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

Lead exposure suppresses the Wnt3a/β-catenin signaling to increase the quiescence of hematopoietic stem cells via reducing the expression of CD70 on bone marrow-resident macrophages

Lead (Pb) is a heavy metal highly toxic to human health in the environment. The aim of this study was to investigate the mechanism of Pb impact on the quiescence of hematopoietic stem cells (HSC). WT C57BL/6 (B6) mice treated with 1250 ppm Pb via drinking water for 8 weeks had increased the quiescence of HSC in the bone marrow (BM), which was caused by the suppressed activation of the Wnt3a/β-catenin signaling. Mechanically, a synergistic action of Pb and IFNγ on BM-resident macrophages (BM-Mφ) reduced their surface expression of CD70, which thereby dampened the Wnt3a/β-catenin signaling to suppress the proliferation of HSC in mice. In addition, a joint action of Pb and IFNγ also suppressed the expression of CD70 on human Mφ to impair the Wnt3a/β-catenin signaling and reduce the proliferation of human HSC purified from umbilical cord blood of healthy donors. Moreover, correlation analyses showed that the blood Pb concentration was or tended to be positively associated with the quiescence of HSC, and was or tended to be negatively associated with the activation of the Wnt3a/β-catenin signaling in HSC in human subjects occupationally exposed to Pb. Collectively, these data indicate that an occupationally relevant level of Pb exposure suppresses the Wnt3a/β-catenin signaling to increase the quiescence of HSC via reducing the expression of CD70 on BM-Mφ in both mice and humans.

Characterization of welding fume and airborne heavy metals in electronic manufacturing workshops in Hangzhou, China: implication for occupational population exposure

Occupational exposure to contaminants created by electronic manufacturing process is not well characterized. The aim of this study was to carry out risk assessments of exposure to welding fume and airborne heavy metals (HMs) in electronic manufacturing workshops. Seventy-six air samples were collected from five sites in Hangzhou, China. In welding workshops, the most abundant contaminant found was welding fume, followed by Fe, Mn, Zn, Cu, Pb, Cd, and Cr. The concentration of Mn was positively correlated with Fe (r = 0.906). When compared with non-welding workshops, the Fe content in the air of welding workshops increased significantly (P < 0.05), while the Cu content decreased significantly (P < 0.05). Singapore semi-quantitative health risk assessment model and the United States Environmental Protection Agency (US EPA) inhalation risk assessment model were applied to assess the occupational exposure. In welding workshops, the levels of 8-h time weighted average (8 h-TWA) calculated for welding fume (range 0.288 ~ 6.281 mg/m³), Mn (range Nd ~ 0.829 mg/m³), and Fe (range 0.027 ~ 2.234 mg/m³) partly exceeded the permissible limits. While, in non-welding workshops, the average of 8 h-TWA for Cu (0.411 mg/m³) was higher than the limit. The risk rates (RR) assessed for Pb (2.4 vs 1.7), Mn (2.0 vs 1.4), and Fe (1.4 vs 1.0) were higher in welding workshops than that in non-welding workshops, but Cu (1.0 vs 2.2) were lower. The mean excess lifetime cancer risks (ELCR) in welding (5.59E - 06 per 1000 people) and non-welding (1.88E - 06 per 1000 people) workshops were acceptable. The mean non-cancer risk (HQ) estimated for Mn was greater than 10 in both welding (HQ = 164) and non-welding (HQ = 11.1) workshops. These results indicate that there was a risk of occupational exposure implication in the electronic manufacturing workshops. Reducing contaminant exposure through engineering controls and management strategies, such as efficient ventilation and reducing exposure hours, is thus suggested.

Assessment of occupational health risk due to inhalation of chemical compounds in an aircraft maintenance, repair, and overhaul company

This study was conducted in an aircraft maintenance, repair, and overhaul (MRO) company in 2021 to identify the extent of occupational exposures and quantitative assessment of the health risk due to inhalation of chemical compounds. According to the inspection of different parts of this company, heavy metals including Co, Cd, Ni, Pb, Cr(VI), and Mn and organic compounds including benzene, toluene, ethylbenzene, xylene (BTEX), and methyl ethyl ketone (MEK) were selected for health risk assessment. In total, the air in the inhalation area of active workers was sampled in 51 workstations. Measurement of the above pollutants showed that the average occupational exposure to Cd, Pb, and all organic compounds fell within the acceptable range of occupational exposure standard, while the measured values for Co, Ni, Mn, and Cr(VI) exceeded the standard limit. According to calculations, the highest carcinogenic risk (CR) was seen in the plating (airplane) workshop for exposure to Cr(VI) (7.58E-01), and the lowest CR was observed in the electronic workshop for exposure to Pb (7.75E-08). The highest non-carcinogenic hazard (HQ) was found in the welding workshop for exposure to Co (1.00E + 04), while the lowest HQ was related to toluene in the fabrication workshop (9.10E-03). Considering the high rate of exposure indicators, CR and HQ exceeded the standards set by the American Environmental Protection Agency (EPA) in most workshops. Accordingly, company managers should take the necessary measures to reduce the vulnerability of individuals working in areas with unacceptable CR and HQ.

Assessment of occupational health and safety risks in a Turkish public hospital using a two-stage hesitant fuzzy linguistic approach

Occupational health and safety (OHS) risk assessment studies have gained importance recently as a result of increasing occupational accidents and occupational diseases. The health sector has a greater risk than many sectors for occupational accidents and occupational diseases. Although the health sector is one of the priority sectors in Turkey, OHS practices have not been fully implemented in this field. For this reason, this study adopts a two-stage approach to assess the OHS risks in the health sector by combining the Fine-Kinney and multi-criteria hesitant fuzzy linguistic term set (HFLTS) methods. The proposed method was applied to the OHS risks in the operating room of a public hospital in Turkey. As a solution to the problem, first, the potential hazards and related risks in the operating room were determined by the experts. In this first stage, 44 hazards were determined from the opinions of experts and records of past incidents. Parameter weights were then determined using the multi-criteria HFLTS method. The multi-criteria HFLTS method was used to evaluate seven hazards to be categorized as substantial-risk or higher according to the Fine-Kinney method, taking into account parameter weights. Sensitivity analysis was then carried out. Finally, actions were taken to mitigate the risks.

Occupational Exposure to Carcinogens and Occupational Epidemiological Cancer Studies in Iran: A Review

INTRODUCTION

The extent of exposure to occupational carcinogens is not well characterized in Iran, and little is known about the burden of occupational cancer.

OBJECTIVES

This study aimed to describe exposure to occupational carcinogens and occupational epidemiology studies in Iran.

METHODS

Relevant studies up to January 2021 in Iran were identified through three databases (PubMed, Web of Science, and Google Scholar).

RESULTS

Forty-nine publications from 2009 to 2020 (one cohort, 11 case-control, 34 exposure monitoring studies, and three cancer burden studies) were included. The exposure monitoring studies were conducted mainly in the petroleum industry, metal industry, manufacturing of electronics, manufacturing of plastics, construction industry, and service industry. A few of the case-control studies also reported increased risk of cancers in relation to work in those industries.

CONCLUSIONS

Occupational cancer epidemiology in Iran is at an early stage. Both epidemiological and exposure monitoring studies are generally limited in size to provide robust evidence of occupational cancer risks. A coherent strategy to estimate the occupational cancer burden in Iran should start with conducting epidemiological studies along with systematic monitoring of occupational carcinogens for use in hazard control and research.

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.