Chronic accumulation of cadmium in the edible tissues of Oreochromis aureus (Steindachner): modification by mercury and lead.

The influence of mercury and lead on cadmium accumulation was investigated by exposing the fish Oreochromis aureus, or Blue Tilapia, to two heavy metals simultaneously. The chronic accumulation profile of cadmium in the liver, brain, gill filaments, intestine, caudal muscle, spleen, trunk kidney, and gonads was determined for exposure to cadmium alone and with lead or mercury. O. aureus was exposed to cadmium alone at 0.05 and 0.10 mg/L, and mixtures of 0.05 mg/L cadmium with 0.05 mg/L mercury or lead (0.05 and 0.50 mg/L). Little research has previously been carried out on the long-term interaction between these heavy metals and their effects on tissue accumulation of heavy metals. In a food fish such as O. aureus, a knowledge of toxic metal accumulation patterns is of great importance. The highest levels of cadmium were consistently accumulated by the kidney, and the presence of other mercury or lead did not change this trend. The spleen, intestine, and liver also accumulated high levels of cadmium, while the caudal muscle and brain accumulated the lowest levels of cadmium. Separating the viscera from the muscle would therefore reduce the cadmium burden of fishmeal.