Heavy metal bioaccumulation in edible fish species from an industrially polluted river and human health risk assessment

Trace metals, such as cadmium and lead, and micronutrients, such as copper, zinc, and manganese, were analyzed in water and muscle tissues of four edible fishes - barramundi, Lates calcarifer (Bloch), flat head gray mullet, Mugil cephalus L., giant catfish, Netuma thalassina (Rüppell) and Mozambique tilapia, Oreochromis mossambicus (Peters) sampled at upstream and downstream sites in the polluted Uppanar River during the dry (December - June) and wet (July - November) seasons from December 2009 to November 2010. The content of heavy metals in the fish species differed depending on the size, sampling site, or, in some cases, season. The analysis of the transfer factor (TF) and positive correlations (P < 0.001) between concentrations of selected metals in fish muscle tissues and water indicated the direct accumulation of metals from the water to the fish. Seasonal variations of metal concentrations in the water and fish muscle tissues indicated elevated concentrations during the dry season. The present study suggests that various metals were present in the fish muscle tissues at different levels, but these were within the maximum residual levels permitted by Indian standards and the WHO/FAO; thus, the fish from these areas are generally safe for human consumption.