Risk Assessment of Heavy Metals in Fish and Shrimp from Songkhla Lake to Thais

Abstract

       The Songkhla Lake (SKL) is an important source of seafood. However, the water pollution of SKL makes people aware about the safety for seafood consumption. Hence, in February-May 2015 The Regional Medical Sciences Center 12 Songkhla co-operate with Coastal aquaculture research and development center region 6 Songkhla collected 179 samples of aquatic animals, including 38 species (141 samples) of fish and 5 species (38 samples) of shrimp. All of samples were analyzed for lead (Pb) and cadmium (Cd) content by Graphite Furnace Atomic Absorption pectrophotometer, and mercury (Hg) by Mercury Analyzer. The results showed that the contamination of Pb, Cd and Hg in seafood were 34.1%, 5.6% and 88.8%, respectively, the amount of metals were ranging from 0.05 - 0.45, 0.03 - 0.05 and 0.01 - 1.63 mg/kg, respectively for fishes and ranging from 0.05 - 0.13, 0.03 - 0.21 and 0.01 - 0.57 mg/kg, respectively for shrimps. The level of Pb, Cd and Hg in most samples (98%) were within regulatory limits, except Bronze feather back, Climbing perch and Stork shrimp (one sample per species) contained 1.63, 0.84 and 0.57 mg/kg of mercury respectively, which higher than Thai regulatory limit (≤ 0.5 mg/kg). Although the exposure assessment of heavy metals in aquatic animal still safe to Thais but the level of Hg exposure was 82 percent of safety level and the level of Hg content in fishes were rather high. Therefore, the continuous consumption of fish from SKL may increase the risk to consumers.