The Evaluation Grades of Health Risk Based on the SPA Model

In this study, Mingshan county—a typical hilly region located on the western edge of the Sichuan basin was selected as the research area. Based on the health risk assessment of Cr(VI), nitrate, fluoride and iron in 41 rural drinking water resources, applying the model recommended by the U.S. Environmental Protection Agency (U.S.EPA), the evaluation grades of health risk associated with drinking water quality (HRWQ) was developed, and the Connection Degree (CD) and the weight of each index of the samples were calculated. And by evaluating them with the criterion of confidence level, Set Pair Analysis (SPA) was established. In this study, it could be seen that the HRWQ of most the resources in the area were of low-medium risk within grade I–III while the HRWQ of some other resources were in a less safe state of medium-high risk.