Inhibitory Effect of Divergent Food Safety Standards on Bilateral Tropical Fruit Trade Between China and Vietnam: A Quasi-natural Experiment DID Estimation

Divergent food safety standards have become critical non-tariff barriers restricting the high-quality development of bilateral agricultural trade between China and Vietnam. As typical time-sensitive and pesticide-intensive agricultural products, tropical fruits are extremely vulnerable to the institutional friction caused by inconsistent cross-border food safety supervision systems. This paper takes the 2021 official implementation of China’s updated national food safety standard GB 2763-2021 (stricter pesticide residue limits for imported fruits) as a quasi-natural experiment, adopts the standard Difference-in-Differences (DID) method, and constructs balanced panel data of HS6-digit tropical fruit trade between China and Vietnam from 2016 to 2025. Taking high-standard-sensitive tropical fruits (durian, pitaya, mango) as the treatment group and low-standard-sensitive tropical fruits (coconut, longan) as the control group, this study systematically evaluates the inhibitory effect of divergent food safety standards on bilateral tropical fruit trade volume, trade frequency and trade stability. The empirical results show that the upgrading and divergence of China-Vietnam food safety standards significantly reduce the bilateral tropical fruit trade volume by 18.72% and suppress trade frequency by 12.35%, verifying the prominent trade-inhibiting effect of standard differences. Parallel trend test confirms that no significant pre-policy trend difference exists between the treatment and control groups, satisfying the quasi-natural experiment identification condition. Heterogeneity analysis indicates that the inhibitory effect is more pronounced for pesticide-intensive, high-value-added tropical fruits and border bulk trade modes. Mechanism testing reveals that divergent standards inhibit trade mainly through three channels: increasing enterprise compliance costs, raising customs clearance detention rates, and reducing market matching efficiency. Placebo test, variable substitution and sample truncation robustness tests all confirm the reliability of the core conclusions. This study expands the theoretical framework of technical trade barrier heterogeneity in tropical agricultural trade, provides precise empirical evidence for the trade friction caused by food safety standard divergence between China and Vietnam, and offers policy references for coordinating bilateral food safety supervision standards and eliminating non-tariff trade barriers under the RCEP framework.