Deltamethrin

Deltamethrin is a pyrethroid ester insecticide. Deltamethrin plays a key role in controlling malaria vectors, and is used in the manufacture of long-lasting insecticidal mosquito nets; however, resistance of mosquitos and bed bugs to deltamethrin has seen a widespread increase.

Deltamethrin
Names
Preferred IUPAC name
(S)-Cyano(3-phenoxyphenyl)methyl (1R,3R)-3-(2,2-dibromoethen-1-yl)-2,2-dimethylcyclopropane-1-carboxylate
Other names
  • Decamethrin
  • Decis
  • Delta dust
  • DeltaGard
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference
 6746312
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.052.943
EC Number
  • 258-256-6
KEGG
PubChem CID
RTECS number
  • GZ1233000
UNII
UN number 3349
InChI
  • InChI=1S/C22H19Br2NO3/c1-22(2)17(12-19(23)24)20(22)21(26)28-18(13-25)14-7-6-10-16(11-14)27-15-8-4-3-5-9-15/h3-12,17-18,20H,1-2H3/t17-,18+,20-/m0/s1 Y
    Key: OWZREIFADZCYQD-NSHGMRRFSA-N Y
  • InChI=1/C22H19Br2NO3/c1-22(2)17(12-19(23)24)20(22)21(26)28-18(13-25)14-7-6-10-16(11-14)27-15-8-4-3-5-9-15/h3-12,17-18,20H,1-2H3/t17-,18+,20-/m0/s1
    Key: OWZREIFADZCYQD-NSHGMRRFBN
SMILES
  • N#C[C@H](c1cccc(c1)Oc1ccccc1)OC(=O)[C@@H]1[C@@H](C1(C)C)C=C(Br)Br
Properties
Chemical formula
 C22H19Br2NO3
Molar mass 505.206 g·mol−1
Density 1.5 g cm−3
Melting point 98 °C (208 °F; 371 K)
Boiling point 300 °C (572 °F; 573 K)
Pharmacology
P03BA03 (WHO) QP53AC11 (WHO)
Hazards
GHS labelling:
Pictograms
Signal word
 Danger
Hazard statements
 H301, H331, H410
Precautionary statements
 P261, P264, P270, P271, P273, P301+P310, P304+P340, P311, P321, P330, P391, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Deltamethrin is toxic to aquatic life, particularly fish. Although generally considered safe to use around humans, it is still neurotoxic. It is an allergen and causes asthma in some people.

Usage

Deltamethrin is a highly effective insecticide. It is used, among other applications, for the production of long-lasting insecticidal nets (LLINs), which, along with indoor residual spraying (IRS), are the main vector control strategies recommended by the World Health Organization (WHO) for the management of malaria.[1]

Deltamethrin plays a key role in controlling malaria vectors, and is used in the manufacture of long-lasting insecticidal mosquito nets. It is used as one of a battery of pyrethroid insecticides in control of malarial vectors, particularly Anopheles gambiae, and whilst being the most employed pyrethroid insecticide, can be used in conjunction with, or as an alternative to, permethrin, cypermethrin and organophosphate-based insecticides, such as malathion and fenthion. Resistance to deltamethrin (and its counterparts) is now extremely widespread and threatens the success of worldwide vector control programmes.

Production

Deltamethrin is a pyrethroid composed of a single stereoisomer, of a possible 8 stereoisomers, selectively prepared by the esterification of (1R,3R)- or cis-2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylic acid with (alpha,S)- or (+)-alpha-cyano-3-phenoxybenzyl alcohol or by selective recrystallization of the racemic esters obtained by esterification of the (1R,3R)- or cis-acid with the racemic or (alpha-R, alpha-S, or alpha-R/S)- or + or − alcohol.

Resistance

Resistance has been identified in several insects, including important vectors of malaria like the mosquito Anopheles gambiae as well as non-disease carrying pests like bed bugs.

Mosquitoes

Methods of resistance include thickening of the cuticle of the insect to limit permeation of the insecticide, metabolic resistance via overexpression of metabolizing cytochrome P450 mono-oxygenases and glutathione-S-transferases, and the knockdown resistance (kdr) sodium channel mutations which render the action of insecticides ineffectual, even when co-administered with piperonyl butoxide. Characterization of the different forms of resistance among mosquitoes has become a top priority in groups studying tropical medicine due to the high mortality of those who reside in endemic areas.[2]

Bed bugs

Two mutations, the valine to leucine mutation (V419L) and the leucine to isoleucine mutation (L925I) in voltage-gated sodium channel α-subunit gene, have been identified as responsible for knockdown resistance to deltamethrin in bed bugs. One study found that 88% of bed bug populations in the US had at least one of the two mutations, if not both, meaning that deltamethrin resistance among bed bugs is currently making this insecticide obsolete.[3]

Side effects

Deltamethrin belongs to a group of pesticides called synthetic pyrethroids. This pesticide is toxic to aquatic life, particularly fish, and therefore must be used with extreme caution around water.

In humans

Although generally considered safe to use around humans, it is still neurotoxic. Pyrethroids like Deltamethrin can be allergens and cause asthma in some people.[4]

Deltamethrin temporarily attacks the nervous system of any animal with which it comes into contact. Skin contact can lead to tingling or reddening of the skin local to the application. If taken in through the eyes or mouth, the most common symptom is facial paraesthesia, which can feel like many different abnormal sensations, including burning, partial numbness, "pins and needles", skin crawling, etc. There is one case report describing chronic intoxication from pyrethroid insecticides leading to a syndrome clinically similar to motor neuron disease.[5] There are no antidotes, and treatment must be symptomatic, as approved by a physician. Over time, deltamethrin is metabolized, with a rapid loss of toxicity, and passed from the body. A poison control center should be contacted in the event of an accidental poisoning.

Deltamethrin is able to pass from a woman's skin through her blood and into her breast milk, although breastfeeding remains safe under prevailing conditions. In South Africa, residues of deltamethrin were found in breast milk, together with DDT, in an area that used DDT treatment for malaria control, as well as pyrethroids in small-scale agriculture.[6]

A 2015 study conducted in Brittany, France, found a negative correlation between deltamethrin exposure (measured through the presence of a metabolite in urine) and cognitive scores in infants.[7]

In domestic animals

Cases of toxicity have been observed in cattle, following use of agricultural deltamethrin preparation in external application for tick control. It is also commonly known as having severe poisoning effects on the cattle, which are vulnerable to the pyrethroid.

References
  1. World Health Organization (30 January 2016). "5.5 Resistance to insecticides". World Malaria Report 2015. World Health Organization. p. 48. ISBN 978-92-4-156515-8.
  2. Müller, Pie; Warr, Emma; Stevenson, Bradley J.; Pignatelli, Patricia M.; Morgan, John C.; Steven, Andrew; Yawson, Alexander E.; Mitchell, Sara N.; Ranson, Hilary; Hemingway, Janet; Paine, Mark J. I.; Donnelly, Martin J. (2008). "Field-Caught Permethrin-Resistant Anopheles gambiae Overexpress CYP6P3, a P450 That Metabolises Pyrethroids". PLOS Genetics. 4 (11): e1000286. doi:10.1371/journal.pgen.1000286. PMC 2583951. PMID 19043575.
  3. Zhu, F.; Wigginton, J.; Romero, A.; Moore, A.; Ferguson, K.; Palli, R.; Potter, M. F.; Haynes, K. F.; Palli, S. R. (2010). "Widespread distribution of knockdown resistance mutations in the bed bug,Cimex lectularius(Hemiptera: Cimicidae), populations in the United States". Archives of Insect Biochemistry and Physiology. 73 (4): 245–57. doi:10.1002/arch.20355. PMID 20301216.
  4. "Cockroach Control". Retrieved August 10, 2016.
  5. Doi, H.; Kikuchi, H.; Murai, H.; Kawano, Y.; Shigeto, H.; Ohyagi, Y.; Kira, J. (2006). "Motor neuron disorder simulating ALS induced by chronic inhalation of pyrethroid insecticides". Neurology. 67 (10): 1894–5. doi:10.1212/01.wnl.0000244489.65670.9f. PMID 17130437. S2CID 29920559.
  6. Bouwman, Sereda B.; Meinhardt, H.M. (December 2006). "Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria endemic area in South Africa". Environmental Pollution. 144 (3): 902–917. doi:10.1016/j.envpol.2006.02.002. PMID 16564119.
  7. Jean-François Viel, Charline Warembourg, Gaïd Le Maner-Idriss, Agnès Lacroix, Gwendolina Limond, Florence Rouget, Christine Monfort, Gaël Durand, Sylvaine Cordier, Cécile Chevrier (2015). "Pyrethroid insecticide exposure and cognitive developmental disabilities in children: The PELAGIE mother–child cohort" (PDF). Environment International. 82 (September 2015): 69–75. doi:10.1016/j.envint.2015.05.009. PMID 26057254.{{cite journal}}: CS1 maint: uses authors parameter (link)
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