Journal of Health and Safety at Work

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Introduction: Occupational exposure to manganese can cause neurobehavioral symptoms. The aim of present study was to survey neurobehavioral symptoms of welders exposed to manganese- containing welding fumes and compare the frequency of these symptoms with unexposed group.

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Material and Method: Twenty seven of welders as exposed group, and 30 administrative workers as unexposed controls, were participated in this study. Neurobehavioral symptoms data were gathered using Q16 questionnaire. Manganese concentrations were determined according to the NIOSH 7300 method. After preparing of blood samples using microwave assisted acid digestion method, all samples were analyzed to determine manganese by graphite furnace- atomic absorption spectroscopy (GF-AAS).

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Result: The mean exposure to air manganese was 0.023± 0.012 mg/m3. Manganese concentrations in blood samples of welders (15.88± 7.11 µg/l) were significantly higher than unexposed workers (9.37± 8.70 µg/l), (P-V<0.05). The frequency of neurobehavioral symptoms of welders was significantly higher compared to unexposed workers (P-V<0.05). The correlation between neurobehavioral symptoms and blood manganese was significant for welders (P-V<0.05).

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Conclusion: Welders’ exposure to manganese and its potential health effects should be evaluated periodically and effective control measures should be applied in order to to prevent neurobehavioral symptoms.

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Introduction: Mercury is one of the toxic metals that damages the nervous system and kidneys. Therefore, monitoring of mercury vapors in the environments is essential.

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Material and Method: A new adsorbent was made from silver nanoparticles on a bed of quartz. The nano-adsorbent was capable for sampling of the trace amounts of mercury vapor from air. In this study, the required mercury vapor was generate by hydride generation atomic absorption spectrometry and the necessary analysis was performed by cold vapor atomic absorption spectrometry.

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Results: Mercury vapors in the Stationary phase, were concentrated as much as 2300 times (Atomic absorption detection limit was 1.15 microgram per liter of air). Thus by this stationary phase, the trace amounts of mercury vapors can be detected up to 0.5 nano gram per liter of air. The detected value of the presented method is 200 times lower than the occupational safety and health administration (OSHA) standards for mercury vapors. Heater accessory at the temperature of 245 °C was used for thermal desorption of mercury from nano silver adsorbent. Optimal time of desorption was obtained 150 seconds and the Repeatability of the method was 58 times. The mercury vapors absorbed on nano silver adsorbent could be maintained at 80 days at the room temperature (25 °C).

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Conclusion: The presented adsorbent is very useful for sampling of the trace amounts of mercury vapors from air. Moreover, it can be regenerated easily is suitable or sampling at 25 to 70 °C. Due to oxidation of silver and reduction in uptake of nanoparticles, oven temperature of 245 °C is used for the recovery of metallic silver. Low amount of adsorbent, high absorbency, high repeatability for sampling, low cost and high accuracy are of the advantages of the presented method.

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Introduction: During recent years, carcinogenic effects of X-ray have been proven. Todays, lead is used in many equipment such as  coats, thyroid shield, and gloves for body protection against X-ray. However, these equipments have several disadvantegous including toxicity, heaviness, and inflexibility. Hence, newer methods like protective semisolid products (cream, ointment) for topical application are being replaced. Therefore, the feasibility of using an ointment containing bismuth oxide nanoparticles (Bi2O3) as a X-ray adsorbent was evaluated in this study.
 

Methods and Materials: First, synthesis of Bi2O3 and then formulating it in the form of ointment was investigated. In this study, X-ray device and dosimeter was employed to check the X-ray absorption in different thickness of bismuth oxide nanoparticles ointment.
 

Results: In dosimetry test, the protective effect of the ointment containing Bi₂O₃ nanoparticles was evaluated significantly (P<0.05) better than control group and equal sheet lead group. Dosimetry tests showed that the bismuth oxide nanoparticles ointment and cream absorb  56% of the radiation whereas this value is  41% for lead. K absorption edge for bismuth is higher than other metals and its nanoparticles have more absorbent surface to volume ratio (S/V).
 

Conclusion: It seems that due to higher atomic number and lower toxicity, Bi₂O₃ nanoparticles have better efficiency in X-ray absorbtion, comparing to the lead. Cream and ointment of bismuth oxide nanoparticles can be used as X-ray absorbant for different professions such as physicians, dentists, radiology experts, and operating room staff and consequently increase health and safety of these employees.

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Introduction: Volatile organic compounds such as xylene are one of the main air pollutants. Adsorption method are of the most common methods used in the control of volatile organic compounds. The aim of this study was to investigate the xylene removal from air through nano activated carbon adsorbent in comparison with NIOSH approved carbon adsorbent.
 

Material and Method: Xylene adsorption tests on nano activated carbon and activated carbon in static mode (batch) were done in glass vials with volume of 10 ml. Gas chromatography with FID detector was used for analysis. Various variables including contact time, amount of adsorbent, concentration of xylene, and temperature were studied.
 

Results: Absorption capacity of xylene at ambient temperature (25° C) in static mode and duration of 10 minutes for activated carbon and nano activated carbon was obtained 349.8 and 435 mg/g, respectively. Results of Scanning Electron Microscope (SEM) images of nano activated carbon showed particle size pf less than 100 nm. Furthermore, Transmission Electron Microscope (TEM) pictures showed particle size of 30 nm. XRD images also showed cube structure of nano activated carbon adsorbent.
 

Conclusion: The results showed that adsorption capacity at constant humidity increased by raising in temperature and contact time. What is more, nano activated carbon absorbent showed greater absorption capacity for xylene removal compared to activated carbon absorbent

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Introduction: Volatile organic compounds from industrial activities are one of the most important pollutants released into the air and have adverse effects on human and environment. Therefore, they should be removed before releasing into atmosphere. The aim of the study was to evaluate xylene removal from air by nano-grapheme and nano-graphene oxide in comparison with activated carbon adsorbent.

Material and Method:  After preparing adsorbents of activated carbon, nano-graphene, and nano-graphene oxide, experiments adsorption capacity in static mode (Batch) were carried out in a glass vial. Some variables including contact time, the amount of adsorbent, the concentration of xylene, and the temperature were studied. Langmuir absorption isotherms were used in order to study the adsorption capacity of xylene on adsorbents. Moreover, sample analysis was done by gas chromatography with Flame Ionization Detector (GC-FID).

Results: The adsorption capacities of activated carbon, nano-graphene oxide and nano-graphene for removal of xylene were obtained 349.8, 14.5, and 490 mg/g, respectively. The results of Scanning Electron Microscope (SEM) for nano-graphene and nano-graphene oxide showed particle size of less than 100 nm. While, the results of Transmission Electron Microscope (TEM) showed particle size of 45nm for nano-graphene and 65 nm for nano-graphene oxide. Also, X-Ray Diffraction (XRD) showed cube structure of nano-adsorbents.

Conclusion: In constant humidity, increase in exposure time and temperature caused an increase in the adsorption capacity. The results revealed greater adsorption capacity of xylene removal for nano-graphene compared to the activated carbon, and nano-graphene oxide.

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Introduction: Volatile organic compounds (VOCs) are hazardous toxic pollutants in the air, which are released from various industrial sources. Due to the adverse effects of xylene on health, the effective removal of VOCs from the air by nano sorbents is crucial. In this study, nanographene (NG) and nanographene oxide (NGO) were used as adsorbents to investigate the efficiency of xylene removal.
Material and Methods: In this study, in order to investigate the absorption efficiency of nanographene and nanographene oxide after the synthesis of nano absorbents in a dynamic system, xylene vapor was produced in a chamber in pure air and stored in a Tedlar sampling bag and then transferred to the adsorbent. Subsequently, the effect of various parameters such as xylene concentration, inlet air flow rate, and absorbent mass values at 32% humidity and 25°C temperature on the absorption rate and performance of the desired absorbents was investigated. Finally, the gas chromatographic flame ion detector (GC-FID) determined the concentration of xylene in air after the adsorption-desorption process.
Results: The average adsorption efficiencies for NG and NGO were found to be 96.8% and 17.5%, respectively. The characteristics of the NG and NGO adsorbents indicated that the particle size range was less than 100 nanometers.
Conclusion: The results demonstrated that the adsorption efficiency of NG for the removal of xylene from the air is higher than that of NGO. The GC-MS method validated the proposed approach in real air samples.