Municipal biosolids are a relatively untapped but universal resource, and the repository for a substantial portion of nutrients consumed in the form of food. Returning these nutrients to food production systems would "close the loop" in nutrient cycling. The challenge is that biosolids contain not only plant and soil nutrients but also contaminants, including pharmaceuticals that can act as endocrine disruptors. Biosolids containing pharmaceutical compounds are currently applied to agricultural fields as a soil amendment and present a potential hazard to soil, human and animal health. Biochar, produced by the pyrolysis of agricultural wastes, has a high affinity for many organic pharmaceutical contaminants, and the coamendment of biochar with biosolids to agricultural land could minimize the bioavailability and mobility of such contaminants.  As a component of a greenhouse study examining the plant uptake of the antibiotics ciprofloxacin, triclocarban and triclosan, the chemically activated luciferase gene expression (CALUX) bioassay was used to determine measurable endocrine-disrupting activity in the soil of different biosolids-biochar treatments.