Fenvalerate accumulation

Synthetic pyrethroids now account for at least 30% of the world insecticide market and are rapidly replacing other agricultural chemicals for control of insect pests. Fenvalerate is one of the more widely used synthetic pyrethroid insecticides. It is derived from a combination of a-cyano-3-phenoxybenzyl alcohol and a-isopropyl phenylacetate ester. Technical fenvalerate is a mixture of four optical isomers, each occurring in equal amounts but with different efficacies against insect pests. Fenvalerate does not usually persist in the environment for >10 weeks, and it does not accumulate readily in the biosphere. Time for 50% loss (Tb 1/2) in fenvalerate-exposed amphibians, birds, and mammals was 6 to 14 h for reptiles, terrestrial insects, aquatic snails, and fish it was >14 h to <2 days and for various species of crop plants, it was 2 to 28 days. Fenvalerate degradation in water is due primarily to photoactivity, and in soils to microbial activity. Half-time persistence in nonbiological materials is variable, but may range up to 6 days in freshwater, 34 days in seawater, 6 weeks in estuarine sediments, and 9 weeks in soils. 

In biological samples, fenvalerate neither persists for lengthy periods nor is readily accumulated (Smith and Stratton 1986 Cooper 1991). In general, fenvalerate is rapidly (i.e., Tb 1/2 of 6 to 14 h) excreted by amphibians, birds, and mammals has low persistence in various reptiles, terrestrial... 

Bioaccumulation factors for fenvalerate by representative freshwater and estuarine organisms during exposure for 28 to 30 days to various sublethal doses ranged from 40 to 570 for fish, 356 to 4700 for invertebrates, and 477 to 933 for algae (Smith and Stratton 1986). Because of its unusually high lipophilicity, fenvalerate is accumulated at only 30% efficiency by aquatic fauna, and uptake is not dose dependent (Coats et al. 1989). Contamination of algal food of daphnids with fenvalerate does not seem to contribute to an increase in whole-body burdens, although reduced filtration rates... 

Fenvalerate persists for <10 weeks in the environment and does not accumulate readily in the biosphere. Time for 50% loss (Tb 1/2) in fenvalerate-exposed amphibians, birds, and mammals is 6 to 14 h. For reptiles, terrestrial insects, aquatic snails, and fish, it is usually >14 h to <2 days and for crop plants, it is 2 to 28 days. In nonbiological compartments, Tb 1/2 is up to 6 days in freshwater, 34 days in seawater, 6 weeks in estuarine sediments, and 9 weeks in soils. 

Wszolek, P.C., D.E. Hogue, and D.J. Lisk. 1981a. Accumulation of fenvalerate insecticide in lamb tissues. Bull. Environ. Contam. Toxicol. 27 869-871. 

Day KE (1991) Effects of dissolved organic carbon on accumulation and acute toxicity of fenvalerate, Deltamethrin and cyhalothrin to Daphnia magna (Straus). Environ Toxicol Chem 10 91-101... 

Oncorhynchus mykiss) - one of the more sensitive aquatic species - have significantly lower rates of metabolism and elimination of fenvalerate than those reported for birds and mammals show little or no esterase activity towards pyrethroids and substantially lower oxidative activity than warm-blooded animals efficiently accumulate fenvalerate from the medium, and show greater intrinsic sensitivity of the central nervous system when compared with birds and mammals. 

In general, fenvalerate administered to mammals was rapidly eliminated and had little tendency to accumulate in tissues. Fenvalerate killed sensitive species of mammals at a brain injection concentration of 1.0 mg/kg FW brain (equivalent to 14.0 xg/kg body weight = BW), an intraperitoneal injection concentration of 3.9 mg/kg BW, acute oral doses of 50.0 to... 

Fenvalerate persists for <10 weeks in the environment and does not accumulate readily in the biosphere. Time for 50% loss (Tbl/2) in fenvalerate-exposed amphibians, birds, and... 

---