Iran Occupational Health

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Background and aims: In recent decades, air quality in different work environments has been a major concern. It is clear that the chemical materials used in industries have a profound effect on the quality of workplace air. In 1942, the number of identified chemicals was about 600,000, in 1947 it was about 4 million, and in 2011 it was about 18 million, while the number of new chemical compounds increased from 1,000 to 2,000 annually. Many people around the world are exposed to a variety of chemicals in the various working environments. Exposure to these substances can lead to numerous health and carcinogenic effects on individuals. Among these substances, volatile organic compounds are one of the main contributors to air pollution and due to high vapor pressure, high evaporation rate and rapid release into the environment, many people are exposed and consequently have irreversible effects on their health in various occupations.
Petrochemical industry is one of the industries where workers are exposed to high levels of chemical pollutants in their respiratory air. One of the hazardous volatile organic compounds used in workplaces, including petrochemicals, is 1,3-butadiene (molecular formula: C4H6). 1,3-Butadiene is a colorless gas with smells like gasoline. Many international agencies and government organizations, including the International Agency for Research on Cancer (IARC), have identified this chemical as a human carcinogen by inhalation and placed it in Group 1 of carcinogens. Health effects of this compound include stimulation of the nervous system, eyes, nose, airways, asthma, fatigue, low blood pressure, and heart rate as well as atrophy in the ovaries. Today, many international organizations, including the World Health Organization (WHO) and the US Environmental Protection Agency (USEPA), consider the use of quantitative risk assessment methods as the legal basis for chemical compounds. Generally, the health risk assessment process involves several steps, first identifying the existing hazards, then measuring the individual's exposure, finally determining the relevant factors and measuring and evaluating the individual's exposure to a particular substance, using different risk assessment methods, graphs, and dose-response values, the probability of adverse effects in the population is calculated. Therefore, due to the deleterious effects of the 1,3- butadiene on the health of those working in the petrochemical industry, and the lack of similar studies in Iran to assess the health risk of the respiratory exposure to 1,3-butadiene in the petrochemical industry, the present study aimed to assess the health risk of occupational exposure to 1,3-butadiene vapors in a petrochemical industry in Iran.
Methods: This cross-sectional study was conducted in the petrochemical industry that producing copolymer ABS (acrylonitrile, butadiene, styrene) in Iran in 2018. To determine the respiratory exposure of participants to 1,3-butadiene, NIOSH 1024 method was used. Samples were collected by surface adsorption using adsorbent tubes containing activated charcoal of coconut (600 mg) and manufactured by SKC UK. It should be noted that similar exposure groups were used to assess individual exposure. Sample Size for research according to the proposed model of the National Institute of Occupational Safety and Health (SEG) and based on the number of workers in each occupational exposure group, were estimated 150 samples of 50 workers' respiratory air. At the sampling site, both sides of the sampling tube were broken and connected to an individual sampling pump made by SKC and calibrated using a soap bubble flowmeter at a flow rate of 200 ml/min according to the sampling method. After sampling, the content of activated charcoal in both front (400 mg) and rear (200 mg) sections of the sample tube was transferred to separate 5-ml vials. Then, by using the optimal NIOSH 1024 method, the extraction of the analyte was carried out by using 4-ml methylene chloride as an extraction solvent. Finally, 1μl of the sample with a 10μl gas-tight syringe manufactured by Hamilton Company was injected into the Gas Chromatography-Flame Ionization Detector (GC-FID) (model CP-3800 gas chromatograph and FID detector, Varian Technologies, Japan).
Assessment of occupational exposure to 1,3-butadiene: In the present study, the occupational exposure limit for 1,3-butadiene (TLV - TWA) was 2 ppm (4.42 mg/m3) based on values reported by the American Conference of governmental Industrial Hygienists (ACGIH). In the present study, occupational exposure index was calculated for each individual. Because the TLV-TWA values are provided with the assumption of working 8-hours a day and 5-days per week, if the working hours per week were more than 40 hours, the TLV-TWA value was corrected by using the Brief and Scala model.
health risk assessment of occupational exposure to 1,3-butadiene: The quantitative risk assessment methodology proposed by the US Environmental Protection Agency (USEPA) has been used to assess the health risk of exposure to 1,3-butadiene. Hazard Quotient (HQ) index was used to calculate the health risk of occupational exposure to 1,3-butadiene.
Health risk is defined as the ratio of chronic daily intake for non-carcinogenic effects to the reference dose. Chronic daily intake (CDI) indicates exposure to a mass of matter per unit of body weight and time in a relatively long period. Inhalation reference dose was derived from the inhalation reference concentration (RfC). Inhalation reference concentration was 2 × 10^-3 mg.m^-3 for 1,3-butadiene according to Integrated Risk Information System (IRIS) databank.  In the present study, information such as exposure duration, body weight, exposure time, and exposure frequency was collected using a questionnaire. The average inhalation rate ranged from 15.7 to 16 cubic meters per day depending on the age of the participants, according to the values presented in the EPA exposure factors handbook. The average lifetime was 70 years. Finally, data analysis was performed using IBM SPSS Statistics Version 25. Descriptive statistics (mean, standard deviation and frequency) were presented. Kruskal-Wallis test and Spearman's correlation coefficient were used at the significant level of 0.05.
Results: The mean respiratory exposure to 1,3-butadiene during work shift among all participants was 560.82 ± 811.36 µg.m^-3 and in all cases, it was below the corrected occupational exposure limit based on job characteristics. Also, the mean exposure index among all subjects was calculated to be 0.198 ± 0.25 and in all cases, it was lower than the permitted level. The results showed that the highest average respiratory exposure was in the safety and fire-fighting station worker. the average concentration of 1,3-butadiene in the workers' respiratory air in the safety and fire-fighting station was 1791.42 μg.m^-3. After the safety and fire-fighting station workers, the highest average concentration of 1,3-butadiene was in the respiratory air of workers in the dryer, compound 1, laboratory, poly-butadiene latex and compound 2 units with exposure index values of 0.38, 0.277, 0.256, 0.223 and 0.189 respectively.
Mean and standard deviation of hazard quotient among all participants was 10.82 ± 14.76. It was found that 60% of all exposed workers were in the unacceptable health risk level and 40% were in the acceptable risk level. The highest average of HQ was related to the safety and fire-fighting station workers with a value of 36.57. After the mentioned unit, the highest value of calculated HQ was observed in the dryer, laboratory, compound 2, installation and compound 1 with the values of 18.51, 16.01, 12.23, 11.57 and 10.82 respectively. The lowest HQ in the present study was obtained in the workers of packing, mechanical repair and coagulation units with the values of 0.18, 0.58 and 1.39 respectively. Among all examined units, the average non-carcinogenic risk values in the packing and mechanical repair units were lower than the permissible limit (HQ < 1.0).
Conclusion: The results of the present study demonstrated that the health risks associated with exposure to 1,3-butadiene in most of the workers (60%) were in the unacceptable health risk level. Therefore, application of suitable control strategies such as design and implementation of appropriate dilution and local ventilation systems due to the non-standardization of all existing ventilation systems in the industry to reduce the level of respiratory exposure of workers to 1,3-butadiene vapors and consequently, the reduction in the amount of health risk caused by exposure to this compound and the use of quantitative health risk assessment methods as a basis for judging the levels of respiratory exposure to hazardous compounds (especially carcinogens due to their high potential risk rates) and prioritizing the various units for the control measures is essential.

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Background and aims: The outbreak of COVID-19 is currently a major concern, and timely understanding of people's mental health status in the workplace has become an important issue. Physical-psychological parameters such as mental workload and job stress are among the most important components in determining the job performance of employees in work environments. This study aimed to evaluate the effect of COVID-19 epidemic on job stress and mental workload of employees in a chemical industry.
Methods: This longitudinal study was conducted in two stages (before and during the COVID-19 outbreak in Iran) from December 2019 to May 2020 in a chemical industry in Bushehr province. It should be noted that the first phase of this study was conducted before the outbreak of coronavirus in the form of a cross-sectional study. However, after the outbreak of coronavirus and in order to investigate the changing trend in the parameters of mental workload and job stress among participants, this study was performed in two stages in the form of a longitudinal study.  The statistical population included all employees working in a chemical industry. The sample size was calculated using Cochran's formula with an error level of 0.05 and included 182 workers who were selected by simple random sampling method.
The inclusion criterion was having at least one year of work experience and exclusion criteria were the presence of chronic mental illness, the use of sedatives, and insufficient willingness to participate in the study. Participants were able to drop out of the study at any stage if they were unwilling. Before starting the study and completing the questionnaires, all the necessary information about how to complete the questionnaires was explained to the staff and they expressed their willingness to take part in the study. However, to prevent a decrease in the number of participants in the study, the number of employees who entered the study included 200 people (182 people + 10% of the total sample size (18 worker)).
The NASA-TLX mental workload questionnaire and the HSE job stress questionnaire were used to evaluate mental workload and job stress, respectively. The data collected during the present study were analyzed using IBM SPSS statistical software version 25. The Kolmogorov-Smirnov test was used to test the normality of data distribution. The findings of this statistical test showed that the distribution of data was normal in all cases (p >0.05). Descriptive statistics (mean, standard deviation, frequency) were reported and statistical analysis was performed using paired sample t-test (to compare the mean of characteristics of the two psychological components of mental workload and job stress before and during the outbreak of coronavirus) as well as Chi-Square / Fisher's exact test. All tests were performed at a significance level of 0.05.
Results: The means of age and work experience of the subjects were 32.88±9.53 and 9.45±4.23 years, respectively. The results of mental workload assessment based on the NASA-TLX index showed that the mean score of mental workload before and during the prevalence of coronavirus disease was 56.32± 9.58 and 66.45±11.82, respectively, and  that there was a significant relationship between these values (p <0.05). Furthermore, a significant correlation was observed between the mean score of the dimensions of mental demand, overall performance, and frustration level before and during the outbreak of coronavirus. It was also found that the average score of all aspects of mental workload, except for temporal demand and overall performance, increased during the outbreak of coronavirus. The greatest increase was observed in the values of mental demand components and frustration level (Table 2).
The results of the job stress assessment showed that the mean score of job stress before and during the outbreak of coronavirus disease was 80.78±18/29 and 68.88±12.74, respectively. Moreover, it was found that the prevalence of coronavirus disease significantly increased the job stress level of employees (p <0.05).
Ultimately, these findings showed a significant relationship between the values of mental workload and job stress in employees before and during the coronavirus disease (p<0.05).
Conclusion: An examination of people's mental workload based on the NASA-TLX index revealed that the prevalence of COVID-19 significantly increased the mental workload of the studied staff. It was found that the mean values of the dimensions of mental demand and the frustration level were significantly increased at the time of the outbreak of COVID-19. The findings revealed that the prevalence of COVID-19 had increased the level of mental workload imposed on employees, as well as the level of frustration, insecurity, and stress of employees when performing their duties. It was also found that the COVID-19 epidemic significantly reduced employee performance, making staff less satisfied with their overall performance in the workplace. Previous studies have also shown that the spread of viral diseases can increase a person's workload, which is consistent with the results of the present study.
The study revealed that occupational stress levels increased during the outbreak of coronavirus. Previous studies have shown that the spread of viral diseases such as Mers and COVID-19 increases the level of anxiety, stress, insomnia, and depression among people. A study by Kim et al. revealed that after the outbreak of viral diseases such as Middle East Respiratory Syndrome (MERS-COV), a person's level of burnout and stress increased, which could severely affect a one’s job performance, which is in tandem with the results of the present study.
The present study was conducted for the first time to investigate the effect of coronavirus outbreak on physical-psychological components in the industrial sector in Iran. Therefore, the results of the present study can provide a novel insight into the impact of coronavirus epidemic on the components of mental workload and job stress in different work environments. The findings of the present study revealed that the prevalence of coronavirus disease has been able to affect different physical and psychological dimensions of personnel in the workplace. Therefore, psychological intervention is essential to improve the mental health of employees during and after the COVID-19 epidemic.