Cadmium Bioaccumulation in Carp (Cyprinus carpio) Tissues during Long-Term High Exposure: Analysis by Inductively Coupled Plasma-Mass Spectrometry

This work was an attempt to investigate cadmium bioaccumulation in the carp (Cyprinus carpio) during simulated pollution. The fish, weighing 100 g, were kept for 140 days in a 1000-liter indoor concrete tank supplied with a continuous flow (8 liters min−1) of unchlorinated, aerated, and filtered well water, the cadmium concentration of which was maintained at 450 μg liter−1. Such a high cadmium concentration was chosen to achieve metal saturation of the fish organs. Carp were fed during exposure. Cadmium accumulation in liver, kidney, and muscle was measured by inductively coupled plasma-mass spectrometry (ICP-MS), which is one of the most sensitive analytical techniques. The reported data indicate that cadmium exposure results in significant cadmium uptake, but the pattern of this uptake varies with the organ. For kidney and liver, cadmium concentration increased rapidly to the saturation level, probably because of the limited ability to store the cadmium as exposure persisted. A positive correlation between the increase in metallothioneins in tissues and the increase in metal tolerance in fish has been suggested. The cadmium concentration increase in muscle was significant only after 3 months, and, then, increased as an exponential function of the exposure time. When the storage capacity limits of the liver and kidney are reached, cadmium accumulation in muscle is stimulated. In this experiment, the high contamination levels reached suggest that such muscle would be unsuitable for human consumption. After 140 days of exposure, the cadmium concentrations in muscle, liver, and kidney were respectively 9 ± 1, 91 ± 7, and 250 ± 16 mg kg−1dry wt.