Cal. Food & Agric. Code § 52485

It is unlawful for any person to sell or divert for use or for processing, either for human or animal consumption, any grain or other crop seed which is treated after harvest with any substance that is likely to be poisonous or toxic to human beings or animals, unless there is an established state or federal pesticide residue tolerance for such poisonous or toxic substance on the specific grain or crop seed, and such pesticide residue tolerance is not exceeded.