Demonstration of Subclinical Early Nephrotoxicity Induced by Occupational Exposure to Silica among Workers in Pottery Industry

Impact of Respiratory Dust on Health: A Comparison Based on the Toxicity of PM2.5, Silica, and Nanosilica

Respiratory dust of different particle sizes in the environment causes diverse health effects when entering the human body and makes acute or chronic damage through multiple systems and organs. However, the precise toxic effects and potential mechanisms induced by dust of different particle sizes have not been systematically summarized. In this study, we described the sources and characteristics of three different particle sizes of dust: PM2.5 (<2.5 μm), silica (<5 μm), and nanosilica (<100 nm). Based on their respective characteristics, we further explored the main toxicity induced by silica, PM2.5, and nanosilica in vivo and in vitro. Furthermore, we evaluated the health implications of respiratory dust on the human body, and especially proposed potential synergistic effects, considering current studies. In summary, this review summarized the health hazards and toxic mechanisms associated with respiratory dust of different particle sizes. It could provide new insights for investigating the synergistic effects of co-exposure to respiratory dust of different particle sizes in mixed environments.

Toxic Kidney Damage in Rats Following Subchronic Intraperitoneal Exposure to Element Oxide Nanoparticles

Chronic diseases of the urogenital tract, such as bladder cancer, prostate cancer, reproductive disorders, and nephropathies, can develop under the effects of chemical hazards in the working environment. In this respect, nanosized particles generated as by-products in many industrial processes seem to be particularly dangerous to organs such as the testes and the kidneys. Nephrotoxicity of element oxide particles has been studied in animal experiments with repeated intraperitoneal injections of Al2O3, TiO2, SiO2, PbO, CdO, CuO, and SeO nanoparticles (NPs) in total doses ranging from 4.5 to 45 mg/kg body weight of rats. NPs were synthesized by laser ablation. After cessation of exposure, we measured kidney weight and analyzed selected biochemical parameters in blood and urine, characterizing the state of the excretory system. We also examined histological sections of kidneys and estimated proportions of different cells in imprint smears of this organ. All element oxide NPs under investigation demonstrated a nephrotoxic effect following subchronic exposure. Following the exposure to SeO and SiO2 NPs, we observed a decrease in serum creatinine and urea, respectively. Exposure to Al2O3 NPs caused an increase in urinary creatinine and urea, while changes in total protein were controversial, as it increased under the effect of Al2O3 NPs and was reduced after exposure to CuO NPs. Histomorphological changes in kidneys are associated with desquamation of the epithelium (following the exposure to all NPs except those of Al2O3 and SiO2) and loss of the brush border (following the exposure to all NPs, except those of Al2O3, TiO2, and SiO2). The cytomorphological evaluation showed greater destruction of proximal sections of renal tubules. Compared to the controls, we observed statistically significant alterations in 42.1% (8 of 19) of parameters following the exposure to PbO, CuO, and SeO NPs in 21.1% (4 of 19)-following that, to CdO and Al2O3 NPs-and in 15.8% (3 of 19) and 10.5% (2 of 19) of indicators, following the exposure to TiO2 and SiO2 nanoparticles, respectively. Histomorphological changes in kidneys are associated with desquamation of epithelium and loss of the brush border. The cytomorphological evaluation showed greater destruction of proximal sections of renal tubules. The severity of cyto- and histological structural changes in kidneys depends on the chemical nature of NPs. These alterations are not always consistent with biochemical ones, thus impeding early clinical diagnosis of renal damage. Unambiguous ranking of the NPs examined by the degree of their nephrotoxicity is difficult. Additional studies are necessary to establish key indicators of the nephrotoxic effect, which can facilitate early diagnosis of occupational and nonoccupational nephropathies.

Pulmonary Functions and Oxidative Stress Biomarkers Among Silica-Exposed Foundry Workers

OBJECTIVE

To investigate the changes of the ventilatory function tests and the oxidative stress biomarkers among silica-exposed foundry workers.

METHODS

The exposed group included 70 workers in an iron foundry. The nonexposed group included 40 subjects from Kasralainy outpatient clinic. Both groups were subjected to history taking, clinical examination, chest radiograph, spirometry, urinary silica, serum malondialdehyde (MDA), glutathione peroxidase (GPx), and 8-hydroxydeoxyguanosine (8-HdG).

RESULTS

Higher urinary silica, serum MDA and serum 8-HdG, whereas lower serum GPx and ventilatory functions were detected in the exposed group compared with the controls. All parameters correlated with urinary silica. The exposed silicotic subgroup had increased work duration, urinary silica, serum MDA, and serum 8-HdG, and decreased serum GPx and ventilatory functions compared with non-silicotic subgroup.

CONCLUSION

Oxidative stress biomarkers were abnormal with impairment of ventilatory functions among silica-exposed workers.

Asymptomatic Renal Function Abnormalities in Patients having Silicosis

BACKGROUND

A number of occupational exposures are associated with various types of renal dysfunction. Several studies for many years have drawn attention to renal dysfunction and nephrotoxicity among workers exposed to silica. This study was conducted to evaluate renal dysfunction, if any, among Indian patients having silicosis and its correlation with the duration of exposure to silica dust.

MATERIALS AND METHODS

This study includes 52 eligible patients with a history of silica dust exposure and silicosis confirm on radiological examination by the pneumoconiosis board. Investigations like serum creatinine, urinary albumin creatinine ratio, etc. were done. The "modification of diet in renal disease" (MDRD) formula was used to calculate the glomerular filtration rate (GFR).

RESULTS

This study showed 53.84% of patients (n = 28) having albuminuria and a mean "urinary albumin to creatinine ratio" (UACR) of 101.88 ± 128.99 mg/gm. Isolated macroalbuminuria was detected in 11.5% of patients (n = 6) while 42.3% of patients (n = 22) presented with microalbuminuria. The mean GFR was 81.94 ± 22.09 mL/min/1.73 m2 among study patients of which four (7.7%) patients had GFR value &lt;60 mL/min/1.73 m2 . We could also identify a significant association between the duration of exposure to silica dust and UACR and GFR (p &lt; 0.01).

CONCLUSION

Albuminuria and reduced estimated GFR in patients with silica dust exposure is not uncommon and reflect early underlying renal dysfunctions. Our study suggests a simple and cost-effective screening strategy for early detection of renal dysfunction among silicosis patients that may be considered as a tool to prevent further renal damage in such patients.

Where do you live and what do you do? Two questions that might impact your kidney health

In many cases the social determinants of health need to be assessed through their interaction with environmental factors. This review looks at the impact of physical location and occupation of individuals on their kidney health. It examines the effect of living at high altitude on kidney function and the relationship between extreme cold or hot temperatures and the incidence of kidney injury. It reviews as well the many occupations that have been linked to kidney disease in high-income and low-and-middle-income countries. As a conclusion, this overview proposes preventive recommendations that could be individualized based on weather, altitude, socio-economic level of the country and occupation of the individual.

Nephrotoxic Biomarkers with Specific Indications for Metallic Pollutants: Implications for Environmental Health

Environmental and occupational exposure to heavy metals and metalloids is a major global health risk. The kidney is often a site of early damage. Nephrotoxicity is both a major consequence of heavy metal exposure and potentially an early warning of greater damage. A paradigm shift occurred at the beginning of the 21st century in the field of renal medicine. The medical model of kidney failure and treatment began to give way to a social model of risk factors and prevention with important implications for environmental health. This development threw into focus the need for better biomarkers: markers of exposure to known nephrotoxins; markers of early damage for diagnosis and prevention; markers of disease development for intervention and choice of therapy. Constituents of electronic waste, e-waste or e-pollution, such as cadmium (Cd), lead (Pb), mercury (HG), arsenic (As) and silica (SiO₂) are all potential nephrotoxins; they target the renal proximal tubules through distinct pathways. Different nephrotoxic biomarkers offer the possibility of identifying exposure to individual pollutants. In this review, a selection of prominent urinary markers of tubule damage is considered as potential tools for identifying environmental exposure to some key metallic pollutants.

Chronic kidney disease of unknown etiology in India: a comparative study with Mesoamerican and Sri Lankan nephropathy

Chronic kidney disease of unknown etiology [CKDu] is a condition characterized by decline in kidney function and is not associated with diabetic nephropathy or hypertensive nephropathy. In this review, we have done a detailed literature analysis on CKDu in India, and then had a comparison with that of Mesoamerica and Sri Lanka. In India, CKDu became the second most common type of CKD after diabetic nephropathy. Silica was seen in the groundwater of both India and Sri Lanka, whereas in Mesoamerica silica exposure through particulate matter was seen among CKDu communities. DDE is a common agrochemical seen in both India and Sri Lanka. The risk factors vary from region to region and it is important to categorize CKDu population based on the risk factors to avoid misinterpretation of the condition as non-CKDu category and to evade further complications. More studies have to be conducted to reveal the detailed pathophysiological mechanisms and its relation with irrational exploitation of environmental resources.

Potent efficacy of Stachybotrys microspora triprenyl phenol-7, a small molecule having anti-inflammatory and antioxidant activities, in a mouse model of acute kidney injury

Acute kidney injury (AKI) increases the risk of chronic kidney disease (CKD), complicates existing CKD, and can lead to the end-stage renal disease. However, there are no approved effective therapeutics for AKI. Recent studies have suggested that inflammation and oxidative stress are the primary causes of AKI. We previously reported the potential anti-inflammatory and antioxidant activities of Stachybotrys microspora triprenyl phenol-7 (SMTP-7). The aim of the present study was to evaluate the efficacy of SMTP-7 in AKI model mice. AKI was induced in mice by ischemia of the left renal artery and vein for 45 min followed by reperfusion, 2 weeks after the removal of right kidney. The efficacy of SMTP-7 was determined by measuring the renal function using urine and serum samples and morphological assessment. For deciphering the mechanism of action of SMTP-7, inflammatory cytokines and oxidative stress in kidney were detected. SMTP-7 (0.01, 0.1, 1, 10 mg/kg) dose-dependently improved the renal function. In addition, it improved the damage to renal tubules and exhibited anti-inflammatory and antioxidant activities in the kidney of AKI mice. These results indicate the potential of SMTP-7 as a medicinal compound for the treatment of AKI.