Pesticide Residues on Sweet Basil, Ocimum basilicum L.(Labiatae) Under Different Production Systems From Central Thailand

Abstract

Pesticide residues on sweet basil under different production systems from Central Thailand from February 2010 to January 2011 were determined using gas chromatography. A total of 93 out of 360 samples had detectable levels of pesticide residues. However, 87 out of those 93 were sampled from conventional production systems; the other 6 samples were from a Good Agricultural Practice (GAP) farm while no pesticide residues were detected from samples of the organic production. Under the conventional systems, the residues of three organophosphorous pesticides were observed—namely, pirimiphos-methyl, chlorpyrifos and dimethoate. Moreover, the residue levels of dimethoate and pirimiphos-methyl in 1 and 10 samples, respectively, exceeded the Maximum Residue Limits of the European Union (EU MRLs). Although, two pyrethroid pesticides (cypermethrin and deltamethrin) were found more often, the residue levels were higher than those of the EU MRLs in only 1 and 4 samples, respectively. These samples were also collected from the conventional farms. Residues of organophosphates were more likely to be greater than the MRLs. The levels of pesticide residues depend on the persistence and application rates of pesticides as well as the pre-harvest interval. The results clearly indicated that the GAP certifi cation system was effective in keeping pesticide residues to levels below the MRLs.