Pydiflumetofen in paddy field environments: Its dissipation dynamics and dietary risk

Pydiflumetofen is a broad-spectrum fungicide, the residues of which contaminate crops or are released into the environment, posing a threat to organisms and human health. In this study, pydiflumetofen residues in paddy field ecosystems were determined using quick, easy, cheap, rugged, safe (QuECHERS) sample preparation coupled to high-performance liquid chromatography-mass spectrometry (HPLC-MS) analysis. The dissipation of pydiflumetofen residues was investigated in four Chinese paddy fields over a two-year period (2019 and 2020). The results show that pydiflumetofen dissipation in paddy water occurs faster than those in rice straw and paddy soil, with half-lives of 0.72-2.47, 1.09-9.34, and 6.08-14.38 d, respectively. Linear analysis revealed that the dissipation half-life of pydiflumetofen in different matrices is positively correlated with soil organic matter content and pH and negatively correlated with rainfall and temperature. The final residues of pydiflumetofen in brown rice were determined to assess its dietary-intake risk, and through the household method of soaking for 2-4 h, 28.65-40.24% pydiflumetofen residue can be removed from the rice. The acute and chronic dietary exposure risks of pydiflumetofen in rice were found to be 4.57%-7.14% (acute hazard index) and 0.58%-2.09% (hazard quotient), respectively, indicating that pydiflumetofen poses little or no health risk to Chinese consumers. These results will help guide the practical application of pydiflumetofen and help minimize the environmental risks associated with its global use.

Automated summary

The study found that the dissipation rate of Pydiflumetofen residues in paddy field ecosystems is correlated with soil organic matter content, pH, rainfall, and temperature. Household soaking method can remove a portion of residues in rice, and the dietary exposure risks of Pydiflumetofen in rice for Chinese consumers are relatively low.