Interpreting Heavy Metal Test Results


Total  Lead 

(ppm or mg/kg)                                                                                                      

Interpretation [1,2]


Background lead 

Soil Pb is at naturally occuring, or background, concentrations and is not polluted with human lead sources. In Ohio, background soil lead is at or below 50 mg/kg. Follow this link to find the background soil lead concentration in your state. There are no restrictions to using a soil with background lead concentrations.


Low lead

Soil lead is elevated above backround concentrations, but poses low risk to gardeners and those consuming garden produce. 


Moderate lead

Mulch all bare soil, including walkways. Use Best Practices to Reduce Exposure and consider Managing and Treating Lead-Contaminated Soil.


High lead

Mulch all bare soil, including walkways, and do not consume leafy or root crops grown in the soil. Consider using raised beds with tested soil. See Managing and Treating Lead-Contaminated Soil for ways to reduce soil lead exposure and toxicity.


Very high lead

Cover bare soil. If soil lead concentration exceed 2,000 mg/kg, contact the local health department.

[1]  Pollutant concentration limits for land-applied biosolids. Code of Federal Regulations Title 40, Part 503. Retrieved from gp=2&SID=3ba5c96eb4bfc5bfdfa86764a30e9901&ty=HTML&h=L&n=pt40.30.503&r=PART#se40.32.503_113.

[2] Stehouwer, R. (2018, December 23). Lead in Residential Soils: Sources, Testing, and Reducing Exposure. Retrieved from