LANDFILL LEACHATE-INDUCED OXIDATIVE DAMAGE IN RAT AND AFRICAN CATFISH

Abstract

Landfill leachate poses potential health hazards for man and his environment. Leachates can generate free radicals in exposed tissues. Free radicals may cause DNA damage and oxidative stress associated with many disease states. Information on oxidative damage that may be induced in eukaryotic systems by landfill leachate in Nigeria is scanty. In this study, the potential of leachates from Olusosun Landfill, Lagos State, Nigeria to induce oxidative damage in rat (Rattus norvegicus) and African catfish (Clarias gariepinus) was investigated. Sixty-six male Wistar rats (120-180g) were allocated in control (tap water) and Olusosun landfill leachate (OLL) treated (10%, 25%, 50%, 75%, and 100%) groups with five animals in each group for sub-acute (14 days) and six animals in each group for sub-chronic (90 days) studies. Thirty Carlias gariepinus (450-500g) equally divided into five groups were respectively exposed to 10%, 20%, 40%, 60% OLL and tap water for seven days. Six milliliters of blood per rat was collected and serum was used to determine Alanine aminotransferase (ALT), Aspartate aminotransferase (AST), Alkaline phosphatase (ALP), Gamma Glutamyl Transferase (GGT), bilirubin, creatinine and urea by spectrophotometry. Lipid Peroxidation (LPO), hydrogen peroxide generation (H2O2), glutathione and activities of Glutathione-S-Transferase (GST), Glutathione Peroxidase (GPx), catalase and Superoxide Dismutase (SOD) were determined by spectrophotometry in the Post Mitochondrial (PMF) of liver and kidney of rats and fishes and also in the gills of the fishes. Damage to DNA was assessed in rats by the extent of micronucleus induction after 24hrs of OLL exposure. Data were analyzed using ANOVA and Student's t-test at p=0.05. In the controls, the values of AST, ALT, ALP, GGT, bilirubin, catalase, H2O2 and LPO in the liver of the rats were 19.8±2.8 U/L, 23.8±1.9 U/L. 45.6±5.9 U/L, 0.6±0.1 U/L, 3.9±0.3 umol/dl, 15.1±0.9 U/mg protein, 20.8±1.9 umol and 2.6±0.2 nmol/mg protein respectively. Exposure to OLL significantly increased the levels of AST (25.3-36.0 U/L), ALT (26.5-30.0 U/L). ALP (98.0-275. 1U/L) GGT (0.8-3, 5U/L.). bilirubin (4.0-15.1 umol/dl), catalase (16.0-19.4U/mg protein), H₂O₂ (21.0-34.3umoL) and LPO (3.3-5.3nmol/mg protein) and significantly decreased GPx activity (3.3-3.0 U/mg protein) relative to control (5.4 ±1.0 U/mg protein). In the kidney of rats, OLL significantly increased the levels of creatinine, urea H₂O₂ and LPO relative to controls (0.7-1.4 versus 0.6±0.1 mg/dl, 7.4- 14.2 versus 1.8±0.6umol/1, 15.6-19.3 versus 14.0±0.8 umol and 6.8-8.5 versus 6.0±0.9nmol/mg protein respectively) but decreased the activities of renal catalase and GPx relative to controls (19.6-16.2 versus 28.1±3.6U/mg protein and 6.4-5.3 versus 9.2-1.3U/mg protein). Treatment with OLL significantly increased LPO (39.0-53.7; 108.6-156.1; 90.0-131.7nmol/mg protein), H₂0₂ (125.3-142.0; 152.0-170.7; 152.0-217.0 umol) and GST (38.0-65.0; 11.3-20.0; 18.0-27.0 umol/min/mg protein) in the liver, kidney and gills of the fishes relative to controls (35.1±4.1nmol/mg protein, 118.7±10.3umol, 24.3±0.6umol/min/mg protein; 100.6±28.5nmol/mg protein, 128.7±7.6umol, 10.0±2.6umol/min/mg protein: 75.3±8.8nmol/mg protein. 127.8±6.4umol, 13.5±2.4umol/min/mg protein respecitvely) but gIutathione was depleted (104.0-66.5; 163.3-114.0; 40.0-20.7ug/ml) compared with controls (114.0±14.0; 181.3±14.0; 44.2±8.3ug/ml). There was a significant increase in micronucleated polychromatic erythrocytes (24.6-48.3) of OLL-treatefil rats relative to control ( I 6.8±4.3). Exposure to Olusosun landfill leachate induced oxidative damage in rats and African catfishes. This may be of health risk in populations exposed to the leachate.