Volatile organic compounds in the nation's drinking-water supply wells - what findings may mean to human health

Figure 2. Human-health benchmarks are available for 35 of the 44 volatile organic compounds (VOCs) detected in domestic and (or) public well samples.Human-health benchmarks such as Maximum Contaminant Levels (MCLs) and Health-Based Screening Levels (HBSLs) provide a basis for evaluating VOC concentrations in the context of human health.27 regulated VOCs with MCLs 8 unregulated VOCs with HBSLs 9 unregulated VOCs without benchmarks 55 VOCs analyzed 44 VOCs detected Figure 1.Volatile organic compounds (VOCs) were not detected in samples from 82 percent of the 3,497 domestic or public wells at a threshold of 0.2 part per billion.VOC concentrations were greater than human-health benchmarks in 45 well samples (about 1 percent of all well samples).Well samples with VOC detections but no benchmarks to compare to concentrations (2 percent)Well samples with VOC detections less than or equal to benchmarks (15 percent)Well samples with VOC detections greater than benchmarks (1 percent)Well samples without VOC detections at a threshold of 0.2 part per billion (82 percent)U.S.