oaming agents (surfactants) are detergents or detergent-like substances used as cleaning agents in industrial and consumer goods such as personal care products; they are also used as inert ingredients in pesticides.156.67 ppb460 ppbNo500 ppbNo500 ppbNitrate & nitriteNitrate and nitrite enter water from fertilizer runoff, leaching from septic tanks, and erosion of natural deposits.0.32 ppm0.33 ppmN