دو ماهنامه سلامت کار ایران
سال نهم شماره 4 (زمستان 1391)

Gasoline is a complex mixture of more than 500 hydrocarbons. The elimination of lead from petrol has been associated with the addition of significant amounts of hematotoxic monocyclic aromatic hydrocarbons such as benzene, toluene and xylene (BTX). The main purpose of this study was to ascertain whether exposure to unleaded petrol, under normal working conditions, is associated with any hematotoxic response.

This was a historical cohort study in which 200 subjects with current exposure to unleaded petrol from Shiraz petrol stations as well as 200 unexposed employees were investigated. Using standard methods, atmospheric concentrations of BTX were measured. Additionally, blood samples were taken from subjects for routine biochemical tests such as RBC, WBC and platelet count, Hemoglobin, hematocrit and RDW.

The geometric means of airborne concentrations of BTX were found to be 0/24,0/37 and0/64 ppm, respectively. The results of blood chemistry tests showed that no significant differences exist between both groups as far as biochemical tests, but RDW and hematocrit, were concerned.

The average exposure of petrol station workers to BTX did not exceed the current TLVs for these chemicals. Additionally, overt hematotoxicity is unlikely to be the outcome of exposure to unleaded petrol under the conditions described in our study.

This is a descriptive and cross sectional study. The aim of this study was to investigate the environmental ranking of industries located at west of Tehran based on the quantitative and qualitative characteristics of industrial wastewaters in 2011. This study was conducted by site visit, questionnaire completion, database production and results analysis. The questionnaire was consisted of 30 questions about quantity, quality and management of industrial wastewater. Total number of industries with over than 50 personnel, was 287. Class-weighted sampling was used and the sample size was contained 50 industries. In this study, industries were scored from 1 to 10, based on the flow rate, BOD and COD, generation of wastewater per worker per day and then were ranked according to the total score. The average flow of wastewater generated by these 50 industries was 9422 m3/day. Wood and cellulose industries with 730 liters wastewater per worker per day was considered as the greatest wastewater generator. Minimum organic loading was related to non- metallic mineral industries with COD of 205 mg/ L and BOD of 85 mg / L. The maximum COD was related to paper industries with the rate of 8800 mg/ L and maximum BOD was related to food and drug industries with the rate of 1536 mg/ L. This environmental ranking was indicated that while paper industries contributed the most pollution load, non- metallic mineral industries had the least pollution load.

Many people have to sit down during daily activities. The process of sitting down especially for a long time in comparison of standing up cause many back pains. Special chairs with special backs and sits are designed for offices, industries and institutes because of back pain of sitting down for a long time and increasing the performance of employees. The target of this research is also the designing of a saddle chair based on the anthropometry characteristics of people and then evaluating the conformance of this chair. A number of 178 males between 25 and 55 years in an assembling industry were cooperated and their eight anthropometry parameters according to Pheasant's criteria at the same anthropometric conditions were measured in this research. Then according to the achieved information, the saddle chair were designed and 30 people were selected randomly to use the saddle chair five hours per day for one month at the second phase. Finally, the comfort of this chair was evaluated by the questionnaire sheet. The saddle chair is designed according to the design parameters; the max and min height, width, depth and width of saddle, the depth of chair identity range and the design criteria of achieved anthropometry characteristics. The evaluation of chair comfort with used quantitative scale is shown in the comfort sense of users and their satisfaction (Average is more than 7.5 of 10). According to the user's expression of comfort in this research and respecting to this fact that other countries have been designing and producing the proper chair according to the anthropometry characteristics consequently recommended to perform the same research on diverse parts of country. Therefore, it is suggested to design and produce the proper chair according to the body dimensions and characteristics of individuals.

Annually, occupational accidents have a major impact on workers health and Impose large costs on employers. The current study was designed to evaluate the efficacy of the theory of planned behavior-based intervention to improve workers safety climate in industrial city of Qazvin in the first half of 2010. A number of 75 workers in each of the control and intervention groups participated in a quasi experimental study. With respect to the fact that the changes of safety climate usually take place in the long term, and for the longer follow-up of participants, data were collected through self-report questionnaires in three different time intervals including initial followed by, 3 and 6 months after the intervention. The intervention consisted of four training courses with 8-15 trainees in each group and its duration was 45-69 minutes. The data were entered into SPSS 16.0 software and were analyzed using statistical tests. The score of Management commitment was significantly increased in the three and six month evaluation in intervention group (p< 0.001). Also, results showed a significant increase in other dimensions such as safety communication, secure environment, responsibility, risk perception, safety climate (P<0.05). Results also indicate a significant change in mean scores of attitude, subjective norm (P<0.05), perceived behavioral control (P<0.001) and attempted (P<0.05) in the intervention group and no significant change in these variables in the control group. Results showed an improvement of worker's safety and common perceptions of workplace safety policies and procedures due to educational intervention based on theory of planned behavior. Thus, the theory of planned behavior can be used as a theoretical framework for the design and implementation of workplace safety interventions.

Technique of Failure Modes Effects and Criticality Analysis, FMECA, is a method for identifying and analyzing all potential failure modes of a system.This technique is used to prevent failures and to reduce their effects on the system. The main goal of this study was identifying and analyzing of the potential failure modes and assessing the effects of failures in the cement kiln by FMECA method. First the boundaries of the system was determined and then system was divided into its components (systems and subsystems) at a specified level with respect to the analysis goals. Then, effects of failures on production and system were appointed and causes and severity of failures were determined. Finally The results were recorded in FMECA appropriate worksheet. Meanwhile failure priority was presented. Totally one hundered failures were identified. While the highest risk priority number was related to body warping with RPN = 270, the lowest risk priority numbers (RPN = 15) were associated to lacking of air supply by fan and unproperly acting of the main brake of kiln. The maximum frequency of failures were found in the kiln body. This study indicated that one failure may led to other defects in various components of the system itself. Therefore, the implementation of a documentation system to record defects was emphasized in order to improve the machinery safety level. Furthermore, it can be concluded that a planned preventive maintenance could effectively decrease the probability of failures and number of defects consequently.

Work skills are among variables which promote the coping abilities of individuals with high job demands at workplaces. This research was administered with the aim of studying the moderating role of work skills in connection between job stress, feeling of energy and emotional exhaustion with deviant behaviors, organizational citizenship behaviors and creativity. Research population were included the employees of two industrial companies, among them, 275 persons were selected via stratified sampling. Research instruments consisted of job stress questionnaire, deviant behaviors questionnaire, organizational citizenship behaviors questionnaire, creativity questionnaire, feeling of energy questionnaire, and researcher made questionnaire of work skills. Data were analyzed using Pearson’s correlation coefficient and hierarchical regression analysis. Results showed that: 1. There are negative significant relationships between work skills with job stress, emotional exhaustion and deviant behaviors (P<0.01), but there are positive significant relationships between work skills with feeling of energy, creativity and organizational citizenship behaviors. 2. The results of hierarchical regression analysis revealed that work skills have been moderated the relationship between emotional exhaustion with deviant and organizational citizenship behaviors. Findings of this research showed that when work skills are low; emotional exhaustion increases deviant behaviors, but decreases organizational citizenship behaviors. Also in high job skills, emotional exhaustion increases organizational citizenship behaviors.

Musculoskeletal disorders (MSDs) are a major cause of time loss, costs and work force injuries in the workplace. Awkward working posture is a main risk factor for developing MSDs. This study was conducted among assembly workers of an electronic industry with the objective of implementing an interventional ergonomic program to reduce postural stress on neck and trunk and to minimize awkward working postures. This interventional study was conducted on 81 assembly workers of an electronic industry. Nordic musculoskeletal questionnaire was used to determine prevalence of MSDs. Numeric rating scale was applied to evaluate body discomfort before and after the intervention (using a magnification lenses to improve visibility of the parts). Statistical analysis including independent t-test was performed using SPSS (version 16) software. The results showed that MSDs occurred among assembly workers at high rate in neck, lower back, and shoulder/upper arm regions (more than 75%). After intervention, significant discomfort decrement was observed in neck, shoulder/upper arm, lower back, elbows and lower arm regions together with the whole body (p<0.05). More than 90% of the assemblers reported that using the magnification lenses facilitated assembly operation and was comfortable. After the intervention, 89% of the workers evaluated working conditions better as compared with that of before the intervention. It was indicated that using magnification lenses reduced discomfort in different body regions as well as the whole body. It could, therefore be expected that its application of magnification lenses would decrease MSDs of different body regions in long term. Findings showed assemblers satisfaction when using the lenses as well as effectiveness of the lenses application in manufacturing process.

Hypertension (HTN) is a common disease with various complications for health. A number of studies suggested that some organic solvents can affect blood pressure and usually workers in work environments expose to mixtures of solvents. We decided to survey the effects of a mixture of organic solvents on blood pressure in workers of a car manufacturing company. In a cross-sectional study, systolic and diastolic blood pressure (SBP&DBP) of 179 workers of a car manufacturing plant was measured. Workers in the repair location as non-exposure group and workers in the paint location as exposure group were compared in terms of systolic and diastolic blood pressure (SBP&DBP) and prevalence of hypertension and pre - hypertension. There were no statistically significant differences between groups in the variables, age, employment duration, smoking and other confounding factors (p<0.05). The mean values of SBP and DBP was significantly higher in exposure group than non-exposure group (p<0.001). After logistic regression analysis with adjustment of confounding variables, prevalence of pre-hypertension and hypertension was significantly higher in exposure group than non-exposure group (p<0.05). Further, in this study there was a significant association between hypertension and variables such as age, smoking, body mass index, regular exercise and shift work (p<0.05). Our results suggested that, exposure to mixture of organic solvents can increase prevalence of hypertension in car manufacture workers. Therefore, more attention should be paid to such workers by prevention and periodic monitoring of blood pressure.

Occupational accident is an unplanned and harmful event which occurs in workplace environments. Among various occupations and activities, large metal industries are the most hazardous industries in the world. This study was designed in one of the Arak metal industries in order to determine the incidence rate of occupational accidents as well as its risk factors. Initially in an incidence study, 873 workers were followed historically to determine the number of accidents since 2005 to 2007. Then the cases were compared with a random sample of workers with no accident (251 workers) in a case control study. After data collection by a structured questionnaire, statistical analysis was conducted using chi-square test, t-test and logistic regression in SPSS software (V.16). During these three years, 359 accidents had been occurred and the annual incidence rate of accident was equal to 137 per 1000 workers. There was a significant relationship between occurrence of accident and age, work experience, education level, height, and systolic blood pressure as well as shift work (p<0.05).The marital status and number of children were not significant risk factors. Moreover, unsafe practices was the first case of accident, age and educational level were remained in regression model as the most important predictors of incident of occupational accidents. Considering the high frequency rate of accidents and based on our findings, planning and implementation of safety training, modifying non-safe conditions, supplying workers with appropriate standard protective equipment and appropriate facilities are recommended.