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Related to Pyrethrins: permethrin, pyrethroids, Piperonyl butoxide



mixtures of substituted (+)-pyrethrolone with esters of (+)-trans-chrysanthemumic and pyrethrinic acids. Pyrethrins have insecticidal properties and are found in various chrysanthemums of the genus Pyrethrum. Pyrethrins are optically active, colorless liquids with high boiling points; they consist of geometric isomers that are easily hydrolyzed by base but are stable in weakly acidic mediums. They are easily decomposed by light, moisture, and air. The median lethal dose for rats ranges from 200 to 2,600 mg/kg, administered orally.

The active constituents of pyrethrins are pyrethrin I (I), pyrethrin II (II), cinerin I (III), cinerin II (IV), jasmoline I (V) and jasmoline II (VI):

Pyrethrins are usually extracted from the crushed flowers of chrysanthemums of the genus Pyrethrum with a mixture of the polar solvent methanol and the nonpolar solvent kerosine. Sometimes a single solvent is used, for example, methylene chloride, dichloroethane, or some other chlorinated hydrocarbon. Admixtures in pyrethrins are removed either by precipitation, by adsorption onto charcoal, or by freezing with subsequent filtration. The technical-grade, 25-percent extract contains 10 percent pyrethrin I, 9 percent pyrethrin II, 3 percent cinerin I, approximately 3 percent cinerin II, and traces of jasmolines. It is a yellow oil that is insoluble in water but soluble in most organic solvents. The ratio of the components and the toxicity for warmblooded animals may be controlled by selecting the type of source flowers, by controlling the conditions of plant growth, and by resorting to various treatments during the extraction process or during distillation of the solvent.

Pyrethrins are contact insecticides with a rapid paralyzing action, that is, they exert a knockdown effect. They are supplied as aerosols, dusts, or emulsions for use against household insects, including true bugs, lice, and cockroaches. They can also be used to exterminate harmful insects in agriculture and in the treatment of stores and supplies, although their action is of very short duration. Because pyrethrins are unstable, insects rarely develop a tolerance. The insecticidal action of pyrethrins is intensified by adding various synergists, for example, piperonyl butoxide, tropital, and sesamex. For most countries, pyrethrins are expensive, imported insecticides, and thus synthetic pyrethrin analogs, known as pyrethroids, are manufactured instead.


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References in periodicals archive ?
According to the report, strict implementation of regulatory frameworks in these countries can encourage the use of natural insecticides such as pyrethrins and drive market growth.
Pyrethrin and pyrethroid exposures in the United States: a longitudinal analysis of incidents reported to poison centers.
Comparative antifeedant activities of polygodial and pyrethrins against whiteflies (Bemisia tabaci) and aphids (Myzus persicae).
halys adults exposed to pyrethrins moved significantly greater horizontal distances compared with the untreated control, during the first 10 min of insecticide exposure (P < 0.
Pyrethroids were manufactured to persist longer in the environment than pyrethrins.
Natural pyrethrins are present in pyrethrum extracts obtained from flowers of some species of chrysanthemum.
Effect of ethrel, chlormequat chloride and paclobutrazol on growth and pyrethrins accumulation in Chrysanthemum cinerariaefolium Vis.
The report also showed that 89% of the illness-causing insecticide exposures, including the fatality, were to pyrethroids, pyrethrins, or both, and were in toxicity category III.
Range of organic acid metabolites available with new organic acid technology Glycolysis Phthalates Krebs Cycle Solvents Amino acid Metabolism Pyrethrins DNA, RNA metabolism Dry cleaning solvents Neurotransmitter metabolism Preservatives Organophosphate metabolism Vinyl chloride Yeast, fungal markers Specific Clostridia marker Markers for beneficial bacteria Specific mitochondrial disease markers Oxalate markers for kidney stones, Vitamin deficiency markers genetic disease Specific marker for ammonia Phosphate marker of bone function toxicity Markers of fatty acid catabolism Marker for glutathione precursor Metabolic diseases causing autism Genetic screening with extremely spectrum disorders sensitive markers
Peter Montague, writing for the Environmental Research Foundation, says there seems to be a strong link between brain cancers and products used to kill fleas and ticks like pyrethrins (natural) and pyrethroids (synthetic pyrethrins: permethrin, tetramethrin, allethrin, resmethrin, and fenvalerate), and chlorpyrifos (known as Dursban).
6) examined the efficacy of the 2005 emergency aerial spray in Sacramento County, which used pyrethrins as the active ingredients to control adult mosquitoes.
Agency for Toxic Substances and Disease Registry (ATSDR) Toxicological profile for Pyrethrins and Pyrethroids.