mohammad javad assari

Exposure to respirable crystalline silica (RCS) causes silicosis, lung cancer, autoimmune diseases of rheumatoid arthritis or systemic scleroderma, and benign respiratory system diseases. The risk assessment has an important scientific role in the control of occupational diseases by estimating the risk of death and determining the dose-response relationship. The present study aimed to evaluate the health risks of occupational exposure to RCS in workers in silica crushing, ceramics, foundry, and cement industrial sectors in Hamadan, Iran.

In this cross-sectional study, occupational exposure to RCS was investigated in 15 job titles. The potential lifetime cancer risk (LCR) was calculated by considering some factors, such as work experience, duration and frequency of exposure, lifetime and the reference rate of inhalation exposure, and the risk coefficient (hazard quotient: HQ), using the Olawoyin model.

The lowest levels of LCR (approximately 8 cases per 1.000.000 workers) and HQ (0.093) were obtained in the job title of Furnace (L) in the foundry, and the highest levels of LCR (approximately 2 cases per 1000 workers) and HQ (26.41) were observed in the job title of Supervisor (D) in silica crushing. The HQ levels in nine job titles were higher than the recommended allowable levels, while in other job titles, they were lower. Moreover, the results indicated a direct relationship between LCR and HQ levels in the studied job titles.

Considering the important and influential role of the parameters used to evaluate LCR and the possibility of HQ determination by the Olawoyin model, it is recommended that this model be employed to evaluate health risks in occupational exposure to RCS in future studies.

We conducted a systematic review of all published epidemiological research related to the relationship between occupational silica exposure and the rates of silicosis incidence and mortality.
  

We searched Scopus, PubMed, and Web of Sciences up to 11/07/2023, for original in any language. The search start date was not limited Observational studies, including cohort, case-control, and cross-sectional that have reported risk estimates for the association between silica exposure and silicosis mortality and incidence rates were considered. The methodological quality of the included articles was assessed using the Newcastle-Ottawa scale. Pooled estimates were calculated using the random effects model. Dose-response relations were explored through a two-stage random-effects model with “drmeta” command in Stata software version 14.
  

Nineteen observational studies were included in the present systematic review and meta-analysis. Based on the linear dose-response analysis, with each mg/m3 increase in daily occupational exposure to silica, the mortality risk of silicosis, the odds and risk of silicosis occurrence significantly increased by 10.19%, 360.02%, and 4.43 × 108%, respectively.
  

This review revealed that there is a linear dose-response relationship between occupational exposure to silica and incidence and mortality from silicosis. Our findings could have practical applications for occupational and public health. Considering the direct relationship between occupational silica exposure and high incidence and mortality rates of silicosis, the level of silica dust should be decreased in different industries.

Toluene, benzene, xylene, and ethylbenzene (BTEX) belong to the class of monocyclic aromatic hydrocarbons and are identified as toxic volatile compounds due to their harmful properties. The reliable biomarkers for occupational exposure to these toxic compounds are hippuric acid (HA), trans,trans-muconic acid (tt-MA), mandelic acid (MA), and methylhippuric acid (MHA), which correlate with toluene, benzene, ethylbenzene, and xylene, respectively.

A novel magnetized imine-linked covalent organic framework (Fe3O4@TFPA-Bd) was synthesized, marking its inaugural use as a sorbent in microextraction by packed sorbent (MEPS). The synthesis of Fe3O4@TFPA-Bd was executed in a straightforward and efficient manner, using Fe3O4 nanoparticles as the magnetic core and benzidine (Bd) and Tris (4-formyl phenyl) amine (TFPA) as the structural building blocks. This newly produced sorbent was tested for the microextraction of hippuric acid (HA), mandelic acid (MA), trans, trans-muconic acid (tt-MA), and m-methyl hippuric acid (m-MHA) from urine samples, which were then analyzed using high-performance liquid chromatography (HPLC). In order to optimize the extraction performance, parameters like sample volume, elution volume, extraction cycles, pH, and sample solution temperature were thoroughly adjusted. The synthesized adsorbent underwent thorough characterization via scanning and transmission electron microscopy (SEM and TEM), Fourier transforms infrared spectrometer (FTIR), and X-ray diffraction (XRD).

The developed method showcased promising attributes: low detection limits (0.02 µg/ml for tt-MA, S/N=3), low quantification limits (0.06 µg/ml for tt-MA, S/N=10), a solid linear range (0.5-320 µg/ml for MA, R > 0.99), and commendable intra- and inter-day precision (2.4%-4.3% and 3.1%-7.8%, respectively) for volatile organic compound (VOC) biomarkers. Furthermore, the method demonstrated recoveries in the 81-87.5% range for spiked samples, indicating its practicality and effectiveness.

The developed procedure was suitable for the determination of BTEX biomarkers from urine samples and can be an alternative to previous methods.

Date palm is a valuable economic product in the southern regions of Iran. Kerman province has the largest cultivated area of date palm in the country. The date palm scale, Parlatoria blanchardi, is one of the key pests of date palm trees in Iran, which sometimes causes significant damage to date palm groves, particularly young trees. Date palm pest control has typically been conducted using insecticides over the past decades. However, considering the negative aspects of chemical control programs, integrated pest management (IPM) and biological control programs have gained attention in recent years. There are significant and effective predators in date palm groves, and one crucial factor in the success of biological control is finding the interactions between predators and their various prey, which is a key criterion for selection. The interactions between prey and predator, and between generalist predators and their various prey, are essential components of ecological studies aimed at explaining the processes of animal population dynamics that can be used in IPM programs. The use of molecular markers has increasingly been employed to determine effective natural enemies. Regular monthly sampling of predators was carried out to determine the frequency of P. blanchardi genome in the digestive systems of predators. DNA extraction was manually conducted using the CTAB–based method, and for examining the P. blanchardi genome, two molecular markers (233 and 186 base pairs) of the mitochondrial cytochrome oxidase I (COI) gene from the date palm scale were used. The number and timing of sampling after feeding depend on the predator species studied and should be considered from the outset. The maximum detection time varies from a few hours to 5 days after feeding on the prey. Therefore, an experiment was designed to determine the maximum time for detecting the remnants of the prey genome in the predator's digestive system. The results confirmed the specificity of the primers used. The best time to detect the genome was determined to be 24 hours after feeding. Additionally, the results indicated that the coccinellid, Chilocorus bipustulatus L., with the highest frequency of detection based on the DNA of the date palm scale, is the dominant and effective species in the evaluated date palm groves. The results of this research have the potential to be used in biological control and ecological studies of predator–prey interactions..

Wastewater treatment plants (WWTPs) are a source of airborne bacterial contamination that can pose health risks to staff. The aim of this study was to evaluate seasonal variations in the health risks of exposure to Staphylococcus aureus bioaerosols using the quantitative microbial risk assessment (QMRA) approach in a WWTP in Hamadan, Iran. Study Design: This was a descriptive cross-sectional study.

This study determined the emission concentrations of S. aureus bioaerosols in summer and winter. Then, the health risks of three exposure scenarios (the worker, field engineer, and laboratory technician) were evaluated using the QMRA approach. The bioaerosol samples were collected every 12 days in both summer and winter of 2021 with a nutrient agar using a single-stage cascade impactor (Quick Take 30, SKC Inc.) in both outdoor and indoor environments.

The results demonstrated that in both seasons, S. aureus bioaerosol concentrations in outdoor and indoor environments were below the standard established by the American Conference of Governmental Industrial Hygienists (500 CFU/m3). While in summer, the annual infection risks and the disease burden for the three exposure scenarios in both outdoor and indoor environments were higher than the United States Environmental Protection Agency (≤ 10-4 pppy) and the World Health Organization (WHO) (≤ 10-6 DALYs pppy-1) benchmarks, respectively.

The findings provided high health risks for staff in the three exposure scenarios of an indoor environment, which should not be ignored, as well as emphasizing the use of the QMRA approach to estimate health risks caused by occupational exposure to bioaerosols and taking executive measures to protect staff working in the WWTPs.

A new and fast sample preparation method was developed to extract Hippuric acid (HA), Trans,trans-muconic acid (tt-MA), Mandelic acid (MA), and m-Methylhippuric acid (m-MHA) in urine samples using Hollow polymer nanospheres (HPSs), Covalent organic frameworks (COFs), and their mixture (HPS:COF) as an adsorbent, combined with high-performance liquid chromatography-ultraviolet spectrophotometry (HPLC-UV). X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used to study the features of the adsorbents. The effect of important factors such as temperature and pH of the sample, amount of sorbent, conditioning and washing solvents, type and volume of desorption solvent, sample volume, and the number of extraction cycles were investigated to achieve the optimal conditions with microextraction by packed sorbent (MEPS) procedure. The applicability of the proposed method was then validated in the laboratory. Finally, the target analytes in the urinary samples of gas station workers were examined. The data analysis showed that using an HPS:COF mixture improves the extraction efficiency in optimal conditions compared to the case where the COF adsorbent is used alone (extraction efficiency, 81-87.5%). Also, a good linear dynamic range (0.1-1000 µg/mL for m-MHA), a low detection limit (0.02 µg/mL for tt-MA), and acceptable intra-day and inter-day precision (1.4-3.6 % and 4.5-8.9 %, respectively) were obtained under similar conditions. Overall, HPS: COF-MEPS exhibited excellent extraction efficiency (85.4-93.3%) and has the potential to replace previous methods in the biomonitoring of BTEX biomarkers in urine.

The date palm scale Parlatoria blanchardi (Targioni Tozzetti, 1892) (Hem.: Diaspididae) is one of the main and important pests of reducing date palm yield. The predatory coccinellid Chilocorus bipustulatus L. (Col.: Coccinellidae) is well known as the most important active natural enemy in date orchards, which feeds on scale insects, especially the date palm scale In this research, the life table parameters of C. bipustulatus were determined by feeding on the date palm scale. The experiments were carried out in growth chamber under laboratory conditions, at 25±1°C, a relative humidity of 70±5%, and a photoperiod of 16:8 h (Light: Dark). A number of 100 coccinellid eggs of the same age with less than 24 h old were studied, and the study continued until the end of the adult stage. After incubation period, the larvae were fed daily with date palm scale nymphs. The biological parameters of the coccinellid and data were analyzed based on the age–stage, two–sex life table theory. The mean and standard error of population growth parameters were calculated based on the Bootstrap method. The intrinsic rate of increase(r) (day), finite rate of increase (λ), The mean generation time (T) and the gross reproductive rate (GRR), were 0.06 ± 0.01, 1.06 ± 0.01, 56.89 ± 0.32, 34.68 ± 3.08, respectively. The results obtained from this study can make it possible to improve the efficiency of this coccinellid in integrated pest management programs against P. blanchardi by increasing its population through mass rearing and mass release.

Azandarian industrial zone with about 40 active silica crushing units is one of the largest industrial area in Hamadan province, Iran.

In this study, the personal exposure of workers in the activated silica crushing units was measured. Assessing the risk of mortality due to exposure to Respirable Crystalline Silica (RCS) in the workplace was then estimated through measuring the personnel exposure in accordance with the National Institute for Occupational Safety and Health (NIOSH) 7601 method. Moreover, the mortality rate of lung cancer and risk of mortality due to exposure to RCS were estimated.

Based on the results, the average exposure of employees to RCS in the crushing units was in the range of 1.70 -0.14 mg/m3. As observed, the lowest and highest exposure was obtained for the admission unit and sandstone, respectively. In general, it can be inferred that in all studied occupation positions, the exposure level was higher than the recommended standard (0.25 mg/m3). As can be seen, the carcinogenic risk level for the exposed workers was in the range 2-26/1000. The results of risk assessment showed that the highest risk level was related to the stamping machine operator unit and the lowest was related to the administrative unit.

Therefore, the workers working in high-risk units such as stamping machine operator and stone separation operator are more likely to suffer from adverse health complications such as silicosis, lung cancer and other respiratory complications.

The date spider mite, Oligonychus afrasiaticus(McGregor) (Acari: Tetranychidae) is a destructive pest on date palm trees, causing high economic losses. Here, we investigated the relationship between population density of O. afrasiaticusand the extent of its injury level as well as the relation between rate of damage and date yield losses indices on six commercial date cultivars in five date palm growing provinces including Khuzestan (Sayer and Berhee), Hormozgan (Pyarum), Kerman (Mazafati), Bushehr (Kabkab), and Sistan and Baluchestan (Rabi) of Iran. The experiment was conducted in a complete randomized block design with five treatments and three replications.To this end, in each replication, four date clusters were selected from four different geographical directions, in each of them, 25 fruits were checked randomly to unveil the number of healthy and infested fruits. The sampling was repeated at seven-day intervals from late May to early September. Finally, the Norton model was used to estimate the economic injury level (EIL) under both biological and chemical control conditions. The highest value of EILin 2019 was estimated for Sayer in the chemical control method (1827 Mite-day) and the lowest one was estimated for Pyarum in the biological control method (25.5 mite-day). Our results also revealed that the cost of biological control was significantly lower than chemical control. The highest and lowest rate of date injury (symptoms of the pest feeding) were observed on Berheeand Mazafati cultivars, respectively. Also, the highest and lowest rate of date loss were observed on Kabkab and Sayer cultivars, respectively. On the other hand, the cost of chemical control in both years was higher than that of biological control.

The silica crushing is a process based on crushing, screening and, granulation of various types of silica rocks. The inhalation of silica dust leads to silicosis by causing irreversible fibrosis in lung tissue. The crystalline silica is classified as a human carcinogenic (group I) by the IARC. Azandarian region is one of the largest silica production units in Iran with 40 silica crushing factories. This study was conducted to application of Arc-GIS for zoning of occupational exposure to respirable crystalline silica (RCS) in this region.

In this descriptive study, the personal exposure levels to RCS in 16 workers silica crushing factories were measured according to the NIOSH method 7602. Also, 16 air samples were collected and quantified simultaneously to evaluate the environmental concentrations in the studied factories.

The results showed that the personal exposure level mean (2.01±2.61mg.m-3) was more than OEL proposed by the Technical Committee of Occupational Health of Iran country (0.025mg.m-3). The results showed a statistically significant difference between the mean concentration of the personal exposure to RCS in the different job activities (P = 0.001).

The results showed that there was no significant relationship between the personal exposure levels and environmental concentrations of the RCS. These findings showed that GIS has a desirable ability for zoning of occupational exposure levels to RCS in workplaces. This study also emphasizes the use of other modeling methods to determine the amount of silica release in the different units of the silica crushing factories.

One of the topics of Shiite belief is the Imam's unique knowledge of invisible things. The compilation of some hadith books and the narration of hadiths related to the knowledge of the Imam's invisible things, since the third century, provided the ground for a scientific proposal of this issue. What is remarkable is the seemingly contradictory historical reports that sometimes deny the Imam's knowledge of the invisible things, and some others approve it. Some of those conflicting reports have been collected by Sayyid Razi in Nahj al-Balaghah. Therefore, there is no conflict between them, and anyone can quickly summarize by correctly explaining the concept of "knowledge of invisible ". Despite conducted studies, no specific research has been done on the different perceptions obtained from these reports and its solution. This article has been done in a library method using historical and hadith sources and explanations of Nahj al-Balaghah. It aimed to remove ambiguity about the Imam's knowledge of the invisible and examine how to combine such reports in the same sense regarding "God's invisible knowledge" and "Imam's knowledge of invisible". According to the findings, the knowledge of the divine invisible knowledge has four characteristics of independence, detail, certainty, and actuality, while Imam's knowledge of invisible has lack of autonomy, conciseness, variability, and dignity.

Cold-Fiber Solid-Phase Microextraction (CF-SPME) is often used for the extraction of volatile and semi-volatile compounds from complex matrices. Multivariate statistical optimization techniques can save time and chemicals and thus decrease the analytical cost in comparison with the Single Variable Approach (SVA). Over the past few decades, different beneficial mathematical tools have been developed for the optimization of separation processes.

In this study, the Artificial Neural Network (ANN) and Response Surface Methodology (RSM) applications were compared for CF-SPME optimization to determine 2, 5-hexandion in urine samples. 2, 5-Hexanedione is a colorless liquid and the main metabolite of n-hexane as a result of occupational exposure.

N-hexane is widely used in the rubber industry, food processing, solvents, and medicinal drugs and has adverse effects such as neurotoxicity on humans. Thus, biological monitoring, analytic methods, and mathematical and statistical techniques concerning 2.5-HD are very important. The RSM and ANN are mathematical and statistical techniques applied for the optimization and process modeling. Designing an experiment based on the Historical Data Design (HDD) of RSM was adopted to evaluate the relationship between independent parameters such as extraction temperature, extraction time, sample volume, and extraction efficiency of 2, 5-hexandion.

The models were compared for their predictive ability by the coefficient of determination (R2) and Root Mean Square Error (RSME) based on the train and test dataset.

The results were highly significant (P < 0.05) for the optimization of variables. The ANN model had more generalizability than the RSM model. Also, the ANN had higher predictive accuracy.

In recent years, the drying blossom of date palm caused extensive damage to a considerable part of date palm orchards of Bam and Baravat, south of Iran. Drying blossom is responsible for a large amount of product loss and has been expanding in recent years. In this study, the technology of GIS was used as a quick and easy solution for monitoring of the drying blossom of date palm. It was carried out in three stages: collecting field information from damaged orchards,  feeding GIS with all collected data, and extracting  required information and the maps from the system which showed the severity and distribution of drying blossom in Bam and the suburb by three methods nearest neighbor, inverse distance weighted (IDW), and kriging. Results, upon data normalization, and the trend analysis showed that the severity of the damage in the southern coastal orchards was much higher than that in central and northern regions; the finding led us to focus on certain geographical coordinates (58 degrees and 20 minutes east longitude and 29 degrees and 4 minutes northern latitude to 58 degrees and and 26 minutes east longitude and 29 degrees and 2 minutes north latitude). It has been found  that the rate of drying blossom of date palm in 57.2% of the total damaged orchards were between 20-30%, and in 5.9% of the damaged gardens higher than 40%. Interpreting the results of the distribution of drying blossom on maps showed a relation between the severity of the disorder and the elevation of the area. It could be seen that the palm trees grown at altitudes above 1000 m suffered less damage; in other words, the higher the altitude, the less severity of drying blossom. The pictures received from Sentinel satellite showed that 56.2% or 2049 ha out of 3647 ha total area of palm orchards of Bam and Baravat was affected by drying blossom.

Dubas bug, Ommatissus lybicus, is one of the key pests of date palm groves in Iran. Chemical control is currently used regardless of the population of pests and its economic problems. The aim of this study was to determine O. lybicus economic injury level with a different method from the conventional method which is easier with the same precision. Therefore, Delphi method or expert system was used. It was carried out in the three provinces of Kerman (Bam), Fars (Farashband), and Bushehr (Tang-e zard). Twenty-five questionnaires were distributed between experts and farmers in each province. The completed questionnaires were collected. According to the results of the first questionnaire, the second questionnaire was compiled and the stages were repeated. The results showed that the Delphi method provides valuable results such as the description of individual variables (the age of palm growers, literacy, level of experience, garden area and gardener pest management) that can be effective in pest management planning. However it could not produce accurate results for quantitative data such as determining the timing of chemical control according to pest number, the amount and percentage of damage, because this data is available and the Delphi method should not be used as an excuse, in such cases the Delphi technique can be used as a complementary method.

Dubas bug, Ommatissus lybicus Bergevin (1930), is one of the key pests of date palms in Iran, which drastically reduces the quality and quantity of dates produced. The Present study aimed to determine economic injury level of O. lybicus on two commercial date cultivars in three main date palm growing provinces of southern Iran. The economic injury level of dubas bug on date palm was estimated by Pedigo method. A date palm grove infested by dubas bug was chosen in Kerman (Bam), Fars (Farashband), and Bushehr (Tang-e Zard) provinces. The study was conducted in randomized complete block design with seven treatments replicated three times. Each experimental unit consisted of three identical trees in which the sampling was performed on the middle tree. We reached the intended densities of O. lybicus using natural and artificial infestation by using insecticides. The assessment was made based on the weekly recording the number of nymphs and honey droplets. In addition, the total weight of the harvested date was determined at harvesting. The results showed that EIL based on the number of nymphs/leaflet of date palm leaf on Zahedi cultivar were 1.06 and 0.34 nymphs for Farashband, respectively, and 0.28 and 0.88 nymphs for Tang-e Zard in studied years. The values for Bam on Mazafati cultivar in the three consecutive years of 2013, 2014 and, 2015 were 0.27, 0.25, and 0.10 nymphs, respectively.

Prolonged exposure to crystalline silica (CS) (SiO2 ) dust enhances the production of reactive oxygen species. In many studies, oxidative stress has been measured in the serum of workers exposed to SiO2 dust.

We investigated the body fluids such as urine, saliva, and serum, which can provide very good results for assessing the health status of workers’ exposures to SiO2 dust.

The oxidative stress biomarkers were evaluated in serum, urine, and saliva of 21 workers who were exposed to SiO2 silica crushing factories in the Hamadan city at the west of Iran as a case group and 28 controls.

The level of malondialdehyde in serum, urine, and saliva was significantly higher than that in case group compared to controls (22.19 ± 8.70, 9.86 ± 5.43, and 9.41 ± 7.31 nmol/L vs. 7.30 ± 2.22, 6.79 ± 3.21, and 3.93 ± 3.73 nmol/L, respectively). In addition, the total antioxidant capacity in urine (0.23 ± 0.06 vs. 0.29 ± 0.08 mmol/L), as well as catalase in the serum and saliva of case group was lower than that compared to control group (5.46 ± 1.56 and 1.32 ± 0.55 IU/L vs. 12.55 ± 5.72 and 2.32 ± 1.53 IU/L, respectively).

The current study indicated that chronic exposure to SiO2 affects significantly on the oxidative stress biomarker levels in serum, urine, and saliva in persons exposed. Furthermore, SiO2 leads to the induction of oxidative stress and decreases the activity of the antioxidant enzyme.

In the hot workplaces, the increase of body core temperature is induced in result of exposure to high air temperature and metabolism heating due to worker activity. Heat exposure can affect how well chemicals are absorbed into the body. Core temperature change can alter absorption, distribution, metabolism and excretion of the toxicants. Increases in respiration can cause further toxicant exposure through inhalation, while increases in sweat and skin blood and pulmonary ventilation flow can make more efficient transcutaneous absorption of toxicants. Therefore, the amounts of xenobiotic absorbed through the lungs and the skin during heat exposure can be raised significantly in result of higher pulmonary ventilation and cutaneous blood flow. Animal studies which are investigated the effects of thermal stress on chemical toxicity showed that heat exposure plays a role on toxins absorption. However, it is difficult to interpret these findings when trying to compare differences between humans and the animal models. It is observed that workers exposure in some work environment suggests that concomitant exposure to heat stress and chemicals is likely to increase the absorption and effects of certain xenobiotics. Tetrachlorethylene is a particular chemical compound is often used for laundry. The main route for human exposure to tetrachlorethylene is via inhalation, but the compound is also adsorbed by mouth contact. As mentioned, most of what is known on the effect of heat exposure on absorption of chemicals comes from animal studies. With regard to the importance of analyzing how thermal stresses can effect on toxicity response of chemical agents and moreover, need to better understanding of its related mechanisms in humans, the present study aimed to investigate the relation of body heat strain level with Tetrachlorethylene concentration in exhaled air among laundry workers in Hamadan city.

This descriptive analytical study was conducted in two steps of winter and summer in 2017. Twenty-four healthy workers employed in laundry workrooms located in the city of Hamadan, Iran, were enrolled in the study. Their age, height and weight were respectively 32.1 ± 5.16 year, 173.7±11.5 cm, 70.3±16.5 kg. The participants were screened using a self-reported questionnaire in terms of their state of mental and physical health. Before initiation of the tests, a written informed consent form was signed by the subjects participating in this research. Based on ISO 9920 (2007), clothing insulations (Clo unit) of the participants were 1 Clo and 0.75 in winter and summer, respectively. Ambient air samples of laundry workroom were obtained using 150 mg coconut shell charcoal tubes (20/40 mesh) SKC and using SKC personal sampling pumps model 222 calibrated to a flow rate of 100 cc/min. The air samples were analyzed by the NIOSH method no 1003 recommended for Tetrachlorethylene. Desorption of Tetrachlorethylene from activated charcoals was done with 1ml of carbon disulfide. After 30 minutes an aliquot of the resultant solution (1 µl) was injected into Shimadzu 2010 gas chromatograph equipped with a flame ionization detector (F.I.D) and Rtx-1 column. One ml volume of the sample was injected into the gas chromatograph with a Hamilton gas—tight syringe. The instrumental temperatures were as follows: injector temperature, 250C; initial oven temperature, 70C (held for 5 min), increased to 120C at a rate of 10C min-1, held for 5 min. For exhaled air samples of the same participants, individuals were asked to exhale normally into a 3 liter Tedlar air bags (SKC) until it was filled. Measuring Tetrachlorethylene in exhaled air was conducted through integrating NIOSH 1003 and NIOSH 3704 methods through optimizing analysis parameters using analytical device GC-FID.  Thermal strain of exposed workers was measured based on oral temperature, heart rate and respiratory rate in accordance standard method ISO 9886:2004. The heart rate was measured using a heart rate device (Beurer PM100). Statistical analysis of the data was performed using the SPSS software version 20. The significance level of the tests was considered 0.05.

The mean of dry temperature, natural wet bulb temperature and globe bulb temperature were 29.42°C, 23.96°C and 30.77°C, respectively. The mean of Tetrachlorethylene concentrations in ambient air of laundry workplace in summer and winter were 45.91 ppm, 50.64 ppm, respectively. The mean values of the thermal strain indexes included oral temperature, heart rate, and pulmonary ventilation in summer and winter were 37.3°C and 37.1°C, 99.95 and 90.95 beats per minute, 26 and 20.5 breath rate per minute, respectively. The mean values work metabolism in summer and winter were 110.86 and 108.73 kcal/h, respectively. The mean of Tetrachlorethylene concentration in exhaled air in summer and winter is 3.18 and 2.23 ppm, respectively, which were higher and lower than national occupational exposure limit (3 ppm). The significant difference was observed between the mean Tetrachlorethylene concentrations in exhaled air in summer and winter (p<0.05). Paired sample t-test was not showed a significant difference between the mean Tetrachlorethylene concentrations in ambient air samples in two steps (p>0.05). According to the results of paired sample t-test, core temperature, heart beat rate and pulmonary ventilation of workers were significantly increased in summer compared to winter (p<0.05). The results showed that correlation between Tetrachlorethylene concentration in the exhaled air and ambient air samples in winter (p= 0.003, r = 0.58) and summer (p= 0.023, r = 0.46) were statistically significant.

Few quantitative data has been published on this subject, and hence, this study aimed to investigate the interaction of coexposure to heat and chemical agents in real work condition. The present study confirmed that the Tetrachlorethylene concentration was increased in the workers̕ exhaled air in result of thermal strain in the laundry workrooms. It can be confirmed that workers who are exposed to extreme heat may be at risk for increased absorption of chemicals into the body. The quantities of Tetrachlorethylene absorbed via the pulmonary routes during work in the studied environment could significantly increase due to the elevation in pulmonary ventilation rate. It should be note that, the increase in skin temperature and skin blood flow as well as the presence of sweat on the skin surface may also promote the cutaneous absorption of chemicals during concomitant exposure to heat. It is suggested to empirically investigate workers skin absorption of chemical agents in exposure to high air temperature compared with natural condition in future studies.

Nanoparticles (NPs) are a heterogeneous group of materials that have various applications, and their risk assessment is an essential condition. This study aimed to review the applicable risk assessment methods in occupational and environmental exposures to NPs. A literature search for articles published since 2005 in Web of Knowledge, Scopus, PubMed, Science Direct, and Google Scholar, using appropriate keywords such as “Risk Assessment,” “Nanoparticle,” and “Nanomaterial,” revealed 56 articles, which were screened by two researchers. A total of 15 articles were reviewed in full text. In total, 11 applied techniques for NP risk assessment were analyzed. Seven methods were quantitative, and four were qualitative. The quantitative methods were Integrated Probabilistic Risk Assessment (IPRA), Integrated Probabilistic Environmental Risk Assessment (IPERA), Quantitative Structure-Activity QSTR-Perturbation Model, Lung Dosimetry Modeling for Quantitative Risk Assessment (LDMQRA), Physiologically Based Pharmacokinetic Modeling (PBPK), Risk assessment based on toxicokinetic modeling, and Risk assessment of NPs with Spray Application. The qualitative methods were Application of Toxicogenomics for Risk Assessment, Luminous Microbial Array for Toxicity Risk Assessment (Lumi MARA), Control Banding Nano Tool (CBNT), and Stoffenmanager Nano Tool. It can be concluded that each of the studied methods evaluates an NP and is specifically used for that NP. A general risk assessment approach cannot be applied to all NPs but should be separately investigated by different processes.

Background and Cyclophosphamide and ifosfamide are two most widely used and hazardous drugs in chemotherapy centers. This study aimed at determining surface contamination with cyclophosphamide and iphosphamide in chemotherapy centers.
This descriptive cross-sectional study was carried out in three chemotherapy centers affiliated with Hamedan University of Medical Sciences, Iran 2016. Twenty eight samples were collected from contaminated surfaces. The samples were then prepared by solid phase extraction and analyzed by HPLC/UV apparatus.
The mean values for surface contamination of cyclophosphamide and ifosfamide were 57.28 ± 63.8 and 44.15 ± 5.5 ng/cm2, respectively. The highest levels of contamination with both drugs were observed at exhaust hood surfaces and the lowest level of contamination was seen in nursing station and staff resting place. The clothes and gloves of nurses were also found to be contaminated.
Daily number of medications, the location of drug preparation room and injection room, nursing station, staff resting place, daily cleaning programs, and repairing and maintenance of ventilation systems were amongst the major factors affecting surface contamination in chemotherapy centers.

When workplace air monitoring is not sufficient to determine the exposure levels, the determination of compounds and some metabolites in exhaled air and personal exposure levels is considered a practical method for biological monitoring. The aim of this study was to determine the relationship between the concentration of tetrachlorethylene in exhaled air and personal exposure levels in the dry cleaning workers
In this descriptive cross - sectional study was performed in 2017, in addition to the collecting samples of exhaled air and personal exposure of 12 workers, the ambient air samples of dry cleaning workplace were examined. Also the ambient air samples were studied simultaneously. Measurement of tetrachlorethylene in the exhaled air was performed using gas chromatograph equipped with flame ionization detector (FID) through an incorporation of 1003 and 3704 NIOSH methods and optimization of analysis parameters.
In this study, the personal exposure levels were above the recommended national occupational exposure limits (OEL-TWA), and tetrachlorethylene concentration in exhaled air of workers were above the biological exposure index (BEI) respectively. The results showed that there is a significant relationship between the concentration of tetrachlorethylene in exhaled air and personal exposure levels (r=0.66, P=0.046). Also, was obtained the significant relationship between the concentration of ambient air with exhaled air concentrations (r=0.59, P=0.003), and personal exposure levels (r=0.91, P The results indicated that tetrachlorethylene measuring in the exhaled air as a non-invasive biomarker is valid enough for assessing occupational exposure in the dry cleanings. And also tetrachlorethylene concentration in exhaled air can be measured with high sensitivity through optimizing of analytical conditions in GC-FID system and the integration of 1003 and 3704 NIOSH methods.

Formaldehyde used in the pathology and histology laboratories as a tissue fixation. Formaldehyde classified in group A1 (human carcinogen) by the International Agency for Research on Cancer (IARC). The aim of this study was the evaluation of relationship between ambient concentrations and time-weighted average or ceiling exposures of formaldehyde the pathology departments.
This descriptive analytical study was performed in the second half of year 1395 at four teaching hospitals in Hamadan university of Medical Sciences. For those purpose 28 TWA samples (by a census method), 17 environmental and, 5 ceiling samples in the peak of pollution were collected simultaneously. The NIOSH 3500 method was used to sampling and analysis of air samples.
The mean ambient concentration of formaldehyde was 1.67±1.81 ppm. The mean personal exposure levels in both TWA and ceiling were obtained 0.31±0.40 ppm and 2.36±2.34 ppm respectively. TWA and ceiling levels were more than from NIOSH recommended exposure limits (REL) and Iran's national occupational exposure limit (OEL) respectively. In this study, there were a significant correlation between the personal concentrations with TWA (r= 0.82 , P=0.0001) and ceiling exposure levels (r=0.47 , P=0.01).
According to the exist challenges in the risk assessment of formaldehyde, this study in addition to measuring the ceiling exposure levels in the contaminant peak emphasized the simultaneously measure ambient concentrations and TWA exposure levels in order to informed of the staffs exposure levels to assurance effectiveness of control measures at the teaching hospitals.

Occupational exposure to halogenated hydrocarbons has been associated with halothane hepatitis, an increase of liver enzymes, and congenital malformations. The objectives of this study were to investigate whether bromide, a urinary metabolite of halothane, could be used as a biological marker of exposure to this anesthetic gas and assessment of associated exposure to halothane with any significant changes in conventional parameters of liver function (serum aminotransferase activities).
Study design: A cross-sectional study.
Seventy-five anesthesiologists, anesthesia nurses, operating room nurses, and surgeons (exposed group) and 75 matched unexposed individuals (reference group) were selected randomly from two public hospitals in Hamadan City, western Iran. Atmospheric concentrations of halothane in the breathing zone of the exposed subjects and urinary bromide levels were measured by headspace gas chromatography. Similarly, serum activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured by the enzymatic method using an automatic Prestige instrument.
Mean atmospheric concentrations of halothane and urinary bromide levels for exposed subjects were 1.49 ±1.36 ppm and 0.83 ±0.29 mM, respectively. A relatively good correlation was found between exposure to halothane and urinary bromide levels (r=0.38). The chi-squared test results showed that the proportions of the subjects with abnormal ALT and AST among the women exposed were significantly higher than those of reference individuals (P Urinary bromide can be used as a potential biomarker of exposure to halothane, although additional studies are necessary to further validate these initial findings.

Nanotechnology as a key technology in the 21st century refers to the science of manipulating molecules and atoms in size range of 1 to 100 nanometers. Given the importance of investment in research and development, promoting knowledge and attitude of students can have a positive effect on expanding the scope and use of these emerging technologies.
In this descriptive analytical study, the knowledge and attitudes of 130 students towards the benefits and risks of nanotechnology were investigated through a questionnaire. The participants were studying occupational and environmental health engineering in Hamadan, Ilam, and Semnan Universities of Medical Sciences.
The mean score of student's knowledge was 16.08 ± 1.61. A significant difference was observed between the mean scores of knowledge in undergraduate and graduate students (P= 0.001). However, no significant deference was observed in the mean score of knowledge between women and men, different age groups, and the year of entrance to university. Using linear regression equation and by considering knowledge level as a dependent variable, it was indicated that age and educational level were significantly related to the state of knowledge.
The results showed that most students did not have an acceptable level of knowledge about nanotechnology. Considering the benefits and risks of this technology, students have a positive attitude to develop use of nanotechnology in Iran.

Formaldehyde (FA) is a colorless toxic gas used as a disinfectant and preservative and known as a carcinogen and strong irritant. Due to its germicidal, preservative and fixative properties, formaldehyde or other chemicals that potentially produce formaldehyde, are used in some cosmetics. OSHA has warned about hair dresser’s exposure to FA higher than threshold limit values. Because of the importance of this air pollutant and the lack of enough studies in Iran, the present study aimed at occupational monitoring of FA exposure in hair salons in Hamedan and Kermanshah cities.
Short term (n=20) and long term (n=45) air samples were collected on sorbent tubes in the breathing zone of selected hair dressers and then analyzed based on methods NIOSH 2016 and 2541, respectively.
The concentrations of FA in short-term and long-term samples were in ranges of 0-0.6935 and 0-0.6034 ppm, respectively. There were no statistically significant differences between mean concentrations of FA in long- term and short-term samples and also between studied work tasks (based on used cosmetics).
According to obtained results, the concentration of FA in some samples was higher than Iran’s OEL (0.3 ppm). Therefore, it is necessary to do more occupational exposure monitoring and apply control measures such as installing proper ventilation systems, correcting the existing systems, supervising the quality of cosmetics, and training programs for target group.

The development of nanotechnology has result in the creation of new job opportunities and economic growth. But the lack of sufficient information about the toxicity and occupational exposure limits to nanomaterials on the toxicity and occupational exposure limits established nanomaterials always has created concerns. In this study design and providing of a simple software package based on Control Banding recommended by NIOSH (National Institute for Occupational Safety and Health), for assessing the risk of occupational exposure to nanomaterials.
In this experimental study, C # 2010 software was utilized in order to design the software package. first, the general principles of Control Banding risk assessment method recommended by the National Institute of Occupational Health and Safety (NIOSH) analyzed carefully. Then, all primary and secondary factors with their relative importance (weight) and influence on the risk level were considered exactly in the design software. Finally, the proposed package was used to assess the individual exposure to nanomaterials in several research laboratories.
From these results, the average (RL2) and acceptable (RL1) risk levels obtained at work stations that manipulated multi-wall nanotubes (MWNT) and titanium dioxide nanoparticles (TiO2) respectively.
The proposed package could be used as a simple, reliable, fast, and easy tool to assess the risk of occupational exposure to nanomaterials. It also will able to provide appropriate solutions to improve working conditions for employees if implement control measures are needed.