Exposure control measures proposed by different organizations: the curious case of nanomaterial-involved activities.

Objectives. The unique properties of nanomaterials have turned them into an emerging threat for humans and the environment. This study therefore aimed to review exposure control measures proposed for nanomaterial-involved activities. Methods. This study is based on the published guidelines of different organizations on safe handling of nanomaterials. The search for documents was provided using the keywords 'Exposure controls', 'Good practices', 'Working safely', 'Safe practices', 'Handling safely', 'Safety guide' and 'Safety and health', combined with 'Nanomaterials', 'Nanotechnology' and 'Nanoparticles' on different databases and websites. Results. Thirty-one guidelines from 27 organizations were included. Most of the guidelines recommended engineering controls, administrative controls and personal protective equipment (PPE). Changing the physical form of nanomaterials or the process, using prevention through design (PtD) and using green chemistry principals were other suggestions to reduce exposure to nanomaterials. Conclusions. Considering the difficulty of implementation and case specificity of the solutions of the first two priorities of the hierarchy of controls (elimination and substitution), the emphasis of the guidelines on the next three priorities for controlling exposure to nanomaterials is understood. The type and method of using PPE and engineering controls should be resolved by referring to cutting-edge articles.

Application of Multiple Occupational Health Risk Assessment Models for Metal Fumes in Welding Process.

Welding fumes have an important role to create the adverse health effects. So, the aim of this study was to use of multiple occupational health risk assessment models for metal fumes in welding process. This cross-sectional study was conducted among welding workers. Sampling of heavy metals such as Sn, Zn, Al, Fe, Cd, Pb, Cu, Mn, Ni, Cr, and As was provided based on the National Institute for Occupational Safety and Health (NIOSH) method 7300 and analyzed by inductively coupled plasma mass spectroscopy (ICP-MS). Risk assessment was managed by four methods including Malaysia's method, Control of Substances Hazardous to Health Essentials (COSHH model), Chinese OHRA standard (GBZ/T 298-2017), and EPA method. Also, Monte Carlo simulation was used to examine the uncertainties by using the Crystal Ball tool. To compare the models, the risk levels of each model were converted into the risk ratio and the SPSS 22.0 software was used to the statistical analysis. The consistency of the two occupational health risk assessment models was examined by Cohen's Kappa. Risk ration was the highest level for Cr (VI) fumes in all models. Also, carcinogenic risk was unacceptable for all examined fumes. Moreover, non-carcinogenic risk was the highest (HI > 1) for As fumes. Mont Carlo simulations suggested that exposure time (ET) had a significant effect on the risk. Also, there was a good consistency between Malaysia method/GBZ/T 298-2017 and COSHH model/GBZ/T 298-2017. Therefore, it is recommended that the engineering and administrative controls should be provided to reduce exposure.

Improving ultraviolet protection properties of cotton textiles using Zinc oxide (ZnO) nanomaterials: an approach for controlling occupational and environmental exposures.

Ultraviolet (UV) radiation exposure is one of the most important risk factor among workers. it may stimulate health outcomes such as multiple skin injuries and blinding eye diseases. So, UV protection is mainly important for people who expose to it. Modification of cotton textiles by nanomaterials is a new approach to overcome this problem. So, the aim of this study is to review studies conducted on using ZnO nanoparticles for improving ultraviolet protection of cotton textiles. The search strategy was provided by cochrane guideline. 45 studies were regarded as appropriate. The results show that UPF for textiles has improved by coated ZnO. However, UPF was depended on the physicochemical characteristics of ZnO and textiles such as yarn structure, effect of woven fabric construction, fabric porosity, and impurity of textiles and laundering conditions. Also, plasma technology has improved UPF, it is recommended that more studies be done to achieve better results.

Laboratory activities involving nanomaterials: risk assessment and investigating researchers symptoms.

The increasing use of nanomaterials is a threat to human health and environment that has led to the expansion of risk assessment methods. Thus, the aim of this study was to assess the occupational risks of activities involving nanomaterials in nanomedicine research laboratories by Control Banding (CB) NanoTool and Guidance methods. Further, the symptoms of researchers working in these laboratories were investigated. This cross-sectional study was managed in nanomedicine research laboratories. Risk assessment was performed by the CB NanoTool and Guidance methods. Moreover, a questionnaire was used to assess the prevalence of non-specific symptoms. Finally, data were analyzed using the IBM SPSS software. Descriptive statistics were used for data analysis. Many activities are located on the risk level RL2 and category A based on the CB NanoTool and Guidance methods, respectively. Further, the highest severity of exposure to nanomaterials belonged to the preparation of suspension and emulsion and manufacture of metal nanopolymers, but the highest probability of exposure was in the manufacturing of carbon nanocomposites. In addition, there was a significant relationship between the level of risk in the two methods (P = 0.003). Although, cutaneous symptoms were the most common symptoms among laboratory researchers, chi-square test did not confirm any significant relationship between symptoms and risk levels (p-value >0.05) in these two methods. Since the NanoTool method uses more diverse parameters for risk assessment and is more acceptable, choosing control measures based on its results seems more reasonable. Moreover, Guidance can be used as a method for initial assessments and determine the need for further assessments.

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.

An analysis on control banding-based methods used for occupational risk assessment of nanomaterials.

Despite all benefits of nanomaterials, their unique characteristics made them an emerging hazard in workplaces, which need to be assessed for their potential risks. So, the aim of this study was to review all the studies conducted on the risk assessment of activities involving nanomaterials with CB-based methods.This study is based on a literature review on databases including Web of science, Scopus, PubMed, and SID. After reviewing and screening studies according to PRISMA, the collected data were meta-analyzed by Comprehensive Meta-Analysis Software. Also, Newcastle-Ottawa checklist was used for quality assessment of the studies. To determine similarity of methods, Cohen's Kappa was used. Sensitivity analysis was used to determine the role of each factor in the risk assessment by using the Crystal Ball tool.There are eight validated methods for risk assessment. Also, some authors used a self-deigned tool based on CB approach. The results of meta-analysis showed that the odds ratio for the risk of activities involved with nanomaterials was 0.654 (high risk). Results of simulation for Nanotool showed that the mean risk level of activities involved with nanomaterials, with a certainty of 95.07%, is moderate (RL3). Moreover, sensitivity analysis showed that the risk was depended on "Hazard band" in all methods except ISO method.The obtained results can be useful in improving existing methods and suggesting new methods. Also, there is a need to design and propose specific methods for risk assessment of incidental and natural nanomaterials.

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.

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.

Evaluating the airborne asbestos dispersion in enclosed parking lots in Iran.

Each time a car's brakes are used, asbestos is dispersed in the air. Breathing the air in enclosed parking lots can expose people working in these places to asbestos. This study aimed to evaluate the airborne asbestos dispersion in enclosed parking lots. In this study, 35 air samples were collected from six enclosed parking lots in Tabriz City. The samples were analyzed quantitatively by phase contrast microscopy (PCM) and qualitatively by a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray analyzer. The mean of fiber concentrations was found 0.155 ± 0.069 PCM f/cc. The SEM data demonstrated that the fibers consisted of synthetic fibers (69.57%) and asbestos (30.43%). Fiber concentrations in many enclosed parking lots in the city were higher than the threshold limit value-time weighted average of the American Conference of Governmental Industrial Hygienists and Occupational Exposure Limits of Iran. However, further investigations are needed to clarify asbestos exposure in such places.

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 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.

8-Hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker of oxidative DNA damage induced by occupational exposure to nanomaterials: a systematic review.

In nuclear and mitochondrial DNA, 8-hydroxy-2'-deoxyguanosine (8-OHdG) is one of the predominant forms of reactive oxygen species (ROSs) lesions, which commonly used as a biomarker for oxidative stress. Studies showed that the different nanomaterials can induce toxicity by ROSs in human body. So, this study is going to review the studies about oxidative DNA damage caused by occupational exposure to nanomaterials, using 8-OHdG biomarker.Systematic review was managed based on Cochrane systematic review guideline. Literature search was conducted in scientific databases with the main terms of "biomarkers," "biological markers," combined with "occupational exposure" and "nanomaterials." All papers in the field of occupational exposure to nanomaterials until 2020 December were included. To evaluate the quality and bias of studies, GRADE method (Grading of Recommendations, Assessment, Development, and Evaluation) was used.Two hundred twenty-six studies were primarily achieved. By considering the inclusion criteria, overall 8 articles were selected. The majority of the studies were classified as the moderate quality studies (six studies). Also, the study-level bias was critical. This review shows that there is a significant relationship between job title and amount of produced nanomaterials and the existence of 8-OHdG. Also, the levels of 8-OHdG can be measured in urine, blood, and inhalation samples by instrumental procedures.Oxidative damages are an important threat for workers exposed to nanomaterial. Blood and EBC 8-OHdG level can be introduced as a biomarker for metal nanomaterials, but urinary 8-OHdG needs to be taken with caution. So, it is recommended that evaluation not be solely based on one biomarker.

An assessment of the cytotoxic effects of graphene nanoparticles on the epithelial cells of the human lung.

Nanomaterials are widely used nowadays in a range of technological and biomedical fields. Graphene as a nanomaterial used in the health-care sector and in workplaces has raised some concerns about its toxicity. This study aimed to evaluate the cytotoxicity of graphene nanoparticles (GNPs) on the A549 epithelial cells of the human lung. The GNPs were synthesized from graphite by the modified Hummer method. The physicochemical characteristics of GNPs were identified by the transmission electron microscope, the scanning electron microscope, and the Brunauer-Emmett-Teller method. The hydrodynamic size of GNPs in the dispersion media was examined using the dynamic light scattering technique. The GNPs were dispersed, after which the A549 cells were cultured. Finally, the cell viability was assayed by the MTT assay. The statistical analysis of variance was used to describe the relationship between the concentration/time variables and the GNP-induced cell deaths. The probit regression model was also used to achieve toxicological indicators. The results showed that the toxicological effects of GNPs on the A549 epithelial cells of the human lung are dose- and time-dependent. The GNPs were more cytotoxic after a 72-h exposure period compared to a 24-h and 48-h exposure period. The inhibitory concentration of 50% and "no observed adverse effect concentration" were estimated to be 40,653.1 and 0.059 µg/mL, respectively. The results of this study can be helpful in developing the occupational exposure limit for GNPs and in improving occupational health programs in workplaces. However, more investigation is needed to specify the toxicological mechanisms of GNPs.