Influence of Uptake Pathways on the Metabolism Fate and Dietary Risk of Spirotetramat in Cucumber and Tomato

In this study, ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to establish a rapid and sensitive detection method for spirotetramat and its metabolites B-enol, B-keto, B-Mono, and B-glu in vegetables and soil matrices. The limit of quantification was 0.01 mg kg -1 and the retention time ranged from 1.8 to 3.5 minutes. The behavioral characteristics of spirotetramat and its metabolites on various substrates in the two absorption pathways were investigated. The degradation rate of spirotetramat in root irrigation mode was higher than that observed in foliage spray applications. Subsequently, the ecological risk of spirotetramat to soil earthworms was evaluated using both Risk Quotient (RQ) and Toxicity Exposure Ratio (TER) frameworks, while dietary and non-carcinogenic risks to various population groups were assessed via deterministic and probabilistic models. The assessment revealed that spirotetramat posed a potential ecological risk under worst-case scenarios, with RQ values ranging from 1.906 to 11.546, consistently exceeding the critical threshold of 1. Notably, the ecological risk associated with root irrigation was 3.6–4.9 times higher than that of foliar spraying. Conversely, spirotetramat did not pose unacceptable acute (0.060–3.113%) or chronic (0.144–87.779%) dietary exposure risks to the Chinese population, indicating that dietary intake remains within safe regulatory margins. Based on the evaluated exposure levels ranging from 0.063% to 33.250%, the current data suggests that the non-carcinogenic risk of spirotetramat to the exposed populations in China remains within acceptable safety margins under the studied application conditions. These results underscore the urgency of establishing tomato-specific MRLs and prioritizing application methods that balance pest control with soil safety. • B-enol and B-keto were the main metabolites of spirotetramat. • The degradation rate of spirotetramat on soil was faster than that on vegetables. • The terminal level of tomatoes were 7 times and 12 times that of cucumbers. • Unacceptable ecological exposure risks were observed by RQ (1.906∼11.546 >1). • The dietary and non-carcinogenic risks of rural were higher than those of urban.