Persistence and safety risk assessment of propineb in Indian tea

A supervised field trial was conducted on tea with propineb at 1,750 and 3,500 g a.i./ha at two locations (Assam and Darjeeling), applied thrice at an interval of 10 days during the year 2006-2007. Propineb residue was measured spectrophotometrically at 435 nm in terms of CS2. The initial deposit of propineb in green tea leaves were found to be in the range of 16.26-35.96 mg/kg and the residue persisted up to 10 days irrespective of doses and locations with half-life value ranging from 2.24 to 2.43 days and preharvest interval of 17.17-21.37 days. Made tea residues ranged from 9.27 to 20.86 mg kg(-1) on 7 days and no residues could be detected on 14 days. Infusion study indicated that propineb did not infuse into tea liquor from made tea. The limit of determination was found to be 0.1 mg kg(-1) in terms of propineb for green tea leaves, made tea, and tea liquor. The tea applied with the recommended dose of propineb is safe for consumption as liquor.