Persistence of Chlorpyriphos in Paddy

Chlorpyriphos when applied @ 375 g a.i. ha−1 on 30, 21 and 14 d before harvest of rice resulted in residues of 0.01, 0.02 and 0.02 g a.i. ha−1 respectively, on polished rice grain which was below the prescribed maximum residue limit (MRL) value of 0.10 mg kg−1. Rice husk contained high concentrations of chlorpyriphos and its average levels were observed to be 0.29, 0.34 and 0.46 mg kg−1 respectively. Residues of chlorpyriphos remained below its detectable level of 0.01 mg kg−1 in rice bran in all the treatments. Analysis of straw revealed maximum concentration of chlorpyriphos and its mean levels were 0 87 0 92 and 1 73 mg kg−1, respectively, in the samples collected from plots treated 30 21 and 14 d before harvest Therefore a strict regulation is required to avoid feeding of straw to milch catties for protection of their body burden by chlorpyriphos and yield of quality milk.