Dissipation kinetics and exposure of spirotetramat and pymetrozine in open fields, a prelude to risk assessment of green bean consumption

Abstract

Determination and dissipation kinetics of pymetrozine and spirotetramat in green bean were studied using a QuEChERS method coupled to high-performance liquid chromatography-tandem mass spectrometry. Pymetrozine recoveries ranged between 88.4–93.7%, with relative standard deviation (RSD) of 5.5–14.4%. For spirotetramat the recoveries ranged between 91.7–103.4%, and the RSD were in the range of 3.2 to 12.4%. The limits of quantification (LOQs) were 0.01 mg/kg and 0.005 mg/kg for pymetrozine and spirotetramat, respectively.The developed analytical method was used to study the degradation rates of pymetrozine and spirotetramat in green bean grown in open field. Results showed that pymetrozine and spirotetramat followed the first-order kinetics model with half-lives of 3.3 days and 4.2 days, respectively. Furthermore, risk assessment was carried out which showed that, the chronic risk quotient (RQc) values for pymetrozine and spirotetramat were much lower than 100%. The present results indicated that the health risks posed for consumers by the pymetrozine and spirotetramat residues were negligible at the recommended dosages.

Uptake and Biotransformation of Spirotetramat and Pymetrozine in Lettuce (Lactuca sativa L. var. ramosa Hort.)

“…Another new pesticide, pymetrozine, is a broad-spectrum insecticide that has been registered for application on a range of crops and vegetables (Figure ). However, the Environmental Protection Agency (EPA) considers pymetrozine to be a “likely” human carcinogen and exhibits slight to moderate toxicity to aquatic invertebrates. ,, Zhang et al found that the half-life of pymetrozine in water is approximately 2 d, while that in soil was 7 d. The half-life of pymetrozine in broccoli is approximately 3.5 d. , When pymetrozine was applied at concentrations of 300 g a.i./hm 2 (recommended dosage), the initial concentration of pymetrozine in the soil was 14.09 mg/kg . To effectively prevent and control pests and delay pest resistance, multiple pesticides are often mixed and applied to crops.…”