The effect of cadmium toxicity on <i>Oreochromis niloticus</i> and human health

Abstract

Cadmium levels below permissible limits can be toxic, affecting the health of exposed aquatic organisms and ultimately human health. Although cause and effect links between aquatic organisms and human health have not been elicidated, this study evaluated the effect of cadmium exposure on the health status of Oreochromis niloticus and human fish consumers. Clinical and post-mortem examinations were performed in situ on fish
samples collected monthly from the Abo-Saleh, Ehnasia fish farm and Nile River. Cadmium was measured in water and fish musculature from the two fish farms and in water samples from the Nile River. Human blood samples of consumers of fish from the two fish farms, as well as non-fish consumers as a control, were collected for estimation of cadmium, uric acid, creatinine and calcium levels. Clinical signs and post-mortem abnormalities of Oreochromis niloticus from Ehnasia fish farm showed congestion of gills, liver, intestine and spleen. Cadmium concentrations in water and musculatures of Oreochromis niloticus obtained from the Ehnasia fish farm was significantly higher than the permissible limit, whereas cadmium concentrations in the Abo-Saleh fish farm and Nile River were within the permissible limit. There were increased levels of cadmium in human blood and creatinine and uric acid in human serum, but decreased levels in calcium in serum of human consumers of fish from the Ehnasia fish farm. The presence of cadmium can be toxic, even at levels below the permissible limit, negatively affecting health, as observed for aquatic organisms and subsequently for humans.

Keywords: clinical signs, fish farm, human fish consumers, post-mortem abnormalities, uric acid