Assessment of Environmental and Human Health Risk for Contamination of Heavy Metal in Tilapia Fish Collected from Langat Basin,Malaysia

This investigation quantified spatial variability of heavy metals and followed methods of the U.S. Environmental Protection Agency (EPA) to estimate the hazard indices as well as cancer risks associated with consuming fish caught in the waters of the Langat river basin area, Malaysia. The calculation of metal pollution index (MPI) was carried out to classify the study area according to the level of contamination and the order of stations from highest to lowest MPI values was Langat river > Cempaka lake > Engineering pond > Pond B > Pond A > Jugra > Bandar. The level of exposure due to the consumption of each chemical in Tilapia fish tissue was estimated in an average daily dose equation. The calculated HI ranging from 0.24 to 1.88 indicated 71% stations were in the risk level. Potential carcinogenic risks associated with the ingestion of heavy metals in Tilapia fish were evaluated probabilistically by performing 10,000 trials for Monte Carlo simulation. Cancer risk calculations exceeding the U.S. EPA's acceptable risk level of 1 in 1,000,000 (or 10 $^{-6}$ ) included Ni (7.3 ×10 $^{-4}$ ) and Cd (2.1 ×10 $^{-6}$ ). However, the average carcinogenic risk (2.4 × 10 $^{-4}$ ) exceeded the accepted risk level to a great extent. The recommended daily ingestion rate of Tilapia for Malaysian people inhabiting Langat river basin area was calculated considering 95th percentile TR value of 10 $^{-6}$ as an acceptable risk where it is revealed that consumption of Tilapia should be reduced about 67% from the current level to have an acceptable risk of cancer.