Heavy metals are widely used in various industries and became a great concern all over the world due to environmental contamination. This study provides an assessment of seasonal variability and risks to human health associated with the exposure to heavy metals concentrated in Langat river water of Malaysia. The Department of Environment (DOE) Malaysia kindly provided the heavy metal concentration data in water for this study. Several multivariate estimation such as an independent t test, box-and-whisker plot and Principal component analysis were carried out to evaluate the seasonal variation of metals concentration in water.

The average value of ten analyzed metals was 250.81 μg/l and followed in order of abundance by August > Jun > February > October > April > December > March > May > September > January > July > November. The calculated HPI was 123.42, which is far above the critical index value of 100, indicating pollution with respect to heavy metals. Estimates of health risks associated with river water were summarized according to non-carcinogenic and carcinogenic health effects. No potential threat was detected for non-carcinogenic risk as the HI values calculated were <1. Potential carcinogenic risks associated with the ingestion and dermal absorption of heavy metals in water were evaluated probabilistically by performing 10,000 trails for Monte Carlo simulation where potential carcinogenic risk exists in case of Cd and As.It is necessary to take proper steps to reduce the pollution of heavy metals in Langat River