Liver functions in silica-exposed workers in Egypt: possible role of matrix remodeling and immunological factors

Brick kiln pollution and its impact on health: A systematic review and meta-analysis

Brick kiln emissions adversely affect air pollution and the health of workers and individuals living near the kilns; however, evidence of their impacts remains limited. We conducted a systematic review of brick kiln pollution (emissions, source contributions and personal exposures) and its effects on health. We extracted articles from electronic databases and through manual citation searching. We estimated pooled, sample-size-weighted means and standard deviations for personal exposures by job type; computed mean emission factors and pollutant concentrations by brick kiln design; and meta-analyzed differences in means or proportions for health outcomes between brick kiln workers and controls or for participants living near or far away from kilns. We identified 104 studies; 74 were conducted in South Asia. The most evaluated pollutants were particulate matter (PM; n = 48), sulfur dioxide (SO2; n = 24) and carbon monoxide (CO; n = 22), and the most evaluated health outcomes were respiratory health (n = 34) and musculoskeletal disorders (n = 9). PM and CO emissions were higher among traditional than improved brick kilns. Mean respirable silica exposures were only measured in 4 (4%) studies and were as high as 620 μg/m3, exceeding the NIOSH recommended exposure limit by a factor of over 12. Brick kiln workers had consistently worse lung function, more respiratory symptoms, more musculoskeletal complaints, and more inflammation when compared to unexposed participants across studies; however, most studies had a small sample size and did not fully describe methods used for sampling or data collection. On average, brick kiln workers had worse health outcomes when compared to unexposed controls but study quality supporting the evidence was low. Few studies reported silica concentrations or personal exposures, but the few that did suggest that exposures are high. Further research is needed to better understand the relationship between brick kiln pollution and health among workers, and to evaluate exposure mitigation strategies.

The impact of brick kilns on environment and society: a bibliometric and thematic review

Bricks have a long history of being utilized as a construction material across the globe. The production processes involved in the manufacture of bricks have a significant impact on the environment, human health, economy, and society. This study conducts a thematic and bibliometric analysis to provide an in-depth review of the effects of brick kilns on humans and the environment. The PRISMA framework was used to identify relevant articles from the Web of Science database, resulting in the selection and critical review of 348 articles. The bibliometric analysis included an evaluation of historical growth, keywords, citation and co-citation, organizations, and countries. The articles were published in 213 journals, written by 1396 authors from 670 institutions in 66 countries. Thematic analysis revealed that brick kilns have a negative impact on the environment, including soil damage, and cause health problems for kiln workers and animals. Modern slavery and societal issues also persist in developing countries. The current research is focused on finding alternative materials for brick manufacturing, improving industry energy efficiency, managing waste, and technological advancements, such as the implementation of the zigzag or Hoffmann kiln to reduce pollution. In developing countries, utilizing waste from other industries in brick production can effectively lower production costs. While developed countries have embraced advanced technologies for brick production, it is recommended that developing countries adopt awareness campaigns to encourage the upgrading of kilns to cleaner and more sustainable systems. Future research directions should aim to support brick kiln owners in adopting such systems.

The effect of silica exposure on the risk of lung cancer: A meta-analysis

Lung cancer is an incurable disease with an increased mortality rate caused by the inhalation of dust-containing crystalline silica particles. Silica exposure is one of the most important occupational hazards in the world. Whether the association between silica exposure and lung cancer is because of the fibrotic process or to the effect of respirable silica itself is unclear. The International Agency for Research on Cancer (IARC) classified silica as a human lung carcinogen. The opinion of lung cancer is a question that has been addressed in this review. Three electronic databases, including MEDLINE, Scopus, and Web of Science, were used to search for relevant literature from 2000 to 2022. To evaluate the relationship between exposure to silica and developing lung cancer, we performed a meta-analysis using the random-effects model. For each study, the overall odds ratio (OR), relative risk (RR) with 95% confidence intervals (CI), and p values were calculated. An extensive database search resulted in the selection of 20 (case-control and nested case-control studies were selected) out of 527 studies. Among the 20 selected studies, 7 studies showed a significant association between silica exposure and an increased risk of lung cancer. Further analysis showed that among the selected studies, six studies showed a significant correlation between combined exposure to silica and smoking with an increased risk of lung cancer. The data from the present study showed that smoking habits increased the impact of silica exposure on the initiation of lung carcinogenesis in exposed workers.

Therapeutic potential of root and stem bark of wild medicinal plant Ziziphus mauritiana (Lamk.) against silica induced toxicity in Wistar albino rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ziziphus mauritiana (Lamk.) of the family Rhamnaceae is a traditional herbal medicinal plant commonly called as 'ber' (Indian jujube). It is traditionally used as food source and helps in treatment of various diseases like malaria, asthma, diarrhoea, typhoid, diabetes, skin diseases and acts as a pain killer.

AIM OF THE STUDY

This study aimed to evaluate the ability of extracts of barks of root and stem of Ziziphus mauritiana (ZM) to cure silica induced toxicity in Wistar albino rats.

MATERIALS AND METHODS

Experiments carried out on the acute toxicity studies of silica and therapeutic potential of ZM extracts were based on OECD guidelines and from these results lethal dose (LD₅₀) values were determined. Silica was administered by IP injection at 20 mg/kg b.w. for 10 days and roots and stem barks extracts of ZM were fed orally by gavage at 400 mg/kg b.w. for 21 days. Assessments of biochemical, haematological parameters as well as liver histological examination were performed in the study.

RESULTS

After 21 days of oral feeding of extracts of root and stem of ZM, it was found to alter the liver histology. Significant decrease in enzymes such as ALT, AST, ALP, LDH and urea, creatinine and uric acid levels in serum were recorded. Treatment with extracts could help enzymatic activity of liver antioxidant enzymes to settle towards normal level and significant decrease in the lipid peroxidation along with increase in the value of GSH in liver, was also observed. In addition, extracts of ZM also helped to reduce the serum NO, IL-6 and TNF-α level.

CONCLUSION

Results of this study has suggested that the extracts of root and stem bark of ZM can be used for therapeutic purpose to prevent silica induced toxicity. ZM extracts could be utilised as natural antioxidant and immunotherapeutic medicines to protect silica induced cell damage.

Determination of crystalline silica in respirable dust upon occupational exposure for Egyptian workers

Crystalline free silica is considered as a lung carcinogen and the occupational exposure to its dust is a health hazard to workers employed in industries that involve ores of mineral dust. In Egypt, thousands of people work under conditions of silica dust exposure exceeding the occupational exposure limit, as a result the monitoring of this occupational exposure to crystalline silica dust is required by government legislation. The assessment of the later is a multi-phase process, depend on workplace measurements, quantitative analyses of samples, and comparison of results with the permissible limits. This study aims to investigate occupational exposure to crystalline silica dust at 22 factories in Egypt with different industrial activities like stone cutting, glass making, ceramic, and sand blasting. Dust samples were collected from work sites at the breathing zone using a personal sampling pump and a size-selective cyclone and analyzed using FTIR. The sampling period was 60-120 min. The results show that the exposure at each of the industrial sectors is very much higher than the current national and international limits, and that lead to a great risk of lung cancer and mortality to workers.

Inflammatory and oxidative stress parameters as potential early biomarkers for silicosis

Workers involved in mining activities are exposed to crystalline silica, which leads to constant pulmonary inflammatory reactions and severe oxidative damage, resulting in silicosis. In this work, we aimed to evaluate inflammatory and oxidative stress parameters as potential early biomarkers of effect to assess crystalline silica toxicity in workers who had occupational exposure during mining. We enrolled 38 workers exposed to crystalline silica (WECS), 24 individuals with silicosis (IWS), and 30 occupationally unexposed workers (OUW), a total of 92 participants. The WECS were divided into 2 groups, according to the time of exposure: 19 workers with 1-15 years of occupational exposure (WECS I) and 19 workers with >16 years of occupational exposure (WECS II). The inflammatory parameters assessed were L-selectin, β-2 integrin, and intercellular adhesion molecule-1 (ICAM-1) surface protein expression in lymphocytes and monocytes, complement C3 and C4, high sensitivity C-reactive protein (hsCRP), and adenosine deaminase (ADA) in serum. Plasma levels of malondialdehyde (MDA) and serum levels of vitamin C were determined as biomarkers of oxidative stress. Biochemical and hematological parameters were also investigated. L-selectin surface protein expression was significantly decreased in the WECS II group (p < 0.05), indicating the importance of this immune system component as a potential marker of crystalline-silica-induced toxicity. The MDA levels were significantly increased in the WECS I, WECS II, and IWS groups compared to the OUW group (p < 0.05). Vitamin C levels were decreased, while C3, hsCRP, ADA, and aspartate aminotransferase (AST) levels were increased in the IWS group compared to the OUW group (p < 0.05). Glucose and urea levels were significantly higher in the WECS I, II, and IWS groups compared to the OUW group (p < 0.05). Negative partial association was found between L-selectin and time of exposure (p < 0.001), supporting the relevance of this biomarker evaluation in long-term exposure to crystalline silica. Significant associations were also observed among inflammatory and oxidative stress biomarkers. Therefore, our results demonstrated the relevance of L-selectin as a potential peripheral biomarker for monitoring crystalline silica-induced toxicity in miners after chronic exposure, before silicosis has developed. However, more studies are necessary for better understanding of the use L-selectin as an early biomarker in exposed workers.

[Well-digger's lung]

The essential occupation of well-digger includes wells drilling and maintenance in order to provide water. He comes in contact with various minerals, especially silica, whose particles unquestionably are a contributing factor to pulmonary diseases known as silicosis. Our study aims to highlight the epidemiological, clinical, radiological and evolutionary features of well-diggers with silicosis. We conducted a retrospective study of 54 well-diggers with silicosis whose data were collected in the Department of Respiratory Diseases at the University Hospital Ibn Rushd of Casablanca from March 1997 to January 2016. All patients were male well-diggers with an average age of 50 years. Smoking was found in 36 cases and a personal history of tuberculosis was observed in eight cases. Chest x-ray showed large opacities in 39 cases, small opacities in 15 cases and septat thickening in 11 cases. Silicosis was complicated by bacterial infection in 37% of cases, by pneumothorax in 4% of cases and by tuberculosis in 20% of cases. Therapeutic approach was established based on these complications. A declaration of occupational disease and compensation was made. Outcome was good in 12 cases, stationary in 17 cases and poor in 16 cases. Silicosis is a common pneumoconiosis among well-diggers. It affects lung function. We here highlight its frequent association with tuberculosis and emphasize on prevention which is the best treatment.

Cement Dust Exposure and Perturbations in Some Elements and Lung and Liver Functions of Cement Factory Workers

Background. Cement dust inhalation is associated with deleterious health effects. The impact of cement dust exposure on the peak expiratory flow rate (PEFR), liver function, and some serum elements in workers and residents near cement factory were assessed. Methods. Two hundred and ten subjects (50 workers, 60 residents, and 100 controls) aged 18–60 years were studied. PEFR, liver function {aspartate and alanine transaminases (AST and ALT) and total and conjugated bilirubin (TB and CB)}, and serum elements {lead (Pb), copper (Cu), manganese (Mn), iron (Fe), cadmium (Cd), selenium (Se), chromium (Cr), zinc (Zn), and arsenic (As)} were determined using peak flow meter, colorimetry, and atomic absorption spectrometry, respectively. Data were analysed using ANOVA and correlation at p = 0.05. Results. The ALT, TB, CB, Pb, As, Cd, Cr, Se, Mn, and Cu were significantly higher and PEFR, Fe, and Zn lower in workers and residents compared to controls (p < 0.05). Higher levels of ALT, AST, and Fe and lower levels of Pb, Cd, Cr, Se, Mn, and Cu were seen in cement workers compared to residents (p < 0.05). Negative correlation was observed between duration of exposure and PEFR (r = −0.416, p = 0.016) in cement workers. Conclusions. Cement dust inhalation may be associated with alterations in serum elements levels and lung and liver functions while long term exposure lowers peak expiratory flow rate.