Persistence of endosulfan and its metabolites in tomato plants and soil

Tests were conducted to study the persistence of 14C-labelled α and β -endosulfan in tomato plants and soil under the greenhouse conditions when applied at the rate and number of applications used by tomato growers in Costa Rica. Two applications, at 30 and 55 days after planting were made. Plant and soil samples were extracted 37, 49, 71 and 125 days after planting and analyzed by LSC, TLC and GC-ECD. At 37 days after planting the compounds identified were α-endosulfan, β-endosulfan and endosulfan sulphate with a combined concentration of 3.6 mg/kg in plant and 0.6 mg/kg in the soil. At 49 days after planting the same three compounds were found at the combined concentration of 1.51 mg/kg in the plant and at 0.34 mg/kg in the soil. After 71 days low levels of α-endosulfan, β-endosulfan, endosulfan sulphate and endosulfan lactone were found in plants and soil. Similarly, at 125 days low levels of these compounds as well as low levels of two other metabolites, endosulfan alcohol and endosulfan ether were detected. Under the conditions of the experiment endosulfan residues do not seem to be significant or persistant. (author)