Studies of Metabolism in Crops are used to elucidate the degradation pathway of the active ingredient and require the identification of the metabolism and/or degradation products when a pesticide is applied to a crop directly or indirectly.

A Metabolism in Crops study should be submitted for each type of crop group. Five categories for crop metabolism studies can be considered: root vegetables, leafy crops, fruits, pulses and oilseeds, and cereals. The active ingredient should be administered such as foliar, soil/seed, or post-harvest treatments to reflect its intended use pattern. It should be labelled, to allow for quantification; the preferred radioisotope is 14C, although 32P, 35S can be used. The study should be performed using a sandy loam soil treated with the radiolabelled test substance. It may be performed either in a greenhouse or in an outdoor test plot or plant growth chambers. The maximum application rate (the proposed Good Agriculture Practice (GAP) application rate) should be utilized. Samples of all raw agricultural commodities are collected for characterization and/or identification of residues and determination of the total radioactive residue.