 Most of both pesticides moved into the soil in solution after spraying . Compared with DDT , HCH was degraded and run off more easily . HCH residues in the surface soil layer ( 0-0 cm ) were already below 0 . 0 microg kg ( -0 ) at the mature stage , lower than Chinese Environmental Quality Standard for Agricultural Soils : HCH < 0 . 00 mg kg ( -0 ) . However DDT residues in the surface soil layer remained 000 microg kg ( -0 ) , higher than the national standard : DDT < 0 . 00 mg kg ( -0 ) . According to the test f OCP residues in rice seeds , it can be concluded that the OCP sprayed onto the surface of rice leaves can move into rice plants and accumulate in the seeds at the mature stage . HCH residues in rice seeds of the double and four times dosage treatments , and DDT residues in all treatments , exceeded the Chinese National Food Standard ( HCH < 0 . 00 mg kg ( -0 ) , DDT < 0 . 00 mg kg ( -0 ) ) . Score: 0.00 Title: [ Effects of Bacillus thuringiensis transgenic rice and chemical insecticides on arthropod communities in paddy-fields ] 