Acoustical role of ear canal in exposure to the typical occupational noise levels.

Background: Exposure to noise associated with injuries has become a public health issue in recent years. This study aimed to show the role of the acoustical structure of the ear canal on the typical occupational sound pressure levels at different frequencies. Methods: This cross-sectional study was done on 20-30-year-old participants. White noise was used at 3 levels, including 75, 85, and 95 dB as the stimulus sound pressure levels (SSPLs). The speakers had a 1.5-meter distance from the participants and at the height of 87 centimeters from the lab ground and were located in front of the participants. The SSPLs were measured outside (cavum part of the external ear) and inside the right ear of each participant. Measurements were done at the total sound pressure level and in the 1/1 octave frequencies. The duration for each measurement was 10 seconds. The independent sample t test was used for the statistical analysis, and the equality of means were rejected at p<0.05. Results: There were 30 (50%) males out of the 60 participants. The mean ± SD for the age of all the participants was 23.29±2.93 years. The total sound pressure level difference between the inside and outside of the ears of male and female participants was statistically significant (p<0.001) at the stimulus sound pressure levels. The peak resonance was observed in the frequencies 2000 Hz and 8000 Hz for males and 8000 Hz for females. Conclusion: The ear canal can amplify the sounds and increase the sound pressure levels. This amplification was found to be greater for males than for females.

Prevalence hearing loss of truck and bus drivers in a cross-sectional study of 65533 subjects.

BACKGROUND: Noise pollution is one of the most important occupational pollutants in heavy-vehicle drivers. Therefore, this epidemiological research was conducted with the aim of determining the prevalence of hearing loss in heavy-vehicle drivers in Iran. METHODS: This cross-sectional research was conducted on 65,533 heavy-vehicle drivers including truck and intercity bus drivers from February 2006 to March 2016. The air and bone threshold of pure tone was measured for each ear at 0.5, 1, 2, 3, 4, 6, and 8 kHz by a skillful radiology expert. The obtained data from this research was analyzed in SPSS software using statistical tests such as descriptive analysis and paired t test. RESULTS: Mean (standard deviation) of hearing loss in left and right ears of all people was 23.02 (8.25) and 22.48 (7.86), respectively. Paired t test showed that hearing loss difference in left and right ears was significant (P < 0.001). Mean and standard deviation of paired t test showed that hearing loss difference in left and right ears was significant in all frequencies except 1000 Hz (P < 0.001). CONCLUSION: The findings of this research generally showed that 26.8% of the studied drivers have hearing loss. Hearing loss in the left ear was more than right ear.

The Effect of Low Frequency Noises Exposure on the Precision of Human at the Mathematical Tasks.

Background: Low-frequency noise is produced from different sources in the working environments such as pumps. Thus, the aim of this study was to investigate the effect of low-frequency noise on precision and focusing of the studied subjects. Methods: This cross-sectional-interventional study was performed on 13 students of Isfahan University of Medical Sciences. The precision of individual subjects was evaluated using the mental arithmetic test. The sound sources with frequencies of 125, 250, and 1000 Hz at 75, 85, and 95 dB sound pressure levels. Also, the rate of precision was measured before the exposure (time "zero"), and at 45 and 90 min. SPSS (Ver. 26) software was used to analyze the data. Results: Comparison of the precision scores of the individuals between the frequencies of 125 and 250 Hz at the sound pressure level of 75 dB and at 45 min (P = 0.032). And 90 min (P = 0.006). And also, the frequencies of 250 Hz and 1000 Hz at the time of 45 min. At the sound pressure levels of 85 dB (P = 0.019). And 95 dB (P = 0.043) and at the time of 90 min. At the sound pressure levels of 85 dB (0.027). And 95 dB (P = 0.009) demonstrated a significant difference. Conclusions: We concluded that low frequency noises could reduce the person's precision. While for 125 Hz noises, just increasing of the exposure time was effective on the precision reduction. But for 250 Hz noises, both parameters increasing including exposure time and sound pressure levels, was effective.

The Efficiency of Hearing Protective Devices against Occupational Low Frequency Noise in Comparison to the New Subjective Suggested Method.

Backround: Noise is one of the most important occupational and environmental health hazards. Exposure to loud noise can cause irrevocable hearing damage and loss of hearing. The aim of this study was to determine the efficiency of two samples of earmuff and earplug in low frequency noise reduction in comparison to subjective method. Methods: All the procedures of the work were done using the simulated human ear canal and the required microphone in the eardrum. At the octave frequencies, that is 31.5 and 63.5, 125, 250, 500, 1000, 2000, 4000, and 8000 Hz, and intensities of 85-90 dB, one stage was done by using the individual's subjective response relative to the received sound before and after using the ear protector. Results: The sound levels before and after the protection were significantly different in both the model and humans (P < 0.05). However, at 315 Hz frequency, the rate of attenuation is increased by 4 dB after placing the earplug and 14 dB after placing the earmuff, showing a reduction of 18 dB. Conclusions: This study verifies the increasing protection by simultaneous application of earplugs and earmuffs. Because of the laboratory evaluation of ear protectors, it is possible not to justify the proficiency of ear protectors in a subjective method.

An Evaluation of the Relationship between Mental Disorders and Driving Accidents among Truck Drivers.

INTRODUCTION: A review of the existing literature shows the importance of mental health in preventing traffic accidents. Therefore, the current study aims to determine the mentioned mental disorders in relation with the history of accidents among truck drivers. METHODS: This cross-sectional study was done with two groups of truck drivers (with and without a history of accidents) in Iran. 56 people with a history of accidents and 410 people without a history of accidents participated in this study. At first, using questionnaires, the demographic information of the participants including age, education level, cigarette use, and addiction to drug was collected. Then, the mental disorders of the participants were evaluated by a 71-question, short form of the multidimensional Minnesota Multiphasic Personality Inventory (MMPI). The evaluated disorders are the HS or hypochondria, D or depression, HY or hysteria, Pd or social mental deviation, Pa or paranoia, Pt or mental weakness, Sc or schizophrenia, and Ma or hypomania. The tests used for data analysis include descriptive tests and Chi square. RESULTS: Man-Whitney U test showed that status of mental disorders, as revealed by the MMPI questionnaire, had a significant difference between the two groups with and without history of driving accidents (P < 0.001). The results showed that mental disorders of depression, hysteria, social mental deviation, paranoia, schizophrenia, and hypomania in individuals with history of driving accidents led to meaningful differences from individuals without history of driving accidents (P < 0.048). CONCLUSION: The results of the current study showed that generally, individuals with history of driving accidents had significantly more mental disorders than people without history of driving accidents.

Overweight, underweight, and obesity among male long-distance professional drivers in Iran.

OBJECTIVE: Long-distance professional drivers, as an occupational group, are hypothesized to have a higher risk of overweight and obesity. The aim of this study was to estimate the prevalence and risk factors of overweight, underweight, and obesity in long-distance professional drivers. METHODS: A cross-sectional study was conducted on 36 625 male long-distance professional drivers age ≥20 years, from April 2013 to Sept. 2016. Drivers were interviewed and underwent clinical and laboratory examinations including measures of blood pressure (BP), blood tests, anthropometric data, and visual and hearing acuity. The mean (standard deviation [SD]) age of participants was 41.9 (10.2) years with a mean (SD) duration of a professional driving of 15.3 (9.6) years and mean (SD) body mass index (BMI) was 25.7 (4.0) kg/m2 . RESULTS: The prevalence of overweight and obesity was 39.1% (95% confidence interval (CI) 38.6, 39.6) and 10.8% (95% CI 10.5, 11.1), respectively. A total percentage of 2.7 (95% CI 2.5, 2.9) were underweight. A total percentage of 10.6 had BMI 30-40 kg/m2 and 0.2% had BMI ≥40 kg/m2 . Using a stepwise binary logistic regression model for overweight, underweight, and obesity, age had a significant independent relationship with underweight, overweight, and obesity. Duration of work, BP, fasting plasma glucose, triglyceride, and cholesterol had significant independent positive association and smoking had a negative association with overweight/obesity when other covariates were considered. CONCLUSIONS: These findings indicate that overweight and obesity are prevalent among long-distance professional drivers in Iran and appears to be similar to the general population.

Evaluation of the effect of fatigue on the coping behavior of international truck drivers.

BACKGROUND: Fatigue can affect the behavior of drivers. While the driver must be able to respond and cope appropriately to the critical situations, which is known as the ability to cope with a crisis. It is likely that the fatigue can change the people's coping style and thereby increase the chance of the crashes. Therefore, the present study aimed to investigate the effects of fatigue on the coping behavior of international truck drivers. METHODS: This study was conducted on 239 of international truck drivers employed in Iran. The Endler and Parker coping strategies questionnaire (CISS) and Persian version of the Fatigue Multidimensional Fatigue Inventory (MFI) were used to evaluate the coping styles of the drivers and the drivers' fatigue, respectively. RESULTS: The mean values of the total fatigue before and after traveling were 36.77 and 76.13, respectively. The mean values of coping styles of the problem-oriented, emotion-oriented, and avoidance before traveling were 53.66, 40.91, and 38.17, respectively, and those after traveling were 45.59, 51.18, and 36.45, respectively. The chi-square test demonstrated that there was a significant difference in the coping style of drivers before and after the trip (P <  0.001), and the percent of individuals with emotion-oriented increased. CONCLUSIONS: In general, the results showed that fatigue due to traveling could change the coping styles of subjects from problem-oriented to emotion-oriented and avoidance. This can increase the statistics of driving accidents.

The prevalence and correlates of hearing loss in drivers in isfahan, iran.

BACKGROUND: There are no data on the prevalence of occupational noise-induced hearing loss in drivers using standard audiometric testing. The aim of this study was to estimate the prevalence and risk factors of occupational noise-induced hearing loss in drivers. METHODS: A cross-sectional study was conducted on a random sample of 4300 long-distance drivers age > or =20 years taken out of a total of 10,000 estimated professionals in the city of Isfahan, Iran, from February 2006 through March 2007. The drivers were interviewed and underwent clinical and laboratory examinations including measurement of blood pressure, anthropometric data, and pure-tone audiometry in a sound-treated booths. The mean (SD) age of the participants was 40.8 (11.0) years with a mean (SD) duration of professional driving of 14.7 (9.6) years. RESULTS: The prevalence of bilateral noise-induced hearing loss was 18.1% [95% confidence interval (CI) 17.0~19.3]. The prevalence rates were higher in the left ear only 6.5% (95% CI: 5.8~7.3) than the right ear only 3.0 percent; (95% CI: 2.5~3.9). Using a stepwise binary logistic regression model for the right and left ear only and for both ears separately, age was a significant independent predictor of bilateral noise-induced hearing loss and for the left or right ear only. When bilateral noise-induced hearing loss was entered in the model, fasting blood glucose was a significant predictor of noise-induced hearing loss. Blood pressure, cholesterol, triglyceride, body mass index, and marital status had no significant independent association with noise-induced hearing loss when other covariates were considered. CONCLUSION: These findings indicate that noise-induced hearing loss among the long-distance drivers appears to be similar to the world's population endures noise-induced hearing loss caused by occupational exposure to noise, with higher prevalence in the left ear only.

Using the Blood Coagulation Factors as a Predictor Component of the Occupational Vibration Exposure.

BACKGROUND: Exposure to hand-arm vibrations higher than permissible standard rates can have destructing effects on workers' health. Pneumatic hammers are among the tools that are used in civil and industrial projects, transferring high vibration acceleration to the workers. This study has considered the probable effects of hand-arm vibrations on the performance of blood coagulation factors in the workers using this tool and exposed to high vibration acceleration. METHODS: Five new workers without any experience in exposure with hand-arm vibrations were selected for this interventional study. Blood sample was taken from each worker before they started working for the required analysis. Sampling was repeated in two other stages in 2-month intervals from the first sampling, whereas the workers were then experienced in working with pneumatic hammers. Measuring the vibration of the pneumatic hammer was done according to ISO 28927-10 standard. RESULTS: The point of measuring the vibration acceleration was selected close to the hand, in accordance with the standard. Regarding the exposure time of the workers, the amount of vibration acceleration was obtained 15.54 m/s2. Activated partial thromboplastin times of four samples in the second and third stages have shown increases in comparison to the first stage in that respect. On the other hand, a number of red blood cells, white blood cells, and platelets did not show a consistent trend in the three stages. CONCLUSIONS: The considered samples showed longer time for blood coagulation as compared to the reference time. Thus, it can be concluded that the main reason is the acceleration in three different coordinate axes of x, y, and z. Hence, the values beyond permissible standard rate of hand-arm vibration in 8 h shifts affect the blood parameters, among which the considered coagulation parameters in this study showed more tangible changes in that respect.

Mobile Phone Distance from Head and Temperature Changes of Radio Frequency Waves on Brain Tissue.

BACKGROUND: Analyzing the possible negative effects of using cell phones on the users' health is an important and vital affair due to rapid growth and extensive use of these devices on human communications and interactions. The aim of this study was to determine the effect of increasing the distance of cell phones to brain tissue on the temperature of the central and gray matters of brain due to the heat generated by radio frequency waves. METHODS: This study was an experimental study. A cow's brain tissue was analyzed in a compartment with three thicknesses of 2, 12, and 22 mm, in the distances of 4 mm and 4 cm from a cell phone for 15 min. Lutron thermometer was used to measure the tissue temperature, and the data analysis were done by Lutron and MATLAB software packages. RESULTS: The tissue temperature was increased while confronting with a cell phone in distances of 4 mm and 4 cm in all the three thicknesses of 2, 12, and 22 mm. The tissue temperature was higher after removing the confrontation at 4 mm distance as compared to the distance of 4 cm. CONCLUSIONS: During confrontation and after that with the cell phone, reducing the distance of brain tissue and the cell phone increased the tissue temperature intensely. In fact, by increasing the cell phone distance from brain tissue, the thermal effect of radiofrequency waves was reduced.

Evaluating Temperature Changes of Brain Tissue Due to Induced Heating of Cell Phone Waves.

BACKGROUND: Worries have recently been increased in the absorption of radiofrequency waves and their destructing effects on human health by increasing use of cell phones (mobile phones). This study performed to determine the thermal changes due to mobile phone radio frequency waves in gray and white brain tissue. METHODS: This study is an empirical study, where the thermal changes of electromagnetic waves resulted from cell phones (900 MHZ, specific absorption rate for head 1.18 w/kg) on the 15 brain tissue of a cow were analyzed in a compartment with three different thickness of 2 mm, 12 mm, and 22 mm, for 15 min. The Lutron thermometer (model: MT-917) with 0.01°C precision was used for measuring the tissue temperature. For each thickness was measured three times. Data analysis is done by Lutron and MATLAB software packages. RESULTS: In confronting of the tissue with the cell phone, the temperature was increased by 0.53°C in the 2 mm thickness that is the gray matter of the brain, increased by 0.99°C in the 12 mm thickness, and also increased by 0.92°C in the 22 mm thickness. Brain temperature showed higher rates than the base temperature after 15 min of confrontation with cell phone waves in all the three thicknesses. CONCLUSIONS: Cell phone radiated radio frequency waves were effective on increasing brain tissue temperature, and this temperature increase has cumulative effect on the tissue, being higher, for some time after the confrontation than the time with no confrontation.

Hand-arm Vibration Effects on Performance, Tactile Acuity, and Temperature of Hand.

Effects of vibration appear as mechanical and psychological disorders, including stress reactions, cognitive and movement disorders, problem in concentration and paying attention to the assigned duties. The common signs and symptoms of hand-arm vibration (HAV) in the fingers and hands may appear as pins and needles feeling, tingling, numbness, and also the loss of finger sensation and dexterity. Laboratory Virtual Instrument Engineering Workbench programming software designed for occupational vibrations measurement was used to calculate HAV acceleration. Hole steadiness test is designed to measure involuntary movement of people. V-Pieron test is designed for one of the other aspects of the psycho motor phenomena of steadiness by moving the stylus across a V-form ruler. The two points test was an experiment of touch acuity, which used a caliper by placing the two styli very close on the pad of finger knuckles. The temperature of finger skin is also measured simultaneous to the above tests. Wilcoxon test indicated that a significant decrement in hand steadiness occurred after gripping a vibrating handle for 2 min (P ≤ 0.003). Wilcoxon test also represented a significant change in errors after gripping a grinder vibratory handle (P ≤ 0.003). The differences at all of the knuckles were significant with a confidence interval percentage of 99%. There was a significant reduction in finger skin temperature before and after exposure to vibration (mean = 0.45°C, based on paired sample test). The obtained results considerably demonstrated the relation between hand performance and vibrations due to gripping a grinder. It can be concluded that an injury or accident may happen after exposure to vibrations for the fine duties, in fast actions.

The Relationship between Trait Anxiety and Driving Behavior with Regard to Self-reported Iranian Accident Involving Drivers.

BACKGROUND: THE AIMS OF THIS STUDY INCLUDED: Determination of the most common driver behavior in drivers and also analyzing the relationship between trait anxiety (TA) with subscale of driving behavior (lapses, errors, ordinary and aggressive violations). METHODS: This cross-sectional study was conducted on 168 drivers that having crash. The self-reporting of the drivers was determined by using Manchester driving behavior questionnaire (DBQ) and Spielberger State-Trait Anxiety Inventory. RESULTS: Independent t-test showed that violations factor (ordinary and aggressive) are the most common behavior in drivers, Pearson correlation revealed that TA had a significant direct positive relation with all DBQ subscales especially error and lapses factor (P < 0.01) also Pearson correlation showed that age had a negative significant relation with factors of DBQ. CONCLUSIONS: It can be concluded from the results (according to the relation between TA with error and lapses factor) that the rate of TA is destructive effective on the memory performance and process in the drivers and cause absent minded and memory imperfect function and process in these people during the driving.

Association between the high risk occupations and bladder cancer in Iran: a case-control study.

OBJECTIVES: The objective of this work was to identify the high-risk occupations in Iran and to re-inspect occupations that were related to bladder cancer. MATERIALS AND METHODS: In the study, 300 patients suffering from bladder cancer and 500 control individuals were interviewed. Demographic information, occupational history, and history of exposure to chemical compounds such as aromatic amines for each participant were collected. ORs and 95% CIs were calculated using unconditional logistic regression for each occupation. RESULTS: There was a significantly increased risk of bladder cancer among truck and bus drivers (OR = 11.3), skilled agricultural, forestry and fishery workers (OR = 6.0), metal industry workers (OR = 6.0), domestic housekeepers (OR = 5.9), and construction workers (OR = 3.8). CONCLUSIONS: The study showed a strong correlation between truck and bus drivers, skilled agricultural, forestry and fishery workers, metal industry workers, domestic housekeepers, as well as construction workers and the increased risk of bladder cancer in these occupations.

Evaluation of Work-related Psychosocial and Ergonomics Factors in Relation to Low Back Discomfort in Emergency Unit Nurses.

BACKGROUND AND AIM: High prevalence of low back pain is one of the most common problems among nurses. The aim of this study was to evaluate the relation of the intensity of low back discomfort to two low back pain contributor factors (Ergonomics risk factors and psychosocial factors). METHODS: This cross-sectional survey was conducted on 120 emergency unit nurses in Esfahan. Job content, ergonomics hazards and nordic questionnaire were used in that order for daily assessment of Psychosocial and Ergonomics factors and the intensity of low back discomfort. Nurses were questioned during a 5-week period, at the end of each shift work. The final results were analyzed with SPSS software18/PASW by using Spearman, Mann-Whitney and Kolmogorov-Smirnove test. RESULTS: There was a significant relationship between work demand, job content, social support and intensity of low back discomfort (P value <0.05). But, there was not any link between intensity of low back discomfort and job control. Also, there was significant relationship between intensity of low back discomfort and ergonomics risk factors. CONCLUSION: This study showed an indirect relationship between the intensity of low back discomfort and social support. This study also confirmed a direct relationship between the intensity of low back discomfort and work demand, job content, ergonomics factors (Awkward Postures (rotating and bending), manual patient handling and repetitiveness, standing continuously more than 30 min). So, to decrease work related low back discomfort, psychosocial factors should be attended in addition to ergonomics factors.