Bioaccumulation of heavy metals in some important freshwater fishes of Pahang, Malaysia

Abstract

A study of the accumulation of four heavy metals (Cr, Cd, As and Pb) in tissues of selected demersal freshwater fish species namely Anabas testudineus, Channa striata, Mystus nemurus and Osteochilus enneaporous from Kuantan, Maran and Temerloh was conducted in dry and wet season. Fish samples were bought from the fishermen along the river banks. Three types of fish tissues were studied; namely stomach, gill and muscle. Heavy metals were detercted using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The fish samples were found to contain total As within the range of 0.014 to 0.828 μg/g (dry wt.) in the muscles and 0.051 to 0.650 μg/g (dry wt.) in the gills and 0.099 to 0.614 μg/g (dry wt.) in the stomach. The highest Cd levels in the muscles were at 1.051 μg/g (dry wt.) in dry season while the lowest was at 0.404 μg/g (dry wt.) in rainy season. In the gills, Pb accumulated from 0.024 μg/g (dry wt.) to 0.569μg/g (dry wt.) in all seasons respectively. For Cr, concentrations in the muscles ranged from 0.849 μg/g (dry wt.) to 6.040 μg/g (dry wt.) while As in the muscle accumulated from 0.014 μg/g (dry wt.) to 0.828 μg/g. It is important to note that levels of Cr ranged between 0.677 μg/g (dry wt.) and 8.369μg/g (dry wt.) in the gills and in the stomach, it was ranged between 0.783 μg/g (dry wt.) to 6.216 μg/g (dry wt.) respectively. The highest Cr accumulation was recorded in Channa striata and the lowest Cr concentration was recorded in Osteochilus eneaporous. Comparison of heavy metal concentration in the fish from different locations showed no significant difference with p>0.05 suggesting the fish as a mobile creature which is less influenced by the heavy metal concentration in the surrounding area. Poor correlations were acquired from heavy metal concentrations in the fish with fish size and length, thus proved bigger and larger fish were possible to contain greater amount of heavy metals. A comparative study was also carried out between the existing data on the metals in the fish tissues and species of freshwater fish from different regions in the world, to observe their trend and status in regional and global contexts. On the whole, the findings from this study revealed that all the heavy metal concentrations in the tissues were lower than the maximum permissible limit as recommended by the Ministry of Health Malaysia (1998) and Food and Agricultural Organization (2002). Results from Provisional Tolerable Weekly Intake (PTWI), Hazard Index (HI) and Metal Pollution Index (MPI) indicate that fish caught from the areas investigated in terms of Cd, Cr, As and Pb concentration in selected tissues are safe for human consumption. However, Cd concentration may exceed the permissible limits in a human’s body if consumed according to the weekly intake recorded thus pose a threat to Malaysian public.