Distribution Characteristics and Health Risk Assessment of Arsenic and Cadmium in Water of Lhasa River Basin

In order to understand the spatial distribution and health risks of carcinogenic chemicals, As and Cd, in the water bodies of the Lhasa River Basin, water samples were collected from 16 sampling points in the middle and lower reaches of the Lhasa River as well as the Duilongqu tributary. The concentrations of As and Cd in the water samples were tested, and the carcinogenic risks caused by As and Cd through drinking water ingestion were evaluated by a health risk assessment model. The results show that the average concentrations of As and Cd in the river water of the Lhasa River Basin were (2.280±0.969) and (0.092±0.017) μg·L^-1, respectively, which meet the Drinking Water Standards in China (GB 5749-2022). These concentrations also qualify as Class Ⅰ and Class Ⅱ in the Environmental Quality Standard for Surface Water in China (GB 3838-2002). The As concentration increased and the Cd concentration decreased along the river in the middle and lower reaches of the Lhasa River, and the concentration of Cd increased along the Duilongqu tributary. Regarding geographical distribution, the As concentration decreased with the increase of latitude and increased with the increase of longitude; the Cd concentration increased with the increase of latitude and decreased with the increase of longitude. The results of health risk assessment show that As was the leading carcinogen in the water bodies of the Lhasa River Basin, contributing to more than 98% of the carcinogenic risk. The overall carcinogenic risk of As and Cd in the Lhasa River Basin is generally at low level through drinking water ingestion. The results also show that young children are more vulnerable to As and Cd contamination comparing to adolescents and adults. Therefore, more attention needs to be given to children's drinking water safety.