Effect of ingested heavy metals (Cd, Pb and Hg) on haematology and serum biochemistry in rabbits

In order to investigate the effects of exposure to possible environmental pollutants such as Cd, Pb and Hg on haematological and serum biochemistry values, New Zealand White female rabbits were treated orally with distilled water solutions of CdSO4 x H2O, Pb(NO3)2 and HgCl2 (n = 4/treatment) in concentrations of 2.3, 4.1, and 30 mg/kg dry matter, respectively, for 28 days. The initial concentrations of Cd, Pb, and Hg in serum were significantly increased by the treatment. Exposure to Pb significantly decreased the red blood cell (RBC) count, haemoglobin (Hgb) concentration and the haematocrit (Hct) value. The Zn-protoporphyrin concentration did not change as a result of Pb exposure. Pb and Hg loading significantly increased the aspartate aminotransferase (AST) activity. Alanine aminotransferase (ALT) activity was also increased by both Hg and Cd exposure. Comparing the treated and the control rabbits, all the trace elements studied significantly reduced the activity of enzymes in the pancreatic tissues. The haematological results indicate that hyperchromic macrocytic anaemia developed in rabbits treated with Pb. The increased activities of both AST and ALT indicate pathophysiological changes of the liver parenchyma, which was verified by focal fatty infiltration seen histopathologically. Cd exposure could exert a toxic effect on the kidneys, although the slight tubulonephrosis developed would not possibly affect the renal function. The reduced activities of amylase, trypsin, protease and lipase induced by Cd, Pb and Hg suggest toxicity to the pancreas.