Residues and dissipation dynamics of chlorpyrifos in Myrica rubra fruits

In order to assess the dissipation and residues of chlorpyrifos in Myrica rubra fruits, the dissipation dynamics and final residue trials of chlorpyrifos in Myrica rubra fruits were carried out from 2013 to 2015. Results showed that:when the whole tree was sprayed once with 800 times diluted solution of 48% chlorpyrifos EC in the spring shoots (young fruit) growing season of Myrica rubra, the dissipation of chlorpyrifos in ‘Dongkui’ and ‘Linhaizaodamei’cultivars were of the similar type, fitting to the first order kinetics with half-lives varied from 4.60 to 5.78 days. The half-life was short and its dissipation speed was fast under those conditions. The 3-year research results demonstrated that the residues of chlorpyrifos in Myrica rubra fruits varied from 0.26 to 0.45 mg/kg 23 days after spraying, which was lower than the maximum residue limit (MRL, 1 mg/kg) of China (apple, pear, litchi and longan) and Japan (other berries). Thirty-four days after applying, chlorpyrifos in Myrica rubra fruits varied from 0.074 to 0.28 mg/kg, which is below the MRLs of strawberry in Hong Kong (0.3 mg/kg). However, 44 days after spraying, chlorpyrifos in Myrica rubra fruits (0.073-0.13mg/kg) were still higher than the MRLs of blueberries and mulberries in EU (0.05 mg/kg). The dietary intake risk assessment showed that after 23, 27, 34 and 44 d pesticide interval, the RQ and ARfD of chlorpyrifos in Myrica rubra fruits were very low (significantly lower than 1), and within safe level for people aging between 2-6, 7-14, 18-30 and 60-70.