Health Risk Assessment of Heavy Metals in Surface Water of the Lhasa River, China

This study was performed in Lhasa River Watershed to explore the contents of heavy metals in river water and assess the health risks. The test results show that the contents of arsenic (As), chromium (Cr) and uranium (U) are relatively low, reaching the Class III of the "Environmental quality standards for surface water (GB3838-2002)". Health risk assessment demonstrates that the average total risk value is 1.79x10(-5) yr(-1), which is lower than the maximum acceptable level of 5.05x10(-5) yr(-1) recommended by USEPA. Moreover, the average value of radionuclide risk (U) is calculated to be 9.47x10(-9) yr(-1), which is five orders of magnitude lower than the standard value of 5.0x10(-4) yr(-1). Therefore, the river water in the study area causes no significant health risk to people.