The SANCO guideline (4145/2000) is used to calculate residue levels and exposure in food items for birds and mammals. However, the estimates are very conservative and are likely to overestimate the risk. A field study can establish more refined estimate for initial concentration and half-time decline for an agrochemical. Studies should be performed in the relevant crop. For orchards a 1 ha apple orchard is used as a substitute crop but other crops are possible. Arthropods/vegetation are collected before and after application and an initial concentration as well as a half-time decline value are established.