The objective of OECD Test Guidelines for the pesticide residue chemistry is to assess pesticide exposure by identifying these residues in food or animal feedstuffs for purposes of dietary risk assessment and setting Maximum Residue Levels. They have been developed and are based on guidelines in use for many years in OECD countries and by the Food and Agriculture Organisation. Because of the unique nature of each study, the pesticide expected use, and the particular methods needed to elucidate the metabolic pathway for each chemical, the description of the test method cannot be as prescriptive as usually required for other OECD Test Guidelines. Pesticide residue studies are complex; guidelines cannot specify all parameters in advance, but each study must be designed individually. Given these characteristics, the guidelines in Part A of Section 5 include elements that differ from those in the other sections (1-4) of the OECD Guidelines for the Testing of Chemicals.