Development of procedures to stabilize chlorfenvinphos in model cattle dips

The environmental fate and dissipation of the acaricide chlorfenvinphos was studied in water and sediment in model cattle dips with monthly recharge and without monthly recharge. Chlorfenvinphos concentration decreased with time in both model dips and the monthly recharge at 10% of the initial concentration was inefficient to maintain the right concentration which would be effective for tick control. Volatilization was the principal factor that influenced the dissipation of the pesticide. The sediment bound residues increased with time. Mineralization of 14C- chlorfenvinphos due to microbial activity showed that the 14CO2 production increased with time in biometers flasks with different amounts of sediment. 2,4 - dichloroacetophenone, and 2,4-dichlorobenzaldehyde were identified as degradation products. Isomerization of chlorfenvinphos from isomer Z to E was influenced by sunlight and it affected the efficiency of the pesticide as Z isomer is more active on tick control than E isomer. (author)