populations in a mountain village "T" and in a town "K" located in a plain area in Gifu prefecture, Japan. The prevalences of RP in T Village were 8.0% (25/314) in males and 3.5% (16/454) in females, and in K Town 2.7% (7/259) in males and 3.2% (21/657) in females. In 52% of the male cases in T Village it was estimated that the exposure to vibration from vibrating tools was the cause of RP. In K Town no male cases of RP were induced by vibration. Exposure to vibration may be one of the important factors when prevalences of RP are investigated in various areas. There were no significant differences between the two areas in the prevalences of PRP (T Village: male 2.9%, female 3.1%; K Town: male 2.7%, female 2.9%). The annual mean air temperature was usually 5-6 degrees C lower in T Village than that in K Town. From the results of this study the differences in the mean air temperature did not appear to have a significant influence on the prevalence of PRP in each area.

Adult↗

PubMed1991

[Analysis of subjective symptoms of upper extremities in dental technicians].

Our review of the literature showed no report on the subjective symptoms of the upper extremities in dental technicians. This study was therefore undertaken on 164 dental technicians in Gifu Prefecture to investigate the relationship between the subjective symptoms of the hands, arms and shoulders and work of dental technicians. The following results were obtained. 1) The prevalence of Raynaud's phenomenon and numbness of the fingers was 5.5 and 18.5 %, respectively. A significant positive correlation was observed between the prevalence and frequency of numbness and cold sensation in the fingers and the daily usage time (h) of high-speed type machines. In addition, pain in the fingers and around the wrists, and pain and numbness in the arms were significantly related to the daily usage time (h) of low-speed type machines. These results suggest that the usage of high- and low-speed type machines may be a cause of vibration syndrome among dental technicians. 2) A high prevalence of pain in the shoulders (30.8%), neck (30.1%), and back (36.3%) was observed in dental technicians. It is considered that these symptoms are related to the working posture and usage of machines.

Adult↗