Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), "unreasonable adverse effects on the environment means (1) any unreasonable risk to man or the environment, taking into account the economic, social, and environmental costs and benefits of any pesticide, or (2) a human dietary risk from residues that result from a use of a pesticide in or on any food..." in excess of that allowed by a tolerance.