Heavy metal levels in two food fish species from Negombo estuary, Sri Lanka: Relationships with the body size
H.A.P. INDRAJITH, K.A.S. PATHIRATNE* AND A. PATHIRATNE
The present study was carried out to assess the levels of eight metals viz. Pb, Cu, Cd, Ni, Cr, Mn, Hg and Zn in two species of food fish, Etroplus suratensis and Ambassis commersoni from Negombo estuary. The levels of Hg were analyzed by cold vapour atomic absorption spectrometry whereas the other metals were analyzed by flame/graphite furnace atomic absorption spectrometry. Total metal levels in muscle, gill and liver tissues of the fish showed a wide range. Accumulation of most metals in the tissues of the fish followed the increasing order, muscle < gills ≤ liver. Of the different metal levels detected in the fish, only the level of Cd in liver tissue of 6% of E. suratensis and 12% of A. commersoni exceeded the level specified for human consumption by European Union. Interspecies comparisons revealed that mean level of Zn in the muscle tissue of A. commersoni was two fold higher than that of E. suratensis. The levels of metals in the muscle tissue of both fish species were positively correlated with the body weight or body length of the fish. Based on the levels of Hg, Pb, and Cd in the fish, edible muscle of both fish species collected from the estuary was found to be safe for human consumption. However, heavy consumption of bigger size fish may pose a health risk to the consumers as there were strong positive correlations between body weight or body length and metal levels in muscle tissues of both species of fish.