There is evidence that semicarbazide (SEM), a marker for the banned nitrofuran nitrofurazone, can arise from other, unrelated sources. Recently, Belgium rejected 54 consignments of Bangladeshi freshwater shrimp (Macrobrachium rosenbergii), following a laboratory decision to test meat and exoskeleton combined. To study the possible natural occurrence of SEM in wild shrimp, samples were collected and analysed from 29 sites across Bangladesh. SEM (