Health-Based Screening Levels for evaluating water-quality data

Health-Based Screening Levels (HBSLs) are non-enforceable water-quality benchmarks that can be used to (1) supplement U.S. Environmental Protection Agency (USEPA) Maximum Contaminant Levels (MCLs) and Human Health Benchmarks for Pesticides (HHBPs), (2) determine whether contaminants found in surface-water or groundwater sources of drinking water may indicate a potential human-health concern, and (3) help prioritize monitoring efforts. HBSLs were developed by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program for contaminants that do not have USEPA MCLs or HHBPs.\r\n\r\nHBSLs were updated in June 2014 in order to:\r\n-Provide benchmarks, when possible, for 267 new contaminants analyzed by the NAWQA Program.\r\n-Remove HBSLs for contaminants that have new USEPA chronic HHBPs.\r\n-Be consistent with new USEPA policies, by calculating both Noncancer and Cancer HBSLs for some contaminants.