Figure 9. Relation of concentration of selected explosive-residue compounds in snow samples collected from background and blast crater sites to the U.S. Environmental Protection Agency (USEPA) 10-4 cancer risk threshold and lifetime health advisory (USEPA, 2000). The 10-4 cancer risk threshold is defined as the concentration of a chemical in drinking water corresponding to an estimated lifetime cancer risk of 1 in 10,000. The lifetime health advisory is the concentration of a chemical in drinking water that is not expected to cause any adverse noncarcinogenic effects for a lifetime of exposure.