Histological analysis of the effects of cadmium, chromium and mercury alone and in combination on the spleen of male Sprague-Dawley rats

Abstract

The mining sector in South Africa is expected to be the fifth largest in the world. Both mining and transport are the most common reasons for an increased risk of human exposure to heavy metal contamination in South Africa. Due to increasing amounts of metals in the environment, this study identified three metals cadmium, chromium and mercury based on the risk of exposure in South Africa. The aim of this study was to investigate the changes in the morphology of the spleen tissue of male Sprague-Dawley rats exposed to these metals alone and in combination by using light microscopy. Forty eight animals in eight experimental groups were exposed, via oral gavage, to these metals at 1000× the World Health Organization’s acceptable water limits of each respective metal, alone and in combination, for 28 days. Changes in the histological structure of the spleen were observed using haematoxylin and eosin and picrosirius red staining. Necrosis was observed in all the groups, with the severity varying between the different exposure groups, alone or in combination. Fibrosis in the spleen tissue was only seen in the experimental groups exposed to cadmium and mercury respectively, as well as in the combination of cadmium and mercury.

Keywords:

• Heavy metals
• toxicity
• spleen
• light microscopy
• morphology
• fibrosis

Acknowledgements

The authors would like to thank Ms Ilse Janse van Renburg and other staff members at the University of Pretoria Biomedical Research Centre for their professional help during the animal study.