Assessment of Pesticide Residues in Organic Rice Production in The Mekong Delta, Vietnam

Organic rice production has been developed in Mekong Delta to reduce toxicity risk for humans and the environment, however, some models have failed due to pesticide residues that were not investigated in advance. So, it is important to test for prohibited residual pesticides in organic farming. The rice samples in ten districts of six provinces in Mekong Delta, Vietnam, were sampled and analyzed to check the presence of 854 substrates that are prohibited for use in organic production. A total of 18 active ingredients were detected. Based on the contamination rates, they are divided into three groups. The high presence group includes only tricyclazole (62.5%). The medium presence group includes difenoconazole (32.5%), chlorpyrifos-ethyl (30%), isoprothiolane (25%), propiconazole (20%), azoxystrobin (17.5%), hexaconazole (15%), chlorfenapyr (15%), cypermethrin (10%). The low presence group includes paclobutrazol (7.5%), tebuconazole (5%) and the seven remaining ingredients niclosamide, chlorfenson, fipronil, fipronil-desulfinyl, fenoxanil, metalaxyl & metalaxyl-M, and chlorfluazuron with the same contamination rate (2.5%). Based on the present period, they are divided into four groups. The four-year presence group includes tricyclazole, difenoconazole, and propiconazole. The three-year presence group includes chlorpyrifos-ethyl, isoprothiolane, hexaconazole, chlorfenapyr, and cypermethrin. The two-year presence group includes azoxystrobin and paclobutrazol. The one-year presence group includes the eight active ingredients with the lowest contamination rate as tebuconazole, niclosamide, chlorfenson, fipronil, fipronil-desulfinyl, fenoxanil, metalaxyl & metalaxyl-M, and chlorfluazuron. Among 18 detected active ingredients, there were 8 substances used for disease control, 8 substances used for insecticides, 1 substance used for killing snails, and 1 substance used for growth regulation. This finding is useful for developing organic rice zones in the Mekong Delta.