Due to their unique physicochemical properties, graphene-family nanomaterials (GFNs) are widely used in many fields, especially in biomedical applications Currently, many studies have investigated the biocompatibility and toxicity of GFNs in vivo and in intro Generally, GFNs may exert different degrees of toxicity in animals or cell models by following with different administration routes and penetrating through physiological barriers, subsequently being distributed in tissues or located in cells, eventually being excreted out of the bodies This review collects studies on the toxic effects of GFNs in several organs and cell models We also point out that various factors determine the toxicity of GFNs including the lateral size, surface structure, functionalization, charge, impurities, aggregations, and corona effect ect In addition, several typical mechanisms underlying GFN toxicity have been revealed, for instance, physical destruction, oxidative stress, DNA damage, inflammatory response, apoptosis, autophagy, and necrosis In these mechanisms, (toll-like receptors-) TLR-, transforming growth factor β- (TGF-β-) and tumor necrosis factor-alpha (TNF-α) dependent-pathways are involved in the signalling pathway network, and oxidative stress plays a crucial role in these pathways In this review, we summarize the available information on regulating factors and the mechanisms of GFNs toxicity, and propose some challenges and suggestions for further investigations of GFNs, with the aim of completing the toxicology mechanisms, and providing suggestions to improve the biological safety of GFNs and facilitate their wide application

/pdf/toxicity-of-graphene-family-nanoparticles-a-general-review-572xnvmnmi.pdf

Toxicity of graphene-family nanoparticles: a general review of the origins and mechanisms

Chromium (Cr) is used in many industries and it is widely distributed in the environment. Exposure to Cr dust has been reported among workers at these industries. Beside its hazardous effects on the lungs, brain injury could be induced, as the absorption of substances through the nasal membrane has been found to provide them a direct delivery to the brain. We investigated the distribution and the effects of Cr in both brain and lung following the intranasal instillation of potassium dichromate (inPDC) in rats. Simultaneously, we used the common intraperitoneal (ipPDC) rat model of acute Cr-toxicity for comparison. Thirty male Wistar rats were randomly allocated into five groups (n = 6); each received a single dose of saline, ipPDC (15 mg/kg), or inPDC in three dose levels: 0.5, 1, or 2 mg/kg. Locomotor activity was assessed before and 24 h after PDC administration, then, the lungs and brain were collected for biochemical, histopathological, and immunohistochemical investigations. Treatment of rats with ipPDC resulted in a recognition of 36% and 31% of the injected dose of Cr in the brain and lung tissues, respectively. In inPDC-treated rats, targeting the brain by Cr was increased in a dose-dependent manner to reach 46% of the instilled dose in the group treated with the highest dose. Moreover, only this high dose of inPDC resulted in a delivery of a significant concentration of Cr, which represented 42% of the instilled dose, to the lungs. The uppermost alteration in the rats locomotor activity as well as in the brain and lung histopathological features and contents of oxidative stress biomarkers, interleukin-1β (IL-1β), phosphorylated protein kinase B (PKB), and cyclooxygenase 2 (COX-2) were observed in the rats treated with inPDC (2 mg/kg). The findings revealed that these toxic manifestations were directly proportional to the delivered concentration of Cr to the tissue. In conclusion, the study showed that a comparably higher concentrations of Cr and more elevated levels of oxidative stress and inflammatory markers were observed in brain and lung tissues of rats subjected to inPDC in a dose that is just 0.13 that of ipPDC dose commonly used in Cr-induced toxicity studies. Therefore, the study suggests a high risk of brain-targeting injury among individuals environmentally or occupationally exposed to Cr dust, even in low doses, and an additional risk of lung injury with higher Cr concentrations. Moreover, the study introduces inPDC (2 mg/kg)-instillation as a new experimental animal model suitable to study the acute brain and lung toxicities induced by intranasal exposure to Cr compounds.

/pdf/intranasal-chromium-induces-acute-brain-and-lung-injuries-in-31r231rf71.pdf

Intranasal Chromium Induces Acute Brain and Lung Injuries in Rats: Assessment of Different Potential Hazardous Effects of Environmental and Occupational Exposure to Chromium and Introduction of a Novel Pharmacological and Toxicological Animal Model.

Hexavalent chromium (CrVI) is a heavy metal widely used in more than 50 industries. Nephrotoxicity is a major adverse effect of chromium poisoning. The present study investigated the potential renoprotective effect of lactoferrin (Lf) against potassium dichromate (PDC)-induced acute kidney injury (AKI) in rats. Beside, because previous studies suggest that interlukin-18 (IL-18) and insulin-like growth factor-1 (IGF-1) play important roles in promoting kidney damage, the present work aimed to evaluate the involvement of these two cytokines in PDC model of AKI and in the potential renoprotective effect of lactoferrin. Adult male albino Wistar rats were pretreated with Lf (200 mg/kg/day, p.o.) or (300 mg/kg/day, p.o.); the doses that are usually used in the experiment studies, for 14 days followed by a single dose of PDC (15 mg/kg, s.c.). PDC caused significant increase in serum urea, creatinine, and total protein levels. This was accompanied with decreased renal glutathione content, and increased renal malondialdehyde, IL-18, IL-4, nuclear factor kappa B (NFκB), IGF-1, and the phosphorylated form of forkhead box protein O1 (FoxO1) levels. Moreover, normal expression IFN-γ mRNA and enhanced expression of TNF-α mRNA was demonstrated in renal tissues. Histopathological investigations provoked deleterious changes in the renal tissues. Tubular epithelial hyperplasia and apoptosis were demonstrated immunohistochemically by positive proliferating cell nuclear antigen (PCNA), Bax, and Caspase-3 expression, respectively. Pretreatment of rats with Lf in both doses significantly corrected all previously mentioned PDC-induced changes with no significant difference between both doses. In conclusion, the findings of the present study demonstrated the involvement of oxidative stress, inflammatory reactions, tubular hyperplasia and apoptosis in PDC-induced AKI. It suggested a role of IL-18 through stimulation of IL-4-induced inflammatory pathway, and IGF-1 through triggering FoxO1-induced cell proliferation. Moreover, the study revealed that Lf protected the kidney against Cr-induced AKI in rats and significantly showed antioxidant, anti-inflammatory, and anti-proliferative properties with down-regulation of IL-18 and IGF-1.

/pdf/renoprotective-effect-of-lactoferrin-against-chromium-2yjb6u8wgp.pdf

Renoprotective Effect of Lactoferrin against Chromium-Induced Acute Kidney Injury in Rats: Involvement of IL-18 and IGF-1 Inhibition

Background: Welding is a common industrial process and is harmful to welders' health. Objective: To determine the effect of toxic gases and metal fumes produced during 3 welding processes on welders' incidence of respiratory symptoms and pulmonary function. Methods: This cross-sectional study was conducted in an Iranian shipbuilding industrial factory in 2018. Using the simple census method, 60 welders were selected as the exposed group. 45 staff members of the administrative unit were also recruited to be served as the control group. Welders' demographic data and respiratory complaints were collected employing a questionnaire. Fumes and gases produced were sampled from the welders' respiratory tract and analyzed by standard methods suggested by the National Institute of Occupational Safety and Health (NIOSH). Pulmonary function test was also performed for each participant. Results: The prevalence of respiratory symptoms in all welders was significantly (p<0.05) higher than the control group. The mean FVC, FEV 1 and FEV 1 /FVC measured in welders involved in all 3 processes were significantly lower than those recorded in the control group. The spirometry pattern in welders involved in flux cored arc welding and shielded metal arc welding was obstructive; that in those involved in gas metal arch welding was mixed (obstructive and restrictive pattern). Conclusion: Exposure to welding fumes and gases was associated with pulmonary function deterioration. Welders involved in gas metal arch welding had a higher prevalence of pulmonary disorders compared with those involved in gas metal arch welding and flux cored arc welding.

https://www.theijoem.com/ijoem/index.php/ijoem/article/download/1540/1064

Respiratory Exposure to Toxic Gases and Metal Fumes Produced by Welding Processes and Pulmonary Function Tests

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.

https://journals.sagepub.com/doi/pdf/10.1177/0748233718817180

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

Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 μg/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 μg/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively).


CONCLUSION
The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use.

Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding

Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 μg/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 μg/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). Conclusion The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use.

Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium in stainless steel welding fumes

To provide quantitative information to choose the best welding processes for minimizing workplace emissions, nine gas metal arc welding (GMAW) processes for mild steel were assessed for fume generation rates, normalized fume generation rates (milligram fume per gram of electrode consumed), and normalized generation rates for elemental manganese, nickel, and iron. Shielded metal arc welding (SMAW) and flux-cored arc-welding (FCAW) processes were also profiled. The fumes were collected quantitatively in an American Welding Society-type fume chamber and weighed, recovered, homogenized, and analyzed by inductively coupled atomic emission spectroscopy for total metals. The processes included GMAW with short circuit, globular transfer, axial spray, pulsed spray, Surface Tension Transfer™, Regulated Metal Deposition™, and Cold Metal Transfer™ (CMT) modes. Flux-cored welding was gas shielded, and SMAW was a single rod type. Results indicate a wide range of fume emission factors for the process variations studied. Fume emission rates per gram of electrode consumed were highest for SMAW (~13 mg fume g −1 electrode) and lowest for GMAW processes such as pulsed spray (~1.5 mg g −1 ) and CMT (~1 mg g −1 ). Manganese emission rates per gram of electrode consumed ranged from 0.45 mg g −1 (SMAW) to 0.08 mg g −1 (CMT). Nickel emission rates were generally low and ranged from ~0.09 (GMAW short circuit) to 0.004 mg g −1 (CMT). Iron emission rates ranged from 3.7 (spray-mode GMAW) to 0.49 mg g −1 (CMT). The processes studied have significantly different costs, and cost factors are presented based on a case study to allow comparisons between processes in specific cost categories. Costs per linear meter of weld were $31.07 (SMAW), $12.37 (GMAW short circuit), and $10.89 (FCAW). Although no single process is the best for minimizing fume emissions and costs while satisfying the weld requirements, there are several processes that can minimize emissions. This study provides information to aid in those choices. Suggestions for overcoming barriers to utilizing new and less hazardous welding processes are also discussed.

/pdf/profiling-mild-steel-welding-processes-to-reduce-fume-5g5xpk661t.pdf

Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr6+). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr6+. GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) t...

/pdf/profiling-stainless-steel-welding-processes-to-reduce-fume-29hb3m23m4.pdf

Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace

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Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding

Selecting Processes to Minimize Hexavalent Chromium from Stainless Steel Welding Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium in stainless steel welding fumes

Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace