Physico-chemical properties and reactive oxygen species generation by respirable coal dust: Implication for human health risk assessment.

This study investigates the mineralogy, micro-morphology, chemical characteristics and oxidation toxicity of respirable dusts generated in underground coal mines. The active sampling was applied to collect airborne particulates with aerodynamic diameter <4 µm (PM4) at depth greater than 500 m from earth surface. The average mass concentration of PM4 was extremely higher than recommended values. QXRD and FESEM-EDS analyses were applied to study the micro-mineralogy and micro-morphology of respirable dusts. The chemical analysis by ICP-MS revealed an enrichment of V, Cr, Cu, Zn, As, Ag, Cd and Sb in respirable dust compared with the background environment and world coals. The EPA's health risk model showed that the health risk posed by Cr and Co in all workplaces exceeded the acceptable risk value for human health. The synthetic respiratory tract lining fluid (RTLF) model was utilized to achieve a novel insight into the toxicity of respirable coal dust. The result showed an overall depletion of lung surface antioxidants with the decreasing trend of ascorbic acid > reduced glutathione >> urate, implying low- to medium level of oxidative stress. The result of this study can be applied globally by decision-makers to decrease hazardous exposure of mine workers to respirable dust.

Simulation of lead fume emissions in the workplace using computational fluid dynamics in the electronics industry.

Computational fluid dynamics (CFD) is a powerful method for predicting the release of pollutants in the workplace and has recently been used as a valuable tool by health authorities. The purpose of this study was to predict the distribution of lead fume in the workplace using computational fluid dynamics in the electronics manufacturing industry. A cross-sectional descriptive and analytical study was conducted in the Neyshabur electronics industry (2019). Individual exposure to lead fume was measured by the OSHA121 method. Simulation and prediction of lead fume emission in the workplace were done using computational fluid dynamics and by the ANSYS16 software. The mean of personal exposure to lead fumes was 0.04 ± 0.01 mg/m3. The software predicted the distribution of lead fumes in the respiratory zone of the worker to be in the range of 0.04 to 0.07 mg/m3, which is very close to the real values. By doubling the suction power of the topical ventilation used, workers' exposure to lead fumes was nearly halved and reached well below the recommended limit. The results showed that CFD is a useful tool for simulating individual contact with pollutants in a geometry. Also, given that the CFD shows the diffusion and distribution of pollutants in all points of a geometry, it is useful to indicate critical locations and conditions.

Quantitative and semi-quantitative risk assessment of occupational exposure to lead among electrical solderers in Neyshabur, Iran.

Lead is one of the most widely used elements in the world. Lead can cause acute and chronic complications such as abnormal hemoglobin synthesis, kidney damage, abortion, nervous system disorders, male infertility, loss of learning ability, behavioral disorders, and even death. The aim of this study was to carry out quantitative and semi-quantitative risk assessments of exposure to lead among the solderers of the Neyshabur electronics industry. This cross-sectional, descriptive, and analytical study was conducted in 2017 and 2018 on 40 female soldering workers exposed to lead. Semi-quantitative risk assessment was carried out according to the Singapore Health Department and quantitative risk assessment according to the Office of Environmental Health Hazard Assessment (OEHHA) method. The average occupational exposure to lead in the electronics manufacturing industry was 93.89 ± 33.40 µg m-3 with a range from 9 to 150 µg m-3. Occupational exposure to lead in the industrial groups of initial soldering with an average of 130.37 ± 40.23 µg m-3 and cutting wires, electroplating, and coating bare parts with an average of 110.24 ± 30.11 µg m-3 was higher than the secondary soldering groups with an average of 90.78 ± 20.22 and shift supervisors with an average of 43.86 ± 10.97 µg m-3. The mean excess lifetime cancer risk (ELCR) was 0.11 per 1000 people and the mean non-carcinogenic risk (HQ) was 7.20. The results of this study indicate that there is a risk of non-carcinogenic complications among electronic solderers. Therefore, managers and employers should reduce lead exposure through engineering controls (substituting lead-free alloys, efficient ventilation) and management strategies such as reducing exposure hours.

Health risk assessment of occupational exposure to styrene in Neyshabur electronic industries.

Styrene is one of the essential components in making thousands of everyday products. Occupational exposure to styrene causes pulmonary, neurological, genetic and ocular complications, and leukemia and affects reproduction. The aim of this study was to assess the health risks of exposure to styrene in the electronics industry of Neyshabur, Iran. This descriptive and analytical cross-sectional study was carried out in three electronics industries, in Neyshabur city, in 2017-2018. Occupational exposure to styrene was measured according to the NIOSH1501 method, using a low-flow rate sampling pump (0.2 L/min) and an active charcoal absorber tube. Health risk assessment was done according to the Singapore semi-quantitative method and the United States Environmental Protection Agency (OEHHA) method. The average occupational exposure to styrene in men employed in the compact plastic parts production halls was 79.61 mg m-3 (range 28-208.33). 45.8% of exposed subjects (27 people) encountered exposure above the permitted limit. The average lifetime carcinogenic risk of styrene was 1.4 × 10-3; therefore, 100% (59 people) had a definite risk of getting cancer. The highest lifetime risk of getting cancer was observed in plastic injection device users (1.9 × 10-3) and then in shift managers (1.6 × 10-3). The results of this study indicate a definite risk of getting cancer for all workers. Strategies to reduce workers exposure to styrene through engineering controls and routine measurements are necessary.

Exposure to lead and its effect on sleep quality and digestive problems in soldering workers.

Some studies show that exposure to lead affects sleep quality and causes digestive disorders. The aim of this study was to evaluate the quality of sleep and digestive disorders in solderers exposed to lead. In a cross-sectional study, the occupational exposure of 40 soldering workers to lead fume and their blood lead levels were measured in the electronics industry of Neyshabur city, according to standard methods. The sleep quality of workers was measured by the Pittsburgh Sleep Quality Index (PSQI) questionnaire and their digestive disorders were recorded in a checklist. This study showed that 67.5% of subjects had poor sleep quality. There was a significant relation between sleep quality, air lead (p = 0.02), and blood lead (p = 0.03). Bad sleep quality was 2.4 times higher in subjects exposed to lead above the threshold (p = 0.03). 92.5% of the population under study suffered from at least one digestive disorder. Digestive disorders such as hiccupping (85%) and nausea (67%) were more common among the workers, and their odds was 3.09 and 2.00 times higher in workers exposed to lead above the threshold, compared with others. Bad sleep quality and gastrointestinal disorders were prevalent among workers exposed to lead. The results of this study confirm the need for further research about the side effects of lead on humans. It also clarifies the need for a revision in the recommended occupational exposure level for lead.

Investigation of occupational exposure to lead and its relation with blood lead levels in electrical solderers.

Occupational exposure to lead compounds can cause headache, nausea, encephalopathy, anemia, chronic muscle pain, and saturnism. Exposure to lead in women can affect fertility, and cause abortion or low IQ in the offspring. The aim of this study was to investigate occupational exposure to lead and its relation with blood lead levels in female electrical parts solderers. This cross-sectional (descriptive and analytical) study was carried out on 40 female solderers, working in two electrical parts manufacturing factories in Neyshabur city in 2017-2018. Occupational exposure to lead was determined by the OSHA 121 method, and the NIOSH 8003 method was used to determine the concentration of lead in blood. Lead in blood and air samples were determined by using a flame atomic absorption analyzer. Blood was measured using a Cell Dyn Hematology device. Data were analyzed using STATA 15. The mean age of the solderers was 35.42 ± 6.80 years, and their average work experience was 7.85 ± 5.60 years. Mean occupational exposure to lead was 0.09 ± 0.01 mg/m3, and the mean levels of lead in the blood of solderers were 10.59 ± 3.25 µg/dL. The mean of red blood cells (RBC) was 4.88 mil/uL, white blood cells (WBC) = 8.53 Tho/uL, hemoglobin = 14.02 g/dL, and hematocrit = 42.38%. There was a significant correlation between the concentrations of lead in air and the level of lead in workers' blood (p = 0.012, r = 0.31). The level of lead in the workers' respiratory region (ß = 0.36, p = 0.033), body mass index (ß = 0.25, p = 0.028), and the season of the year (ß = 0.21, p = 0.019) were the strongest factors affecting blood lead levels. There was a significant relation between lead in workers' air and their blood, although all blood indices were in normal range. Using lead-free alloys and local ventilation systems, and reducing exposure times are recommended to decrease exposure to lead among solderers.

Biomonitoring-based exposure assessment of benzene, toluene, ethylbenzene and xylene among workers at petroleum distribution facilities.

Elevated emissions of volatile organic compounds, including benzene, toluene, ethylbenzene, and o, p, and m-xylenes (BTEX), are an occupational health concern at oil transfer stations. This exploratory study investigated personal exposure to BTEX through environmental air and urine samples collected from 50 male workers at a major oil distribution company in Iran. Airborne BTEX exposures were evaluated over 8h periods during work-shift by using personal passive samplers. Urinary BTEX levels were determined using solid-phase microextraction with gas chromatography mass spectrometry for separation and detection. Mean exposure to ambient concentrations of benzene differed by workers' job type: tanker loading workers (5390µg/m3), tank-gauging workers (830µg/m3), drivers (81.9µg/m3), firefighters (71.2µg/m3) and office workers (19.8µg/m3). Exposure across job type was similarly stratified across all personal exposures to BTEX measured in air samples with maximum concentrations found for tanker loading workers. Average exposures concentrations of BTEX measured in urine were 11.83 ppb benzene, 1.87 ppb toluene, 0.43 ppb ethylebenzene, and 3.76 ppb xylene. Personal air exposure to benzene was found to be positively associated with benzene concentrations measured in urine; however, a relationship was not observed to the other BTEX compounds. Urinary exposure profiles are a potentially useful, noninvasive, and rapid method for assessing exposure to benzene in a developing and relatively remote production region.

BTEX exposure assessment and quantitative risk assessment among petroleum product distributors.

The aim of this study was to evaluate benzene, toluene, ethylbenzene, and xylene (BTEX) exposure among workers at four stations of a major oil distribution company. Personal BTEX exposure samples were collected over working shift (8h) for 50 workers at four stations of a major oil distribution company in Iran. Measured mean values for workers across four sites were benzene (2437, 992, 584, and 2788µg/m3 respectively), toluene (4415, 2830, 1289, and 9407µg/m3), ethylbenzene (781, 522, 187, and 533µg/m3), and xylene (1134, 678, 322, and 525µg/m3). The maximum mean concentration measured across sites for benzene was 2788µg/m3 (Station 4), toluene was 9407µg/m3 (Station 4), ethylbenzene was 781µg/m3 (Station 1) and xylene was 1134µg/m3 (Station 1). The 8h averaged personal exposure benzene concentration exceeded the recommended value of 1600µg/m3 established by the Iranian Committee for Review and Collection of Occupational Exposure Limit and American Conference of Governmental Industrial Hygienists. Mean values for excess lifetime cancer risk for exposure to benzene were then calculated across workers at each site. Estimates of excess risk ranged from 1.74 ± 4.05 (Station 4) to 8.31 ± 25.81 (Station 3). Risk was assessed by calculation of hazard quotients and hazard indexes, which indicated that xylene and particularly benzene were the strongest contributors. Tanker loading was the highest risk occupation at these facilties. Risk management approaches to reducing exposures to BTEX compounds, especially benzene, will be important to the health of workers in Iran.

Assessment of indoor and outdoor particulate air pollution at an urban background site in Iran.

The relationship between indoor and outdoor particulate air pollution was investigated at an urban background site on the Payambar Azam Campus of Mazandaran University of Medical Sciences in Sari, Northern Iran. The concentration of particulate matter sized with a diameter less than 1 µm (PM1.0), 2.5 µm (PM2.5), and 10 µm (PM10) was evaluated at 5 outdoor and 12 indoor locations. Indoor sites included classrooms, corridors, and office sites in four university buildings. Outdoor PM concentrations were characterized at five locations around the university campus. Indoor and outdoor PM measurements (1-min resolution) were conducted in parallel during weekday mornings and afternoons. No difference found between indoor PM10 (50.1 ± 32.1 µg/m3) and outdoor PM10 concentrations (46.5 ± 26.0 µg/m3), indoor PM2.5 (22.6 ± 17.4 µg/m3) and outdoor PM2.5 concentration (22.2 ± 15.4 µg/m3), or indoor PM1.0 (14.5 ± 13.4 µg/m3) and outdoor mean PM1.0 concentrations (14.2 ± 12.3 µg/m3). Despite these similar concentrations, no correlations were found between outdoor and indoor PM levels. The present findings are not only of importance for the potential health effects of particulate air pollution on people who spend their daytime over a period of several hours in closed and confined spaces located at a university campus but also can inform regulatory about the improvement of indoor air quality, especially in developing countries.

Indoor PM1, PM2.5, PM10 and outdoor PM2.5 concentrations in primary schools in Sari, Iran.

This study was carried out to determine the distribution of particles in classrooms in primary schools located in the centre of the city of Sari, Iran and identify the relationship between indoor classroom particle levels and outdoor PM2.5 concentrations. Outdoor PM2.5 and indoor PM1, PM2.5, and PM10 were monitored using a real-time Micro Dust Pro monitor and a GRIMM monitor, respectively. Both monitors were calibrated by gravimetric method using filters. The Kolmogorov-Smirnov test showed that all indoor and outdoor data fitted normal distribution. Mean indoor PM1, PM2.5, PM10 and outdoor PM2.5 concentrations for all of the classrooms were 17.6 µg m(-3), 46.6 µg m(-3), 400.9 µg m(-3), and 36.9 µg m(-3), respectively. The highest levels of indoor and outdoor PM2.5 concentrations were measured at the Shahed Boys School (69.1 µg m(-3) and 115.8 µg m(-3), respectively). The Kazemi school had the lowest levels of indoor and outdoor PM2.5 (29.1 µg m(-3) and 15.5 µg m(-3), respectively). In schools located near both main and small roads, the association between indoor fine particle (PM2.5 and PM1) and outdoor PM2.5 levels was stronger than that between indoor PM10 and outdoor PM2.5 levels. Mean indoor PM2.5 and PM10 and outdoor PM2.5 were higher than the standards for PM2.5 and PM10, and there was a good correlation between indoor and outdoor fine particle concentrations.

Occupational exposure to respirable crystalline silica in the Iranian Mazandaran province industry workers.

This study investigated occupational exposure to silica dust of 48 workers in stone cutting, glass making, ceramic, and sand blasting plants in the north of Iran. Samples were collected from the breathing zone using a personal sampling pump and a size-selective cyclone. Sample filters and blanks were analysed using infrared spectroscopy. The mean sampling period was 4.83 h. Mean exposure of workers to crystalline silica dust in glass making, ceramic, sand blasting, and stone cutting was 0.129 mg m-3, 0.169 mg m-3, 0.313 mg m-3 and 0.318 mg m-3, respectively. As exposure at each of the workplaces is three to 12 times higher than the current national and international thresholds, these workers run a greater risk of lung cancer and mortality. Our findings call for specific ventilation design and personal protection improvements in the four plants as well as stricter enforcement of the existing regulations by the authorities.