7 U.S.C. § 6511: Additional guidelines

The Secretary, the applicable governing State official, and the certifying agent shall utilize a system of residue testing to test products sold or labeled as organically produced under this chapter to assist in the enforcement of this chapter. The Secretary, the applicable governing State official, or the certifying agent may require preharvest tissue testing of any crop grown on soil suspected of harboring contaminants. If the Secretary, the applicable governing State official, or the certifying agent determines that an agricultural product sold or labeled as organically produced under this chapter contains any detectable pesticide or other non-organic residue or prohibited natural substance the Secretary, the applicable governing State official, or the certifying agent shall conduct an investigation to determine if the organic certification program has been violated, and may require the producer or handler of such product to prove that any prohibited substance was not applied to such product. the result of intentional application of a prohibited substance; or present at levels that are greater than unavoidable residual environmental contamination as prescribed by the Secretary or the applicable governing State official in consultation with the appropriate environmental regulatory agencies;