نشریه طب کار
سال نهم شماره 4 (پیاپی 29، زمستان 1396)

Sound is one of the most important work-related risk factors and most widespread physical factors threatening the health of workers. Almost one of the best ways to control the sound, is sound absorber. Due to the extensive entrance nano in various fields of science one their applications design and use sound-absorbing panels containing nanoparticles.The aim of this study to determine the sound absorption coefficient of nanocomposites, containing aluminum nanoparticles at different percentages.
This study had an experimental – Laboratory procedure. First of aluminum particles (100 nm), wood chips and glue polyvinyl acetate weight was measured the ratio of identified and wellmixed. In the next step, the obtained mixture is poured into the mold Heat resistant and transferred to 37 ° C. After the preparation ofmentionednanocomposites then sound absorption coefficient values were determined by acoustic impedance tube at four frequencies, 250, 500, 1000 and 2000 Hz.
The Comparison between the sound absorption coefficient of four weight percentage (1, 2, 3 and 4% of 100nm-aluminum nanoparticles) of aluminum indicated thatthealuminum nanocomposite had the highest sound absorption coefficient of weight percentage 4% at frequencyof 2000 HZ. While theallweight percentagesaluminumnanocomposites was seen the lowest sound absorptioncoefficient at frequency of 500 Hz.
The results showed that the increasing of the percentage of aluminum nanoparticles led to increase of sound absorption coefficient and aluminum nanocomposite can be a good choice to reduce environmental and industrial noise.

Agricultural mechanization is a method for transiting from traditional agriculture towards industrial and sustainable one that follows the body and psychic discomfort reduction by method, devices and work condition reformation. The aim of the present study was to assess risk factors related to musculoskeletal disorders (MSDs) and mechanization intervention to reduce these disorders.
This interventional study (descriptive-analytical) was conducted on 80 workers in a edible mushroom producing unit. The Nordic MSDs Questionnaire and mixed-method were used to collect data and the postural workloads evaluation before and after the interventions, respectively. χ2 and logistic regression were performed to analyze the data.
Results and Regression analysis showed significant relationship between, shoulder, fingerhands and wrist and mechanization, between the pain of back and knee and The number of working hours per week and body math index, between the pain of back, knee, shoulder and arm and age. Due to significant reduction in MSDs after mechanization intervention, use of standard equipments in the semi machanization levels of mushroom harvesting and packaging is suggested.

Recognition of maternal exposure to solvents and its relationship with congenital heart defects in infants can be effective in identifying effective environmental factors in the occurrence of anomalies. The aim of this study was to determine the relationship between maternal occupational exposure to solvent and birth congenital heart defects in infants.
In this case control study, 200 infants referred to Afshar Hospital of Yazd, who had congenital heart defects, were included in the sample as well as 400 healthy matched infants. A questionnaire consisting of three parts was used as a tool. The questionnaires were completed through a telephone interview. Mother's job information was extracted from the questionnaires and a survey of maternal care was done using a matrix of job evaluation. Demographic characteristics were assessed by statistical tests. The relationship between occupational exposure to solvent and anomalies was calculated using odds ratios and adjusted odds ratios.
The maternal occupational exposure to solvents in the case sample (91.5%) was significantly higher than the control sample (83.2%), and this relationship was statistically significant (OR = 2/16, 95% CI=1/21-4/05) after the elimination of the effect of interfering factors, there was no significant difference between mother's exposure to solvent and cardiac anomalies in infants (AOR = 1.85 , 95% CI=0/69-5).
The findings of this study indicate that one of the factors that may affect the health of the fetus is the mother's contact with solvents. In this regard, mother's training on compliance with occupational safety standards can have a significant effect on occupational exposure control.

Exposure to noise can induce hearing loss. Thus noise induced hearing loss is one of the main concerns in interventional study on health effect of noise exposure. We analyzed pre and post exposure audiometeries of volunteers in a clinical trial study that we conducted for effect of noise exposure on cardiovascular system.
In a clinical trial study, 100 healthy, 20-40 aged, volunteer men exposed to 90 dB noise for 30 minute. We take pre and post exposure pure tone audiometric test from all of subjects.
Mean of PTA among 100 subjects was reduced 0.72 dB in right ear and 0.44 dB in left ear. Mean of hearing threshold in each of 250, 500, 3000, 4000 and 8000HZ frequencies rise in left ear and was reduced in all of other frequencies in right and left ear.
Results of our study indicated that short term exposure to 90 dB noise in interventional studies cannot produce clinically significant hearing loss.

Professional and occupational diseases, pain, large losses to workers, businesses, social security funds and their communities in general. According to International Lab our Organization estimates, due to the working conditions, work-related accidents are six times more likely to cause their death. Aim of this study check and improvement in muscular-skeletal disorders in a support software company in Tehran.
In this cross-sectional study of 70 randomly selected operators. Using data from the Cornell Musculoskeletal Discomfort Questionnaire and Rapid office strain assessment were collected. Data were analyzed using Pearson correlation test and analysis of variance and the improvement was achieved using the Taguchi method.
ROSA results showed that 43/11 percent and 57/88 percent of operators in the notification area of ergonomic interventions are needed in the area. Using Taguchi Methods designed to change workstations, Selection and changes need to be applied. The results reveal a decrease in the average final score to 74.5 and its improvement and reduction of 7% of the ergonomic intervention and improvement of the alert level.

Manual material handling activities in long and short periods may lead to complications such as laceration, fracture, cardiovascular stress, muscle fatigue, and musculoskeletal disorders especially in the vertebrae column. The purpose of this study was to assess ergonomic risk factors in workers of a stone cutting industry and the impact of ergonomic interventions on reducing these risk factors in their workplaces.
Material and In a pre and post interventional study, identifying ergonomic risk factors of 50 male workers was done using WISHA checklist. Ergonomic interventions were implemented was: installation of a crankcase of the manorial vacuum and clamping crank, using a pallet with a portable two-way portable lift truck, a pallet for collecting waste with a roof crane or forklift truck, and a wagon lifting device. Statistical analyses were done using SPSS 20 and statistical tests of variance and Wilcoxon analysis.
Based on the results of the study, 78% of the workers had ergonomic risk factors at least in one of the 7 awkward postures at the beginning of the study, The most frequent risk factors were related to workers in stone loading, collecting stone waste (100%), middle part (76.2%), cutting-off (71.4%) and sub stations (50%). These values ​​were eliminated after ergonomic interventions in the loading workshop, sub, accumulation of stone waste (100%), and in the middle and cut-off workstations (42.8%). There was a significant difference between ergonomic risk factors before and after interventions (p The results of this study indicate that the prevalence of work-related ergonomic risk factors of workers in this industry was very high, but after the interventions, ergonomic risk factors decreased from 42.8% to 100%.

Deviant behaviors at workplace, affect the individual performance and organizational outcomes by violation of rules and organizational regulations. The present study investigates the mediating role of work engagement in the relationship between emotional exhaustion and deviant behaviors at work place.
This study is an applied research in terms of purpose and a descriptive-correlation research in terms of method. The statistical population is the faculty members of ............ University. A sample comprising of 120 members was selected using simple random sampling method. They responded the items of three questionnaires including the scales of work engagement (Schaufeli, Salanova, Gonzalez-Roma & Bakker, 2002), emotional exhaustion (Maslach and Jackson, 1981) and workplace deviant behaviors (Bennett and Robinson, 2000). Data analysis was done using structural equation modeling with Bootstrap method in software environment of AMOS .
Emotional exhaustion is a negative predictor of work engagement (path coefficient= -0.59) and predicts workplace deviant behaviors indirectly and through the mediating role of work engagement (path coefficient= .28). Also, improving work engagement results in reducing deviant behaviors at workplace (path coefficient= -0.42).
Emotional exhaustion has influence on deviant behaviors through the mediating role of work engagement. So, taking some considerations into account, controlling or reducing emotional exhaustion of faculty members, can improve their work engagement and reduce deviant behaviors at workplace.

textile industry due to noise pollution may cause noise annoyance. Noise annoyance can increase the risk of health problems and sleep disturbance. Thus, this study was conducted to assess the effect of noise annoyance on the sleep disturbance among workers of a textile industry.
Material and All the workers have been divided into four groups according to their noise exposure levels, including Knitting unit, Screw warp and sizing, Control area and Reel Decal. The equivalent A weighted noise levels were measured for each of the study working groups, using ISO 9612 standard method. Information related to the noise annoyance and sleep disturbance were determined by ISO15666 standard and the Epworth Sleepiness Scale, respectively.
Based on the analysis of variance, average noise annoyance caused by occupational groups, age and work experience was different. Two independent samples t-test showed that the education does not significantly associated with noise annoyance. Kruskal - Wallis showed that the mean score of sleep disorder are significant differences between occupational groups. According to this test sleep disorder was significantly associated with the noise annoyance.
In this study, workers with more noise annoyance had more sleep disturbance.
Therefore, in addition to the direct effects of noise on sleep disturbance, it can indirectly exacerbate sleep disturbances.