Noise-induced Hearing Loss: Continuous versus Impact/impulse Noise

Background

Impact/impulse and continuous noise are two main causes of noise-induced hearing loss (NIHL) in workplaces. The aim of this study was to compare the effects of impulse/impact noise and continuous noise on hearing status.

Methods

In this study, 259 workers referred to the occupational medicine clinic of Shahid Rahnemoun hospital, Yazd, Iran, entered the study and were divided into two groups: with exposure to impact/impulse noise and with exposure to continuous noise. Hearing thresholds were measured and compared between the two groups by pure-tone audiometry (PTA). The frequency of hearing loss and audiometric notch according to the results of PTA was compared between the two groups. Data were analyzed by SPSS (ver. 16) using Student's t-test, Chi-square test, and Mann-Whitney U test.

Results

Hearing thresholds were significantly higher at all frequencies in the impact noise group. The hearing threshold at 6000 Hz was higher than other frequencies in both groups. The frequency of hearing loss at high frequencies was higher in the impact group. The frequency of audiometric notch was not significantly different between the two groups.

Conclusions

The results of this study showed that hearing loss after exposure to impact/impulse noise is probably more frequent and more severe than exposure to continuous noise, but the pattern of hearing loss is similar in both types of noise exposure.

The Effect of Water-Pipe and Cigarette Smoking on Exhaled Nitric Oxide

CONTEXT

Fractional exhaled nitric oxide can be used as a biomarker of some respiratory diseases.

AIMS

This study was conducted to compare exhaled nitric oxide in cigarette and water-pipe smokers with nonsmokers.

METHODS

This cross-sectional study was conducted on 549 adult subjects as a sub-study of Shahedieh cohort in Yazd. Participants were divided into 5 groups according to their smoking habits: non-smokers (n = 202), cigarette smokers (n = 121), water-pipe smokers (n = 129), cigarette ex-smokers (n = 58), water-pipe and cigarette smokers (n = 39). The smokers were also categorized into heavy and light smokers. Fractional exhaled nitric oxide was compared between the groups.

STATISTICAL ANALYSIS USED

The data were analyzed by SPSS (ver. 20) using Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests.

RESULTS

Fractional exhaled NO was lower in all smokers than nonsmokers, but cigarette smokers showed the least level of NO than other groups. Fractional exhaled NO was not significantly lower in water-pipe smokers than nonsmokers.

CONCLUSIONS

Cigarette smoking significantly affect fractional exhaled NO, but water-pipe smoking did not significantly affect exhaled NO level.

Twenty Years' Follow-up of a Family with Marfan Syndrome: A Case Series

Marfan syndrome is a rare connective tissue disorder manifesting with cardiovascular pathologies which are also the leading cause of death. Herein, we present the past 20 years follow up of a family with 17 members afflicted with Marfan syndrome. 3 members of the family were deceased and none were due to cardiovascular events. We assume to some extent traumas are a neglected cause for a part of mortality in Marfan syndrome.

A review of covid-19 disesse and Occupational Considerations

Introduction: Due to the prevalence of Covid-19 disease in the country, there is a possibility of infecting employees who provide services in different work environments. Our purpose in writing this review article is to assess and analyze studies on the nature of the disease, its causative agent, occupations at risk, and the prevention and control of Covid-19 in the workplace. Materials and Methods: In this study, intending to investigate high-risk occupations and prevent and control Covid-19 disease in the workplace, Google Scholar, PubMed, Scopus databases from 2019 to 2020, and CDC, ACOEM, OSHA, CCHOS, WHO guidelines were assessed by thematic search method. Twenty-four articles and 12 instructions were selected and used in writing this article. Results: Studies have shown that many occupations, including healthcare staff, public transport staff, customs and airport staff, waste collection and disposal workers, and bathhouse staff, are at risk for this disease. Conclusion: To take effective action to control this emerging disease in the workplace and maintain the health of workers and the continuation of economic activities, first we must better understand this disease and its causative agent, and all components of society must have sufficient information about the nature of the disease, ways of transmitting the virus, and ways to prevent and control Covid-19 disease, this can be effective in reducing lost workdays, absenteeism and preventing the spread of the virus in the community.

Effect of myricetin on the gene expressions of NOX3, TGF-β1, prestin, and HSP-70 and anti-oxidant activity in the cochlea of noise-exposed rats

Objective(s):

Noise-induced hearing loss is one of the most common occupational diseases in industrialized countries and can be affected by various environmental and genetic factors. This study was designed to examine the effect of myricetin in preventing this disorder.

Materials and Methods:

Twenty-one Wistar rats were randomly divided into five groups: Non-exposed, noise exposure only, noise exposure with vehicle, noise exposure with myricetin 5 mg/Kg, and noise exposure with myricetin 10 mg/kg. All animals were sacrificed after last noise exposure. The left cochlea was dissected from each rat. It was used for mRNA expression analysis (NOX3, TGF-β1, prestin, and HSP-70). Blood samples were collected to assess superoxide dismutase (SOD) activity, 1, 1 diphenyl picrylhydrazyl (DPPH), and malondialdehyde (MDA) measurements.

Results:

Real time-PCR assay revealed that noise decreased NOX3 and increased TGF-β1, prestin, and HSP-70 gene expressions. Administration of myricetin at the dose of 5 mg/kg, but not at 10 mg/kg, significantly reversed these changes. Noise also increased MDA levels and decreased SOD and DPPH scavenging activities. Myricetin at the doses of 5 and 10 mg/kg also reversed these changes.

Conclusion:

The findings of this study showed that myricetin at the dose of 5 mg/Kg was able to reverse noise-induced abnormalities in gene expression and oxidant/anti-oxidant balance. It is a possibility that myricetin via enhancement of anti-oxidant activity induced these effects.

Effect of Myricetin on the Prevention of Noise-Induced Hearing Loss-An Animal Model

INTRODUCTION

Exposure to hazardous noise induces one of the forms of acquired and preventable hearing loss that is noise-induced hearing loss (NIHL). Considering oxidative stress as the main mechanism of NIHL, it is possible that myricetin can protect NIHL by its antioxidant effect. Therefore, the present study aimed to investigate the preventive effect of myricetin on NIHL.

MATERIALS AND METHODS

A total of 21 Wistar rats were randomly divided into five groups, namely (1) noise exposure only as control group, (2) noise exposure with the vehicle of myricetin as solvent group, (3) noise exposure with myricetin 5 mg/kg as myricetin 5 mg group, (4) noise exposure with myricetin 10 mg/kg as myricetin 10 mg group, (5) and non-exposed as sham group. The hearing status of each animal was assessed by Distortion Product Otoacoustic Emissions.

RESULTS

The levels of response amplitude decreased after the exposure to noise in all groups and returned to a higher level after 14 days of noise abstinence at most frequencies; however, the difference was not significant in the myricetin-receiving or control groups.

CONCLUSION

The results of this study showed that two doses of myricetin (5 and 10 mg/kg) administered intraperitoneally could not significantly decrease transient or permanent threshold shifts in rats exposed to loud noise.

Shift Work Effects and Pregnancy Outcome: A Historical Cohort Study

Objective: Employed mothers face considerable amount of hazards. Especially shift work can impact pregnant women by affecting some hormones. This study was conducted to assess the adverse effects of shift work on pregnancy outcomes. Materials and methods: This historical cohort study was conducted in 2017 in order to assess the effect of shift work on pregnancy outcomes. The subjects were consecutively selected from pregnant women, which referred to Al Zahra and Shahid Beheshti hospitals, Isfahan, Iran for their pregnancy care. The effect of shift work on pregnancy and labor complications (low birth weight, small for gestational age, pre-eclampsia and eclampsia, intra-uterine growth retardation, spontaneous abortion, preterm delivery, excessive bleeding during labor, and type of labor) was assessed. The effect was adjusted for occupation and number of children as well. Data were analyzed by SPSS (ver. 17) usingT-test, chi-Square test and logistic regression analysis. Results: Totally, 429 pregnant women entered the study. There was not a statistically significant difference between morning and shift workers regarding age. It was found that shift work probably increases the incidence of small for gestational age, pre-eclampsia and eclampsia, intra-uterine growth retardation, spontaneous abortion, and preterm delivery, but after adjustment for job and number of children the effect was observed only on preterm delivery. Conclusion: Working in a rapid cycling schedule of shift work may cause an increase in the incidence of preterm delivery in pregnant mothers.

Anthropometry of Iranian Guidance School Students with Different Ethnicities: A Comparative Study

Objective. We measured some anthropometric dimensions of Iranian guidance school students selected from different ethnicities. Background. Anthropometric dimensions are used for design of equipment, furniture, and clothing. Furniture with inappropriate design not fulfilling the users' anthropometric dimensions may have a negative effect on health. Method. A total of 7400 Iranian guidance school students aged 12-14 years entered the study and their static anthropometric dimensions were measured. Descriptive statistics such as mean, standard deviation, and key percentiles were calculated. All dimensions were compared among different ethnicities and different genders. Results. This study showed significant differences in a set of 22 anthropometric dimensions regarding gender, age, and ethnicity. Conclusion. According to the results of this study, difference between genders and among different ethnicities should be taken into account by designers and manufacturers of guidance school furniture. Application. This study has prepared a data bank of anthropometric dimensions of 12-14-year-old students which can be used as basic information to find appropriate dimensions of school furniture.

Simultaneous effects of noise exposure and smoking on OAEs

Noise is one of the most pervasive hazardous factors in the workplace. Noise-induced hearing loss (NIHL) is the most common disorder related to noise exposure. Smoking is probably associated with hearing loss. The simultaneous effect of noise and smoking on hearing is a recent concern. In this study, we assessed the simultaneous effect of noise and smoking on standard pure tone audiometry (PTA) and distortion product otoacoustic emissions (DP-OAEs). This was an historical cohort study on 224 workers exposed to noise who were divided into two groups: Smokers and nonsmokers. DP-OAE response amplitudes were assessed. Data were analyzed by SPSS software (version 19) using Student's t-test and Mann-Whitney U test. One hundred and five subjects were smokers (case group) and 119 individuals were nonsmokers (control group). All the subjects were exposed to 91.08 + 2.29 dBA [time-weighted average (TWA) for an 8 h work shift]. Mean DP-OAE response amplitude at frequencies higher than 1,000 Hz was significantly higher in the smokers than the nonsmokers. This study showed that smoking can aggravate the effect of noise on hearing in DP-OAEs.

Static anthropometric dimensions in a population of Iranian high school students: considering ethnic differences

BACKGROUND

Anthropometric dimensions of the end users should be measured in order to create a basis for manufacturing of different products. This study was designed to measure some static anthropometric dimensions in Iranian high school students, considering ethnic differences.

METHOD

Nineteen static anthropometric dimensions of high school students were measured and compared among different Iranian ethnicities (Fars, Turk, Kurd, Lor, Baluch, and Arab) and different genders.

RESULTS

In this study, 9,476 subjects (4,703 boys and 4,773 girls) ages 15 to 18 years in six ethnicities were assessed. The difference among ethnicities was statistically significant for all dimensions (p values < .001 for each dimension).

CONCLUSION

This study showed statistically significant differences in 19 static anthropometric dimensions among high school students regarding gender, age, and ethnicity.

Concurrent effect of noise exposure and smoking on extended high-frequency pure-tone thresholds

OBJECTIVE

Concurrent effect of noise and smoking on hearing loss is a recent concern. In this study, the concurrent effect of noise and smoking on hearing loss in conventional frequencies and frequencies higher than 8 kHz was assessed.

DESIGN

This was a cross-sectional study on workers exposed to noise who were divided into two groups: smokers and non-smokers. Hearing thresholds were assessed by conventional audiometry, and HFA. Data were analysed using non-parametric tests and Student's t-test.

STUDY SAMPLE

There were 212 workers.

RESULTS

Ninety-seven subjects were smokers and 115 individuals were non-smokers. All subjects were exposed to 92.1 ± 2.4 dBA (Leq8h). The highest threshold in conventional and high-frequency audiometry was observed at 6 kHz and 16 kHz, respectively. Hearing threshold at frequencies above 1 kHz was significantly higher in the smokers than non-smokers. There was no correlation between hearing thresholds and pack-years of smoking.

CONCLUSIONS

Concurrent exposure to noise and smoking may be associated with more hearing loss than exposure to noise alone in the conventional and high frequencies. However, other differences between smokers and non-smokers may explain these differences as well.

Ergonomic intervention, workplace exercises and musculoskeletal complaints: a comparative study

BACKGROUND

Musculoskeletal disorders are among the most prevalent occupational disorders in different jobs such as office work. Some interventions such as ergonomic modifications and workplace exercises are introduced as the methods for alleviating these disorders. In this study we compared the effect of ergonomic modifications and workplace exercises on musculoskeletal pain and discomfort in a group of office workers.

METHODS

In an interventional study on office workers, the effect of two interventions was compared. Ergonomic modification consisted of correcting the arrangement of workstation and changing some equipment; workplace exercises included stretching exercises focusing on neck, shoulders, low back, and hand and wrist. Musculoskeletal complaints were assessed and compared before and after 1 month interventions.

RESULTS

The frequency of musculoskeletal complaints was high before the study. Both interventions significantly reduced complaints in a similar manner except for low back pain which was reduced in exercise group more than the other group.

CONCLUSION

In this study we found a beneficial short-term effect for both ergonomic modifications and stretching work-place exercises on reducing musculoskeletal pain in office workers.

Marfan syndrome in an Iranian family: a case series

Marfan syndrome (MFS) is a genetic disorder which is inherited by autosomal dominant traits. In MFS, lens displacement and cardiovascular involvement are important causes of morbidity and mortality in the clinical course of the disease. In this case study, the ocular involvement in a family with severe penetration of MFS is reported. Twelve members of a family (father, two daughters, three sons, and six grandchildren) had MFS. Lens ectopia was the most common ophthalmic involvement among the family (100%). Other ocular involvements were as follows; Hypoplastic iris or ciliary's muscle hypoplasia (50%), on gated eyeball (42%), flat cornea (30%), glaucoma and cataract (25%), retinal detachment (16%). Three members of the family underwent eye surgery including lens extraction, glaucoma surgery and retinal surgery.

Evaluation of the return to work and its duration after myocardial infarction

BACKGROUND

The evaluation of the ability for return to work among patients after myocardial infarction (MI) is subject to controversy. Understanding various factors, which may affect return to work process, will help in promoting effective communication between physicians and patients. Return to work is dependent on such factors as patients' functional capacity, MI expansion, cardiac muscle function, some psychiatric variables, job satisfaction, economic status, and age. In this study, we aimed to assess the frequency of return to work after first MI attack, and factors affecting it.

METHODS

This was a follow-up study performed in Yazd, Iran from September 2007 until September 2010 on 200 patients suffering from their first MI attack. Patients were assessed 6 months and 1-year after MI regarding their cardiac function. Job satisfaction was evaluated by Direct Support Professional job satisfaction questionnaire.

RESULTS

Seventy-seven percent of MI patients returned to work after 1-year. Mean time for return to work was 46.00 ± 4.12 days. Sixty percent of patients returned to work during the first 50 days after MI and 50% of them during 40 days after MI. The most common reason for not returning to work was patient's decision.

CONCLUSION

This study showed that a considerable numbers of patients returned to work after 1-year. The only factors which affected the rate of return to work were left ventricular function after MI and job satisfaction.

Conventional Audiometry, Extended High-Frequency Audiometry, and DPOAE for Early Diagnosis of NIHL

Background:

Noise most frequently affects hearing system, as it may typically cause a bilateral, progressive sensorineural hearing loss at high frequencies.

Objectives:

This study was designed to compare three different methods to evaluate noise-induced hearing loss (conventional audiometry, high-frequency audiometry, and distortion product otoacoustic emission).

Material and Methods:

This was a cross-sectional study. Data was analyzed by SPSS (ver. 19) using chi square, T test and repeated measures analysis. Study samples were workers from tile and ceramic industry.

Results:

We found that conventional audiometry, extended high-frequency audiometry, low-tone distortion product otoacoustic emission and high-tone distortion product otoacoustic emission had abnormal findings in 29 %, 69 %, 22 %, and 52 % of participants. Most frequently affected frequencies were 4000 and 6000Hz in conventional audiometry, and 14000 and 16000 in extended high-frequency audiometry.

Conclusions:

Extended high-frequency audiometry was the most sensitive test for detection of hearing loss in workers exposed to hazardous noise compared with conventional audiometry and distortion product otoacoustic.

Effect of workplace noise on hearing ability in tile and ceramic industry workers in Iran: a 2-year follow-up study

INTRODUCTION

Noise as a common physical hazard may lead to noise-induced hearing loss, an irreversible but preventable disorder. Annual audiometric evaluations help detect changes in hearing status before clinically significant hearing loss develops. This study was designed to track hearing threshold changes during 2-year follow-up among tile and ceramic workers.

METHODS

This follow-up study was conducted on 555 workers (totally 1110 ears). Subjects were divided into four groups according to the level of noise exposure. Hearing threshold in conventional audiometric frequencies was measured and standard threshold shift was calculated for each ear.

RESULTS

Hearing threshold was increased during 2 years of follow-up. Increased hearing threshold was most frequently observed at 4000, 6000, and 3000 Hz. Standard threshold shift was observed in 13 (2.34%), 49 (8.83%), 22 (3.96%), and 63 (11.35%) subjects in the first and second years of follow-up in the right and left ears, respectively.

CONCLUSIONS

This study has documented a high incidence of noise-induced hearing loss in tile and ceramic workers that would put stress on the importance of using hearing protection devices.

Prevalence of Cardiovascular Risk Factors among Tile and Ceramic Workers in Yazd, Iran

Introduction. Cardiovascular disorders (CVDs) are among the most important diseases in the world and determination of their risk factors is essential for primary and secondary prevention. This study aimed to evaluate these risk factors in workers of tile and ceramic industry, a main industry in Yazd. Materials and Methods. In a cross-sectional study, 1075 tile and ceramic workers were selected by simple sampling method. BMI, blood pressure, FBS, and lipid profile were measured and compared to international standards. Results. 731 individuals (68%) had at least one risk factor, and 52%, 12%, 3%, and 0.7% had one, two, three, and four risk factors, respectively. The most common risk factor was abnormal BMI (49.6%); low HDL (48.4%) and high TG (14.1%) were in the second and third orders. Conclusion. This study showed a relatively high prevalence for CVD risk factors among tile and ceramic workers. Low HDL, high TG, and overweight were the most frequent risk factors in this population.

Correlation between serum lipids and age-related macular degeneration: a case-control study

BACKGROUND

Age-related macular degeneration (AMD) is one of the leading causes of visual loss among people aged 65 yr and older. The pathophysiology of AMD is poorly understood. The purpose of this study was to evaluate the relationship between serum lipid concentrations and age-related macular degeneration.

METHODS

In this case-control study, total cholesterol (TCH), low density lipoprotein (LDL), high density lipoprotein (HDL) and triglyceride (TG) of 32 patients with AMD were compared with 32 subjects without AMD that were matched for age. Data were analyzed using Independent t and Chi-Square Tests.

RESULTS

TCH, LDL, and TG serum concentrations were significantly higher in AMD patients compared with control group (P<0.001, P<0.001 and P<0.017 respectively). There was no difference in HDL concentration between two groups (P=0.781).

CONCLUSION

High level of total cholesterol, TG and LDL were associated with increased risk of AMD. Results of this study suggest further research to better understand the underlying biological mechanisms of AMD related to serum cholesterol.

A 2-year follow-up of spirometric parameters in workers of a tile and ceramic industry, Yazd, southeastern Iran

BACKGROUND

Respiratory diseases cause a considerable amount of morbidity and mortality in the world. Pulmonary function tests are important measures for the diagnosis and management of respiratory disorders. Workers in tile and ceramic industry are exposed to high amounts of respiratory pollutants.

OBJECTIVE

To identify the changes in spirometric parameters in a 2-year period among tile and ceramic workers in Yazd and compare it with a control group.

METHODS

The study was conducted in 5 tile and ceramic factories selected by cluster sampling between 2009 and 2011 in Yazd, southeastern Iran. Demographic data and spirometric parameters of participants were recorded.

RESULTS

Spirometric parameters were significantly reduced during the 2 years. The largest decrease was observed in FVC (≈500 mL) in ball-mill and grinding after 2 years. Decrease in all spirometric parameters was significantly higher in industrial workers than office workers.

CONCLUSION

Respiratory exposure in tile and ceramic industry can significantly affect pulmonary function tests.

Assessment of bronchodilator response in various spirometric patterns

BACKGROUND

Spirometry is a physiologic test that measures the volume of air an individual inhales or exhales and the rate at which the volume is changed as a function of time. Bronchodilator response, as a beneficial test for diagnosis of bronchial responsiveness is measured using the percent change from baseline and absolute changes in forced expiratory volume in 1 second and/or forced vital capacity. In this study we aimed to assess the increase in spirometric parameters in patients with symptoms of asthma regardless of spirometric pattern.

MATERIALS AND METHODS

In this cross-sectional study bronchodilator test was performed in individuals with dyspnea, cough or wheezing and the mean increase in various spirometric parameters was measured and compared among individuals with different spirometric patterns.

RESULTS

Among all individuals 24.5% responded to bronchodilator. Forced expiratory volume in 1 second was the parameter with the most frequent response to bronchodilator. Patients with mixed pattern had the highest frequency of response to bronchodilator. Response to bronchodilator was more than 50% in most mid flow volumes.

CONCLUSION

Some patients with symptoms of asthma may show restrictive or mixed pattern in spirometry which may respond to bronchodilator administration.

Cardiovascular Manifestation of a Family with Marfan's Syndrome

Marfan's syndrome (MFS) is a genetic disorder associated with autosomal dominant inheritance. In MFS, the most prevalent cause of death is cardiovascular involvement. Here we introduce a family with a severe penetration of MFS. Eleven members of this family have MFS (father, two daughters, three sons, and five grandchildren). The most common cardiac involvement in our patients was mitral valve prolapse as manifested by mitral regurgitation. At ten years' follow-up, two patients had aortic root dilatation running the risk of aortic dissection; they were, therefore, scheduled for cardiac surgery, during which the Bental procedure was successfully performed. Fortunately, all of the members of this family are currently alive.