Allethrin is a synthetic duplicate of a component of pyrethrum (pyrethrins). Pyrethrum is a botanical insecticide extracted from chrysanthemum flowers, known as pyrethrum daisies (tropical flower) for centuries. Allethrin, the first synthetic pyrethroid, was introduced in 1949, and is a mixture of several isomeric forms.
Allethrin is almost exclusively used in homes and gardens for control of flies and mosquitoes, and in combination with other pesticides to control more flying and crawling insects. The purified d-trans-isomer of allethrin (bioallethrin) is more toxic to insects and is used for control of crawling insects in homes and restaurants. The combination D-trans allethrin - synergist piperonyl-butoxide (Meister, R.T. (ed.). 1992) is for killing animal’s parasites.
Bioallethrin (d-trans alletrin) is listed under category III, although as bioallethrin and also permethrin have been shown to bind to human androgen receptors. It might be more appropriate to list this group of substances under category II (Eil & Nisula, 1990) .
Allethrin paralyses the insect's nervous system, paralyses the insect’s breathing, which kills it.
Allethrin produces its neurotoxic responses in mammals (mice) also by acting on the brain and spinal levels (Nishimura M et al 1984) . Furthermore, Nishimura M et al presumed that adrenergic excitatory and serotonergic inhibitory mechanisms are involved in the neural pathway, that facilitates the allethrin evoked tremors.
General poisoning symptoms, so neurotoxic symptoms, consist of mild salivation, hyper excitability, tremors and convulsions resulting in death.
Chemistry
Chemical structure:
Research
Behaviour
Studied was the development of rat pups’ brains being exposed to alletrin (airosols) during the prenatal, postnatal and perinatal period of development. Significant oxidative stress was observed: An increase in lipid peroxidation and a decrease in antioxidants (glutathione, superoxide dismutase and catalase) in various brain areas (cerebellum, corpus striatum, frontal cortex and hippocampus). The hippocampus was the most affected region. There was significant decrease in cholinergic (muscarinic) receptor binding and inhibition in acetylcholinesterase activity. The neurochemical changes were found to accompany decrease in learning and memory performance in exposed rats (Sinha C, et al 2006).
The same effect was already proven for mice by Fischer C et al (2005). Here even a single oral dose bioallethrin was sufficient to provoke a persistent and a significantly higher activity level in locomotion, rearing and total activity. This when given in the neonatal period.
Eriksson P et al (1990, 1991) also found this effect of bioallethrin. Bioallethrin affected the muscarinic receptors in the cerebral cortex (the cholinergic system ) from ten-day-old NMRI mice. More specific: the ratio high- and low-affinity binding sites changed.
And 4 months old adult mice demonstrated a significant increase in spontaneous motor behaviour. And a decrease in the density of MAChR (muscarinic cholinergic receptors) in the cerebral cortex.
Adult mice, exposed neonatally to a low dose of bioallethrin, are increased susceptible to renewed exposure to bioallethrin. These mice showed more learning and memory deficits and behavioural disturbances (Talts U et al 1998).
Unfortunately the same mechanism was due to DDT. Here too an increased susceptibility in adult mice to bioallethrin became evident: Decreased muscarinic receptor site densities, an increased susceptibility in the cholinergic muscarinic receptors, a different behaviour reaction, increased levels of locomotor and total activity and decreased rearing (Eriksson P et al 1993).
Even irreversible muscarinic acetylcholine receptor changes, and behavioural disturbances with additional changes 2 months after the exposure (Johansson U et al 1995).
Allethrin (i.p.) had a dual effect on dopamine release. The increase in the extracellular level of striatal dopamine by 10 mg/kg allethrin reached a maximum of 178% of baseline but 20 and 60 mg/kg inhibited dopamine release (Mubarak Hossain M et al 2006).
Moya-Quiles MR et al (1995) note that allethrin increased the membrane instability. Sooner Gusovsky F et al (1989) already concluded that allethrin induces phosphoinositide breakdown.
Immune system
S-bioallethrin induced histamine release from human basophiles (allergic reactions), but also caused inhibition of lymphocyte proliferation (Diel et al 1998)
