Development of a New Sequential Extraction Procedure of Nickel Species on Workplace Airborne Particulate Matter: Assessing the Occupational Exposure to Carcinogenic Metal Species

Heavy metal contents of selected commercially available oil-based house paints intended for residential use in Ethiopia

Environmental pollution by paint-based heavy metals have been continued to be a great concern. Thus, this study was aimed at investigating the levels of selected heavy metals (Ni, Cd, Cr, Zn, and Pb) in oil-based paint samples being manufactured and sold in Ethiopia. An optimized acid digestion procedure using conc. HNO₃, conc. HClO₄, and 30% H₂O₂ mixture by volume ratio of 3:4:1 mL, respectively, for 2 h at 200 °C were used for paint samples digestion, and the contents of heavy metals were assayed by flame atomic absorption spectroscopy. The 13 out of 14 (92.9%) analyzed paint samples had contained Pb > 90 mg/kg with the highest content of 51,200 mg/kg (dry weight) in the orange colored paint. Likewise, the levels of Cr, Ni, and Zn obtained were ranged from 43.75 to 50.00, 60.02 to 128.81, and 323.69 to 1102.16 mg/kg (dry weight), respectively, while Cd was not detected in all the paint samples. Generally, the mean contents of heavy metals in the investigated paint samples have followed the order: Pb > > Cr > Zn > Ni, demonstrating the occurrence of higher lead metal content. The elevated levels of heavy metals detected in the oil-based paint samples could be attributed to the continued usage of these metals in different form during paint manufacture. On the bases of the findings, a strict monitoring and evaluation of paints being produced in Ethiopia has been recommended so that the manufacturers comply with the national (policy issue) and/or international regulations on the levels of toxic metals in paints to ensure consumers safety.

Assessment of metals induced histopathological and gene expression changes in different organs of non-diabetic and diabetic rats

Diabetes is a complex metabolic disorder and different environmental toxicants including heavy metals have been involved in diabetes induction. Therefore, assessment of the environmental risk factors and heavy metals induced toxicity have become critical for reducing the consequences of metals pollutants. Previously, we reported heavy metals induced nephrotoxicity in non-diabetic and diabetic rats. Here, we extended our analysis by examining the heavy metals induced organs (heart, kidney, liver, pancreas, and spleen) damage in diabetic and non-diabetic Wistar rats using histopathology and quantitative real-time PCR (qRT-PCR). Following the generation of the diabetic rat model, the animals were exposed to heavy metals including lead (Pb), arsenic (As), manganese (Mn) and cadmium (Cd). Both non-diabetic and diabetic rats were exposed to heavy metals for 30 days and subsequently, the heart, kidney, liver, pancreas and spleen tissues were examined. Heavy metal treatment resulted in irregularly arranged myofibrils and vacuolization in the heart tissue of metal treated groups as evident from hematoxylin and eosin (H & E) staining. The kidney tissue of rats treated with heavy metals showed tubular degeneration, fibrosis, hemorrhage, and vacuolation. The liver of the heavy metals treated rats exhibited cellular degeneration and necrosis. The pancreatic tissue of streptozotocin injected untreated and metal treated rats revealed severe degeneration, necrosis, degranulation, shrinkage, and depression in the islets of Langerhans. Increased red pulp area and congestion were observed in the spleen of the metal mixture treated non-diabetic and diabetic rats. In line with the histological data, the qRT-PCR analysis showed downregulated expression of Bcl₂ and upregulation of Caspase-3 in non-diabetic and diabetic metal treated rats as compared to the non-diabetic untreated rats. In conclusion, the present study revealed, diabetic rats are more prone to metal alone as well as metal mixture induced organ damage as compared to non-diabetic rats.