The allethrins are a group of related synthetic compounds used in insecticides. They are classified as pyrethroids, i.e. synthetic versions of pyrethrin, a chemical with insecticidal properties found naturally in Chrysanthemum flowers. They were first synthesized in the United States by Milton S. Schechter in 1949. Allethrin was the first pyrethroid.
Allethrin I and allethrin II differ by having a methyl group and a methyl ester, respectively, on one terminus. Each of these allethrins consists of the eight possible stereoisomers. A partly enantiopure variant of allethrin I, consisting of only two stereoisomers in an approximate ratio of 1:1, is called bioallethrin. The same mixture of isomers, but in an approximate ratio of 3:1, is known as esbiothrin.
Toxicity
Chronic exposure to allethrins alters the plasma biochemical profile of humans and may have adverse health effects.[1]Bioallethrin has been shown to cause oxidative damage, cellular toxicity and necrosis of human lymphocytes studied in vitro.[2] It is highly toxic to fish and aquatic invertebrates. At normal application rates, allethrin is slightly toxic to bees.[3] Insects subject to exposure become paralyzed (nervous system effect) before dying. Allethrins are toxic to cats[4] because they either do not produce, or produce less of certain isoforms of glucuronosyltransferase, which serve in hepatic detoxifying metabolism pathways.[5]
