Comparing Lead and Cadmium Levels in Liver of Catfish (Clarias Gariepinus) from Nyalenda waste Stabilization Ponds and Ogal Beach on Lake Victoria, Kenya.

Abstract

The bio accumulation of Cadmium and Lead metals in fish species poses danger to Kisumu city residents whose diet revolves around fish. Nyalenda Waste Stabilization Ponds (NWSPs), are sinks to domestic waste, hospital waste and other none point source materials from the city responsible for accelerating cadmium and lead contamination to the environment. Ogal beach of Lake Victoria is with sparsely populated environs releases less cadmium and lead contamination to the environment. The study was a case control study where Ogal beach was used as a controlled site compared to NWSPs used as case study. Cadmium and lead levels from the two sites were found to be influenced by activities around them. Catfish from Nyalenda Waste Stabilization Ponds is being sold in Kisumu with no knowledge of their safety from cadmium and lead contamination. A research done in 2008 on heavy metal concentrations in water and sediments of rivers around Kisumu city draining into Lake Victoria found enrichment of Cadmium and Lead to be in all the river sediment samples. No studies have been carried out to analyze and establish the safety of fish harvested from Nyalenda waste stabilization ponds (NWSPs). The purpose of the study is to compare levels of Lead and Cadmium in catfish (Clariasgariepinusi from Nyalenda Waste Stabilization Ponds and Ogal beach of Lake Victoria. The specific objectives of this study were to determine cadmium and lead levels in the liver tissue of catfish (Clarias gariepinus) from Nyalenda Waste Stabilization Ponds and Ogal beach; compare the influence of body size of catfish (Clarias gariepinus) on the level of lead and cadmium in the liver tissues; and establish the suitability of catfish (Clarias gariepinus) liver tissue from the Nyalenda Waste Stabilization Ponds and Ogal Beach for human consumption. A total of 70 fish samples were collected (35 from Ogal Beach and 35 from NWSP). The catfish tClarias gariepinusi were caught using gill nets. The length and weight of fish samples were measured and recorded, then liver tissues extracted and stored in sample containers under ice. Liver tissue samples were then transported to Kenya Government chemists in the same conditions. Flame atomic absorption spectrophotometer AAS-600 was used to analyze cadmium and lead in the liver muscles of catfish (Clarias gariepinus). Larger catfish (in both weight and length) were obtained from Ogal beach than NWSPs. Mean lead concentration was found to be about twice higher in the liver tissues of Catfish (Clarias gariepinus) from Nyalenda Waste Stabilization Ponds than those from Ogal beach, while mean cadmium concentration was found to be about 2362 times higher in the same tissues from Nyalenda Waste Stabilization Ponds than Ogalbeach. The European Union maximum limit for cadmium in edible tissues offish species is set at 0.05 ppm wet weight. The research has revealed that mean levels of cadmium concentration in the liver tissue of catfish from Ogal Beach is 2.86 x 10-05ppm and was safe for human consumption while that of Nyalenda Waste Stabilization Ponds of 0.0675429 ppm was found to be slightly higher than the European Union maximum limits. Ogal beach mean lead concentration in the liver tissue of 0.055889 ppm and that ofNyalenda Waste Stabilization ponds of 0.116357 ppm were both found to be higher than the European Union maximum limits, therefore were found to be unsafe for human consumption. The European Union maximum limit for lead in edible tissues of fish species is set at 0.2 ppm wet weight. Control measures by banning fishing at NWSPs to protect consumers are recommended.