Interpreting Heavy Metal Test Results

Interpreting Heavy Metal Test Results for Food production

Use this table to interpret your soil heavy metal test results. The values in the table are for total metal soil tests (also called XRF, x-ray fluoresence, strong acid extraction, total acid extraction; USEPA 3050 or USEPA 3051a). This table should no be used for lead estimates (also called weak acid extraction, nutrient tests, M3 or Mehlich-3, Modified Morgan). These tests do not extract all the lead in a soil and need a different interpretation, which may be available from that soil testing lab.

Interpretations for arsenic and cadmium are coming soon!


Total  Lead 

(ppm or mg/kg)                                                                                                      

Interpretation [1,2]


Low lead

Mulching beds and walkways is suggested to improve plant health.


Moderate lead

Mulching beds and walkways is suggested to reduce dust and improve plant health.


High lead

Restricted use. Mulch beds and aisles. Do not consume leafy or root crops grown in the soil. Restrictions can be lifted by using practices to Manage and Treat Lead-Contaminated Soil.


Very high lead

Cover bare soil. Do not consume crops grown in the soil. 

[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