Iran Occupational Health

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Background and aims: Recently, there is an increasing concern about the quality of breath air in cabins of public transportation system. Present study measured the driver’s occupational exposure of BTEX as the most important and toxic group of VOCs in cabins of Tehran bus rapid transit (BRT) system.
Methods: NIOSH 1501 was used for sampling and analyzing. Samples were extracted by CS2 and analyzed by GC-FID. The main sources of target pollutants were determined and the risk carcinogenic and non- carcinogenic of these compounds were evaluated by USEPA and WHO methods. SPSS Ver.20 was used for Statistical processing of data and Wilcox-test and Kendal were used for comparison and correlation, respectively.
Results: The mean inner concentration of Benzene, Toluene, Ethylbenzene, (m+p) - Xylene, o- Xylene and BTEX was measured 8.75, 24.33, 25.90, 43.71, 33.46 and 136.15 µg/m3, respectively. The lifetime cancer risk (LTCR) of Benzene in line 1, 2 and 7 was 7.07×10-5, 4.68×10-5 and 3.08×10-5, respectively.
Conclusion: Mean concentration of Benzene was more than Iran environmental protection organization and European :::::union::::: (EU) recommended levels. LTCR of Benzene was more than recommended levels by USEPA and WHO. The Hazard Quotient (HQ) of all under investigation compounds were less than 1. Therefore, non-carcinogenic risk of them was in acceptable range.

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Background and aim:
Microwave radiations are one of the most environmental workplace factors that exposed too many workers. In microwave spectrum, radar frequency with 1-300 GHz range have varied applications such as satellite, communications, military, Network, navigation, air-traffic Control, navigation, marine and weather. Uncontrolled occupational exposure to radar radiation caused to various disease and disorders such as oxidative stress, different kinds of cancers and other thermal and non-thermal adverse health effects. Regard to the importance of identification work related carcinogenic factors in prevention and decreasing cancer related costs and lack of similar studies, this study was conducted to systematically review the research on the risk of cancer in occupational exposure to radar radiation with frequency ranges 1 to 3000 GHz.
 Methods: The present systematic search was carried out based on PRISMA guidelines and comprehensive search strategy was focused from March 2017 to September 2018 and update on September 2018 in PubMed, ISI Web of Science, Scopus and Google scholar, MAGIRAN and SID databases with English and Persian articles without time limits were searched .Keywords were selected based on PICO principle and collected from MeSH database. comprehensive search  were accomplishment by the following search  terms  : (worker OR technician OR occupation OR military OR airline OR navy OR police officer OR  Weather )  AND (occupational exposure OR  workplace OR  long-term exposure OR  exposure  OR  radar OR  microwave OR  wireless OR  high frequency range OR  radiofrequency OR radiation OR  electromagnetic) AND (control group, cohort OR prospective OR retrospective OR follow-up OR randomized control trial OR case-control) AND (cancer OR malignant OR melanoma OR metastatic OR non-thermal effect OR biological effect OR health effect OR Adverse Effect OR risk factor OR Sarcoma OR tumor or leukemia OR neoplasm OR Carcinoma OR Hepatoma OR lymphoma OR mortality ) as single or complex terms in titles, abstracts and keywords.
Then, taking into inclusion and exclusion criteria, the process of reviewing, screening and limiting the repeated and unrelated articles was carried out. In addition, manual references checking were done to retrieve the related articles. Also, any disagreements were resolved by consensus between reviewers.
The inclusion criteria for selection studies were in design of case–control, cohort and randomized control trial studies, with control group and referring to the association between occupational exposure to radar radiation and all types of cancer in workers.
The exclusion criteria were as follows: 1) studies without control group 2) reviews, case and field studies, 3) studies with inhumane population such as in vitro, in vivo and animal studies. 4) Studies that radar frequencies were out of considered ranges (1-300 GHz) .5) studies with other occupational or non-occupational carcinogenic risk factors (such as solvents, workplace air pollution, environmental air pollution, smoking and etc).
After implementation of inclusion and exclusion criteria, data were extracted after preparation of the full text of included articles.
The Results: A total of 533 studies was found. After removal of duplicated references, 272 studies were included for the title, keywords and abstract screening. Then, 219 studies were excluded since they did not meet inclusion criteria. Hence, 53 studies were selected for the eligibility assessment. At the end of selection process and after the quality assessment, 7 studies remained in the systematic review that including 3 case-control studies and 4 cohort studies with no randomized control trial study. A manual search of the reference lists added no more articles in this review.
 All included studies were from English language and external databases in various countries including USA, Germany, and France. In this systematic review, a study of clinical trials and Persian studies were not found. Finally, based on inclusion and exclusion criteria, 7 articles (4 cohorts and 3 case-control) were included, which were conducted during the 1950 to 2005 with 51898 sample size and range of ages 15–69 years that published from 1993 to 2016. Included studies examined relationship between occupational exposure to radar radiation and cancer strength among workers. Whole of the studies put determination of cancers and risk estimates in military workers. The great majority of included studies reported risk estimates with 95% confidence interval. Most included studies were conducted on testicular cancer (4 from 7 included studies) and brain cancer (4 from 7 included studies). In included studies, Relative risk were estimated, particularly about testicular, leukemia and brain cancers and mortality ratio in various types of cancers has been reported. The included studies reported no significant increase in mortality ratio about testicular cancer but increasing in relative risk were significant in two studies. There was also a significant increase in the relative risk of brain cancer in workers who occupationally exposed to radar radiation. Increase in mortality ratio due to brain cancer were significantly reported in two included studies.
Conclusion:
The current systematic review was carried out to investigate the cancer among workers with occupational exposure to radar radiation.
It is noticeable that previous related studies focused on both environmental and occupational exposure in worker and public population and it clearly did not determine the relationship between occupational radar exposure and cancer risk in workplace. Whilst, our study just focused on occupational exposure to radar radiation that lead to small number of included studies.
The results of this study can be useful to prepare the occupational health policies in related to radar radiation and provide some information to conduct associated meta-analysis in future studies. On the limitations of the included studies, the continuation of experimental studies on humans with control groups, and focusing on the study of cancer-causing radar radiation in occupational exposure to workers is necessary.in this line, World Health Organization propose to conduct further differences studies  especially case-control studies.
However, it should be mentioned that these results are yielded by a few numbers of available studies with no report in occupational dose and time exposure to radar frequency range. also, considering to some limitation such as few numbers of included studies, lack of data about exposure characterizations (exposure time, dose-response, average of exposure level) and demographic characterizations (average of age, average of experience, radar frequency range) it is better to continue further studies about this topic and future review studies include the congress publications without limitation in language. It is also suggested that other published articles in congresses also be used and the limitation in language of publications in the search process be removed.
It is noticeable that, slight researches about occupational cancers in Iran were conducted in yet, such as studies in related to asbestosis, aromatic amines and chromium. Therefore, regarding the fast growing of cancer in developing countries like Iran, determination of occupational cancer risk factors could be useful to provide the cancer prevention and control program. So in this line, designing epidemiologic studies to focus on occupational cancers are very important especially about microwave and radar radiation.

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Background and aims: Currently, as a result of research on laboratory animals, abundant information has been obtained on the impact of various environmental factors on the occurrence of congenital malformations, but there is still no comprehensive information on the causes of congenital heart malformations (CHD) in human populations. Congenital heart defects (CHDs) constitute the major class of congenital anomalies. Although the incidence of CHDs is close to one percent of live births, its prevalence in the fetus is higher. The prevalence of CHDs is 0.5-0.8% in the live-term neonate, 2% in premature infants and 10-25% in the aborted fetus. The exact causes of CHDs are not clear. About 25% of all CHDs are attributed to the genetic factors. The interaction of genetic and environment is also considered in the etiology of the CHDs. Researchers say occupations such as pharmacy, chemical engineering, dyeing, increase the risk of neonatal eye, heart and intestinal defects and cleft lip and palate. Several studies have shown the effect of non-genetic factors such as environment and lifestyle on the occurrence of CHDs. In the Snijder study, no relationship was found between maternal occupational contact and CHD offspring, whereas fathers' exposure to phthalates increased CHD in neonates. According to the above mentioned content Identify paternal exposure to solvents and its relationship with congenital malformations heart defect can be effective in identifying the factors affecting the incidence of malformations. However, there is no consensus on the role of paternal and maternal exposures and susceptible window of exposure on the CHDs across studies. Additionally, the body of evidence on the association between occupational exposures and congenital malformations especially CHDs are limited. This study aimed to investigate paternal occupational exposure to solvents and congenital heart abnormalities in neonates.
Methods: The study was approved by the Ethics Committee of Shahid Sadoughi University of Medical Sciences (Registration Code: ir.ssu.medicine.rec.1359.37). In this case-control study 200 children with congenital heart defect and 400 matched healthy infants were considered as case and control groups respectively. Cases were randomly selected from the medically diagnosed and registered CHDs newborns during 2015-2017 (1393-1395 Persian year) in Yazd, Afshar referral hospital. Controls were selected from healthy newborns of Yazd province referred to the Yazd city health centers for receiving their routine health care services. Controls were matched case by case with the cases in term of age. A researcher-made questionnaire was used to collect the data by the telephone interview. The questionnaire comprised of three sections including a) general items regarding demographic characteristics b) lifestyle of parents and c) occupational and environmental exposures of the parents. Information on paternal occupation of questionnaires and paternal occupational exposure was performed using job exposure matrix. For this purpose, a matrix of occupational exposure assessment of solvents was prepared in Excel software. Exposure ratings of each job were solved based on the opinions of 10 experienced and well-known occupational health professionals. After completing the job matrix, the mean score of solvent exposure was calculated and the mean scores were used as fathers' exposure to solvents. Outcomes definition was performed according to international Classification of Disease version 10 (ICD 10). All refereed children with maximum three years of age which were diagnosed with at least one of CHDs according to the ICD10 classification were entered into the study.  Data were analyzed using SPSS16 software, descriptive and inferential statistics such as frequency and percentage. STATA14 software was used to evaluate job contact and logistic regression tests were used to estimate odds ratios and odds ratios. 95% confidence interval and 0.05 were considered significant.
Results: Among the analyzed cases, ventricular septal defect with 31.5% (n = 63) and patent ducts arteriosus with 24% (n= 48), had the highest prevalence. Results showed that mothers of case group had lower level of education compared to control group (p-value <0.001). In this study, the sex ratio of girls to boys was 1/1.06. The BMI in mothers in the case group (26.61± 5.74) was significantly higher than the mothers BMI in the control group (25.06± 3.71). Eight percent increase in the risk of CHDs was found per one unit increase in the BMI in the crude model (95% CI: 1.04:1.13). Eight percent increase in the risk of CHDs was found per one unit increase in the BMI in the crude model (95% CI: 1.04:1.13). About 72% (n=144) of mothers in the case group and 83% (n=332) in the control group reported no history of a diagnosed medical problem during their pregnancy. Significant difference was observed between the frequency of heart problems in the newborns of mothers with and without health problems during pregnancy (OR: 1.83; 95% CI: 1.23: 2.74). 26.5% (n=53) of the mothers in the case group and 21.25% (n=85) in the control group were a passive smoker. However, the risk increase due to passive smoking was not statistically significant (OR: 1.34; 95% CI: 0.90: 1.98). Use of folic acid during pregnancy was associated with 41% lower risk of CHDs (95% CI: 0.30: 0.86). Use of Iron supplement during pregnancy was also associated with 40% lower risk of CHDs (95% CI: 0.36: 0.99). Familial history of other congenital anomalies and also CHDs was associated with increase in the odds of CHDs. The prevalent of Paternal occupational exposure to solvents was 66% and 55% in the case and control groups respectively in which relationship was statistically significant (OR = 1.53, 95% CI = 1.06-2.21). After a removing the effect of confounding factors the significant differences was not observed between paternal exposure to solvents and heart defects in child (AOR = 1.28, 95% CI = 0.84-1.6). Investigation of the relationship between patent ducts arteriosus and occupational exposure to solvents showed that fathers' occupational exposure to solvents was higher in the case group (72%) than in the control group (58%), whereas between arterial openness and occupational exposure to solvents. With and without confounding factors, no significant relationship was observed despite high index ratio (OR: 1.94 4- 95% CI: 0.97-94.09 and OR: 64% CI95: 0.76- 3.55 / 1: AOR))
Conclusion: The limitations of the this study were the small number of samples, the limitation of study to a specific timeframe, use of the job evaluation matrix alone and the lack of evaluation of solvent biomarkers in parental and fetal body tissues and fluids. Despite the limitations of the study, the findings of the study showed that one of the environmental factors affecting the fetal health was occupational exposure Father’s with solvents. therefore father's job may affect the child health.  the results of Studies have also shown that exposure to chemicals reduces the quality of semen and can affect epigenetic planning during sperm cell maturation. These changes may lead to abnormal gene transcription in fetal tissue that may later lead to congenital defects. In addition, occupational exposure to chemicals is generally much higher than exposure to such substances in the diet and the environment, which may further impact such exposure. An animal study has also shown that the cardiovascular system in Fetal growth stage is highly sensitive to many environmental contaminants such as dioxins, polycarbonate biphenyls and some pesticides. In this way, training parents about compliance with occupational safety standards can increase the health of next generation. Also, since this study was conducted as a job and solvents are highly diverse, it is recommended to study the effect of each solvent on the biomarkers and the effect of each solvent.
 

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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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Abstract
Background and aims: Decades after the introduction of nanotechnology as a new field of research and production, the pace of development of this field has been remarkable. These advances have enabled nanomaterials to be used in various sectors and industries including electronics, optics, consumer goods, energy production and storage, soil and water conservation, as well as in medicine for therapeutic and diagnostic purposes. Worldwide sales of nanomaterials were $ 22.9 billion in 2013 and with annual growth of 19.8%, it is expected to reach US $ 64.2 billion by the end of 2019; Therefore, many economists consider the production and use of nanomaterials an integral part of future economic activities. These advances are due to the unique physico-chemical and biological properties of nanoscale materials. The large surface-to-volume ratio, size and surface characteristics of nanomaterials are the most important physico-chemical properties of them. The specific physico-chemical properties of nanomaterials have led them to show specific behaviors in interaction with biological systems; The most important of these behaviors are moving towards secondary target organs, poor clearance by macrophages, the ability to transmit through the axons of sensory neurons, and to reach intracellular structures such as mitochondria and the nucleus. These properties, in addition to their many applications, have also raised concerns about the potential effects of these substances on human health and the environment. These concerns have generated a large wave of research in the fields of nanomaterials safety, health and toxicology. Forecasts show that the number of staff exposed to nanomaterials will reach about 6 million by the end of 2020. Concerns are increasing day by day as the number of workers exposed to nanomaterials increases. In our country more than 200 companies are active in the field of production and using nanomaterials. These companies have received 517 nanoscale certification for their products, until January 2019. Their products are exported to 49 countries and 5 continents worldwide. The increasing growth of these activities in the country necessitates attention to the safety, health and environmental aspects of nanotechnology. According to what was said, this study aimed to investigate the relationship between the symptoms of employees of nanomaterials producing and consuming companies with chemical composition (as a factor affecting the type and severity of effects) and physical state (as an influencing factor on exposure) of the nanomaterials.
Methods: The present study is a descriptive cross-sectional study carried out in 2018 among employees of nanotechnology companies in Tehran. Specifications of the companies were provided by correspondence with the Ministry of Industry, Mine & Trade. Of the companies invited, 52 companies agreed to participate in the study. Staff symptoms were assessed using a nonspecific symptoms questionnaire. The questionnaire was designed and validated in a period of two months by a team of 19 experts in the fields of occupational health, occupational medicine, toxicology, medical nanotechnology and health education. The required information about the occupational characteristics, chemical composition and physical state of the nanomaterials used in the companies was also collected using the NanoTool method form. The questionnaire and the form were then emailed to staff exposed to nanomaterials. Staff inclusion criteria were "to have direct exposure to nanomaterials, that is, to produce or consume nanomaterials during their daily working processes" and "to have at least one year of experience". Of the 52 companies that agreed to participate in the study, 198 completed questionnaires and completed forms were received. Finally, data were analyzed using SPSS.22 software. Frequency distribution tables and Chi-squared test, Fisher exact test and Kruskal-Wallis test were used for this purpose.
Results: The study of the characteristics of the subjects showed that their mean age was 33.76 (SD = 6.108) years; Their average work experience was 6.76 (SD = 5.217) years. Study participants were well educated, with 61.2% having a master's or doctorate degree. 49% (96) of the subjects were men and 51% (100) of them were women. Manufactured / consumed nanomaterials in companies were investigated in similar groups in terms of chemical composition (metal, metal oxide, carbonous and the others) and physical state (dry powder, suspension/ emulsion, paste/gel and the others). The results of investigating the frequency of symptoms of nanotechnology companies’ employees using nonspecific symptoms questionnaire showed that the frequency of some skin symptoms such as "redness", "itching" and "roughness" were 72.7%, 67.2% and 62.6%, respectively. the frequency of some respiratory symptoms were also high; "cough" (64.1%), "sneezing" (60.6%) and "sore throat" (60.1%). High-frequency ocular symptoms included "eye irritation" (66.2%), "itchy eyes" (28.3%), and "red eyes" (25.3%).
Investigation of the correlation between the skin symptoms of the employees with the chemical composition and physical state of the nanomaterials used in the companies showed that the symptoms "skin roughness", "skin itching", "skin rash" and "hair loss" have significant correlation with the physical state of nanomaterials and "skin redness", " Skin darkness "and" skin rash" have significant relationship with the chemical composition of nanomaterials. Investigation of the relationship between employees' gastrointestinal symptoms with the chemical composition and physical state of the nanomaterials used in the companies showed that the symptoms "appetite suppression", "thirst", "nausea/vomiting" and "darkness of stool color" have significant relationship with the physical state of nanomaterials and "thirst", "Nausea/vomiting" and "inability to detect taste" have significant relationship with the chemical composition of nanomaterials. Evaluation of the relationship between neurological symptoms of staff with the physical state and chemical composition of nanomaterials showed the significant relationship between "movement problems" and chemical composition of nanomaterials. Also, "dizziness" and "sleeplessness/wakefulness" were significantly associated with both the chemical composition and the physical state of the nanomaterials. Investigating the relationship between the chemical composition and physical state of the nanomaterials with the respiratory symptoms of staff revealed "shortness of breath", "wheezing", "chest heaviness", "difficult breathing", "increased phlegm" and "voice change" significantly correlated with Both the chemical composition and the physical state of the nanomaterials. "Cough" was also significantly associated with the chemical composition of the nanomaterials. Examination of the correlation between ophthalmic symptoms and chemical composition and physical state of nanomaterials indicated that the symptoms "blurred vision" and "visual impairment" were significantly correlated with the chemical composition of the nanomaterials. Also, "increased eye gum" and "red eyes" were significantly associated with both the chemical composition and the physical state of the nanomaterials.
Conclusion: Given the frequency of symptoms in staff exposed to nanomaterials, their statistical association with the chemical composition and physical state of nanomaterials, Staff's attitude toward nanomaterials that are generally considered safe, inadequate and generally inappropriate use of personal protective equipment appropriate to work with nanomaterials and lack of education and training about the effects of nanomaterials on health and the environment, existing these problems among the employees of these companies are reasonable and that is an important issue. Therefore, the following are suggested to reduce occupational exposure to nanomaterials: Provide adequate training to the staff of these companies in the areas of basic concepts of nanosafety, standard work procedures when working with nanomaterials, appropriate personal protective equipment for working with nanomaterials and using them properly and waste management of nanomaterials.