The status of work-related COVID-19 prevention measures and risk factors in hospitals.

BACKGROUND: Health care workers (HCWs) in hospitals are at risk of infection with coronavirus disease 2019 (COVID-19). Prevention measures are necessary to protect HCWs against COVID-19. OBJECTIVE: This study aimed to determine the status of occupational risk factors and prevention measures for COVID-19 in hospitals. METHODS: This cross-sectional study was conducted in Iranian hospitals. Based on the results of reviewing the literature and guidelines, two checklists on occupational risk factors and prevention measures for COVID-19 in hospitals were designed and validated. The status of occupational risk factors and prevention measures against COVID-19 in governmental, non-governmental public, private, and military hospitals were determined using designed checklists. RESULTS: Results confirmed the validity of checklists for assessing the status of COVID-19 prevention measures in hospitals. The military hospitals had the lowest mean risk factors compared to other hospitals, but there was no significant difference in occupational risk factors of infection with COVID-19 among governmental, non-governmental public, private, and military hospitals (P-value > 0.05). In the checklist of occupational risk factors of Covid-19, the type of hospital had a significant relationship with the provision and use of personal protective equipment (P-value<0.05). The mean of implementation of prevention measures among all hospitals were not statistically significant difference (P-value > 0.05). CONCLUSION: The provided checklists could be a suitable tool for monitoring of status of prevention measures for COVID-19 in hospitals. Improving ventilation systems is necessary in most of the hospitals.

Health risk assessment of exposure to benzene, toluene, ethyl benzene, and xylene in shoe industry-related workplaces.

Benzene, toluene, ethyl benzene, and xylene (BTEX) are prevalent pollutants in shoe industry-related workplaces. The aim of this study was to assess exposure to BTEX and their carcinogenic and non-carcinogenic risks in shoe-industry-related workplaces. This study was carried out at different shoe manufactures, small shoe workshop units, shoe markets, and shoe stores in Tabriz, Iran in 2021. Personal inhalation exposure to BTEX was measured using the National Institute for Occupational Safety and Health (NIOSH) 1501 method. Carcinogenic and non-carcinogenic risks due to inhalation exposure to BTEX were estimated by United States Environmental Protection Agency (U.S. EPA) method based on Mont Carlo simulation. Results showed that the concentrations of benzene and toluene were higher than the threshold limit value (TLV) in both gluing and non-gluing units of shoe manufactures. The total carcinogenic risk (TCR) due to exposure to benzene and ethyl benzene was considerable in all shoe industry-related workplaces. Also, the hazard index (HI) as a non-carcinogenic index was higher than standard levels in all shoe industry-related workplaces. Therefore, shoe industry-related workers are at cancer and non-cancer risks due to exposure to BTEX. Prevention measures need to be implemented to reduce the concentration of BTEX in shoe industry-related workplaces.

DNA damage in foundry workers using non-invasive micronucleus cytome assay.

Workers in the foundry industry are exposed to hazardous chemical agents such as metal fumes, gases, vapor of molten metal, and respirable dust and hazardous physical agents such as heat, noise, and electromagnetic fields. Co-exposures to hazardous physical and chemical agents in foundry workplaces may cause DNA damage in workers. This study aimed to evaluate DNA damage in foundry workers. Thirty-three exposed foundry workers as a exposure groups and 33 non-exposed individuals as a control groups participated in this study. Buccal micronucleus cytome (BMCyt assay) assay was used to assess DNA damage. Results showed that foundry workers were under exposure to hazardous chemical and physical agents such as metal fumes and noise. The percentage of micronucleus (MN) cells in exposure group (0.59 ± 0.93 %) were statistically higher than control group (0.23 ± 0.23 %) (P < 0.05) %). Also, the percentage of nuclear bud cells and binucleated cells in exposure group were statistically higher than control group (P < 0.05). The percentage of differentiated normal cells were significantly higher in the control group compared to the exposed group (P < 0.05). Foundry workers are at risk of DNA damage; therefore, prevention measures need to be implemented to reduce exposure to air pollutants in foundry workplaces.

Carcinogenic and non-carcinogenic risk of exposure to metal fume in different types of welding processes.

The international agency for cancer research (IARC) has classified welding fumes as definitive carcinogens. The aim of the present study was to assess health risk due to exposure to welding fumes in different welding types. In this study, exposure to fumes of iron (Fe), chromium (Cr), and nickel (Ni) in the breathing zone air of 31 welder engaged in arc, argon and CO2 welding was assessed. Carcinogenic and non-carcinogenic risk assessments due to exposure to fumes were performed using the method proposed by the Environmental Protection Agency (EPA) by Monte Carlo simulation. The results showed that in the CO2 welding, concentration of Ni, Cr, and Fe was lower than the 8-h Time-Weighted Average Threshold Limit Value (TWA-TLV), recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). In argon welding, Cr and Fe concentrations were higher than the TWA-TLV. In arc welding, concentrations of Ni and Fe were more than the TWA-TLV. In addition, the risk of non-carcinogenicity due to exposure to Ni and Fe in all three types of welding was more than standard level (HQ>1). The results indicated that the welders are at health risk due to exposure to metal fumes. Preventive exposure control measures such as local ventilation need to be implemented in welding workplaces.

Micronucleus assay of DNA damage among welders: Effects of welding processes.

Metal fumes, gases, noise, and radiation are hazardous occupational exposures that may be encountered by welders. We have evaluated DNA damage among welders; the buccal micronucleus cytome (BMCyt) assay was used. Thirty-four exposed welders (cases) and an equal number of non-welders (controls) participated in this study. Cell types including basal, early and late differentiated cells with micronucleus (MN), dense chromatin, karyorrhectic, pyknotic, karyolitic, and binucleated cells (NBUD) were measured. Damage levels among, arc, argon, and CO2 welders were statistically significantly higher, compared to the control group. Results showed that mean of MN and NBUDs as indicators of DNA damages among arc, argon and CO2 welding's were significantly higher compared to control group. Also, the mean of DNA damage levels were statistically higher among the arc welders than among the argon or CO2 welders; and levels were higher among the argon welders than the CO2 welders. Preventative measures need to be implemented to reduce exposure to harmful agents during welding.

Cancer risk assessment of exposure to asbestos during old building demolition.

BACKGROUND: Years ago, the use of asbestos in construction materials was common. Although asbestos has been recently banned in many countries, exposure to asbestos during old building demolition is not unexpected. OBJECTIVE: The aim of this study is to assess the concentration of exposure to asbestos and estimate its cancer risk among old building demolition workers. METHODS: In this study, personal air samples were collected during building demolition. The number of asbestos fibers in collected samples were determined according to the NIOSH-7400 standard method. Chemical compositions of fibers were assessed using scanning electron microscopy (SEM). The carcinogenic risk of exposure to asbestos was determined based on the recommended United State Environmental Protection Agency (USEPA) method and Monte-Carlo simulation used to estimate the probability of cancer. RESULTS: Chemical analysis confirmed the presence of asbestos in collected air samples, and 67% of counted fibers were asbestos. In a number of buildings, workers had exposed to asbestos that was higher than occupational exposure limit (0.10 f/ml). Results of cancer risk estimation showed that cancer risk were considerable among workers. CONCLUSION: Implementation of asbestos risk management program such as separation of asbestos containing material, personal protective equipment's and use of wet method in demolition could minimize asbestos exposure during old building demolition.

Occupational Exposure to Metal Fumes Among Iranian Welders: Systematic Review and Simulation-Based Health Risk Assessment.

There have been numerous reports of welder's worker exposure to metal fumes. Carcinogenic and non-carcinogenic (neurological, dermal, and etc.) effects are the adverse outcomes of exposure to welding fumes. In this review study, data were collected from previous studies conducted in Iran from 1900 to 2020. The risk of carcinogenicity and non-carcinogenicity due to exposure to welding metal fumes was assessed using the United States Environmental Protection Agency (USEPA) method based on the Monte Carlo simulation (MCS). Results showed mean of metal fume concentration in gas welding was in the range of 1.8248 to 1060.6 (µg/m3) and in arc welding was 54.935 to 4882.72 (µg/m3). The mean concentration of fumes in gas welding is below the recommended American Conference of Governmental Industrial Hygienists (ACGIH) standard exposure limit except for manganese, and in the arc welding, all metal fume concentrations are below the standard exposure limit except for manganese and aluminum. The results showed that the risk of carcinogenicity due to exposure to nickel, manganese in both gas and arc welding, and cadmium in gas welding was higher than standard level (hazard quotient (HQ) more than 1). Cancer risk due to exposure to nickel in both gas and arc welding was probable (1 × 10-6 < cancer risk (CR) < 1 × 10-4). Health risk assessment showed that welders are exposed to health risks. Preventive measures should be applied in welding workplaces to reduce the concentrations of metal fumes.

Seat belt use among rural non-drivers: the role of demographic and traffic-related variables.

BACKGROUND: The rate of seat belt use in rural societies is less than in urban societies. The present study aimed to determine the effect of demographic and traffic-related variables on seat belt use among rural non-drivers based on the theory of planned behavior (TPB). METHODS: This study was conducted among 450 non-drivers in the rural areas of Hashtroud district in Iran. For collection of data, a questionnaire containing questions about demographic characteristics and general information on traffic-related behaviors of non-drivers, and questions on seat belt use based on constructs of the TPB was used. RESULTS: The lowest seat belt use rate was for non-drivers that sit in the rear seat of a car on rural roads (22.4 % never, 14.4 % always). Also, the rate of seat belt use among parents of participants on rural roads was lower than on city roads. Adherence to traffic rules and having training about seat belt use had significant effects on the construct of TPB, including attitude, subjective norms, perceived behavioral control, behavioral intention, and behavior of seat belt use. With increasing age, subjective norms about seat belt use have improved. The attitude toward seat belt use among females was better than males. CONCLUSIONS: The result indicated that most of rural non-drivers did not adhere to traffic rules. Adherence to the traffic rules and having training on seat belt use had a significant impact on seat belt use behavior. Training seat belt use especially by parents could be effective in improving seat belt use.

Risk Assessment of Silicosis and Lung Cancer Mortality associated with Occupational Exposure to Crystalline Silica in Iran.

BACKGROUND: Exposure to crystalline silica has long been identified to be associated with lung diseases. Therefore, the present study aimed to assess the risk of silicosis and lung cancer associated with occupational exposure to crystalline silica in Iran. STUDY DESIGN: It is a systematic review study. METHODS: Different databases were searched, and the Cochrane method was used for the systematic review. Thereafter, cumulative exposure to crystalline silica (mg/m3-y) was calculated in every industry. The relative risk of death from silicosis was performed using Mannetje's method. Based on the geometric mean of exposure, the lung cancer risk of exposure to crystalline silica was also calculated. RESULTS: As evidenced by the results, worker's exposure to silica ranged from a geometric mean of 0.0212- 0.2689 mg/m3 (Recommended standard by the American Conference of Governmental Industrial Hygienists (ACGIH) was 0.025 mg/m3), which is generally higher than the occupational exposure limit recommended by National Institute for Occupational Safety and Health (NIOSH), ACGIH, and occupational exposure limits. The relative risk of silicosis was in the range of 1 to 14 per 1000 people, and the risk of lung cancer in workers ranged from 13-137 per 1000 people. CONCLUSION: Since workers are at considerable risk of cancer due to exposure to silica in Iran, exposure control programs need to be implemented in workplaces to decrease the concentration of silica.

Lung Cancer and Pleural Mesothelioma Risk Assessment for the General Population Exposed to Asbestos in Different Regions of Tehran, Iran.

BACKGROUND: Asbestos is a natural fiber leading to health risks like chronic lung diseases. The current study aimed to estimate pleural mesothelioma and lung cancer risk for population exposure to asbestos in Tehran, Iran. STUDY DESIGN: A cross-sectional study. METHODS: According to the annual report of Air Quality Control Company (AQCC), from 2011-2020, carcinogenic risk and mesothelioma were assessed based on the Environmental Protection Agency (EPA) method using the Monte Carlo simulation (MCS). The relative risk (RR) of mortality cancer was calculated based on Camus and colleagues' model. Moreover, mesothelioma risk was estimated by Bourgault and colleagues' model. RESULTS: The mean concentration and health risk of asbestos in ambient air generally reduced from 2011 to 2020. The highest mortality risk for lung cancer was 8.4 per 100000 persons in 2011 and reduced to 1.8 in 2017. For mesothelioma, the corresponding values were 8.96 per 100000 persons in 2011 and reduced to 1.92 in 2017. CONCLUSION: The findings of this study could be helpful to health policymakers in the management of asbestos risk.

The exposure to formaldehyde in industries and health care centers: A systematic review and probabilistic health risk assessment.

Formaldehyde is classified as a definitive human carcinogen by the International Agency for Research on Cancer (IARC). The workers in several industries such as foundry, melamine, resin, and health care centers (pathology and anatomy laboratories and operating rooms) are exposed to airborne formaldehyde. In this systematic review, studies conducted from 2000 to 2020 on occupational exposure to airborne formaldehyde in Iran were collected and analyzed. The carcinogenic and non-carcinogenic risk assessments of exposure to airborne formaldehyde were estimated using the recommended United State Environmental Protection Agency (USEPA) method by Monte-Carlo simulation. Results demonstrated that in both health care centers and industrial settings, mean concentrations of airborne formaldehyde were higher than that 8- hour time-weighted average threshold limit value (TWA-TLV) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). Also, results showed that cancer and non-cancer risks due to exposure to airborne formaldehyde (Neurological, dermal, respiratory effects and so on) were considerable in both industrial settings and health care settings. The results of this study could be used by health policy makers to eliminate or reduce exposure to airborne formaldehyde in workplaces.

Health Risk Assessment of Occupational Exposure to Hexavalent Chromium in Iranian Workplaces: a Meta-analysis Study.

Occupational exposure to hexavalent chromium (Cr+6) has reported in different industries. The Cr6+ has the carcinogenic and non-carcinogenic effects. The aim of this study was to provide a meta-analysis and health risk assessment of occupational exposure to Cr6+ in Iranian workplaces. Databases including Scopus, Web of Sciences (WOS), and Scientific Information Database (SID), as a national database, were searched from 2000 to February 2021. The related studies to occupational exposure to Cr6+ were selected by Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Lung cancer and non-cancer risk (nasal mucosal irritation, atrophy, and perforation) of Cr6+ were estimated by Environmental Protection Agency (EPA) method, based on the Monte Carlo simulation (MCS). Also, the results of spirometry and biomonitoring of previous studies were reviewed. We found 14 articles based on inclusion criteria. Pooled concentration of Cr6+ was estimated 0.037 ± 0.002 mg/m3 which was higher than the recommended exposure limit by the ACGIH (0.002 mg/m3). The mean lung cancer risk was estimated to be 5.49E-2, which was considerable risk. In the Cr6+-exposed workers, all parameters of pulmonary function had decreased. The level of Cr6+ in urinary and blood samples was higher than threshold limit. Results indicated that exposure to Cr6+ and its health risk were more than recommended exposure limit. The results of present study could be helpful for health policy maker to control exposure to Cr6+ in workplaces.

Toxicity of Carbon-Based Nanomaterials in the Human Lung: A Comparative In-Vitro Study.

Background: Carbon-based nanomaterials (CBNs) are the key elements in nanotechnology. The main challenge presented by CBNs is their relationship with the toxicity exposed in the biological systems, because of the incomplete information on their toxicity. This study is aimed to compare the cytotoxicity of graphite nanoparticles (GRNPs), graphene nanoparticles (GNPs), and multi-walled carbon nanotubes (MWCNTs) in A549 cells. Materials and Methods: The physicochemical properties of nanomaterials were determined by instrumental techniques. CBNs were dispersed by the nongenotoxic standard procedure. After the cells were cultured, they were exposed to different concentrations of CBNs. Cellular viability was determined by the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) method. Moreover, toxicological indicators were obtained using linear probit regression. Results: The degree of cytotoxicity of CBNs in A549 cells was related to the time and, particularly, dose. At the concentrations of lower than 300 µg/mL, GNPs had stronger toxicity than MWCNTs, but the cytotoxic effects were reversed with the increase of the concentrations. The no-observed-adverse-effect concentration (NOAEC) of GRNPs, GNPs, and MWCNTs was 1.76, 0.06, and 0.65 µg/mL, respectively. Conclusion: The results indicated that CBNs were toxic and GNPs had stronger toxicity than the others. The experimental results can be useful in increasing the knowledge about the toxicity and health risk management of CBNs.

Toxicity risks of occupational exposure in 3D printing and bioprinting industries: A systematic review.

3-Dimensional (3D) printing and bioprinting are the new technologies. In 3D printing, synthetic polymers such as acrylonitrile, butadiene, and styrene, polylactic acid, nylon, and some metals are used as feedstocks. During 3D printing, volatile organic compounds (VOCs) and nanoparticles can be released. In the bioprinting process, natural polymers are most commonly used. All of these materials have direct and indirect toxic effects in exposed people. Therefore, the aim of this study was to provide a comprehensive review of toxicity risks due to occupational exposure to pollutants in the 3D printing and bioprinting industries. The Cochrane review method was used as a guideline for systematic review. Articles were searched in the databases including PubMed, Scopus, Web of Science, and Google Scholar. This systematic review showed that VOCs and ultra-fine particles are often released in fused deposition modeling and selective laser sintering, respectively. Asthma, chronic obstructive pulmonary disease, allergic rhinitis, and DNA damage were observed in occupational exposure to synthetic polymers. Metal nanoparticles can induce adverse health effects on the respiratory and nervous systems. This study emphasized the need to further study the toxicity of 3D printing and bioprinting-induced air pollutants. Also, consideration of safety and health principles is necessary in 3D printing and bioprinting workplaces.

The Effect of Particle Size on the Cytotoxicity of Amorphous Silicon Dioxide: An in Vitro Toxicological Study.

INTRODUCTION: Amorphous silicon dioxide (A-SiO2) is abundant in the Earth's crust, the A-SiO2 nano and microparticles are released into the air through industrial and manufacturing activities. Due to the limited available toxicological information, the objective of the present study was to evaluate the toxicity of different sizes of A-SiO2 particles on the A549 cell-lines in an in vitro study. MATERIALS AND METHODS: The A-SiO2 particles in two categories of nano (10-100 nm) and micro (< 5um) were used in this study. The human lung A549 cell-line was exposed to either nano- or micro-sized A-SiO2 particles at 10, 50, 100, and 250 µg/ml, and the effects were investigated. RESULTS: The cytotoxicity of A-SiO2 nano and microparticles in both 24- and 72-hour exposure times resulted in decreased cell survival, mitochondrial membrane potential, and increased ROS generation which was concentration-time dependent (P <0.05) but glutathione content was not affected in a time-dependent manner. Cytotoxicity of nanoparticles, contrary to the previous study, was not higher than microparticles in the comparable dose and exposure times. CONCLUSION: The rate of ROS generation in the A549 cell-line exposed to A-SiO2 nanoparticles was higher than microparticles. And at the same time, cell survival for exposed cells to A-SiO2 nano and microparticles were higher for nanoparticles in shorter exposure periods and was inversely concentration- and time-dependent. Further studies on exploring the effect of size and its possible toxic mechanism are recommended to achieve a more credible risk assessment.

The concentration of benzene, toluene, ethylbenzene, and xylene in ambient air of the gas stations in Iran: A systematic review and probabilistic health risk assessment.

Exposure to benzene, toluene, ethylbenzene, and xylene (BTEX) has been reported in gas stations. Exposure to BTEX can result in adverse health outcomes in workers such as cancer and neurological effects. The health risk assessments of exposure to BTEX could be useful in choosing suitable control measures. In this review, data from previous studies of gas station environments in Iran were collected from years 2000 to 2020. The health risk assessments were conducted through the estimation of cancer and noncancer risks using a Monte Carlo simulation based on the US Environmental Protection Agency method. The results showed that exposure to BTEX in some cities of Iran was greater than the occupational exposure limits. The results of cancer risk assessments demonstrated that cancer risk was not increased. However, results of noncancer risk assessments demonstrated that neurological toxicity from exposure to BTEX was significant in different cities of Iran. The health risk assessments indicated that workers at gas station are at health risk.

Apoptosis and DNA damage induced by silica nanoparticles and formaldehyde in human lung epithelial cells.

Human exposure to silica nanoparticles (SNPs) and formaldehyde (FA) is increasing and this has raised some concerns over their possible toxic effects on the exposed working populations. Notwithstanding several studies in this area, the combined toxicological effects of these contaminants have not been yet studied. Therefore, this in vitro study was designed to evaluate the SNPs and FA combined toxicity on human lung epithelial cells (A549 cells). The cells were exposed to SNPs and FA separately and in combined form and the single and combined toxicity of SNPs and FA were evaluated by focusing on cellular viability, DNA damage, and apoptosis via MTT, DAPI staining, DNA ladder, and Annexin V-FITC apoptosis assays. The results showed a significant increase in cytotoxicity, DNA damage, and chromatin fragmentation and late apoptotic\necrotic rates in combined treated cells compared with SNPs and FA-treated cells (P value < 0.05). Two-factorial analysis showed an additive toxic interaction between SNPs and FA. Eventually, this can be deduced that workers exposed simultaneously to SNPs and FA may be at high risk compared with exposure to each other.

Additive toxicity of Co-exposure to pristine multi-walled carbon nanotubes and benzo α pyrene in lung cells.

The Mixture exposure to pristine multi-walled carbon nanotubes (P-MWCNTs) and polycyclic aromatic hydrocarbons (PAHs) such as benzo α pyrene (BaP) in the environment is inevitable. Assessment toxicity of P-MWCNTs and BaP individually may not provide sufficient toxicological information. The objective of this work is to investigate the combined toxicity of P-MWCNTs and BaP in human epithelial lung cells (A549). The physico-chemical properties of P-MWCNTs were determined suing analytical instruments. The toxicity of P-MWCNTs and BaP on A549 lung cells individually or combined were assessed. For toxicity assessment, cell viability, ROS generation, oxidative DNA damage, and apoptosis experiments were conducted. The results of this study demonstrated that P-MWCNTs and BaP individually reduced cell viability in A549 lung cells, and oxidative stress was as the possible mechanism of cytotoxicity. The co-exposure to P-MWCNTs and BaP enhanced the cytotoxicity compared to exposure to P-MWCNTs and BaP individually, but not statistically significant. The two-factorial analysis demonstrated an additive toxicity interaction for co-exposure to P-MWCNTs and BaP. The complicated toxicity interaction among BaP with fibers and metal impurities of P-MWCNTS could be probable reasons for additive toxicity interaction. Results of this study could be helpful as the basis for future studies and risk assessment of co-exposure to MWCNTs and PAHs.

Comparing in vitro cytotoxicity of graphite, short multi-walled carbon nanotubes, and long multi-walled carbon nanotubes.

Occupational and environmental exposures to carbon-based materials in nano- and micro-size have been reported. There is incomplete information on the impact of size on the toxicity of carbon-based materials. The objective of this study is to compare the toxicity of graphite, short multi-walled carbon nanotubes (S-MWCNTs), and long multi-walled carbon nanotubes (L-MWCNTs) in lung cells (A 549). The physicochemical properties of MWCNTs were determined using analytical instruments. The fibers of MWCNTs were dispersed in the sterile-filtered 0.05% bovine serum albumin in MilliQ water. Cytotoxicity of graphite and MWCNTs were assessed using the cell viability, reactive oxygen species (ROS), and lipid peroxidation experiments. Results showed that MWCNTs induced cytotoxicity through the generation of oxidative stress in the exposed lung cells. Mean cytotoxicity of S-MWCNTs was statistically more than that of L-MWCNTs. The graphite induced cytotoxicity only at high concentrations. The mean cytotoxicity of both S-MWCNTs and L-MWCNTs was statistically more than that of graphite. The results also indicated that oxidative stress was the probable toxicity mechanism of carbon-based materials. The decreasing size of carbon-based materials could increase their toxicity. Because of the toxicity of MWCNTs, it is imperative to consider health and safety issues in working with nanomaterials.

Investigation of the effect of magnetite iron oxide particles size on cytotoxicity in A549 cell line.

INTRODUCTION: Magnetite as iron oxide is widely used in various industries, in the pharmaceutical industry in particular where it is used for its magnetic properties. The environmental and occupational exposure to airborne nanoparticles and microparticles of iron oxide compounds have been reported. Since authors have reported contradictory results, the objective of this study was to investigate the effect of particles' size in their toxicities. METHODS: The human cell line A549 was exposed with magnetite iron oxide in two size categories of micro (≥5 µm) and nano (<100 nm), with four concentrations of 10, 50, 100, and 250 µg/ml at two time periods of 24 and 72 h. The cell viability, reactive oxygen species (ROS), changes in mitochondrial membrane potential, and incidence of apoptosis were studied. RESULTS: Nano and micro magnetite particles demonstrated diverse toxicity effects on the A549 cell line at the 24- and 72-h exposure periods; however, the effects produced were time- and concentration-dependent. Nano magnetite particles produced greater cellular toxicities in forms of decreased viabilities at concentration exposures greater than 50 µg/ml (p < 0.05), along with increased ROS (p < 0.05), decreased cellular membrane potential (p < 0.05), and reduced rate of apoptosis (p < 0.05). DISCUSSION: The results of this study demonstrated that magnetite iron in nano-range sizes had a greater absorbability for the A549 cell line compared to micro sizes, and at the same time, nanoparticles were more toxic than microparticles, demonstrating higher production of ROS and decreased viabilities. Considering the greater toxicity of nanoparticles of magnetite iron in this study, thorough precautionary control measures must be taken before they can be used in various industries.