Investigation in tea on fate of fenazaquin residue and its transfer in brew.

Fenazaquin is a non-systemic acaricide/insecticide used widely in controlling mites and other related pests in fruits, vegetables and tea. The objective of this research was to investigate the disappearance trend in tea of fenazaquin residue level and its transfer in brew. Fenazaquin was applied on a tea crop at two rates, 125 and 250 g A.I./ha in wet and dry seasons under field conditions. Samples (green shoots, made tea and its brew) were analyzed for fenazaquin and quantification was by high performance liquid chromatography using a UV detector. The residue dissipated faster in the wet season than in the dry season. Seven days after the treatment (normal round of plucking) the residues observed in green shoots at the two rates were 0.32, 0.50 mg/kg and 2.04, 2.84 mg/kg in the wet and dry seasons, respectively. However, the degradation rate in both seasons followed first order kinetics. Half lives in green shoots were in the range 1.20-1.32 and 2.10-2.21 days and in made tea 1.03-1.06 and 1.87-1.94 days for wet and dry seasons, respectively. During processing of green shoots to made tea considerable loss (42-70%) of residue was observed. The transfer of residue from made tea to brew was in the range 3-17%. In brew residues were below 0.003 mg/l after 5 days of application at both the rates in either of the seasons. The estimated intake with brew (normal consumption of 10 cup/day/adult) thus would be below the acceptable daily intake for fenazaquin (0.005 mg/kg-body weight). To avoid health hazards due to the toxic effect of residues in brew, a waiting period for plucking the tea shoots after fenazaquin application of more than 3 days for wet season and 5 days for dry season at recommended rate (125 g A.I./ha) may be suggested and considered quite safe.