Residue behavior and risk assessment of difenoconazole in celery and soil

The field trials on terminal residue and dissipation of difenoconazole in celery were carried out in Hunan and Shandong Provinces, and the acute toxicity of 10% difenoconazole water dispersible granule (WG) on soil organisms were studied in the laboratory. Based on the residue data and toxicity endpoints, the long-term and short-term dietary intake risks of difenoconazole to different populations in China and the environmental risks to soil organisms were evaluated. The results showed that the half-life of difenoconazole in celery leaves, stems and soil were 5.2-8.8 d, 8.0-8.2 d and 13.6-15.0 d, respectively. After the formulation was applied for three times with the interval of 5 days at the recommended dosage of 120 g/hm², the residue of difenoconazole in celery leaves was higher than MRL (3 mg/kg, China) and the residues in celery stem and the whole celery seedling were less than MRL on the 5th day after last application. The short-term dietary intake risk quotient (RQ_a) for the general population and children aged 1-6 years were 0.09 and 0.10, respectively. The long-term dietary risk assessment results showed that the contribution rate of the residues in celery for different populations in China was 9.4%-19.8%. The primary risk of 10% difenoconazole WG to soil organism was acceptable with acute risk quotient (RQ_e) of 0.368-0.890.