Chemical Properties
White Powder
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.
Definition
ChEBI: A carboxylic ester obtained by formal condensation between 3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid and cyano(3-phenoxyphenyl)methanol.
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)
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure,
begin rescue breathing (using universal precautions) if
breathing has stopped, and CPR if heart action has stopped.
Transfer promptly to a medical facility. When this chemical
has been swallowed, get medical attention. Do not induce
vomiting when formulations containing petroleum solvents
are ingested. Otherwise, give large quantities of water and
induce vomiting. Do not make an unconscious person
vomit.
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.
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.
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.
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).
