Aquatic ecosystem is the ultimate recipient of almost everything including heavy metals. Pollution of heavy metals in aquatic environment is a growing problem worldwide, and currently it has reached an alarming rate. There are various sources of heavy metals; and some originate from the anthropogenic activities. Therefore, the distribution of some potential hazardous toxic elements (i.e., Cr, Mn, Cu, Zn, As and Pb) in the sediments, water and some fishes of Kutubdia Channel near Matarbari, Cox's Bazar of Bangladesh have been determined using X-ray Fluorescence (XRF) method. The heavy metal contamination levels in the studies samples and their source identification have been assessed using several pollution assessment indices: geoaccumulation, degree of contamination, modified degree of contamination, pollution load index, potential ecological risk; and estimated daily intake of heavy metal due to consumption of fishes. However, a series of chapters on human health risk (non-cancer risk and cancer risk) assessment due to heavy metals contamination have been discussed in this book following the US-EPA models.