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Various studies have evaluated the accumulation of ClO4- in lettuce (Lactuca sativa), but very few have dealt with the variables that can interfere with its capture. The present study evaluates the transfer of ClO4- in two L. sativa varieties: butter head (L. sativa var. capitata) and cos lettuce (L. sativa var. crispa) under hydroponic conditions. The ClO4- concentrations used correspond to levels (1 and 2 mg L-1), measured in irrigation water in the Iquique region in the north of Chile. Results indicate that the capture of ClO4- is dependent on its concentration, lettuce genotype, and temperature. The butter head variety accumulates the highest perchlorate concentrations. Anion competition involving NO3- (16 and 48 mM), Cl- (23 and 56 mM), and SO42- (10 and 20 mM) was evaluated, being NO3- (48 mM), the most significant competition reducing the concentration of ClO4- in tissues of L. sativa varieties. (C) 2014 Elsevier Ltd. All rights reserved.