Alterations in morphology and hepatorenal indices in rats subacutely exposed to bitumen extract

Abstract

Bitumen is a complex mixture of dense and extremely viscous organic liquids produced by distillation of crude oil during petroleum refining. Nigeria has a large deposit of natural bitumen, yet to be fully exploited. Discharges of petroleum hydrocarbons and other petroleum-derived products have caused environmental pollution and adverse human health effects in several oil-rich communities. In this study, bitumen obtained from a seepage source in Agbabu, the town of first discovery, was used in sub-acute toxicity studies in a rat experimental model, in order to assess potential health risks posed to local populace sequel to full exploitation of bitumen. Dosages were chosen to accommodate low to high cases of environmental exposures. Male Wistar rats were administered, per os, dosages of bitumen extract at 5, 3, 2, and 1 mg/kg body weight. Following euthanasia 28 days later, histological findings revealed severe portal congestion and cellular infiltration in the liver, while in the kidney there were protein casts in the tubular lumen. The relative liver and kidney weights in the 5 mg/kg groups were 34% and 40% higher than in the controls, with a concomitant decrease in food and water consumption. Furthermore, plasma clinical analyses revealed marked elevation in aspartate aminotransferase and triglycerides levels in bitumen extract-intoxicated rats. The results indicate the potential hepatorenal toxicity in adult rats following repeated exposure to bitumen extract. ARTICLE HISTORY

Occupational Exposure to Paving Asphalt Fumes, Impact on Liver and Kidney Function Test Parameters

“…One of the findings of the present study is the significant elevation of AST enzyme in the asphalt-exposed group compared to the control group. Just like in our study, previous works confirmed the significant elevation of AST activity in rats exposed to bitumen extract [3]. AST is found in the mitochondria of liver, kidney, and heart cells.…”

“…Previous studies confirmed that hepatotoxicity in the experimental rat model could be assessed by plasma triglyceride assay. Otuechere et al had already reported a similar finding of an increased level of triglyceride in an experimental rat model exposed to bitumen extract [3]. Contrary to our findings, decreased levels of AST and ALT were reported for those subjects occupationally exposed to petroleum oil [28].…”

“…Previous studies on plasma biochemical parameters in road paving workers had shown higher levels of reactive oxygen species, increase DNA damage, and cytogenetic alterations [19,20]. In the experimental studies, it was concluded that the liver is one of the target organs for toxicity by the bitumen extract [3]. In the initial phase of organ toxicity, the patient looks healthy, and the clinical problem is not apparent [17].…”

“…Asphalt contains about 7% to 10% bitumen and is heated up to 230°C-250°C to be processed for working. Bitumen is widely used in the construction industry for roofing, road paving, and sealing cracks and joints in pavements [3]. Bitumen contains carbon, hydrogen, nitrogen, sulfur, and heavy metals [4].…”