Deltamethrin

Description

Deltamethrin is a type II pyrethroid insecticide and a modulator of voltage-gated sodium channels (Na_v). It binds to Drosophila para Na_v channels in a use-dependent manner following brief depolarizing prepulses and with increasing concentrations of 1 to 5 nM, indicating that it preferentially binds to the channel in the open state. It slowly activates Na_v1.8 channels, delays inactivation by longer than 40 ms, and induces persistent tail currents for channels expressed in X. laevis oocytes. Deltamethrin decreases proliferation of MCF-7 cells and inhibits androgen receptor transactivation when used at concentrations of 10 and 20 μM or greater, respectively. However, it is not cytotoxic to MCF-7 and CHO cells at concentrations of 25 and 100 μM, respectively, and does not induce transactivation of the estrogen receptor. Deltamethrin is lethal to mice with an LD₅₀ value of 50 mg/kg and at low sublethal doses of 0.05 and 0.1 mg/kg it induces histopathological changes in the liver, kidney, spleen, and testes, including a loss of spermatozoa and Sertoli cells.

Description

Deltamethrin is a kind of synthetic pyrethroids insecticide used worldwide in agriculture for home pest control and protection of foodstuff and disease vector control. Deltamethrin belongs to the type II pyrethroids, which is hydrophobic in nature. It kills the insects through producing severe delay in sodium channel inactivation, leading to a persistent depolarization of the nerve membrane without repetitive discharge. However, this pesticide can be contained in contaminated food and water, and is readily absorbed by the oral route. Recent studies have shown that it can have certain toxicity through inducing oxidative stress. Vitamin can be used to alleviate its toxicity.

Chemical Properties

White Powder

Chemical Properties

Colorless, white, or off-white crystalline solid or powder. Odorless. Combustible.

Uses

A Type II pyrethroid insecticide that potently inhibits calcineurin

Uses

Synthetic pyrethroid insecticide, which acts as a potent inhibitor of calcineurin (protein phosphatase 2B) and has an IC50 of about 100pM. This inhibition action results in cellular hyperexcitability by causing non-mutated calcium channels to remain open for an extended period of time allowing an abundance of Ca2+ to enter the cell.

Uses

Insecticide.

Uses

Deltamethrin is effective against a wide range of insects in fruit, cereals, vegetables, cotton, soyabeans and oilseed rape. It is also used for the control of crawling and flying insects indoors, in stored grain and timber and for ectoparasite control on animals.

Definition

ChEBI: A carboxylic ester obtained by formal condensation between 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid and cyano(3-phenoxyphenyl)methanol.

Contact allergens

Pyrethroids, also called pyrethrinoids, are neurotoxic synthetic compounds used as insecticides, with irritant properties. Cypermethrin and fenvalerate have been reported as causing positive allergic patch tests, but only fenvalerate was relevant in an agricultural worker.

Potential Exposure

Deltamethrin is a synthetic pyrethroid insecticide that kills insects on contact and through diges- tion. It is used to control a variety of chewing and sucking insects that infest fruit, vegetables and field crops, includ- ing apples, pears and plums; peas, glasshouse cucumbers, tomatoes, peppers, potted plants, and ornamentals; hops, oats, cotton and other field crops. Deltamethrin is also used to control residential and commercial insect pests. Some formulations are RUPs)

Environmental Fate

Deltamethrin is a type II pyrethroid, a functional neurotoxin slowing the inactivation of voltage-gated sodium channels leading to a state of hyperexcitability which in turn causes fine tremor, salivation, and choreoathetosis. Other proposed contributory actions include antagonism of gammaaminobutyric acid A receptor inhibition and voltage-gated chloride and calcium channels.

Metabolic pathway

After oral administration of 14C-deltamethrin to lactating dairy cows, deltamethrin is metabolized and excreted in the bile and urine with very little accumulation in major edible tissues. The major portion (78-82%) of the radioactivity in feces is deltamethrin. Only 4-6% is eliminated in the urine and 0.42 1.62% is secreted in the milk. The primary biotransformation is via the hydrolysis of the ester linkage followed by oxidation of the geminal methyl groups of cyclopropane carboxylic acids and phenoxy benzaldehyde, resulting in dicarboxylic acid, lactonecarboxylic acid, or phenoxybenzoic acid derivatives. Deltamethrin is not metabolized within algae cells and mouse fibroblasts, but is partially transformed into less or not active isomers. In algae and fibroblast culture media, many metabolites of deltamethrin resulting mostly from hydrolysis of the molecule are found. This metabolism seems to be linked with the release of enzymes by cells into the culture medium.

Shipping

UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required.UN3349 Pyrethroid pesticide, solid toxic, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Degradation

Deltamethrin is very stable as a solid but it is readily hydrolysed in solution under alkaline conditions with a DT₅₀ of 2.5 days at pH 9 (25 °C). By analogy with cypermethrin, the rate-determining step in dilute solution is nucleophilic attack by OH^-.
Isomerisation has been shown to occur in natural waters under dark conditions, yielding the inactive 1 ScisaS isomer (Maguire, 1992). Aqueous photolysis (sunlight) causes slow degradation but also isomerism to the insecticidally active 1RtransaS form. These isomerisation reactions, which are more rapid than those of cypermethrin, were reported much earlier by Ruzo et al. (1977). This is due to the heavy atom effect (bromine). Similarly, the decreased bond strength of C-Br (ct C-Cl) leads to photocatalysed reductive debromination, with tans- favoured over cisdebromination by a factor of 4. The DT₅₀ on soil photolysis is 9 days (PM).
Photolysis of the ester bond is the main reaction of deltamethrin. Solvent effects are important. cis-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid (2) and 3PBA (4) are the major products in water (Scheme 1). A minor product (5) was formed by decarboxylation. Deltamethrin is resistant to photo-oxidation. The mechanisms of photodegradation of the pyrethroids have been reviewed by Ruzo (1982).

Toxicity evaluation

Deltamethrin is twofold more persistent in aquatic environments than in soil. Depending on conditions the environmental half-life ranges from 2 days (for hydrolysis at pH 9) to 80 days (for degradation in an aquatic environment).

Incompatibilities

May react violently with strong oxidi- zers, bromine, 90% hydrogen peroxide, phosphorus trichloride, silver powders or dust. Incompatible with silver compounds. Mixture with some silver compounds forms explosive salts of silver oxalate.

Waste Disposal

ncineration would be an effective disposal procedure where permitted. If an efficient incinerator is not available, the product should be mixed with large amounts of combustible material and contact with the smoke should be avoided. In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers.

References

Adams, A. J. "A review of the efficacy and uses of deltamethrin for wood preservation." Document - the International Research Group on Wood Preservation (Sweden) (1996).
Sayeed, I, et al. "Oxidative stress biomarkers of exposure to deltamethrin in freshwater fish, Channapunctatus Bloch." Ecotoxicology & Environmental Safety 56.2(2003):295-301.
Yousef, Mokhtar I., T. I. Awad, and E. H. Mohamed. "Deltamethrin-induced oxidative damage and biochemical alterations in rat and its attenuation by Vitamin E." Toxicology 227.3(2006):240-247.