Screening Level
The Screening Levels are chemical-specific concentrations for individual contaminants in air, drinking water and soil that may warrant further investigation or site cleanup.
| Resident Soil | Industrial Soil | Resident Air | Industrial Air | Tapwater |
| 400 mg/kg | 800 mg/kg | 0.15 ug/m3 | N/A | 15 ug/L |
MCL: Treatment Technique (TT)
Lead in drinking water is regulated by a Treatment Technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take action.
Action Level: 15 μg/L
National Primary Drinking Water Regulations for “Lead” (Last Updated by the EPA in May 2009)
Units
| Abbreviation | Meaning | Notes |
|---|---|---|
| mg/kg | mass of chemical (milligrams, mg) per mass of soil (kilogram, kg) | Equivalent to parts per million (ppm) |
| μg/m3 | mass of chemical (micrograms, mg) per volume of air (cubic meter, m3) | This can be converted to ppm using the molecular weight of the chemical |
| μg/L | mass of chemical (micrograms, μg) per volume of water (liter, L) | Equivalent to parts per billion (ppb); divide by 1,000 to get ppm |
For more information about these units and their conversion factors, visit https://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.files/fileid/14285.