The objectives of the present study were to determine the concentrations of heavy metals and metalloids in water, sediment and Osteochilus vittatus fish, and to assess chromosome aberrations, serum biochemical changes and histopathological alterations in O. vittatus from the Nam Kok river near the Sepon gold-copper mine, Lao People’s Democratic Republic compared with the reference area. The results showed that Fe, Mn and Ni in water, As and Cd in sediment as well as As, Cd, Cr, Mn and Ni in O. vittatus muscle samples near the gold-copper mine exceeded standard values. Furthermore, the chromosome assessment in O. vittatus revealed seven types of chromosome aberrations, and the highest total number of chromosome aberrations was a centromere gap. The total number of chromosome aberrations, cell number with chromosome aberrations and percentage of chromosome aberrations in O. vittatus as well as serum liver enzymes between the studied areas were significantly different (p < 0.05). The liver histopathological alterations of the fish near the gold-copper mine revealed atypical cellular structures as nuclear membrane degeneration, rough endoplasmic reticulum disintegration and abnormal cytoplasmic mitochondria. The results of this study suggested that heavy metal and metalloid contaminations from the Sepon gold-copper mine area negatively affect O. vittatus fish in terms of chromosomal defects, serum biochemical changes and liver histopathological appearances.

This study aimed to determine toxic element concentrations in aquatic environments, including water and sediment, and in the Hampala macrolepidota fish, and to evaluate chromosome abnormalities, serum liver enzyme changes and liver histopathological alterations in H. macrolepidota from the Nam Kok River near the Sepon gold–copper mine, Lao People’s Democratic Republic, as compared with a control area without mining activity. The results revealed significant differences (p < 0.05) in As, Ba, Cu, Fe, Mn, Ni, Se and Zn in water, in all of the studied potentially toxic elements in sediment, and in As, Ba, Cd, Cr, Cu, Mn, Ni, Se, and Zn in the fish between the study and control areas. A chromosome assessment demonstrated 6 types of chromosome abnormalities, among which centric gap had the highest total number of chromosome abnormalities. Percentage of chromosome abnormalities, percentage of cells with chromosome abnormalities and serum liver enzymes in H. macrolepidota were significantly different (p < 0.05) between the two studied areas and were higher in the contaminated fish than in the control fish. The observation of liver histopathological changes revealed cellular degeneration, such as nuclear damage, abnormal cytoplasmic mitochondria and the disintegration of rough endoplasmic reticulum. The results indicate that the contamination of potentially toxic elements in the Nam Kok River near the Sepon gold–copper mine area negatively affected chromosomes, serum liver enzymes and liver cell structures in H. macrolepidota.

The objectives of the present study were to determine the concentrations of heavy metals and metalloids in frogs (Sylvirana nigrovittata) and to assess chromosome aberrations (CAs) in frogs collected from the Nam Kok River near the Sepon gold-copper mine, Lao PDR, as compared with those from a reference site. The results showed that the concentrations of As, Cd, Cr, and Mn in the frog muscle samples exceeded the standard values, and the accumulation of heavy metals in the frogs from the two sampling sites was significantly different (P <0.05), particularly Ba, Cd, Cr, Cu, Fe, Mn and Ni. Chromosome assessment of S. nigrovittata from the study site revealed 13 types of CAs, and the highest total number of CAs was isochromatid gap with a percentage of 31.80%. Furthermore, the total number of CAs, cell number with CAs and percentage of CAs in the frogs from both sites were significantly different (P <0.05). The results of this study suggest that heavy metal and metalloid from the Sepon gold-copper mine area negatively affected S. nigrovittata in terms of chromosomal defects. Keywords: Aberration, Abnormality, Amphibian, Animal, Toxicant