WORLD HEALTH ORGANIZATION FOOD AND AGRICULTURE
ORGANISATION MONDIALE DE LA SANTE ORGANISATION POUR L'ALIMENTATION
DATA SHEET ON PESTICIDES No. 50
Primary use: Insecticide
Chemical group: Pyrethroid
It must be noted that the issue of a Data Sheet for a
particular pesticide does not imply endorsement of the pesticide by
WHO or FAO for any particular use, or exclude its use for other
purposes not stated. While the information provided is believed to
be accurate according to data available at the time when the sheet
was compiled, neither WHO nor FAO are responsible for any errors or
omissions, or any consequences therefrom.
The issue of this document does Ce document ne constitue pas une
not constitute formal publication. Il ne doit faire
publication. It should not be l'objet d'aucun compte rendu ou
reviewed, abstracted or quoted résumé ni d'aucune citation sans
without the agreement of the l'autorisation de l'Organisation
Food and Agriculture des Nations Unies pour
Organization of the United l'Alimentation et l'Agriculture
Nations or of the World Health ou de l'Organisation Mondiale de
Organization. la Santé.
1. GENERAL INFORMATION
1.1 COMMON NAME: Deltamethrin (ISO, BSI), formerly Decamethrin
IUPAC: (S)- -cyano-3-pehoxybenzyl(1R)-cis-3-(2,2-
CAS No. 1: (lR (S*),3 )-cyano(3-phenoxybenzyl) methyl 3-
CAS Reg. No.: 52918-63-5
Molecular formula: C22H19Br2NO3
Molecular weight: 505.2
1.1.2 Synonyms: Decamethrin; Decis (R); K-othrin(R); NRDC 161;
OMS 1998; RU-22974
1.2 SYNOPSIS: Deltamethrin is a non-composite synthetic pyrethroid;
a broad spectrum, non-cumulative insecticide; a fast-acting
neurotoxic agent with good contact and stomach action and no
fumigant action. Its biological activity is very stable in the
envirorment since it has good residual activity on many insects
and most surfaces. Deltamethrin is non-systemic in plants. It
is of moderately high toxicity in mammals, and is readily
metabolized with rapid loss of toxicity. It has a repellent
effect for some insects.
1.3 SELECTED PROPERTIES
1.3.1 Physical characteristics - The technical material is a
colourless, crystalline powder with a melting point at 98-101°C;
it is odourless and non-corrosive; its optical rotation1
( )20 is +58° ± 1°(4% in toluene).
1.3.2 Solubility - At 20°C, 2 µg/l in water. Deltamethrin is soluble
in most aromatic solvents, acetone, ethanol and dioxane.
1.3.3 Stability - Deltamethrin is a very stable compound; it does not
degrade at 40°C for two years;1 it is resistant to air and
1.3.4 Vapour pressure - at 25°C, 1.9996 x 10-9 kPa (1.5 x 10-8 mmHg).
1.4 AGRICULTURE, HORTICULTURE AND FORESTRY
1.4.1 Common formulations - Emulsifiable concentrates (25 g a.i./l);
ULV concentrates (4, 5 and 10 g/l); wettable powder (25 and 50
g/kg); dusts (0.5 and 1.0 g/kg); granules (0.5 and 1.0 g/kg);
and flowable (25 g a.i./l).
1.4.2 Susceptible pests - Deltamethrin is effective as larvicide,
ovicide and adulticide against a number of plant parasitic pests
(Lepidoptera, Homoptera, Coleoptera, Diptera and Acarides). It
is also effective against a number of biting, disease vector and
nuisance insects of man and animals.
1.4.3 Use pattern - Used alone, Deltamethrin is effective against most
plant pests except cotton mites and cotton boll weevils. It may
be applied to food and field crops, market gardens, orchards and
vineyards by air or ground spray equipment, at rates of up to 11
g/ha or as recommended by the manufacturer. It may also be
sprayed on greenhouse plants, on buildings and other inert
surfaces, and on animals. Special formulations for oral or
dipping applications have also proved effective against cattle
1.4.4 Unintended effects - Deltamethrin is not phytotoxic when used as
recommended. Its insect repellent action is not likely to be
detrimental to pollination when used as directed on flowering
1.5 PUBLIC HEALTH USE - Deltamethrin has had some experimental use
against disease vector insects with limited success. Its repellent
action may limit its effectiveness in some eradication programmes.
1.6 HOUSEHOLD USE - Deltamethrin is primarily an agricultural
insecticide and has no recommended household use.
2. TOXICOLOGY AND RISKS
2.1 TOXICOLOGY - MAMMALS
2.1.1 Absorption route - Deltamethrin is primarily absorbed from the
gastrointestinal tract. It is also readily absorbed by
inhalation of spray mist. Dermal absorption has not been
demonstrated in preliminary trials with labelled deltamethrin in
1 Data provided by the manufacturer.
2.1.2 Mode of action - The parent compound is the active toxin;
deltamethrin is a neurotoxin acting primarily on the basal
ganglia of the central nervous system. It causes
repetitive nerve action through prolongation of sodium
permeability during the recovery phase of the action potential
2.1.3 Excretion - Deltamethrin metabolism and excretion have been
extensively studied in rats, mice, and cows. The pattern does not
vary significantly among these species. Deltamethrin is
metabolized by liver microsomal esterases and oxidases.
Hydrolysis initially cleaves the parent compound into two
fragments - cyclopropanecarboxylic acid and 3-phenoxybenzyl
alcohol. The latter is then oxidised to 3-phenoxybenzoic acid
which is the major excretion compound of this moiety.
Hydroxylation of a significant portion of this moiety, primarily
at the carbon 4' site but also to some extent at sites 5 and 2,
can occur either before or after hydrolysis. Deltamethrin is
completely eliminated from the body within six to eight days of
oral administration. The hydrolysis products are primarily
excreted in the urine, from 7 to 15% of the oral dose is found in
the faeces as the parent compound and its hydroxylates, and a
smaller portion is found in the integument as a thiocyanate. The
half-life of the alcohol moiety is approximately 0.3 days; it is
primarily excreted as a free acid and to some extent as
conjugates of glucuronic and amino-acids. The half-life of the
acid moiety is about 0.3 days; it too is excreted as a free acid
and as a glycine conjugate. A small amount of the cyano group is
rapidly excreted as in iminotriazolidine derivative. However,
the major portion is thiocyanate which has a half-life of 2.4
2.1.4 Toxicity, single dose - The toxicity of deltamethrin varies with
the type of vehicle used, vegetable oil solutions being less
toxic than propylene glycol 200 (PEG 200) solutions. The results
shown below are for vegetable oil solutions, with the results
obtained with PEG solutions shown in parentheses.
Rat (F) 139 (86) mg/kg b.w.
Rat (M) 128 (67) mg/kg b.w.
Rat (M, F) +5000 mg/kg b.w. (aqueous suspension)1
Mouse (F) 34 (19) mg/kg b.w.
Mouse (M) 33 (21) mg/kg b.w.
Beagle dog (M, F) +300 mg/kg b.w.
Rat (M, F) (+2940) mg/kg b.w.
Rabbit (M, F) (+2000) mg/kg b.w.
Rat (F) 186 (25) mg/kg b.w.
Rat (M) 209 (24) mg/kg b.w.
Mouse (F) 166 (12) mg/kg b.w.
Mouse (M) 171 (18) mg/kg b.w.
Rat (M, F) (3) mg/kg b.w.
Mouse (M, F) (4) mg/kg b.w.
Rats (6-hour exposure) +0.72 g a.i./m3 of air
1 Data provided by the manufacturer.
In general pyrethroid poisoning is characterized by hyperactivity
and hypersensitivity (somatosensory). Deltamethrin in particular
is included among a group of pyrethroids producing the CS-
syndrome, in sequence: pawing and burrowing behaviour,
salivation, coarse tremors progressing to choreoathetosis and
occasionally, terminal clonic seizures. In rats,
inhalation-induced lesions were dose-dependent and included
massive haemorrhages and oedema of the lungs. In acute
toxicity studies the most susceptible species is the mouse.
2.1.5 Toxicity, repeated doses:
Oral: Male and female rats were gavaged for 13 weeks with 0, 1.0,
2.5 or 10.0 (mg/kg b.w.)/day in PEG 200. Behaviourial,
morphological and biochemical changes in the treatment groups
were transitory in the early stage of treatment at the 1.0 mg
dose level and over. There were no consistent treatment-related
clinical signs of toxicity, behaviour changes, or changes in
gross and microscopic anatomy at 13 weeks of treatment.
Autopsies performed on males after a four-week recovery period
revealed treatment-related increased thyroid weights which were
not dose-dependent. The marginal no effect level was 1.0
Male and female beagle dogs were daily dosed with deltamethrin
(in PEG 200) in gelatin capsules at doses of 0.1, 1.0, 2.5 or 10
mg/kg/b.w. for 13 weeks; two dogs were observed for an additional
two-week observation period. All treated animals showed some
treatment-related ill-effects which were not dose-dependent
(pupil dilation, changes in EEG, reduced food and water
consumption, reduced weight gain, body tremors and uncoordinated
motor functions). Vomiting and diarrhoea were dose-related. A
clear no-adverse-effect level was not established.
Dermal: Male and female albino guinea-pigs were dermally dosed at
0.5 g/animal three times a week for 24 days. The treatment
interval was 48 hours with an occlusive patch. There was no
evidence of sensitization when the animals were challenged at day
Cumulation of compound: The slow clearance rate of thiocyanate
suggests a potential for bioaccumulation; however, the signs of
poisoning in repeated doses are not respiratory. Adipose tissue
shows a marginal tendency toward bioaccumulation of the
Cumulation of effect: No information available.
2.1.6 Dietary studies
Short-term: No information available.
Long-term: No clear compound-related ill-effects were observed in
a two-year study of rats fed deltamethrin at dosage levels of 0,
2, 20 or 50 mg/kg (diet). The level causing no toxicological
effect was determined to be 50 mg/kg (diet) or (2.1 mg/kg
b. w.)/day. (See also the neurotoxicity section under 2.1.7.)
Male and female Charles River CD-1 mice were fed deltamethrin at
dosage levels 0, 1, 5, 25 or 100 mg/kg diet. There were no
consistent treatment-related ill-effects observed at any dosage
level. The no-adverse-effect level was determined to be 100
mg/kg (diet) or (12 mg/kg b.w.)/day.
Deltamethrin in corn oil was administered to dogs of both sexes
at dosage levels of 1, 10 or 40 mg/kg (diet) for two years. No
compound-related ill-effects were observed at the highest dose
level used. The level causing no toxicological effect was
concluded to be 40 mg/kg (diet), the equivalent of (1.0 mg,/kg
b.w.)/day.1 (See also the neurotoxicity section under 2.1.7.)
1 Data provided by the manufacturer.
2.1.7 Supplementary studies of toxicity
Carcinogenicity: There was no evidence in the rat, mouse or dog
long-term diet studies that deltamethrin caused an increased
tumour incidence. This finding, supported by microbial,
mammalian cell and in vivo mammalian mutagenicity studies
suggests that deltamethrin has no carcinogenic potential.
Teratogenicity: No evidence of teratogenic activity was observed
in mice, rats or rabbits even at doses sufficient to produce
clinical signs of toxicity in the pregnant dams. A significant
dose-related increase in supernumerary rib occurrence in foetal
mice was attributed to maternal stress rather than to compound
Reproduction: Deltamethrin was slightly embryotoxic in a three
generation rat study but did not adversely affect reproduction.
It did induce significant maternal and perinatal pup weight
losses which were reversed upon cessation of treatment and
Mutagenicity: Deltamethrin was not genetically active in
microbial growth inhibition assays with E. coli, in an Ames test
with S. typhimurium, or in a DNA recombinant assay with S.
cerevisiae. In a mammalian cell test, using hamster ovary
cells, activated deltamethrin did not induce an increased
incidence of chromosomal or chromatid aberrations. In gavaged
male and female rats deltamethrin did not increase the incidence
of chromosomal aberrations in bone marrow cells or micronuclei of
Neurotoxicity: Sublethal doses of deltamethrin-induced reversible
sequelae - see section 2.1.4. These effects were partially
antagonized by atropine and mephenesin but not by diazepam and
related compounds, confirming the CNS as the site of action and
discounting any single neurotransmitter involvement.
Metabolism: A progressive increase in blood glucose and an
increased utilization of glucose by the cerebellum, colliculi and
hypothalamus follows deltamethrin administration. Increased
cerebellum glucose utilization reflects an increased neuronal
activity which is correlated with deltamethrin-induced increases
in cyclic GMP.
Cardiovascular: Deltamethrin administered intravenously first
induced a reversible and rapid fall in blood pressure, and severe
bradycardia in anaesthetized dogs. These effects were rapidly
reversed by a delayed adrenergic response which elevated the
arterial pulse pressure. Bivagotomy and atropine pretreatment
abolished the cholinergic effects and exacerbated the adrenergic
hypertensive effects. At 3 mg/kg b.w. (i.v.), deltamethrin
induced changes in the ECG which suggested a tendency to provoke
an atrioventricular block, and caused a deviation in the cardiac
electrical axis toward the left side.
Primary irritation and sensitization: There was no evidence of
primary skin irritation in rabbits at 0.5 g/animal nor skin
sensitization in guinea-pigs at 0.5 g/animal. Transitory, mild
ocular irritation was produced in rabbits given 0.1 g/animal,
with and without immediate rinsing.
2.1.8 Modification of toxicity: Substances which suppress or inhibit
liver microsomal oxidase and esterase enzyme systems will
increase the toxicity of deltamethrin, especially in mammals.
After repeated daily doses rats became more tolerant to
2.2 TOXICOLOGY - MAN
2.2.1 Absorption - Deltamethrin is primarily absorbed from the
gastrointestinal tract. It is also readily absorbed by
inhalation and to a lesser extent through the intact skin.
2.2.2 Dangerous doses
Single: No information available.
Repeated: No information available.
2.2.3 Observations on occupationally exposed workers - In a WHO Stage
V deltamethrin (w.d.p.) trial of two days duration the
personnel did not complain of adverse effects and clinical
examinations of the workers did not reveal any signs of
toxicity. in extended Stage V trials of several weeks duration
the workers complained of itching or burning sensations about
the face, eyes and upper torso lasting for several hours after
the cessation of spraying. After exposure studies had
been carried out, this was considered to be a local effect.
2.2.4 Observations of the general population - Inhabitants of the
locations of the WHO Stage V trials did not complain of any
2.2.5 Observations of volunteers - No information available.
2.2.6 Mishaps - No information available.
2.3 TOXICITY TO NON-MAMMALIAN SPECIES
2.3.1 Fish - Deltamethrin was observed to be very toxic to fish under
laboratory conditions. However, in static pond studies several
species of fish have survived larvicidal levels and have
2.3.2 Birds - Deltamethrin is of low toxicity to birds.
Chicken (F) +2500 mg/kg b.w.
Ducks +4000 mg/kg b.w.
Grey partridge (M, F) +1800 mg/kg b.w.
Red partridge (M, F) +3000 mg/kg b.w.
2.3.3 Beneficial insects - The moderately high toxicity is offset by
low concentrations in spray formulations and the repellent
effect on terrestrial and flying insects.
2.3.4 Other organisms - Lobster and other aquatic macroinvertebrates
are highly susceptible to the toxic effects of deltamethrin,
especially if periodic flushing action does not occur.
3. FOR REGULATORY AUTHORITIES - RECOMMENDATIONS ON REGULATION OF
3.1 RECOMMENDED RESTRICTIONS ON AVAILABILITY - (For definition of
categories see introduction). All current liquid formulations
over 20%: category 4. All other formulations: category 5.
3.2 TRANSPORT AND STORAGE
Formulations in category 4 - Should be transported in clearly
labelled, rigid and leak-proof containers out of reach of
children, away from food and drink. Storage should be under
lock and key and secure from access by children and other
unauthorized persons. Avoid contact with metals other than
aluminium and tin.
Formulations in category 5 - Should be transported and stored in
clearly labelled, leak-proof containers out of reach of children,
away from food and drink. Avoid contact with metals other than
aluminium and tin.
Fomulations in category 4 - Protective clothing should be used by
all handling the compound. Adequate washing facilities should be
available at all times during handling and they should be close to
the site of handling. Eating, drinking and smoking should be
prohibited during handling and before washing of hands and face
after handling the compound.
Formulations in category 5 - No facilities other than those needed
for the handling of any chemical are required.
3.4 DISPOSAL AND/OR DECONTAMINATION OF CONTAINERS
All formulations - Containers may be decontaminated (for method
see paragraph 4.3 of Part 4). Decontaminated containers should
not be used for food and drink. Containers that are not
decontaminated should be burned or should be crushed and buried
below topsoil. Care must be taken to avoid subsequent
contamination of water sources.
3.5 SELECTION, TRAINING AND MEDICAL SUPERVISION OF WORKERS
Formulations in category 4 - Workers suffering from asthma,
allergies and other respiratory disorders and cardiovascular
disorders should be excluded from contact. Persons under
medication with neuroactive drugs should avoid contact. Special
account should be taken of the worker's ability to comprehend and
follow instructions. Training of workers in techniques to avoid
contact is essential. Pre-employment and periodic medical
examinations are not required.
Formulations in category 5 - Warning of workers to minimize
contact is essential.
3.6 ADDITIONAL REGULATIONS RECOMMENDED IF DISTRIBUTED BY AIRCRAFT
All formulations - Pilots and loaders should have special training
to application methods and recognition of early warning symptoms
of poisoning and they must wear a suitable respirator. Flagmen
should wear overalls and a broad brimmed hat and be well away from
the dropping zone.
Formulations in category 4 - Minimum cautionary statement -
"WARNING - POISON" (skull and cross-bones insignia). Deltamethrin
is a synthetic pyrethroid pesticide, a neurotoxin, and it may be
poisonous if swallowed or inhaled as a dust or mist. It may be
irritating to the skin and eyes. Avoid skin contact, wear
protective clothing and impermeable gloves and eye protection when
handling the material. Wash thoroughly with soap and water after
using the product. Keep the material out of reach of children and
well away from foodstuffs, animal feed and food containers. If
poisoning occurs, call a physician. There are no specific
antidotes. Artificial resuscitation may be required.
Formulations in category 5 - Minimum cautionary statement - This
formulation contains deltamethrin; it is poisonous if swallowed.
Keep the material out of reach of children and well away from
foodstuffs, animal feed and food containers.
3.8 RESIDUES IN FOOD - Maximum residue limits for deltamethrin have
been recommended by the Joint FAO/WHO Meeting on Pesticide
4. PREVENTION OF POISONING IN MAN AND EMERGENCY AID
4.1 PRECAUTIONS IN USE
4.1.1 General - Deltamethrin is a synthetic pyrethroid, a neurotoxic
agent of moderate toxicity to mammals. It is readily absorbed
from the gastrointestinal tract and by inhalation of dust and
spray mist. Absorption through the intact skin has not been
demonstrated in laboratory animals. The health hazard is
considerably diminished by the low concentrations of the active
ingredient in all formulations.
4.1.2 Manufacture and formulation
T.L.V.: No information. Closed systems and forced ventilation
may be required to reduce, as much as possible, the exposure of
workers to the chemical.
4.1.3 Mixers and applicators - When opening a container and when
mixing, protective impermeable boots, clean overalls, impermeable
gloves, eye protection and a respirator should be worn. Mixing,
if not mechanical, should always be carried out with a paddle of
appropriate length. Avoid contact with mouth and eyes. Before
eating, drinking or smoking, hands and other exposed skin should
be thoroughly washed with alkaline soap.
4.1.4 Other associated workers (including flagmen in aerial
operations) - Persons exposed to deltamethrin and associated with
its application should observe the precautions described above in
4.1.5 Other populations likely to be affected - With good practice,
subject to section 4.2 below, other populations should not be
exposed to hazardous amounts of deltamethrin.
4.2 ENTRY OF PERSONS INTO TREATED AREAS - Though deltamethrin is
relatively persistent, low application rates ensure low residue
levels. Unprotected persons may enter treated areas immediately
after spraying without being exposed to hazardous amounts of
4.3 SAFE DISPOSAL OF CONTAINERS AND SPILLAGES - Residues in containers
should be emptied in a diluted form into a deep pit taking care to
avoid ground waters. The empty container may be decontaminated by
rinsing two or three times with water and detergent and scrubbing
the sides. The hands should be protected during this work.
Decontaminated containers should not be used for food and drink.
4.4 EMERGENCY AID
4.4.1 Early symptoms of poisoning - Based on animal studies, these may
include excessive salivation, nausea and vomiting, shortness of
breath and laboured breathing, coarse tremors, hypersensitivity
to external stimuli and general weakness, a burning or itching
sensation of the face and/or shoulders, hypotension and slow
heart rate. These may be followed by hypertension, increased
heart rate and convulsive muscle contractions.
4.4.2 Treatment before person is seen by a physician, if these symptoms
appear following exposure - The person should stop work
immediately, remove contaminated clothing and clean the affected
skin area. First, soak up any liquid remaining on the skin with
readily disposable material (e. g., talcum powder or absorbent
cloth or paper), wash the affected area with warm water and
alkaline soap. For eye contamination, wash with copious amounts
of 4% sodium bicarbonate or water. Avoid exposing affected skin
or eyes to bright light. If the material was swallowed and signs
of toxicity are severe, induce vomiting if person is conscious
and aspiration of vomit can be avoided. In the event of
collapse, apply artificial respiration. Keep in mind that if
mouth-to-mouth resuscitation is used, vomit may contain toxic
amounts of deltamethrin. Keep the person calm and comfortable
and obtain medical assistance as soon as possible.
5. FOR MEDICAL AND LABORATORY PERSONNEL
5.1 MEDICAL DIAGNOSIS AND TREATMENT OF POISONING
5.1.1 General information - Deltamethrin is a synthetic pyrethroid, a
neurotoxic agent of moderate toxicity to mammals. It is readily
absorbed from the gastrointestinal tract and by inhalation of
dust and spray mist. Systemic poisoning and absorption through
the intact skin have not been observed following dermal
application of the compound. It undergoes rapid detoxification
by metabolism, and, except for thiocyanate, the metabolic
products are rapidly excreted.
5.1.2 Signs and symptoms - Little information is available on the acute
toxic effects of deltamethrin in humans. Based upon animal
studies, high doses may be expected to cause repetitive activity
in motor and sensory nerves. Early signs of poisoning may be
salivation, irritability, tremors and ataxia. Hypotension and
bradycardia have been observed in dogs exposed to high doses of
deltamethrin. These effects were rapid in onset and of brief
duration and frequently followed by adrenergic responses
(increased pulse pressure and tachycardia). In man, facial
paraesthesia is a useful indication of exposure.
5.1.3 Laboratory - There are no established, practical methods for
determining deltamethrin in body fluids. Urinary levels of
bromide, cyanide and 3-phenoxybenzyl degradation products may be
a useful parameter in cases of severe intoxication.
Electrophysiological monitoring of sensory nerve action
potentials and central nervous and cardiac activities (EEG and
ECG) may be useful in diagnosis and assessment of therapy.
5.1.4 Treatment - There are no specific antidotes; treatment must be
symptomatic. Keep the patient warm and calm. In cases of severe
intoxication, therapy should include a sedative and
anticonvulsant (e.g., barbiturates, diazepam, paraldehyde, etc.).
The use of antispasmodic drugs is of limited value; mephenesin
and atropine have been found to effectively alleviate the
symptoms of deltamethrin poisoning in laboratory animals. If a
large quantity of deltamethrin has been swallowed, unless the
patient is unconscious or vomiting, gastric lavage should be
performed using a 5% sodium bicarbonate solution, followed with
powdered activated charcoal. For skin contact, soak up any
liquid remaining on skin with readily disposable absorbent
material, then wash the affected area with warm water and
alkaline soap. If skin irritation occurs treat with a soothing
skin cream and avoid exposure to direct light. For eye
contamination, wash the eye with 4% sodium bicarbonate or any
other non-irritating, alkaline aqueous solution.
5.1.5 Prognosis - There have been no reports or overt symptoms
resulting from poisoning of man by deltamethrin; the
prognosis therefore is not known. However, by analogy with
laboratory animals, it may be assumed that if the acute toxic
effect is survived the chances of complete recovery are good.
5.1.6 References of previously reported cases - No published
5.2 SURVEILLANCE TESTS - None.
5.3 LABORATORY METHODS - References only are given.
5.3.1 Detection and assay of compound and residues - Krasnykh, A. A. &
Pavlova, L. G. (1980) Gig. Sanit., 45(5), 62-63; Mestres, R. et
al. (1978) Trav. Soc. Pharm. Montpellier, 38(2) , 183-191;
Mestres, R. et al. (1979) Trav. Soc. Pharm. Montpellier, 39(4),
329-336; Mourot, D. et al. (1979) J. Chrom., 173, 412-414