Assessment of Cypermethrin Residue in Peri-Urban Agriculture : A case study of Chinese Kale and soils in Thailand

A commercial cypermethrin product containing (RS)-- cyano-3-phenoxybenzyl (1Rs, 3RS; 1RS, 3RS)-3 (2, 2- dichlorovinyl)-2, 2-dimethylcyclopropanecarboxylate having effective concentration 25% w/v, was used throughout the study. The experiment was designed in a RCBD consisting of four blocks and three replicates under each block. The soil pH was slightly acidic (5-6.5), soil organic carbon was high (4%) and the soil type was clay. The amount of cypermethrin found in the soil samples were directly correlated with the doses applied. In this experiment, it was found that water has no potential effect in removing the pesticide residue from the Chinese kale plants. The degradation time needed to be degraded 50% of the compound (DT50) was found from 4 to 5 days and DT90 was found from 17-19 days. A filter paper acute toxicity test using earthworms as the test organism was also conducted in the laboratory condition with the local Thai earthworms and the median lethal concentration that kills 50% of the organism (LC50) was found at 1.03 mg/cm2, LOEL was observed at 0.001 mg/ cm2 and the NOEL was observed at 0.0001 mg/cm2 of the filter paper.