CYPERMETHRIN
Human Health Effects:
Human Toxicity Excerpts:
One notable form of toxicity associated with synthetic pyrethroids has been a cutaneous
paresthesia observed in workers spraying esters containing alpha-cyano substituent
(deltamethrin, cypermethrin, fenvalerate). The
paresthesia developed several hours following exposure, being described as a stinging or
burning sensation on the skin which, in some cases, progressed to a tingling &
numbness, the effects lasting some 12 to 18 hr.
45 cases of moderate intoxication including oral ingestion of up to 140 mg/kg, all of
which survived after gastric lavage.
Pesticide workers exposed to cypermethrin
& other pyrethroids developed a transient abnormal facial sensation similar to that
described for fenvalerate after accidental direct contact with solutions or after use of
fine powder formulations. The facial sensation was not associated with any abnormal
neurological or electrophysiological changes. Similar sensations were produced by
experimental dermal application of cypermethrin
to the ear lobe of human volunteers at 130 ug/sq cm.
Cypermethrin was the first pyrethroid to be
reported as having caused a human fatality. In Greece a man died 3 hr after eating a meal
cooked in a 10% cypermethrin concentrate used in
error instead of oil. Nausea, prolonged vomiting with colicky pain, tenesmus, &
diarrhea began within a few minutes after eating the meal & progressed to convulsions,
unconsciousness, & coma. Death due to respiratory failure occurred despite intensive
emergency treatment. Other family members developed less severe symptoms & survived
after intensive hospital treatment. Tissue residues of cypermethrin
were below detection levels, but 0.7 gm remained in the stomach.
Clinical manifestations of 573 cases of acute pyrethroid poisoning are reviewed. The
cases occurred in 14 provinces in China & involved 325 patients exposed to
deltamethrin, 196 to fenvalerte, 45 to cypermethrin,
& 7 to other pyrethroid cmpds. Of the 573 cases, 229 were of occupational origin
resulting from inappropriate handling of the chemicals such as spraying with higher concns
than allowed, sustaining longer exposure durations than recommended, spraying against the
wind, clearing stoppage of sprays by mouth & hands, spraying closer than every row of
crops, or not wearing personal protective equipment. Those occupationally exposed patients
experienced initial burning or itching sensations of the face within a few min of exposure
or dizziness developing at 4 to 6 hr after exposure. Half of those occupationally exposed
experienced abnormal facial sensations such as burning, itching, or tingling sensation
which were exacerbated by sweating & washing with warm water. These symptoms
disappeared several hours to 1 day after exposure. Systemic symptoms included dizziness,
60.6%; headache, 44.5%; nausea, 59.7%; anorexia, 45%; & fatigue, 26%. Vomiting
occurred in 16% of those who were occupationally exposed. Other symptoms included chest
tightness, 13.1%; parasthesia, 11.89%; palpitation, 13.1%; blurred vision, 7%; & incr
sweating, 6.7%. Coarse muscular fasciculations developed in large muscles of extremities
in the more serious cases. In those suffering from convulsions, seizures could arise up to
30 times a day for the first wk. Blood tests revealed leukocytosis in 15%. Treatment
consisted of symptomatic & supportive therapy including gastric lavage. Most recovered
in 6 days.
Cypermethrin poisoning was reported in 5
office workers at an accounting office of approx 1000 sq ft in size that was treated for
insect control. Treatment inside the building was accomplished by vertical drilling &
injecting the chemical under the slab. Exterior walls were drilled from outside the
foundation; cypermethrin was then injected in
these holes. The employees entered the building 2 days after treatment & experienced
dizziness, headaches, nausea, & vertigo immediately. Turning on the air conditioning
system worsened their symptoms. After 5 min they left the building; however, they
repeatedly reentered the building for short periods. Six days later fans were used to draw
off the vapors. Airborne concn were below the limit of analysis by 13 days after treatment
whereupon the employees reentered the building, only to suffer a return of their symptoms
which again worsened when the air conditioning unit was turned on. Six weeks later air
sampling indicated concn less than the detection limit. Wipe samples showed the greatest
concn, 4240.0 ug/sq ft to be on the hallway carpet between two applicator holes. Several
of the holes drilled by the applicator were drilled into the transverse ducts running
underground & connecting with the main duct. Cypermethrin
had been directly injected into the ventilation ducts. The exact exposure levels to which
the workers had been subjected when they turned on the air conditioning unit was not
known.
Contact allergy from pyrethroids ... has not been observed. /Pyrethroids/
The allergenic properties of pyrethroids /with early pyrethrum preparations/ are marked
in comparison with other pesticides. Many cases of contact dermatitis and respiratory
allergy have been reported. Persons sensitive to ragweed pollen are particularly prone to
such reactions. Preparations containing synthetic pyrethroids are less likely to cause
allergic reactions than are the preparations made from pyrethrum powder. /Pyrethroids/
Seizures have been reported in severe cases of pyrethroid intoxication. ... Seizures
are more common with exposure to the more toxic
Some pyrethroid (eg, deltamethrin, fenvalerate, cyhalothrin, lambda-cyhalothrin,
flucythrinate, & cypermethrin) may cause a
transient itching &/or burning sensation in exposed human skin. /Synthetic
pyrethroids/
The clinical manifestations of inhalation exposure to pyrethrins can be local or
systemic. Localized reactors confined to the upper respiratory tract include rhinitis,
sneezing, scratchy throat, oral mucosal edema, & even laryngeal mucosal edema.
Localized reaction of the lower respiratory tract include cough, shortness of breath,
wheezing, & chest pain. An asthmalike reaction occurs with acute exposures in
sensitized patients. Hypersensitivity pneumonitis characterized by chest pain, cough,
dyspnea, & bronchospasm may occur in an individual chronically exposed. /Pyrethrum
& synthetic pyrethroids/
The low toxicity of pyrethroids in mammals is due largely to their rapid
biotransformation by ester hydrolysis and/or hydroxylation. /Pyrethroids/
The differences in the extent of paraesthesia induced by a number of pyrethroids /was
studied/. Field strength formulated cypermthein (0.13 mg/sq cm) was applied (0.05 ml) to a
4 sq cm area of the earlobe of volunteers on 5 occasions. Distilled water was applied to
the opposite earlobe. Participant evaluation after each application continued for 48 hr
& involved description of the cutaneous sensations. Each participant was treated after
each application with one of the other pyrethroids. Cypermethrin
(as the other pyrethroids) induced sensation. The paraesthesia developed with a latency
period of approx 30 min, peaked by 8 hr & deteriorated as early as 24 hr. D1-alpha
tocopheryl acetate markedly inhibited the occurrence of the paraesthesia.
A biological monitoring & health surveillance study on 11 workers spraying
organophosphate carbamate & pyrethroid pesticides in greenhouses during the whole year
in comparison with 10 control persons. During the work, protective clothing & masks
were worn before & after a regular spraying period with pyrethroids (including cypermethrin). Extensive medical exams, such as
urinalysis, hematology, immunoglobulin levels, whole blood cholinesterase activity,
serum-gamma-glutamyltransferase activity, chromosome analysis & electro cardiography
were performed over a period of 3 months. The amount of cypermethrin
in the blood was just at the limit of detection. No health injuries or other significant
changes in the parameters studied were found.
A slight skin irritant, a mild eye irritant.
One notable form of toxicity associated with synthetic pyrethroids has been a cutaneous
paresthesia observed in workers spraying esters containing alpha-cyano substituent
(deltamethrin, cypermethrin, fenvalerate). The
paresthesia developed several hours following exposure, being described as a stinging or
burning sensation on the skin which, in some cases, progressed to a tingling and numbness,
the effects lasting some 12 to 18 hr.
In the present study 61 male pesticide applicators who worked in cotton fields &
regularly sprayed pesticides such as DDT, BHC, endosulfan, malathion, methyl parathion,
phosphamidon, dimethoate, monocrotophos, quinalophos fenvelrate, & cypermethrin
were analyzed for sister chromatid exchanges, mitotic index, & cell cycle kinetics in
peripheral lymphocytes. Subjects who handled pesticides were non-smokers & teetotalers
& the data were compared with the matched control group. Statistical analysis revealed
that the frequency of sister chromatid exchanges was significantly higher among the
pesticide applicators at all the durations of exposure when compared to controls. Subjects
exposed to pesticides also showed cell cycle delay & decr in mitotic index when
compared to the control group.
Skin, Eye and Respiratory Irritations:
Immediately irritating to the eye. /Pyrethrins/
The chief effect from exposure ... is skin rash particularly on moist areas of the
skin. ... May irritate the eyes.
Medical Surveillance:
Initial medical screening: Employees should be screened for history of certain medical
conditions ... which might place the employee at increased risk from /pyrethroid/
exposure. Chronic respiratory disease: In persons with chronic respiratory disease,
especially asthma, the inhalation of /pyrethroids/ might cause exacerbation of symptoms
due to its sensitizing properities. Skin disease: /Pyrethroids/ can cause dermatitis which
may be allergic in nature. Persons with pre-existing skin disorders may be more
susceptible to the effects of this agent. Any employee developing the above-listed
conditions should be referred for further medical examination. /Pyrethrum/
Probable Routes of Human Exposure:
Occupational exposure to cypermethrin may
occur through inhalation and dermal contact with this compound at workplaces where cypermethrin is produced or used(SRC). Dermal exposure
to workers applying spray applications of cypermethrin
in tea plantations was measured(1); exposure rates (in ug/100 cu cm) were as follows(1):
face: 0.06-0.72, chest: 0.11-2.06, abdomen: 0.09-2.68, thigh: 0.41-17.3, ankle:
0.15-32.6(1); total dermal exposure based upon spray amounts was 186-1140 mg/kg for
nonhand areas and 46.1 mg/kg for hands only(1). Agricultural airplane pilots and workers
involved in mixing and loading aerial sprayers were monitored for dermal exposure to cypermethrin(2); potential (protected and exposed
skin) exposure was 1.07 (0.26 to 2.65) mg/8 hr for pilots and 10.5 (2.50 to 23.1) mg/8 hr
for mixer-loaders(2); the actual exposure to pilots was predominantly of the hands,
whereas that of the mixer-loaders was more uniform since their hands were protected by
gloves(2). Monitoring data indicate that the general population may be exposed to cypermethrin via inhalation of ambient air and
ingestion of food containing cypermethrin(SRC).
Emergency Medical Treatment:
Emergency Medical Treatment:
| EMT Copyright Disclaimer: |
| Portions of the POISINDEX(R) database are provided here for general
reference. THE COMPLETE POISINDEX(R) DATABASE, AVAILABLE FROM MICROMEDEX, SHOULD BE
CONSULTED FOR ASSISTANCE IN THE DIAGNOSIS OR TREATMENT OF SPECIFIC CASES. Copyright
1974-1998 Micromedex, Inc. Denver, Colorado. All Rights Reserved. Any duplication,
replication or redistribution of all or part of the POISINDEX(R) database is a violation
of Micromedex' copyrights and is strictly prohibited. The following Overview, *** PYRETHRINS ***, is relevant for this HSDB record chemical. |
| Life Support: |
o This overview assumes that basic life support measures
have been instituted.
|
| Clinical Effects: |
SUMMARY OF EXPOSURE
0.2.1.1 ACUTE EXPOSURE
o The mammalian toxicity of natural pyrethrins is
generally low. Very young children are perhaps more
susceptible to poisoning because they may not hydrolyze
the pyrethrum esters efficiently. In humans, allergic
reactions are the main toxic manifestations of
pyrethrin exposure.
1. Pyrethrum and the pyrethrins produce typical type I
motor symptoms in mammals. Severe type I poisoning
may include the following signs in humans:
Severe fine tremor
Marked reflex hyperexcitability
Sympathetic activation
Paresthesia (dermal exposure)
o DERMAL - These compounds are not primary irritants.
The chief effect, however, from exposure is dermatitis.
The usual lesion is a mild erythematous dermatitis with
vesicles, papules in moist areas, and intense pruritus;
a bulbous dermatitis may also occur. Pyrethrins can
cause allergic dermatitis and systemic allergic
reactions.
o INHALATION is the major route of exposure, with airway
irritation as the primary toxic effect. Following
inhalation, a stuffy, runny nose and scratchy throat
are common. Hypersensitivity reactions including
wheezing, sneezing, shortness of breath and
bronchospasm may be noted.
o OCULAR - Eye exposures may result in mild to severe
corneal damage that generally resolves with
conservative care.
o Piperonyl butoxide and other compounds are often added
to pyrethrin insecticides as synergists and may
contribute to toxicity.
o Synthetic pyrethroids, which are related to pyrethrins,
are covered in a separate management.
HEENT
0.2.4.1 ACUTE EXPOSURE
o A stuffy, runny nose and scratchy throat following
inhalational exposure may be noted.
o Eye exposures may result in mild to severe corneal
damage, decreased visual acuity and periorbital edema.
CARDIOVASCULAR
0.2.5.1 ACUTE EXPOSURE
o Hypotension and tachycardia, associated with
anaphylaxis, may occur.
RESPIRATORY
0.2.6.1 ACUTE EXPOSURE
o Hypersensitivity reactions characterized by
pneumonitis, cough, dyspnea, wheezing, chest pain, and
bronchospasm may occur. Rare cases of respiratory
failure and cardiopulmonary arrest have been reported.
NEUROLOGIC
0.2.7.1 ACUTE EXPOSURE
o Paresthesias, headaches, and dizziness are common.
Massive exposure may result in hyperexcitability and
seizures, but this is rare.
GASTROINTESTINAL
0.2.8.1 ACUTE EXPOSURE
o Nausea, vomiting and abdominal pain commonly occur and
develop within 10 to 60 minutes following ingestion.
DERMATOLOGIC
0.2.14.1 ACUTE EXPOSURE
o Irritant and contact dermatitis may develop. Erythema
which mimics sunburn has also been noted after
prolonged repeated exposure.
ENDOCRINE
0.2.16.1 ACUTE EXPOSURE
o Type I motor symptoms following severe poisoning may
result in sympathetic activation.
IMMUNOLOGIC
0.2.19.1 ACUTE EXPOSURE
o Sudden bronchospasm, swelling of oral and laryngeal
mucous membranes, and anaphylactoid reactions have been
reported after pyrethrum inhalation. Hypersensitivity
pneumonitis characterized by cough, shortness of
breath, chest pain, and bronchospasm may be noted.
GENOTOXICITY
o Pyrethrum is not mutagenic in bacterial reversion tests
(Ray, 1991).
|
| Laboratory: |
o Pyrethrin plasma levels are not clinically useful or
readily available.
o Monitor for allergic responses such as asthma or contact
dermatitis.
|
| Treatment Overview: |
ORAL EXPOSURE
o There is no specific antidote for pyrethrin poisoning.
Treatment is symptomatic and supportive and includes
monitoring for the development of hypersensitivity
reactions with respiratory distress. Provide adequate
airway management when needed. Gastric decontamination
is usually not required unless the pyrethrin product is
combined with a hydrocarbon.
o ALLERGIC REACTION: MILD: antihistamines with or
without epinephrine. SEVERE: oxygen, aggressive
airway management, antihistamines, epinephrine (ADULT:
0.3 to 0.5 mL of a 1:1000 solution subcutaneously;
CHILD: 0.01 mL/kg; may repeat in 20 to 30 min),
corticosteroids, ECG monitoring, and IV fluids.
INHALATION EXPOSURE
o INHALATION: Move patient to fresh air. Monitor for
respiratory distress. If cough or difficulty breathing
develops, evaluate for respiratory tract irritation,
bronchitis, or pneumonitis. Administer oxygen and
assist ventilation as required. Treat bronchospasm with
beta2 agonist and corticosteroid aerosols.
EYE EXPOSURE
o DECONTAMINATION: Irrigate exposed eyes with copious
amounts of tepid water for at least 15 minutes. If
irritation, pain, swelling, lacrimation, or photophobia
persist, the patient should be seen in a health care
facility.
DERMAL EXPOSURE
o DECONTAMINATION: Remove contaminated clothing and wash
exposed area thoroughly with soap and water. A
physician may need to examine the area if irritation or
pain persists.
o Vitamin E topical application is highly effective in
relieving paresthesias.
|
| Range of Toxicity: |
o The minimal lethal dose of pyrethrum is not established,
but is probably in the range of 10 to 100 grams.
o Hypersensitivity reactions may be noted, especially
following a chronic dermal or inhalation exposure.
Patients with underlying asthma may be predisposed to
severe bronchospastic reactions after exposure.
|
Antidote and Emergency Treatment:
Treatment is supportive, and most casual exposures require only decontamination.
Topical vitamin E may ameliorate the parethesias that accompany contact with synthetic
pyrethroids containing an alpha-cyano group (eg fenvalerate, cypermethrin,
flucythrinate).
No specific antidote known. Symptomatic treatment. If ingested, do not induce vomiting
or give liquids.
The additives (e.g. petroleum distillate), when present, represent a greater toxic
threat to the patient than the active ingredient itself. ... Emesis should not be induced
when petroleum distillate additives are present unless the product ingested is estimated
to contain a near lethal dose (1 g/kg) of pyrethrum or pyrethrins. The alert person with
an intact gag reflex & a sublethal pyrethrum ingestion without other toxic
constituents may have emesis induced by ipecac, followed by a saline cathartic &
slurry of activated charcoal. ... Pulmonary & allergic sequelae are treated
symptomatically with airway maintenance, oxygen, & ventilatory assistance as required.
Standard drugs and management protocols may be used for treatment of bronchospasm &
anaphylaxis. Seizures are treated with diazepam. /Pyrethrum and synthetic pyrethroids/
Skin decontamination. Wash skin promptly with soap and water ... . If irritant or
paresthetic effects occur, obtain treatment by a physician. Because volatilization of
pyrethroids apparently accounts for paresthesia affecting the face, strenuous measures
should be taken (ventilation, protective face mask and hood) to avoid vapor contact with
the face and eyes. Vitamin E oil preparations (dL-alpha tocopheryl acetate) are uniquely
effective in preventing and stopping the paresthetic reaction. They are safe for
application to the skin under field conditions. Corn oil is somewhat effective, but
possible side effects with continuing use make it less suitable. Vaseline is less
effective than corn oil. Zinc oxide actually worsens the reaction. /Pyrethroids/
Eye contamination. Some pyrethroid compounds can be very corrosive to the eyes.
Extraordinary measures should be taken to avoid eye contamination. the eye should be
treated immediately by prolonged flushing of the eye with copious amounts of clean water
or saline. If irritation persists, obtain professional ophthalmologic care. /Pyrethroids/
Gastrointestinal decontamination. If large amounts of pyrethroids, especially the
cyano-pyrethroids, have been ingested and the patient is seen soon after exposure,
consider gastrointestinal decontamination ... . Based on observations in laboratory
animals and humans, large ingestions of allethrin, cismethrin, fluvalinate, fenvalerate,
or deltamethrin would be the most likely to generate neurotoxic manifestations. If only
small amounts of pyrethroid have been ingested, or if treatment has been delayed, oral
administration of activated charcoal and cathartic probably represents optimal management.
Do not give cathartic if patient has diarrhea or on ileus. /Pyrethroids/
Other treatments. Several drugs are effective in relieving the pyrethroid neurotoxic
manifestations observed in deliberately poisoned laboratory animals, but none has been
tested in human poisonings. Therefore, neither efficacy nor safety under these
circumstances is known. Furthermore, moderate neurotoxic symptoms and signs are likely to
resolve spontaneously if they do occur. /Pyrethroids/
Animal Toxicity Studies:
Non-Human Toxicity Excerpts:
It is relatively toxic to fish and bees but is of low toxicity to birds.
In 2 yr feeding trials no compound related toxicological effects were observed in rats
receiving 100 mg/kg diet and dogs 300 mg/kg diet.
These compounds /including fenvalerate and cypermethrin/
are generally very toxic to crustaceans and fish in laboratory bioassays.
Groups of beagle dogs, 6/sex, were dosed with 0, 1, 5, 15 mg/kg/day of cypermethrin in corn oil for 52 wk. The test material
was admin by gelatin capsule & the amount admin was based on the current weight of the
dog. Males & females in the high dose group, 15 mg/kg/day, displayed signs of nervous
system stimulation in the form of body tremors, abnormalities & in-coordination,
disorientation, & hypersensitivity to noise. At all doses, the dogs showed incr in
vomiting during the first wk & the passing of liquid feces throughout the study. The
incr incidence of liquid feces was 10-fold for groups dosed with 5 mg/kg/day & 30 fold
for groups dosed with 15 mg/kg/day. An NOEL for systemic effects is 1 mg/kg/day based on
the incr incidence of liquid feces observed at 5 mg/kg/day.
The type II pyrethroids /including cypermethrin/
produce a complex poisoning syndrome & act on a wide range of tissues. They give
sodium tail currents with relatively long time constants, which may be the reason for
their ability to act on the whole range of excitable tissues. Type II poisoning in rats
involves progressive development of nosing & exaggerated jaw opening similar to that
seen in response to an irritant placed on the tongue, salivation which may be profuse,
incr extensor tone in the hind limbs causing a rolling gait, incoordination progressing to
a very coarse tremor, choreoform movements of the limbs & tail often precipitated by
sensory stimuli, generalized choreoathetosis (writhing spasms), tonic seizures, apnea,
& death. At lower doses more subtle repetitive behavior is seen. In dogs, similar
symptoms are seen but salivation & upper airway hypersecretion & GI symptoms are
more prominent.
Rats receiving 750 ppm of the potent cis isomer of cypermethrin
in their diet for 5 wk showed gross motor symptoms but no fatalities, whereas 1500 ppm
caused deaths from 4 to 17 days. Fatalities were associated with axonal swelling &
demyelination in the sciatic nerve. This peripheral nerve damage was not seen in the 750
ppm group in survivors from the higher dose group, or in rats fed a racemic mixture of
1000 ppm for 2 yr.
Dogs were rather less susceptible to cypermethrin,
dietary levels of 1500 ppm for 13 weeks producing motor symptoms but no fatalities. Cypermethrin has been reported to have no teratogenic
or mutagenic activity.
[Hayes WJ, Laws ER, eds; Handbook of Pesticide Toxicology V2 p.594 (1991)] It was
reported that cypermethrin increased the
incidence of polychromatic erythrocytes with micronuclei in mouse bone marrow. This
increase was significant after feeding cypermethrin
at 900 but not 300 ppm in the diet for 7 days and disappeared after a 14 day recovery
period. No deaths were seen at this dosage.
Toxicity tests revealed the Indian catfish, Heteropneustes fossils, is highly sensitive
to cypermethrin, a synthetic pyrethroid. The
LC50 value decr with incr exposure time, revealing a time-dependent action of cypermethrin. Biochemical studies confirmed this,
showing that the effects on carbohydrate metabolites also revealed a time-dependent
response. The propable reasons for the disturbance in the homeostatic mechanisms of
carbohydrate metabolism are discussed.
The genotoxicity of cypermethrin, a synthetic
pyrethroid insecticide, has been studied in vivo in mice. Bone marrow chromosome
aberrations were not dose, time or route dependent, but most of the results differed
significantly from controls except after 6 & 24 hr of treatment using the ip & sc
routes, respectively. In the micronucleus test, the occurrence of polychromatic
erythrocytes with micronuclei incr slightly with dose, but was significantly higher than
controls at all dose levels. Only a marginal difference in the incidence of sperm
abnormalities was noted with the 3 doses of cypermethrin
tested. However all results differed significantly from the respective control values.
In the course of acute & subchronic experiments performed by the admin of 1/2 &
1/40, 1/20, & 1/10 proportions of the oral LD50 value, no significant changes were
found in the general toxicologic tests. The compound known to affect the CNS, however,
induced only a mild enhancement of the central excitation level shown by the EEG
investigations in the doses applied. In the immunotoxicologic studies an early &
dose-dependent suppression was induced as a result of humoral immune response of rabbits
immunized by Salmonella typhi following the admin of cypermethrin.
The cell-mediated immune response was also decr. In rats the immune response determined by
anti-sheep erythrocyte & antiovalbumin titer as well as by autologous rosette
formation of spleen lymphocytes was hindered. The earliest detectable group of symptoms
indicating the effect of a mild cypermethrin
exposure is the appearance of the positivity of the immunotoxicologic tests. On the basis
of the experimental findings the sensitive immunotoxicologic tests have been regarded as
of great importance in the series of toxicologic methods.
The synthetic alpha-cyano-phenoxybenzyl-containing pyrethroid insecticides act on the
CNS of vertebrates & show a species-selective toxicity in the order fish
>amphibians much >mammals >birds. Concn of (14)Ccis-cypermethrin
in the brains of representative members of each of these classes of chordates were
measured at toxic signs (an onset of hyperactivity followed by seizures & loss of
balance/equilibrium) as an indicator of target organ sensitivity. The concn of cis-cypermethrin in brain, associated with toxic signs, in
ug/g (mean + or - SE) as determined by HPLC was 0.08 + or - 0.03 (frog), 0.23 + or - 0.05
(trout), 1.71 + or - (mouse), & 3.94 + or - 0.88 (quail). Trout brain was equally
sensitive to the cis & trans isomers of cypermethrin.
In both mouse & quail, some 90% of the radioactivity in the brain was parent
pyrethroid. Trout & frog, however, afforded only 56 & 32%, respectively, of the
brain (14)C as cypermethrin, with the remaining
radioactivity in both extractable & nonextractable metabolites, including
4'-hydroxy-cis-cypermethrin, which is
potentially neuroactive. Following oral admin, cis-cypermethrin
was readily absorbed & metabolized by quail. Intestinal uptake was far less rapid in
trout & mouse, the unchanged cypermethrin
dispersed in secreted bile, being readily eliminated from the intestines of fish. The
uptake & metabolism of cis-cypermethrin
& the brain sensitivities of these animals to the pyrethroid account for the observed
differences in acute toxicity. /cis-Cypermethrin/
The embryotoxicity & teratogenicity was studied in female rats after admin of cypermethrin. Cypermethrin
(0, 2, 4 & 8 mg/kg) was given orally to rats from day 6 to 15 of their gestation. In
spontaneous delivery groups perturient abnormalities were not observed. The changes of
body weight of animals & other teratological parameters of rats given cypermethrin were not significantly different than the
control. The variations in razor cut sections were very minor. There were incidence of
cerebral hypoplasia & enlargement of renal pelvis but these variations were not
statistically significant. The number of fetuses having skeletal variations were 9 in the
control groups, 10 in the 2 mg/kg group, 9 each in the 4 & 8 mg/kg groups. The list of
skeletal variations included the presence of 14th rib & incomplete calcification. The
% of skeletal variations in each group were not significantly different. The viability
index ranged from 96.34 to 98.76%.
Acute and cumulative toxicity of cypermethrin
was studied in mice, rats & rabbits. The oral LD50 in mice, rats & rabbits of
either sex ranged from 34-1500 mg/kg. The toxicity decr in order mice >rats
>rabbits. There was no sex difference in mice & rats. The toxic effects were
dose-dependent & were characteristic of CNS poisoning. The cumulative toxicity
experiments in mice revealed that the mortality was highest during 1-3 wk of the treatment
& the cumulative effects reached max within 7 wk. The CLD50 (cumulative lethal dose)
at the end of 13 wk was 10.42 mg/kg having a cumulative toxicity factor of 3.27. The
consumption of feed & water was not affected.
Cypermethrin at sublethal concn induced
significant changes in acetylcholinesterase activity & acetylcholine content in the
brain tissue of both juvenile & adult fish. Max inhibition of acetylcholinesterase
activity is noticed at 6 hr & 12 hr after exposure to cypermethrin
in juvenile & adult fish respectively. In contrast, the acetylcholine levels
registered an elevation in both cases. During subsequent periods the rate of recovery in
acetylcholinesterase activity & acetylcholine content is variable in both the groups.
The inhibitory action of synthetic pyrethroids & some chlorinated hydrocarbon
insecticides on the neural calcium-calmodulin-dependent protein phosphatase, calcineurin,
was studied using one radiotracer & two colorimetric methods. It was found that all
insecticidal Type II pyrethroids (cypermethrin,
deltamethrin & fenvalerate) are potent inhibitors of isolated calcineurin from bovine
brain. Their IC50 values were approximately 1X10-9 to 1X10-11 M. By contrast, neither
noninsecticidal chiral isomers of these pyrethroids, neuroactive. Type I pyrethroids nor
neroactive chlorinated hydrocarbon insecticdees showed comparable potencies against this
enzyme. To confirm the action of Type II pyrethroid in situ, isolated intact rat brain
synaptosomes were incubated with (32)P phosphoric acid & subsequently depolarized in
the presence & absence of 0.1 uM deltamethrin. As expected, there was a sharp rise in
protein phosphorylation due to the action of calcineurin. Deltamethrin caused a distinct
delay in the dephosphorylation process. The results clearly indicate that calcineurin is
specifically inhibited by Type II pyrethroids.
Synthetic pyrethroids are neuropoisons acting on the axons in the peripheral & CNS
by interacting with sodium channels in mammals &/or insects. A single dose produces
toxic signs in mammals, such as tremors, hyperexcitability, salivation, choreoathetosis,
& paralysis. ... At near-lethal dose levels, synthetic pyrethroids cause transient
changes in the nervous system, such as axonal swelling &/or breaks & myelin
degeneration in sciatic nerves. They are not considered to cause delayed neurotoxicity of
the kind induced by some organophosphorus compounds. /Synthetic prethroids/
Synthetic pyrethroids have been shown to be toxic for fish, aquatic arthropods, &
honeybees in laboratory tests. But, in practical usage, no serious adverse effects have
been noticed because of the low rates of application & lack of persistence in the
environment. The toxicity of synthetic pyrethroids in birds & domestic animals is low.
/Synthetic pyrethroids/
The Type II /poisoning/ syndrome, also known as the "CS syndrome," is
produced by those esters containing the alpha-cyano substituent & elicits intense
hyperactivity, incoordination, & convulsions in cockroaches, whereas rats display
burrowing behavior, coarse tremors, clonic seizures, sinuous writhing (choreoathetosis),
& profuse salivation without lacrimation; hence the term CS
(choreoathetosis/salivation) syndrome. /Pyrethroid esters containing the alpha-cyano
substituent/
Following absorption through the chitinous exoskeleton of arthropods, pyrethrins
stimulate the nervous system, apparently by competitively interfering with cationic
conductances in the lipid layer of nerve cells, thereby blocking nerve impulse
transmissions. Paralysis and death follow. /Pyrethrins/
Non-systemic insecticide with contact action. Causes paralysis initially, with death
occurring later. Has some acaricidal activity. /Pyrethrins/
Non-systemic insecticide with contact and stomach action. Also exhibits anti-feeding
action. Good residual activity on treated plants.
Oral toxicity values for cypermethrin depend
on such factors as: carrier, cis:trans ratio of the sample, species, sex, age and degree
of fasting. Values reported sometimes differ markedly.
Non-Human Toxicity Values:
LD50 Rat oral 4123 mg/kg
LD50 Rabbit dermal >2460 mg/kg
LD50 Rat skin 1,600 mg/kg
LD50 Mouse oral 138 mg/kg
LD50 Chicken oral 7 g/kg
LD50 Rabbit oral 3 g/kg
LD50 Rat oral 7180 mg/kg /Tech. cypermethrin/
LC50 Rat inhalation 2.5 mg/l/4 hr
Ecotoxicity Values:
LC50 Salmo salar (Atlantic salmon) 1.4-12 ug/l/96 hr, juvenile /Conditions of bioassay
not specified/
LC50 Rainbow trout technical grade 55 ppb active ingredient/24 hr (static test)
LC50 Rainbow trout formulated product 11 ppb active ingredient/24 hr (static test)
Metabolism/Pharmacokinetics:
Metabolism/Metabolites:
In the case of cypermethrin, the relative
importance of an esterase attack as opposed to an oxidative one is more important than for
permethrin; for trans-cypermethrin the ratio is
93.2% to 17.3% and for cis-cypermethrin 41.5% to
37.6% in the mouse system. In case of deltamethrin (which has only a cis-isomer) the ratio
is 28.3% to 41%. Since the mouse system shows a high oxidative ratio, the above figures
seem to indicate that esterase metabolism in these pyrethroids is at least as important as
the oxidative ones.
The major degradation pathway of cypermethrin
is hydrolysis of the ester linkage to /yield ultimately/ 3-phenoxybenzoic acid and
3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropanecarboxylic acid. (From the cis-isomer both
cis- and trans- cyclopropanecarboxylic acids are found.) A minor degradative route is ring
hydroxylation to give an alpha-cyano-3-(4-hydroxyphenyl)benzyl ester followed by
hydrolysis to produce the corresponding hydroxycarboxylic acid.
When administered to rats and mice, a large part of trans-cypermethrin
was eliminated in urine in 24 hr. Under similar conditions, 80% of administered
3-phenoxybenzoic acid was eliminated. When cis-cypermethrin
was administered, more was excreted via feces. The major urinary metabolite in mice, from
trans-cypermethrin and 3-phenoxybenzoic acid,
was identified with the aid of MS and NMR as N-(3-phenoxybenzoyl)taurine. A minor
metabolite was identified as the sulfate of 3-(4-hydroxyphenoxy)benzoic acid. The taurine
conjugate was not found in the rat urine. In rats, the major metabolite was the sulfate
conjugate of 3-(4-hydroxyphenoxy)-benzoic acid. Mouse liver microsomal + NADPH
preparations hydroxylated trans- and cis-cypermethrin
at the t- and c-methyl groups and the 4' and 5 positions. Hydroxylation at the 5 position
of trans-cypermethrin was detected only with
microsomes treated with tetraethyl pyrophosphate to inhibit esterase activity.
Metabolism of cypermethrin in rats closely
resembles that of other alpha-cyano-3-phenoxybenzyl pyrethroids, with rapid hydroxylation
& cleavage at the ester bond.
The excretion and metabolism of cis- and trans(14)C benzyl)cypermethrin
has been compared in quail, rat and mouse. Radioactivity was rapidly eliminated by quails
dosed orally with (14)C cypermethrin (2 mg/kg),
as was the case in the rat and the mouse. When the birds were dosed ip with the (14)C
labelled pyrethroid, radioactivity was excreted more slowly than after oral dosing, and
almost 20% of the ip dose of (14)C remained in the tissues after 7 days. Both mammalian
species excreted (14)C cypermethrin more rapidly
than did the avian species after ip administration, and less than 6% of the dose remained
in their tissues after several days. The biotransformation of the pyrethroid was more
complex in the avian species (34 metabolites) than in the two mammals (some 10 metabolites
in each species). In quail the predominant reactions were ester bond cleavage of cypermethrin together with either aromatic
hydroxylation or amino acid conjugation of the 3-phenoxybenzyl moiety. The hydroxylated
derivatives were eliminated mainly as sulphates. The major metabolite of cypermethrin
in the rat was the sulphate conjugate of 3-(4-hydroxyphenoxy)benzoic acid, whereas in the
mouse the major products were 3-phenoxybenzoic acid and its taurine conjugate. Thus, in
the mammalian species where hydroxylation was maximal, amino acid conjugation was a minor
metabolic route and vice versa. However, in the quail, aromatic hydroxylation and amino
acid conjugation of the 3-phenoxybenzyl moiety of cypermethrin
were both major reactions. The rapid metabolism of cypermethrin
to a variety of polar conjugated that are readily excreted, together with the low brain
sensitivity of birds compared with mammals to its neurotoxic effects, explain the low
acute toxicity of this pyrethroid to avian species.
The pyrethroid insecticides are extremely toxic to fish, with 96 hr LC50 values
generally below 10 ug/l and ip and iv LD50 values below 20 mg/kg. Corresponding LD50
values in mammals and birds are in the range of several hundred to several thousand
milligrams per kilogram. The review examines pyrethroid toxicokinetics and toxicodynamics
in fish as critical factors associated with species selectivity. Studies with permethrin, cypermethrin and fenvalerate have established that
rates of metabolism and elimination in rainbow trout are significantly lower than those
reported for birds and mammals. Comparatively low lethal brain pyrethroid concn and
nonneural aspects of pyrethroid intoxication in fish suggest that variations in
toxicodynamics are also crucial in evaluating pyrethroid selectivity.
The metabolic pathways for the breakdown of the pyrethroids vary little between
mammalian species but vary somewhat with structure. ... Essentially, pyrethrum &
allethrin are broken down mainly by oxidation of the isobutenyl side chain of the acid
moiety & of the unsaturated side chain of the alcohol moiety with ester hydrolysis
playing an important part, whereas for the other pyrethroids ester hydrolysis
predominates. /Pyrethrum and pyrethroids/
The relative resistance of mammals to the pyrethroids is almost wholly attributable to
their ability to hydrolyze the pyrethroids rapidly to their inactive acid & alcohol
components, since direct injection into the mammalian CNS leads to a susceptibility
similar to that seen in insects. Some additional resistance of homeothermic organisms can
also be attributed to the negative temperature coefficient of action of the pyrethroids,
which are thus less toxic at mammalian body temperatures, but the major effect is
metabolic. Metabolic disposal of the pyrethroids is very rapid, which means that toxicity
is high by the iv route, moderate by slower oral absorption, & often unmeasureably low
by dermal absorption. /Pyrethroids/
FASTEST BREAKDOWN IS SEEN WITH PRIMARY ALCOHOL ESTERS OF TRANS-SUBSTITUTED ACIDS SINCE
THEY UNDERGO RAPID HYDROLYTIC & OXIDATIVE ATTACK. FOR ALL SECONDARY ALCOHOL ESTERS
& FOR PRIMARY ALCOHOL CIS-SUBSTITUTED CYCLOPROPANECARBOXYLATES, OXIDATIVE ATTACK IS
PREDOMINANT. /PYRETHROIDS/
Pyrethrins are reportedly inactivated in the GI tract following ingestion. In animals,
pyrethrins are rapidly metabolized to water soluble, inactive compounds. /Pyrethrins/
Synthetic pyrethroids are generally metabolized in mammals through ester hydrolysis,
oxidation, and conjugation, and there is no tendency to accumulate in tissues. In the
environment, synthetic pyrethroids are fairly rapidly degraded in soil and in plants.
Ester hydrolysis and oxidation at various sites on the molecule are the major degradation
processes. /Synthetic pyrethroids/
Absorption, Distribution & Excretion:
Dermal exposure to cypermethrin during spray
application at up to 46 mg/hr led to an estimation that approximately 3% was absorbed.
Exposure to cypermethrin & its absorption
during aerial spraying of an ultra low volume formulation were studies. A contract pilot
& mixer/loader at each of two commercial cotton farms in Mississippi were monitored
for dermal exposure to cypermethrin during 12
aerial spray applications. Each operation consisted of 1 mixing/loading operation & 1
application of 50 gal of dilute spray soln for about 30 min. Three volunteer mixer/loaders
collected their total urine output for 24 hr periods from 1 or 2 days before to 6 days
after exposure. Absorption of cypermethrin was
evaluated by determining cypermethrin urinary
metabolites. All mixer/loaders wore protective equipment. Total potential & actual
dermal exposures were estimated. Avg potential exposures (protected & exposed skin)
were 1.07 & 10.5 mg/8 hr day (mg/day) for pilots & mixer/loaders, respectively.
Actual skin exposures averaged 0.67 mg/day for pilots & 2.43 mg/day for mixer/loaders.
67% of the total potential exposures to pilots occurred on the hands. For the
mixer/loaders, exposure involved primarily the arms, trunk, & hands, amounting to 37,
24, & 17% of total exposure, respectively. Absorption by mixer/loaders determined from
analyses of urinary metabolites amounted to 46 to 78 ug cypermethrin
equivalents per 3 mixed loads & per 12 simulated mixed loads. /It was/ concluded that
exposure of pilots & mixer/loaders during aerial application of ultra low volumes is
minimal. Only a small proportion of the cypermethrin
that contacts the skin is absorbed.
1. Dose excretion studies with cypermethrin
(as a 1:1 cis/trans mixture) & alphacypermethrin (1 of the 2 disastereoisomer pairs
which constitute cis cypermethrin) were carried
out with, in each case, 2 volunteers/dose level. The studies included (a) single oral
alphacypermethrin doses of 0.25 mg, 0.50 mg & 0.75 mg followed by repeated
alphacypermethrin doses at the same levels, daily for 5 days, (b) repeated oral cypermethrin doses of 0.25 mg, 0.75 mg & 1.5 mg
daily for 5 days, & (c) a single dermal application of 25 mg cypermethrin
to the forearm. Urine was monitored for the free & conjugated
3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylic acid before & after dosing.
2. Metab & rate of excretion of a single oral dose of alphacypermethrin was similar to
that of cis cypermethrin, on average, 43% of the
dose was excreted as the cyclopropanecarboxylic acid in the first 24 hr urine. There was
no incr in urinary metabolite excretion when alphacypermethrin was admin as a repeated
oral dose. Subjects excreted, on average, 49% of the dose as the cyclopropanecarboxylic
acid in the subsequent 24 hr periods after dosing. 3. There was no incr in the urinary
cyclopropanecarboxylic acid excretion when cypermethrin
was admin as a repeated oral dose. Subjects excreted, on average, 72% of the trans isomer
dose & 45% of the cis isomer dose respectively in the subsequent 24 hr periods after
dosing. 4. Approx 0.1% of the applied dermal dose of 25 mg cypermethrin
was excreted within 72 hr as the urinary cyclopropanecarboxylic acid. No conclusions can
be drawn from such urinary excretion data as to the concn of cypermethrin
& its metabolites in the skin or other organs, or the possibility of other routes of
metab or excretion.
/PYRETHROIDS/ READILY PENETRATE INSECT CUTICLE AS SHOWN BY TOPICAL LD50 TO PERIPLANETA
(COCKROACH) ... /PYRETHROIDS/
WHEN RADIOACTIVE PYRETHROID IS ADMIN ORALLY TO MAMMALS, IT IS ABSORBED FROM INTESTINAL
TRACT OF THE ANIMALS & DISTRIBUTED IN EVERY TISSUE EXAMINED. EXCRETION OF
RADIOACTIVITY IN RATS ADMIN TRANS-ISOMER: DOSAGE: 500 MG/KG; INTERVAL 20 DAYS; URINE 36%;
FECES 64%; TOTAL 100%. /PYRETHROIDS/
Pyrethrins are absorbed through intact skin when applied topically. When animals were
exposed to aerosols of pyrethrins with piperonyl butoxide being released into the air,
little or none of the combination was systemically absorbed. /Pyrethrins/
Although limited absorption may account for the low toxicity of some pyrethroids, rapid
biodegradation by mammalian liver enzymes (ester hydrolysis and oxidation) is probably the
major factor responsible. Most pyrethroid metabolites are promptly excreted, at least in
part, by the kidney. /Pyrethroids/
Elimination of radioactivity was measured in male Swiss-Webster mice, dosed once orally
with cis- or trans- cypermethrin, C-labeled in
either the benzyl (8 mg/kg bw) or cyclopropyl (7 mg/kg bw) moiety. The C-benzyl-dosed mice
eliminated 22% & 34% of the admin dose of cis-isomer in the urine & feces,
respectively, in 1 day; values for the trans-isomer were 41% & 16%, respectively. The
C-cyclopropyl-dosed mice eliminated 20% of the admin dose of cis-isomer in the urine &
50% in the feces in 1 day; the values for the trans-isomer were 55% & 16%,
respectively. Thus, radioactivity from the trans-isomer was mainly eliminated in the urine
& that from the cis-isomer in the feces. The C-benzyl-treated mice were killed 1, 3,
or 8 days after dosing; the C-cyclopropyl-treated mice, 3 days after dosing. Residues of
radioactivity from both labels, 3 days after dosing, were low in all tissues except for
the fat. The sequence of the residues in different organs was fat >liver =kidneys
>blood =muscle >brain. Residues fell rapidly during the C-benzyl study, with the
exception of the residues derived from the cis-isomer in fat, which did not decr during
the study period. However, in a further study, radioactivity was measured in fat samples
from 10 male mice taken up to 42 days after a single oral dose of approx 8.8 mg/kg bw
(C-benzyl)-cis-cypermethrin. The residue was
eliminated exponentially with a half-life of 13.1 (3.6-18.4) days. At 8 & 22 days
after dosing, approx 90% of the radioactivity present in 2 pooled fat samples was
attributable to unchanged cis-cypermethrin.
Mechanism of Action:
Pyrethroid insecticides are synthetic neurotoxins patterned after the naturally
occurring pyrethrins. Their mechanism of action is thought to involve effects primarily at
the voltage-sensitive sodium channel of both insect & mammalian neurons, although
recent studies have raised the possibility that these cmpds may also act at the
gamma-aminobutyric acid receptor-chloride ionophore complex. Here we show that active
pyrethroids of the alpha-cyano-3-phenoxybenzyl class allosterically enhance the binding of
(3)H-batrachotoxinin-A 20-alpha-benzoate to voltage-sensitive sodium channels of rat brain
in a dose-dependent & stereospecific manner. Comparison of the rank order of potency
for enhancement of (3)H-batrachotoxinin-A 20-alpha-benzoate binding & insecticidal
activity in a series of toxic steroisomers of cypermethrin,
representative of the class, reveals a correlation between the two measures. These results
support a sodium channel site model for pyrethroid action & suggest a useful &
practical method to help evaluate the relationship between the sodium channel &
insecticidal potency for members of this class of cmpds.
The efforts of this study were directed at defining the importance of esterases, mixed
function oxidases and mitochondrial respiratory chain enzymes in in vitro covalent binding
of cismethrin and the two cyanopyrethroids, cypermethrin
and deltamethrin to phenobarbital induced rat liver homogenate and microsomes. Each enzyme
system was selectively inhibited to elucidate the activation mechanism involved.
Piperonyl-butoxide and carbon-monoxide were used to inhibit mixed function oxidases.
Tetraethylpyrophosphate inhibited esterase and trichloropropene-oxide inhibited
epoxide-hydrolase. Potassium cyanide or rotenone was used to block the mitochondrial
electron transport. The study demonstrated that covalent binding of cismethrin, cypermethrin, and deltamethrin was dependent on
pyrethroid concentration. Inhibition of esterases and mitochondrial respiration only
slightly altered the covalent binding level. Inhibition of cytochrome p450 and mixed
function oxidases reduced the covalent binding, making it almost nonexistent. The covalent
binding was decreased by 50%through an 80% inhibition of epoxide-hydrolase. In vitro, the
comparison of data between alcohol and acid labeling of the same pyrethroid suggested that
the whole molecule was bound to proteins in an activation process, perhaps epoxidation,
and that hydrolysis could only occur afterwards. The role of cytochrome p450 dependent
monooxygenases in the covalent binding process was stressed.
The synthetic pyrethroids delay closure of the sodium channel, resulting in a sodium
tail current that is characterized by a slow influx of sodium during the end of
depolarization. Apparently the pyrethroid molecule holds the activation gate in the open
position. Pyrethroids with an alpha-cyano group (e.g., fenvalerate) produce more prolonged
sodium tail currents than do other pyrethroids (e.g., permethrin, bioresmethrin). The
former group of pyrethroids causes more cutaneous sensations than the latter. /Synthetic
pyrethroids/
Interaction with sodium channels is not the only mechanism of action proposed for the
pyrethroids. Their effects on the CNS have led various workers to suggest actions via
antagonism of gamma-aminobutyric acid (GABA)-mediated inhibition, modulation of nicotinic
cholinergic transmission, enhancement of noradrenaline release, or actions on calcium
ions. Since neurotransmitter specific pharmacological agents offer only poor or partial
protection against poisoning, it is unlikely that one of these effects represents the
primary mechanism of action of the pyrethroids, & most neurotransmitter release is
secondary to incr sodium entry. /Pyrethroids/
The symptoms of pyrethrin poisoning follow the typical pattern ... : (1) excitation,
(2) convulsions, (3) paralysis, and (4) death. The effects of pyrethrins on the insect
nervous system closely resemble those of DDT, but are apparently much less persistent.
Regular, rhythmic, and spontaneous nerve discharges have been observed in insect and
crustacean nerve-muscle preparations poisoned with pyrethrins. The primary target of
pyrethrins seems to be the ganglia of the insect central nervous system although some
pyrethrin-poisoning effect can be observed in isolated legs. /Pyrethrins/
Electrophysiologically, pyrethrins cause repetitive discharges and conduction block.
/Pyrethrins/
The interaction of a series of pyrethroid insecticides with the sodium channels in
myelinated nerve fibers of the clawed frog, Xenopus laevis, was investigated using the
voltage clamp technique. Of 11 pyrethroids, 9 insecticidally active cmpd induced a slowly
decaying sodium tail current on termination of a step depolarization, whereas the sodium
current during depolarization was hardly affected. /Pyrethroids/
Mode of action of pyrethrum & related cmpd has been studied more in insects &
in other invertebrates than in mammals. This action involves ion transport through the
membrane of nerve axons &, at least in invertebrates & lower vertebrates, it
exhibits a negative temperature coefficient. In both of these important ways & in many
details, the mode of action of pyrethrin & pyrethroids resembles that of DDT.
Esterases & mixed-function oxidase system differ in their relative importance for
metabolizing different synthetic pyrethroids. The same may be true of the constituents of
pyrethrum, depending on strain, species, & other factors. /Pyrethrins and pyrethroids/
The interactions of natural pyrethrins and 9 pyrethroids with the nicotinic
acetylcholine (ACh) receptor/channel complex of Torpedo electronic organ membranes were
studied. None reduced (3)H-ACh binding to the receptor sites, but all inhibited
(3)H-labeled perhydrohistrionicotoxin binding to the channel sites in presence of
carbamylcholine. Allethrin inhibited binding noncompetitively, but (3H)-labeled imipramine
binding competitively, suggesting that allethrin binds to the receptor's channel sites
that bind imipramine. The pyrethroids were divided into 2 types according to their action:
type A, which included allethrin, was more potent in inhibiting (3)H-H12-HTX binding and
acted more rapidly. Type B, which included permethrin, was less potent and their potency
increased slowly with time. The high affinities that several pyrethroids have for this
nicotinic ACh receptor suggest that pyrethroids may have a synaptic site of action in
addition to their well known effects on the axonal channels. /Pyrethrins and Pyrethroids/
The primary target site of pyrethroid insecticides in the vertebrate nervous system is
the sodium channel in the nerve membrane. Pyrethroids without an alpha-cyano group
(allethrin, d-phenothrin, permethrin, and cismethrin) cause a moderate prolongation of the
transient increase in sodium permeability of the nerve membrane during excitation. This
results in relatively short trains of repetitive nerve impulses in sense organs, sensory
(afferent) nerve fibers, and, in effect, nerve terminals. On the other hand the
alpha-cyano pyrethroids cause a long lasting prolongation of the transient increase in
sodium permeability of the nerve membrane during excitation. This results in long-lasting
trains of repetitive impulses in sense organs and a frequency-dependent depression of the
nerve impulse in nerve fibers. The difference in effects between permethrin and cypermethrin, which have identical molecular
structures except for the presence of an alpha-cyano group on the phenoxybenzyl alcohol,
indicates that it is this alpha-cyano group that is responsible for the long-lasting
prolongation of the sodium permeability. Since the mechanisms responsible for nerve
impulse generation and conduction are basically the same throughout the entire nervous
system, pyrethroids may also induce repetitive activity in various parts of the brain. The
difference in symptoms of poisoning by alpha-cyano pyrethroids, compared with the
classical pyrethroids, is not necessarily due to an exclusive central site of action. It
may be related to the long-lasting repetitive activity in sense organs and possibly in
other parts of the nervous system, which, in a more advance state of poisoning, may be
accompanied by a frequency-dependent depression of the nervous impulse. /Synthetic
pyrethroids/
Pyrethroids also cause pronounced repetitive activity and a prolongation of the
transient increase in sodium permeability of the nerve membrane in insects and other
invertebrates. Available information indicates that the sodium channel in the nerve
membrane is also the most important target site of pyrethroids in the invertebrate nervous
system. /Synthetic pyrethroids/
In the electrophysiological experiments using giant axons of cray-fish, the Type II
pyrethroids retain sodium channels in a modified continuous open state persistently,
depolarize the membrane, and block the action potential without causing repetitive firing.
/Pyrethroids type II/
Diazepam, which facilitates GABA reaction, delayed the onset of action of deltamethrin
& fenvalerate, but not permethrin & allethrin, in both the mouse & cockroach.
Possible mechanisms of the Type II pyrethroid syndrome include action at the GABA receptor
complex or a closely linked class of neuroreceptor. /Pyrethroids type II/
Type I Pyrethroid esters /lacking the alpha-cyano substituents/ affect sodium channels
in nerve membranes, causing repetitive (sensory, motor) neuronal discharge and a prolonged
negative afterpotential, the effects being quite similar to those produced by DDT.
/Pyrethroid esters lacking the alpha-cyano substituent/
Pyrethroids are not cholinesterase inhibitors. /Pyrethroids/
Interactions:
The effects of dissolved organic carbon in the form of Aldrich humic acid on the
accumulation and acute toxicities of three synthetic pyrethroids - fenvalerate,
deltamethrin, and cyhalothrin - to Daphnia magna in laboratory experiments were
investigated. Concn o dissolved organic carbon as low as 2.6 mg/l, 3.2 mg/l, and 3.1 mg/l
for deltamethrin fenvalerate, and cyhalothrin, respectively, resulted in a significant
decrease in bioaccumulation. Acute toxicities of all three pyrethroids were found to
decrease as dissolved organic carbon concn increased; eg, at a dissolved organic carbon
concn of 15.5 mg/l, the acute toxicity of fenvalerate was reduced by a factor of 17. The
percentages of deltamethrin and fenvalerate bound to dissolved organic carbon increased as
dissolved organic carbon concn increased after 2 hr and 24 hr contact times. At low concn
of dissolved organic carbon (eg, 1.7 mg/l), as much as 40% of fenvalerate and 20% of
deltamethrin were found sorbed to the dissolved material. After 24 hr contact times, 76.4
and 80.8% of fenvalerate and deltamethrin, respectively, were bound to dissolved organic
carbon. Reverse-phase partition coefficients for both fenvalerate and deltamethrin were
found to vary with dissolved organic carbon concn and were in the range 1.0 to 4.8 to 5.6.
The acute administration of 1R,cis, alpha S-cypermethrin,
deltamethrin fenvalerate and permethrin produced a dose-dependent lowering of the dose of
pentylenetetrazol required to elicit a seizure in rats. The proconvulsant action of cypermethrin displayed stereospecificity in that the
1R, cis, alpha S isomer of cypermethrin was the
most potent compound tested, while the non-insecticidal isomer, 1S,cis, alpha R-cypermethrin, was devoid of proconvulsant activity.
Pretreatment of rats with PK 11195, an antagonist of the peripheral-type benzodiazepine
binding site, elicited a complete reversal of the proconvulsant actions of both
deltamethrin and permethrin. In contrast, pretreatment with phenytoin did not alter the
pyrethroid-induced proconvulsant activity. These results suggest that the effects of
pyrethroids on pentylenetetrazol seizure threshold are mediated via an interaction with
peripheral-type benzodiazepine binding sites.
/Pyrethroid/ detoxification ... important in flies, may be delayed by the addition of
synergists ... organophosphates or carbamates ... to guarantee a lethal effect. ...
/Pyrethroid/
Piperonyl butoxide potentiates /insecticidal activity/ of pyrethrins by inhibiting the
hydrolytic enzymes responsible for pyrethrins' metabolism in arthropods. When piperonyl
butoxide is combined with pyrethrins, the insecticidal activity of the latter drug is
increased 2-12 times /Pyrethrins/
At dietary level of 1000 ppm pyrethrins & 10000 ppm piperonyl butoxide ...
/enlargement, margination, & cytoplasmic inclusions in liver cells of rats/ were well
developed in only 8 days, but ... were not maximal. Changes were proportional to dosage
& similar to those produced by DDT. Effects of the 2 ... were additive. /Pyrethrins/
Pharmacology:
Therapeutic Uses:
MEDICATION (VET): ectoparasiticide
Pyrethrins with piperonyl butoxide are used for topical treatment of pediculosis(lice
infestations). Combinations of pyrethrins with piperonyl butoxide are not effective for
treatment of scabies (mite infestations). Although there are no well-controlled
comparative studies, many clinicians consider 1% lindane to be pediculicide of choice.
However, some clinicians recommend use of pyrethrins with piperonyl butoxide, esp in
infants, young children, & pregnant or lactating women ... . If used correctly, 1-3
treatments ... are usually 100% effective ... Oil based (eg, petroleum distillate)
combinations ... produce the quickest results. ... For treatment of pediculosis, enough
gel, shampoo, or solution ... should be applied to cover affected hair & adjacent
areas ... After 10 min, hair is ... washed thoroughly ... treatment should be repeated
after 7-10 days to kill any newly hatched lice. /Pyrethrins/
Interactions:
The effects of dissolved organic carbon in the form of Aldrich humic acid on the
accumulation and acute toxicities of three synthetic pyrethroids - fenvalerate,
deltamethrin, and cyhalothrin - to Daphnia magna in laboratory experiments were
investigated. Concn o dissolved organic carbon as low as 2.6 mg/l, 3.2 mg/l, and 3.1 mg/l
for deltamethrin fenvalerate, and cyhalothrin, respectively, resulted in a significant
decrease in bioaccumulation. Acute toxicities of all three pyrethroids were found to
decrease as dissolved organic carbon concn increased; eg, at a dissolved organic carbon
concn of 15.5 mg/l, the acute toxicity of fenvalerate was reduced by a factor of 17. The
percentages of deltamethrin and fenvalerate bound to dissolved organic carbon increased as
dissolved organic carbon concn increased after 2 hr and 24 hr contact times. At low concn
of dissolved organic carbon (eg, 1.7 mg/l), as much as 40% of fenvalerate and 20% of
deltamethrin were found sorbed to the dissolved material. After 24 hr contact times, 76.4
and 80.8% of fenvalerate and deltamethrin, respectively, were bound to dissolved organic
carbon. Reverse-phase partition coefficients for both fenvalerate and deltamethrin were
found to vary with dissolved organic carbon concn and were in the range 1.0 to 4.8 to 5.6.
The acute administration of 1R,cis, alpha S-cypermethrin,
deltamethrin fenvalerate and permethrin produced a dose-dependent lowering of the dose of
pentylenetetrazol required to elicit a seizure in rats. The proconvulsant action of cypermethrin displayed stereospecificity in that the
1R, cis, alpha S isomer of cypermethrin was the
most potent compound tested, while the non-insecticidal isomer, 1S,cis, alpha R-cypermethrin, was devoid of proconvulsant activity.
Pretreatment of rats with PK 11195, an antagonist of the peripheral-type benzodiazepine
binding site, elicited a complete reversal of the proconvulsant actions of both
deltamethrin and permethrin. In contrast, pretreatment with phenytoin did not alter the
pyrethroid-induced proconvulsant activity. These results suggest that the effects of
pyrethroids on pentylenetetrazol seizure threshold are mediated via an interaction with
peripheral-type benzodiazepine binding sites.
/Pyrethroid/ detoxification ... important in flies, may be delayed by the addition of
synergists ... organophosphates or carbamates ... to guarantee a lethal effect. ...
/Pyrethroid/
Piperonyl butoxide potentiates /insecticidal activity/ of pyrethrins by inhibiting the
hydrolytic enzymes responsible for pyrethrins' metabolism in arthropods. When piperonyl
butoxide is combined with pyrethrins, the insecticidal activity of the latter drug is
increased 2-12 times /Pyrethrins/
At dietary level of 1000 ppm pyrethrins & 10000 ppm piperonyl butoxide ...
/enlargement, margination, & cytoplasmic inclusions in liver cells of rats/ were well
developed in only 8 days, but ... were not maximal. Changes were proportional to dosage
& similar to those produced by DDT. Effects of the 2 ... were additive. /Pyrethrins/
Environmental Fate & Exposure:
Environmental Fate/Exposure Summary:
Cypermethrin's production and use as an
insecticide is expected to result in its direct release to the environment. If released to
air, a vapor pressure of 3.1X10-9 mm Hg at 20 deg C indicates cypermethrin
will exist solely in the particulate phase in the ambient atmosphere. Particulate-phase cypermethrin will be removed from the atmosphere by
wet and dry deposition. If released to soil, cypermethrin
is expected to have no mobility based upon a range of Koc values from 5,800 to 160,000.
Volatilization from moist soil surfaces is not expected to be an important fate process
based upon an estimated Henry's Law constant of 4.2X10-7 atm-cu m/mole. Cypermethrin
degrades rapidly in soil under aerobic conditions. The half-lives were 4.1 to 17.6 days
for trans- cypermethrin and 12.5 to 56.4 days
for the cis-cypermethrin under aerobic
conditions in an incubated soil. If released into water, cypermethrin
is expected to adsorb to suspended solids and sediment based upon the Koc values.
Volatilization from water surfaces is not expected to be an important fate process based
upon this compound's estimated Henry's Law constant. BCF values of 420 and 430 for golden
ide fish and rainbow trout suggest that bioconcentration in aquatic organisms is high. The
abiotic hydrolysis half-life of cypermethrin was
63 weeks at pH 7. The photodegradation half-lives of the cis- and trans-isomers of cypermethrin in distilled water solution ranged from
2.6 to 3.6 days in sunlight and >10 days in dark controls; the half-lives in river and
seawater ranged from 0.6 to 1.0 days. Occupational exposure to cypermethrin
may occur through inhalation of dust particles and dermal contact with this compound at
workplaces where cypermethrin is produced or
used. Monitoring data indicate that the general population may be exposed to cypermethrin via inhalation of ambient air and
ingestion of food containing cypermethrin. (SRC)
Probable Routes of Human Exposure:
Occupational exposure to cypermethrin may
occur through inhalation and dermal contact with this compound at workplaces where cypermethrin is produced or used(SRC). Dermal exposure
to workers applying spray applications of cypermethrin
in tea plantations was measured(1); exposure rates (in ug/100 cu cm) were as follows(1):
face: 0.06-0.72, chest: 0.11-2.06, abdomen: 0.09-2.68, thigh: 0.41-17.3, ankle:
0.15-32.6(1); total dermal exposure based upon spray amounts was 186-1140 mg/kg for
nonhand areas and 46.1 mg/kg for hands only(1). Agricultural airplane pilots and workers
involved in mixing and loading aerial sprayers were monitored for dermal exposure to cypermethrin(2); potential (protected and exposed
skin) exposure was 1.07 (0.26 to 2.65) mg/8 hr for pilots and 10.5 (2.50 to 23.1) mg/8 hr
for mixer-loaders(2); the actual exposure to pilots was predominantly of the hands,
whereas that of the mixer-loaders was more uniform since their hands were protected by
gloves(2). Monitoring data indicate that the general population may be exposed to cypermethrin via inhalation of ambient air and
ingestion of food containing cypermethrin(SRC).
Artificial Pollution Sources:
Cypermethrin's production and use as an
insecticide(1) is expected to result in its direct release to the environment(SRC).
Environmental Fate:
TERRESTRIAL FATE: Based on a classification scheme(1), Koc values ranging from 5,800 to
160,000(2), indicate that cypermethrin is
expected to be immobile in soil(SRC). Volatilization of cypermethrin
from moist soil surfaces is not expected to be an important fate process(SRC) given an
estimated Henry's Law constant of 4.2X10-7 atm-cu m/mole(SRC), derived from its vapor
pressure, 3.1X10-9 mm Hg(2), and water solubility, 4.0X10-3 mg/l(3). Cypermethrin
is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor
pressure(2). The photodegradation of the cis- and trans-isomers of cypermethrin
was studied by exposing various soil surface applications to sunlight for 7-10 days(4);
half-lives on soil surfaces exposed to sunlight ranged from 0.6-1.9 days while half-lives
on dark soil were >7 days(4). Cypermethrin
degrades rapidly in soil under aerobic conditions(5). For example, the half-lives were 4.1
to 17.6 days for trans-cypermethrin and 12.5 to
56.4 days for the cis-cypermethrin under aerobic
conditions in an incubated soil(5). Using a standardized soil test under laboratory
conditions, the persistence half-life of cypermethrin
was determined to be 21 days(6); however, when formulated with various sawdusts the
half-life increased to 30-110 days(6). In a field persistence study conducted in India
(max temperatures of 30.7-34.7 deg C) at applications of 75-150 g cypermethrin/ha,
cypermethrin residues did not persist past 45
days (initial half-lives of about 3 days)(7). After spray applications in an orchard, the
half-life of cypermethrin on vegetation under
pear and apricot trees ranged from 14-17 days(8); soil contained no detectable cypermethrin after 100-120 days(8). After spraying
wheat herbage, cypermethrin residues fell to 50%
after 1 day and to 5% after 27 days(9).
AQUATIC FATE: Based on a classification scheme(1), Koc values ranging from 5,800 to
160,000(2), indicate that cypermethrin is
expected to adsorb to suspended solids and sediment(SRC). In a pond experiment, surface
applications of cypermethrin gradually
partitioned to sediment with sediment concns exceeding surface and subsurface water concns
after 13 days(3); in another pond experiment, dispersion of surface applications to
subsurface water and sediment was very slow(3); however, after 4 wks, the concn in the
sediment exceeded the water concns(3). Volatilization from water surfaces is not
expected(4) based upon an estimated Henry's Law constant of 4.2X10-7 atm-cu m/mole(SRC),
derived from its vapor pressure, 3.1X10-9 mm Hg(2), and water solubility, 4.0X10-3
mg/l(5). According to a classification scheme(6), a BCF of 420 in golden ide fish
(Leuciscus idus melanotus)(7) and 430 in rainbow trout (Oncorhynchus mykiss)(8), suggests
the potential for bioconcentration in aquatic organisms is high(SRC). The aqueous
hydrolysis half-life of cypermethrin in sterile
water-ethanol (99:1) phosphate buffers at 25 deg C was determined to be 99, 69, 63, and 50
weeks at pHs of 4.5, 6, 7, and 8, respectively(9). In a photomineralization study using a
UV light (>290 nm), 30.2% of initial cypermethrin
was mineralized to CO2 during a 17-hr exposure period(7). The photodegradation of the cis-
and trans-isomers of cypermethrin was studied by
exposing various aqueous solutions to sunlight for 7-10 days; the half-lives in distilled
water solution were 2.6-3.6 days in sunlight and >10 days in dark controls(10); the
half-lives in river and seawater were 0.6-1.0 days and >10 days in dark controls(10). Cypermethrin degrades rapidly in soil under aerobic
conditions(11). For example, in an incubated soil, the half-lives were 4.1 to 17.6 days
for trans-cypermethrin and 12.5 to 56.4 days for
the cis-cypermethrin under aerobic
conditions(11). Cypermethrin should also degrade
rapidly in aqueous systems(SRC).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile
organic compounds in the atmosphere(1), cypermethrin,
which has a vapor pressure of 3.1X10-9 mm Hg at 20 deg C(2), is expected to exist solely
in the particulate phase in the ambient atmosphere(SRC). Particulate-phase cypermethrin may be removed from the air by wet and
dry deposition(SRC).
Environmental Biodegradation:
Cypermethrin degradation in soil was rapid
and the trans isomer degraded more rapidly than the cis-isomer. Thirty to 60% of cypermethrin applied was converted to (14)CO2.
Hydrolysis of the ester was the primary pathway and produced the carboxylic acid plus
3-phenoxybenzyl alcohol or 3-phenoxybenzaldehyde cyanohydrin. Both of the latter compounds
were converted to 3-phenoxybenzoic acid. Another pathway produced the
3-(4-hydroxyphenoxy)benzyl ester which was in turn hydrolyzed. The degradation rate of
trans-cypermethrin and cis-cypermethrin
was most rapid on sandy clay and sandy loam. About 50% of trans-cypermethrin
and cis-cyprmethrin applied to the soils decomposed in 2 weeks and 4 weeks, respectively.
Six degradation products were observed in soil: the 3-(4-hydroxyphenoxy)benzyl ester;
3-(4-hydroxyphenoxy)benzoic acid; 3-phenoxybenzoic acid; and (+ or -)-cis- and (+ or
-)-trans-3-(2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid. Carbon dioxide was
also observed.
AEROBIC: In a biomineralization study using an activated sludge inocula, 0.4% of
initial cypermethrin was mineralized to CO2
during a 5-day incubation period(1). In soil degradation studies using a mineral and an
organic soil, 84-96% of applied cypermethrin
disappeared after an 8-week incubation period(2); in sterile soil controls, only 7-8% of
applied cypermethrin disappeared suggesting that
the disappearance was primarily due to biotic processes(2). The results of laboratory soil
persistence studies, using unformulated cypermethrin
and cypermethrin formulated with other chemicals
(eg pentachlorophenol) that prevented microbial degradation, suggested that cypermethrin degradation in the soil was primarily due
to soil microbes(3). In laboratory tests, the half-lives of the cis-isomers of cypermethrin in soil were about 4 weeks, but 10-12
weeks in a biologically inactive soil(4). The trans-isomer usually displayed much shorter
half-lives of <2 weeks and <4 weeks in the less active soil(4); there was little
difference between the rates of degradation of cypermethrin
observed in the laboratory and the field(4). In incubated soil, the half-lives were 4.1 to
17.6 days for trans-cypermethrin and 12.5 to
56.4 days for the cis-cypermethrin under aerobic
conditions(5); the degradation rate of cypermethrin
greatly depended on the soil types(5). In litter and Elm forest soil, cypermethrin
isomers dissipated very quickly with half-lives ranging from 9 to 29 days(6). Cypermethrin degraded via pathways including cleavage
of the ester producing cis- and
trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid and 3-phenoxybenzoic
acid cleavage of the diphenyl ether bond forming the desphenoxy derivative, hydroxylation
at the 4-position of the phenoxy ring, and hydrolysis of the cyano group to the amide and
carboxy groups(4,6).
ANAEROBIC: The degradation of cypermethrin in
soil was slowed under anaerobic conditions with respect to aerobic conditions(1).
Environmental Abiotic Degradation:
In the absence of a UV absorber, cypermethrin
(alpha-isomer) on cotton fabric degraded rapidly when exposed to UV light (simulating
midday natural sunlight) for a 6-hr period(1); however, when applied as a mixture with
2,4-dihydroxybenzophenone (a UV absorber), it photodegraded at a much lower rate(1).
The rate constant for the vapor-phase reaction of cypermethrin
with photochemically-produced hydroxyl radicals has been estimated as 3.70X10-11 cu
cm/molecule-sec at 25 deg C(SRC) using a structure estimation method(1). This corresponds
to an atmospheric half-life of about 18 hours at an atmospheric concentration of 5X10+5
hydroxyl radicals per cu cm(1). The rate constant for the vapor-phase reaction of cypermethrin with ozone has been estimated as
2.33X10-19 cu cm/molecule-sec at 25 deg C(SRC) using a structure estimation method(1).
This corresponds to an atmospheric half-life of about 49 days at an atmospheric
concentration of 7X10+11 ozone molecules per cu cm(2). The aqueous hydrolysis half-life of
cypermethrin in sterile water-ethanol (99:1)
phosphate buffers at 25 deg C was determined to be 99, 69, 63 and 50 weeks at pHs of 4.5,
6, 7 and 8, respectively(3). Based upon measured rate constants (combined acid-catalyzed,
base-catalyzed and neutral hydrolysis) of 3.63X10-8/sec and 5.91X10-8/sec for the cis- and
trans-isomers of cypermethrin at pH 7 and 25 deg
C(4), the half-lives at pH 8 and 9 would be 14.5-21 days and 1.45-2.1 days,
respectively(4); a half-life of 23-38 min was observed at pH 11 and 25 deg C(4).
In a photomineralization study using a UV light (>290 nm), 30.2% of initial cypermethrin was mineralized to CO2 during a 17-hr
exposure period(1). The photodegradation of the cis- and trans-isomers of cypermethrin was studied by exposing various aqueous
solutions and soil surface applications to sunlight for 7-10 days and then determining the
differences in cypermethrin losses as compared
to dark controls(2); the half-lives in distilled water solution were 2.6-3.6 days in
sunlight and >10 days in dark controls(2); the half-lives in river and seawater were
0.6-1.0 days and >10 days in dark controls(2); the faster half-lives in natural water
(as compared to distilled water) were thought to result from photosensitizers occurring in
the natural waters which were demonstrated by half-lives of <0.5 days in
acetone-photosensitized solutions(2); half-lives on soil surfaces exposed to sunlight
ranged from 0.6-1.9 days while half-lives on dark soil were >7 days(2); the
photodegradation products resulting from exposure of cypermethrin
to sunlight included various carbamoyl and hydroxy derivatives, a variety of benzoic acid
derivatives, several lactone derivatives, and several aliphatic carboxylic acid
derivatives(2).
Environmental Bioconcentration:
Using a static test system, a 3-day cypermethrin
BCF of 420 was measured in golden ide fish (Leuciscus idus melanotus)(1). The BCF for
rainbow trout (Oncorhynchus mykiss) was approx 430(2). According to a classification
scheme(3), these BCF values suggest that bioconcentration in aquatic organisms is
high(SRC). A 1-day BCF of 3280 was measured in algae (Chlorella fusca)(1). The BCF for
chironomid larvae exposed to cis- and trans-cypermethrin
in water and sediment ranged from 34 to 385(4).
Soil Adsorption/Mobility:
Koc values for loamy sand (pH 5.4, 2.1% organic matter), sandy loam (pH 6.5, 3.4%
organic matter), silt loam (pH 5.6, 2.0% organic matter), loamy sand (pH 4.7, 15.6%
organic matter), and loam (pH 7.1, 5.2% organic matter) were 160,000, 84,000, 22,000,
34,000,and 5,800, respectively(1). According to a classification scheme(2), these Koc
values suggest that cypermethrin is expected to
be immobile in soil(SRC). The mobility of cis- and trans-cypermethrin
in soil was studied in soil column experiments and by soil thin-layer chromatography (TLC)
using a Hagerstown silty clay soil, a silty clay loam soil and a Tifton loamy sand(3); cypermethrin was found to be immobile in all soils(3).
During field persistence studies, cypermethrin
did not leach below soil depths of 7.5-15 cm(4). In laboratory studies, cypermethrin
did not leach from three soils when percolated immediately after treatment or after a
30-day incubation period(5); only trace amounts leached from sand(5).
Volatilization from Water/Soil:
The Henry's Law constant for cypermethrin is
estimated as 4.20X10-7 atm-cu m/mole(SRC) based upon its vapor pressure, 3.1X10-9 mm
Hg(1), and water solubility, 4.0X10-3 mg/l(2). This Henry's Law constant indicates that cypermethrin is expected to be essentially nonvolatile
from water surfaces(3). Cypermethrin is not
expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(1).
Environmental Water Concentrations:
SURFACE WATER: Deposits of cypermethrin on
the surface of three streams adjacent to vineyards in France that were sprayed (via
mistblowers) with cypermethrin insecticide were
in the range of 0.04-0.45 mg/sq m(1); cypermethrin
concns in subsurface water of the streams were in the range of 0.4-1.7 ug/l soon after
spraying, and decreasing to <0.1 ug/l within a period of about 5 hours(1).
Effluent Concentrations:
A leachate collected near a pesticide manufacturing plant in Barcelona, Spain in the
summer of 1984 contained cypermethrin
concentrations of >5-10 ppm(1).
Atmospheric Concentrations:
SOURCE DOMINATED: The concn of cypermethrin
detected in air of vacant dormitory rooms following its application for cockroach control
were 18.2, 8.5, 3.0,7.1, 4.4, 4.4, 0.6, and 0.3 ug/cu m at 0, 7, 28, 42, 56, 70, and 84
days postapplication, respectively(1).
URBAN/SUBURBAN: The mean concn of cypermetrin residues in air particulates after use of
the pesticide in the Muna Valley region of Saudi Arabia ranged from 0.60 to 1.35 ug/cu
m(1).
Food Survey Values:
According to compiled results of the US Food and Drug Administration's pesticide
residue monitoring programs (including the Total Diet Study) for fiscal years 1978-1990, cypermethrin has been detected as a pesticide residue
in American foods(1-4). As part of the FDA Total Diet Study, the concns of cypermethrin detected in boiled collards, raw iceberg
lettuce, and boiled broccoli were 0.442 ppm (range, 0.052-1.247 ppm), 0.0185 ppm (range,
0.013-0.024 ppm), and 0.013 ppm, respectively(5). During a 5-yr period from 1982-1986,
FDA's Los Angeles District Laboratory analyzed 19,581 samples of domestic and imported
food and feed commodities for pesticide residues(2); cypermethrin
was detected in only 2 samples at concns of 0.1-0.5 ppm(2). For fiscal years 1988 and
1989, 27,065 food samples were collected and analyzed for pesticide residues by 10 state
laboratories (CA, NY, FL, IN, MA, MI, NC, OR, VA and WI)(6); cypermethrin
was detected in only 1 sample (concn not reported)(7). Between July 1988 and June 1990 in
Pakistan, cypermethrin residues were detected in
luffa (turi; 1.63 mg/kg), pumpkin (range, trace-0.011 mg/kg), cauliflower (range, 0.01-0.8
mg/kg), spinach (traces), white gourd (tinda; range, 0.11-0.15 mg/kg), coriander (range,
0.17-0.3 mg/kg), cucumber (range, 0.16-1.80 mg/kg), butter gourd (1.50 mg/kg), lettuce
(1.0 mg/kg), onion (1.23-1.8 mg/kg), turnip (range, 0.05-3.0 mg/kg), tomato (range,
traces-0.15 mg/kg), Lady's finger (range, 0.3-3.43 mg/kg), cabbage (range, 1.1-3.3 mg/kg),
mint (range, 0.14-2.5), dill (soya; 1.2 mg/kg), beet sugar (0.10 mg/kg), carrot (range,
0.04-3.0), Lambs quarter (bathwa; traces), green peas (1.1 mg/kg), mango (1.10 mg/kg),
guava (4.0 mg/kg), and dates (1.4 mg/kg)(8). Cypermethrin
was detected in cabbage at concn of 23 ug/kg in Greece between March and April 1998(9). Cypermethrin residues were detected in tomatoes from
Egyptian markets in 1995 at a concn of 1.1 mg/kg(10).
Milk Concentrations:
A study was undertaken to determine residues of cypermethrin
in the milk of cows wearing ear tags impregnated with cypermethrin
(to control horn flies and other insects)(1); 60 milk samples were collected from 10 cows
over a 21-day period(1); 49 samples were below detection limits of 4 ug/kg(1); concns in
the buttermilk of the other samples ranged from 4.0 to 9.6 ug/kg(1).
Other Environmental Concentrations:
Fabrics, simulating clothing worn by workers applying cypermethrin
insecticides, were found to contain 1.8-2.3 ug cypermethrin/cu
cm before laundering(1); after laundering (by various methods), levels of 0.3-0.4 ng/cu cm
remained in the fabric(1).
Environmental Standards & Regulations:
FIFRA Requirements:
As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of
older pesticides to consider their health and environmental effects and make decisions
about their future use. Under this pesticide reregistration program, EPA examines health
and safety data for pesticide active ingredients initially registered before November 1,
1984, and determines whether they are eligible for reregistration. In addition, all
pesticides must meet the new safety standard of the Food Quality Protection Act of 1996.
Pesticides for which EPA had not issued Registration Standards prior to the effective date
of FIFRA, as amended in 1988, were divided into three lists based upon their potential for
human exposure and other factors, with List B containing pesticides of greater concern and
List D pesticides of less concern. Cypermethrin
is found on List B. Case No: 2130; Pesticide type: Insecticide (Acaricide); Case Status:
OPP is reviewing data from the pesticide's producers regarding its human health and/or
environmental effects, or OPP is determining the pesticide's eligibility for
reregistration and developing the Reregistration Eligibility Decision (RED) document.;
Active ingredient (AI):
alpha-cyano(3-phenoxyphenyl)methyl(+-)cis,trans-3-(2,2-dichlorovinyl-
2,2-dimethylcyclopropanecarboxylate; Data Call-in (DCI) Date(s): 07/01/91, 03/03/95,
10/13/95; AI Status: The producers of the pesticide has made commitments to conduct the
studies and pay the fees required for reregistration, and are meeting those commitments in
a timely manner.
Tolerances are established for residues of the insecticide cypermethrin
(+-)alpha cyano-(3-phenoxyphenyl)methyl(+-)cis,trans-3(2,2-dichloroethenyl-2,2-dimethylcyc
lopropanecarboxylate in or on the following commodities: brassica, head and stem;
brassica, leafy; cattle, fat; cattle, mbyp; cattle, meat; cottonseed; goats, fat; goats,
mbyp; goats, meat; hogs, fat; hogs, mbyp; hogs, meat; horses, fat; horses, mbyp; horses,
meat; lettuce, head; milk; onions, bulb; onions, green; pecans; sheep, fat; sheep, mbyp;
and sheep, meat.
Tolerances are established for residues of the insecticide zeta-cypermethrin
(s-cyano(3-phenoxyphenyl)methyl(+-)cis,trans-3(2,2-dichloroethenyl)-2,2-dimethyl
cyclopropanecarboxylate) in or on the following commodities: cabbage; cattle, fat; cattle,
mbyp; cattle, meat; cottonseed; goats, fat; goats, mbyp; goats, meat; hogs, fat; hogs,
mbyp; hogs, meat; horses, fat; horses, mbyp; horses, meat; lettuce, head; milk; onions,
bulb; pecans; sheep, fat; sheep, mbyp; and sheep, meat.
Acceptable Daily Intakes:
OPP RfD= 0.01 mg/kg; EPA RfD= 0.01 mg/kg; WHO RfD= 0.05 mg/kg
State Drinking Water Guidelines:
(FL) FLORIDA 70 ug/l
Allowable Tolerances:
Tolerances are established for residues of the insecticide cypermethrin
(+-)alpha cyano-(3-phenoxyphenyl)methyl(+-)cis,trans-3(2,2-dichloroethenyl-2,2-dimethylcyc
lopropanecarboxylate in or on the following commodities: brassica, head and stem, 2.0 ppm;
brassica, leafy, 14.0 ppm; cattle, fat, 0.05 ppm; cattle, mbyp, 0.05 ppm; cattle, meat,
0.05 ppm; cottonseed, 0.5 ppm; goats, fat, 0.05 ppm; goats, mbyp, 0.05 ppm; goats, meat,
0.05 ppm; hogs, fat, 0.05 ppm; hogs, mbyp, 0.05 ppm; hogs, meat, 0.05 ppm; horses, fat,
0.05 ppm; horses, mbyp, 0.05 ppm; horses, meat, 0.05 ppm; lettuce, head, 10.0 ppm; milk,
0.05 ppm; onions, bulb, 0.10 ppm; onions, green, 6.0 ppm; pecans, 0.05 ppm; sheep, fat,
0.05 ppm; sheep, mbyp, 0.05 ppm; and sheep, meat, 0.05 ppm.
Tolerances are established for residues of the insecticide zeta-cypermethrin
(s-cyano(3-phenoxyphenyl)methyl(+-)cis,trans-3(2,2-dichloroethenyl)-2,2-dimethyl
cyclopropanecarboxylate) in or on the following commodities: cabbage, 2.0 ppm; cattle,
fat, 0.05 ppm; cattle, mbyp, 0.05 ppm; cattle, meat, 0.05 ppm; cottonseed, 0.5 ppm; goats,
fat, 0.05 ppm; goats, mbyp, 0.05 ppm; goats, meat, 0.05 ppm; hogs, fat, 0.05 ppm; hogs,
mbyp, 0.05 ppm; hogs, meat, 0.05 ppm; horses, fat, 0.05 ppm; horses, mbyp, 0.05 ppm;
horses, meat, 0.05 ppm; lettuce, head, 10.0 ppm; milk, 0.05 ppm; onions, bulb, 0.10 ppm;
pecans, 0.05 ppm; sheep, fat, 0.05 ppm; sheep, mbyp, 0.05 ppm; and sheep, meat, 0.05 ppm.
Chemical/Physical Properties:
Molecular Formula:
C22-H19-C12-N-O3
Molecular Weight:
416.30
Color/Form:
Viscous semi-solid
Pure isomers; colorless crystals
Odor:
Odorless
Melting Point:
80.5 deg C
Corrosivity:
Non-corrosive to metals
Density/Specific Gravity:
1.25 g/cu cm @ 20 deg C
Octanol/Water Partition Coefficient:
log Kow = 6.60
Solubilities:
In acetone, chloroform, cyclohexanone, xylene greater than 450, ethanol 337, hexane 103
(all in g/l at 20 deg C).
Soluble in methanol and methylene dichloride
In water, 4X10-3 mg/l @ 20 deg C
Vapor Pressure:
3.07X10-9 mm Hg @ 20 deg C
Other Chemical/Physical Properties:
Yellow-brown viscous semi-solid /Technical/
Chemical Safety & Handling:
Skin, Eye and Respiratory Irritations:
Immediately irritating to the eye. /Pyrethrins/
The chief effect from exposure ... is skin rash particularly on moist areas of the
skin. ... May irritate the eyes.
Fire Fighting Procedures:
Use carbon dioxide, foam, or dry chemical /on fires involving pyrethroids/. /Pyrethrum/
Fire-fighting: Self-contained breathing apparatus with a full facepiece operated in
pressure-demand or other positive-pressure mode. /Pyrethrum/
Extinguish fire using agent suitable for type of surrounding fire. /Pyrethrins/
Hazardous Reactivities & Incompatibilities:
Incompatibility: Strong oxidizers. /Pyrethrins/
... Incompatible with lime & ordinary soaps because acids & alkalies speed up
processes of hydrolysis. /Pyrethrins/
Hazardous Decomposition:
When heated to decomp it emits toxic fumes of /hydrogen cyanide, nitrogen oxide,
hydrogen chloride/.
Prior History of Accidents:
Cypermethrin poisoning was reported in five
office workers at an accounting office of approximately 1000 sq ft in size that was
treated for insect control. Treatment inside the building was accomplished by vertical
drilling and injecting the chemical under the slab. Exterior walls were drilled from
outside the foundation; cypermethrin was then
injected in these holes. The employees entered the building 2 days after treatment and
experienced dizziness, headaches, nausea, and vertigo immediately. Turning on the air
conditioning system worsened their symptoms After 5 min they left the building; however,
they repeatedly reentered the building for short periods. Six days later fans were used to
draw off the vapors. Airborne concn were below the limit of analysis by 13 days after
treatment whereupon the employees reentered the building, only to suffer a return of their
symptoms which again worsened when the air conditioning unit was turned on. Six weeks
later air sampling indicated concn less than the detection limit. Wipe samples showed the
greatest concn, 4240.0 ug/sq foot to be on the hallway carpet between two applicator
holes. Several of the holes drilled by the applicator were drilled into the transverse
ducts running underground and connecting with the main duct. Cypermethrin
had been directly injected into the ventilation ducts. The exact exposure levels to which
the workers had been subjected when they turned on the air conditioning unit was not
known.
Protective Equipment & Clothing:
Wear protective clothing, gloves, and face shield when handling concentrate or
spraying.
Employees should be provided with and required to use dust- and splash-proof safety
goggles where /pyrethroids/ ... may contact the eyes. /Pyrethroids/
Employees should be provided with and be required to use impervious clothing, gloves,
and face shields (eight-inch minimum). /Pyrethroids/
Wear appropriate equipment to prevent: Repeated or prolonged skin contact. /Pyrethrum
and pyrethrins/
Wear eye protection to prevent: Reasonable probability of eye contact. /Pyrethrins/
Recommendations for respirator selection. Max concn for use: 50 mg/cu m: Respirator
Classes: Any chemical cartridge respirator with organic vapor cartridge(s) in combination
with a dust, mist, and fume filter. May require eye protection. Any supplied-air
respirator. May require eye protection. Any self-contained breathing apparatus. May
require eye protection. /Pyrethrins/
Recommendations for respirator selection. Max concn for use: 125 mg/cu m: Respirator
Classes: Any supplied-air respirator operated in a continuous flow mode. May require eye
protection. Any powered, air-purifying respirator with organic vapor cartridge(s) in
combination with a dust, mist, and fume filter. May require eye protection. /Pyrethrins/
Recommendations for respirator selection. Max concn for use: 250 mg/cu m: Respirator
Classes: Any chemical cartridge respirator with a full facepiece and organic vapor
cartridge(s) in combination with a high-efficiency particulate filter. Any self-contained
breathing apparatus with a full facepiece. Any supplied-air respirator with a full
facepiece. Any powered, air-purifying respirator with a tight-fitting facepiece and
organic vapor cartridge(s) in combination with a high-efficiency particulate filter. May
require eye protection. /Pyrethrins/
Recommendations for respirator selection. Max concn for use: 5,000 mg/cu m: Respirator
Class: Any supplied-air respirator with a full facepiece and operated in a pressure-demand
or other positive pressure mode. /Pyrethrins/
Recommendations for respirator selection. Condition: Emergency or planned entry into
unknown concn or IDLH conditions: Respirator Classes: Any self-contained breathing
apparatus that has a full facepiece and is operated in a pressure-demand or other positive
pressure mode. Any supplied-air respirator with a full face piece and operated in
pressure-demand or other positive pressure mode in combination with an auxiliary
self-contained breathing apparatus operated in pressure-demand or other positive pressure
mode. /Pyrethrins/
Recommendations for respirator selection. Condition: Escape from suddenly occurring
respiratory hazards: Respirator Classes: Any air-purifying, full-facepiece respirator (gas
mask) with a chin-style, front- or back-mounted organic vapor canister having a
high-efficiency particulate filter. Any appropriate escape-type, self-contained breathing
apparatus. /Pyrethrins/
Preventive Measures:
SRP: Contaminated protective clothing should be segregated in such a manner so that
there is no direct personal contact by personnel who handle, dispose, or clean the
clothing. Quality assurance to ascertain the completeness of the cleaning procedures
should be implemented before the decontaminated protective clothing is returned for reuse
by the workers. Contaminated clothing should not be taken home at end of shift, but should
remain at employee's place of work for cleaning.
Skin that becomes contaminated with /pyrethrum/ should be promptly washed or showered
with soap or mild detergent and water. /Pyrethrum/
Clothing contaminated with /pyrethrum/ should be placed in closed containers for
storage until provision is made for the removal of /pyrethrum/ from the clothing.
/Pyrethrum/
Respirators may be used when engineering and work practice controls are not technically
feasible, when such controls are in the process of being installed, or when they fail or
need to be supplemented. Respirators may also be used for operations which require entry
into tanks or closed vessels, and in emergency situations. /Pyrethrum/
Employees who handle /pyrethrum/ ... should wash their hands thoroughly with soap or
mild detergent and water before eating, smoking, or using toilet facilities. /Pyrethrum/
Avoid contact with skin. Keep out of any body of water. Do not contaminate water by
cleaning of equipment or disposal of waste. Do not reuse empty container. Destroy it by
perforating or crushing. /Pyrethrum/
Contact lenses should not be worn when working with this chemical. /Pyrethrins/
Workers should wash: Promptly when skin becomes contaminated. /Pyrethrins/
Work clothing should be changed daily: If it is reasonably probable that the clothing
may be contaminated. /Pyrethrins/
Remove clothing: Promptly if it is non-impervious clothing that becomes contaminated.
/Pyrethrins/
If /pyrethrins/ are not involved in a fire: keep /pyrethrins/ out of water sources and
sewers. Build dikes to contain flow as necessary. /Pyrethrins/
SRP: The scientific literature for the use of contact lenses in industry is
conflicting. The benefit or detrimental effects of wearing contact lenses depend not only
upon the substance, but also on factors including the form of the substance,
characteristics and duration of the exposure, the uses of other eye protection equipment,
and the hygiene of the lenses. However, there may be individual substances whose
irritating or corrosive properties are such that the wearing of contact lenses would be
harmful to the eye. In those specific cases, contact lenses should not be worn. In any
event, the usual eye protection equipment should be worn even when contact lenses are in
place.
Stability/Shelf Life:
Relatively stable in neutral & weakly acidic media, with optimum stability at pH 4.
Hydrolyzed in alkaline media. Relatively stable to light in field situations. Thermally
stable up to 220 deg C.
Pyrethrins ... /are/ stable for long periods in water-based aerosols where ...
emulsifiers give neutral water systems. /Pyrethrins/
Storage Conditions:
Pyrethrins with piperonyl butoxide topical preparations should be stored in well-closed
containers at a temperature less than 40 deg C, preferably between 15-30 deg C.
/Pyrethrins/
Cleanup Methods:
Spillages of pesticides at any stage of their storage or handling should be treated
with great care. Liquid formulations may be reduced to solid phase by evaporation. Dry
sweeping of solids is always hazardous: these should be removed by vacuum cleaning, or by
dissolving them in water, or other solvent in the factory environment. /Pesticides/
Disposal Methods:
SRP: At the time of review, criteria for land treatment or burial (sanitary landfill)
disposal practices are subject to significant revision. Prior to implementing land
disposal of waste residue (including waste sludge), consult with environmental regulatory
agencies for guidance on acceptable disposal practices.
Incinerate cypermethrin in a unit with
effluent gas scrubbing. (Peer-review conclusions of an IRPTC expert (May 1985)).
Incineration 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. /Pyrethrin products/
Occupational Exposure Standards:
Manufacturing/Use Information:
Major Uses:
For Cypermethrin (USEPA/OPP Pesticide Code:
109702) ACTIVE products with label matches. /SRP: Registered for use in the U.S. but
approved pesticide uses may change periodically and so federal, state and local
authorities must be consulted for currently approved uses./
Control of a wide range of insects; control of flies in animal houses; and mosquitoes,
cockroaches, houseflies, and other insects pests in public health.
Insecticide
MEDICATION (VET)
MEDICATION
Manufacturers:
AstraZeneca LP, Zeneca Ag Products, 725 Chesterbrook Blvd., Wayne, PA 19087, (800)
237-8898; Production site: Cold Creek, AL 36512
FMC Corp., Agricultural Products Group, 200 E. Randolph Dr., Chicago, IL 60601, (312)
861-6000; Production site: Baltimore, MD 21226
Methods of Manufacturing:
Prepared from 3-phenoxybenzaldehyde and 3-(2,2-dichlorovinyl)2,2-dimethylcyclopropane
carboxylic acid (esterification)
General Manufacturing Information:
Cypermethrin is a mixture of 4
diastereoismers, each of which is present as a pair of enantiomers. The ratio of the 2
enantiomers in each diastereoisomer is 1:1.
Potent synthetic pyrethroid insecticide. Commercial product is a mixture of eight
isomers.
Incompatible with alkaline materials.
/Pyrethroids/ are modern synthetic insecticides similar chemically to natural
pyrethrins, but modified to increase stability in the natural environment. /Pyrethroids/
Introduced commercially in 1977 as an emulsifiable concentrate to be used against a
wide range of insect pests.
Experimental photostable pyrethroid
Formulations/Preparations:
USEPA/OPP Pesticide Code 109-702; Trade Names: Cymbush
2E Insecticide , Cymbush 3E insecticide,
Barricade, Folcord, Imperator, Kafil super, PP 383, Siperin, Flectron,
Ustaad, Cyrux, WL 43467.
25%, 10%, and 5% emulsifiable concentrates and 1.5% ULV; also 400 g/l.
Tech. grade is 90& pure
Emulsifiable concentrate; granules; wettable powder; ultra-low volume liquid.
Mixtures: (cypermethrin +) monocrotophos;
phefenofos; sulfur; chlorofenvinphos
Consumption Patterns:
In 1992, the estimated annual agricultural application of cypermethrin
in the United States was 98 metric tons.
Laboratory Methods:
Analytic Laboratory Methods:
AOAC Method 986.02. Cypermethrin isomers in
pesticide formulations are determined by capillary GC method with FID. Detection limit not
specified.
AOAC Method 985.03. Cypermethrin in Pesticide
Formulations by Capillary Column Gas Chromatography. Detection limit not specified.
Product analysis is by HPLC or by GLC with flame ionization detector. Residues may be
determined by GLC with ECD.
AOAC Method 982.02. Pyrethrins in pesticide formulations are analyzed using gas
chromatography equipped with FID. Average recovery is 98% with a precision of
0.0044-0.011. Detection limit not specified. /Pyrethrins/
... Liquid chromatography method has been developed to quantitate pyrethrins in
pesticide formulations. ... Detection was monitored at 240 nm. ... Percent coefficients of
variation ranged from 1.39 to 9.68 with the majority less than 5.00. ... /Pyrethrins/
Pyrethrins were detected in soils by gas chromatography after extraction with hexane.
/Pyrethrins/
Low level pyrethrin formulations are extracted with tetrahydrofuran and determined via
capillary gas chromatography with electron capture detection. ... Analysis of 5
formulations gave an average standard deviation of 3.3%. /Pyrethrins/
Special References:
Special Reports:
WHO; Environ Health Criteria 82: Cypermethrin
(1991)
Clark JR et al; Toxicity of pyrethroids to Marine Invertebrates and Fish: A Literature
Review and Test Results with sediment-sorbed chemicals; Environ Toxicol Chem 8 (5):
393-401 (1989). Data on acute and chronic toxicity of permethrin, fenvalerate, cypermethrin, and flucythinate to marine invertebrates
and fishes are reviewed.
ALDRIDGE WN; AN ASSESSMENT OF THE TOXICOLOGICAL PROPERTIES OF PYRETHROIDS AND THEIR
NEUROTOXICITY. CRIT REV TOXICOL 21 (2): 89-104 (1990). REVIEW RESMETHRIN CISMETHRIN
PERMETHRIN CIS PERMETHRIN DELTAMETHRIN CYFLUTHRIN CYPERMETHRIN
CIS CYPERMETHRIN TRANS CYPERMETHRIN
ALPHAMETHRIN FENPROPATHRIN FENVALERATE FLUCYTHRINATE FLUVALINATE INSECTICIDE PARASTHESIA
TOXICOKINETICS
BRADBURY SP, COATS JR; TOXICOKINETICS AND TOXICODYNAMICS OF PYRETHROID INSECTICIDES IN
FISH; SYMPOSIUM ON AQ TOXICOL OF THE SYNTHETIC PYRETHROID INSECTICIDES HELD AT THE 7TH
ANNUAL MEETING OF THE SOCIETY OF ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY, ALEXAND REVIEW
PERMETHRIN CYPERMETHRIN FENVALERATE.
Greenwood R et al; The In Vivo Distribution of Pyrethroid Insecticides During Insect
Poisoning. Pestic Sci 30 (1): 97-122 (1990). The distribution of pyrethroids in insects
has been studied using a combination of mathematical modelling and experimental
observation. ...
Mian LS, Mulla MS; Effects of Pyrethroid Insecticides on Nontarget Invertebratesin
Aquatic Ecosystems. J Agric Entomol 9 (2): 73-98 (1992). This review presents data on the
impacts of pyrethroid insecticides on nontarget aquatic invertebrates.
Miyamoto J; Environ Health Perspect 14: 15-28 (1976). Degradation, metabolism, and
toxicity of synthetic pyrethroids.
Miyamoto J, et al; Pure Appl Chem 53: 1967-2022 (1981). The chemistry, metabolism, and
residue analysis of synthetic pyrethroids.
Hutson DH; Progress in Drug Metabolism 3: 215-252 (1979). The metabolic fate of
synthetic pyrethroid insecticides in mammals.
Gammon DW; Fundam Appl Toxicol (5) 1: 9-23 (1985). Correlations between in vitro and in
vivo mechanisms of pyrethroid insecticide action.
Casida JE et al; Ann Rev Pharmacol Toxicol 23: 413-38 (1983). The mechanisms of
selective action of pyrethroid insecticide are discussed.
Papadopoulou-Mourkidou E; Residue Rev 89: 179-208 (1983). A review with many references
on analysis of allethrin & other pyrethroid insecticides.
Synonyms and Identifiers:
Related HSDB Records:
6554 [ALPHACYPERMETHRIN]
Synonyms:
Agrothrin
**PEER REVIEWED**
Ambush C
**PEER REVIEWED**
Ammo
**PEER REVIEWED**
ARDAP
**PEER REVIEWED**
Arrivo
**PEER REVIEWED**
Barricade
**PEER REVIEWED**
CCN52
**PEER REVIEWED**
CNN52
**PEER REVIEWED**
(+)Alpha-cyano-3-phenoxybenzyl-(+)cis,trans-2,2-dichlorovinyl-2,2-
dimethylcyclopropanecarboxylate
**PEER REVIEWED**
(+ -)-Alpha-cyano-3-phenoxybenzyl-(+ -)-cis, trans-3-(2,2-dichlorovinyl)-2,2-
dimethylcyclopropane carboxylate
**PEER REVIEWED**
Cyano(3-phenoxyphenyl)methyl
3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropanecarboxylate.
**PEER REVIEWED**
(Cyano(3-phenoxyphenyl)methyl 3-(2,2-Dichlorovinyl-2,2-dimethylcyclopropane carboxylate
**PEER REVIEWED**
Cymbush
**PEER REVIEWED**
Cypercare
**PEER REVIEWED**
Cypercopal
**PEER REVIEWED**
Cyperkill
**PEER REVIEWED**
Cypermethrine
**PEER REVIEWED**
Cypersect
**PEER REVIEWED**
Cyrux
**PEER REVIEWED**
Demon
**PEER REVIEWED**
3-(2,2-Dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid cyano(3-
phenoxyphenyl)-methyl ester
**PEER REVIEWED**
Dysect
**PEER REVIEWED**
Pesticide Code 109-702
**PEER REVIEWED**
Fastac
**PEER REVIEWED**
Fenom
**PEER REVIEWED**
Flectron
**PEER REVIEWED**
FMC 30980
**PEER REVIEWED**
FMC 45497
**PEER REVIEWED**
FMC 45806
**PEER REVIEWED**
Imperator
**PEER REVIEWED**
JF 5705F
**PEER REVIEWED**
Kalif Super
**PEER REVIEWED**
NRDC 149
**PEER REVIEWED**
NRDC 160
**PEER REVIEWED**
NRDC 166
**PEER REVIEWED**
Nurelle
**PEER REVIEWED**
Polytrin
**PEER REVIEWED**
PP 383
**PEER REVIEWED**
Ripcord
**PEER REVIEWED**
(RS)-Alpha-cyano-3-phenoxybenzyl (1RS)-cis,trans-3-(2,2-dichlorovinyl)-2,2-
dimethylcyclopropanecarboxylate
**PEER REVIEWED**
Rycopel
**PEER REVIEWED**
Sherpa
**PEER REVIEWED**
Siperin
**PEER REVIEWED**
STOCKADE
**PEER REVIEWED**
Topclip Parasol
**PEER REVIEWED**
Toppel
**PEER REVIEWED**
Ustaad
**PEER REVIEWED**
WL 43467
**PEER REVIEWED**
WRDC149
**PEER REVIEWED**
Formulations/Preparations:
USEPA/OPP Pesticide Code 109-702; Trade Names: Cymbush
2E Insecticide , Cymbush 3E insecticide,
Barricade, Folcord, Imperator, Kafil super, PP 383, Siperin, Flectron,
Ustaad, Cyrux, WL 43467.
25%, 10%, and 5% emulsifiable concentrates and 1.5% ULV; also 400 g/l.
Tech. grade is 90& pure
Emulsifiable concentrate; granules; wettable powder; ultra-low volume liquid.
Mixtures: (cypermethrin +) monocrotophos;
phefenofos; sulfur; chlorofenvinphos
Administrative Information:
Hazardous Substances Databank Number: 6600
Last Revision Date: 20011010
Last Review Date: Reviewed by SRP on 5/10/2001
Update History:
Complete Update on 10/10/2001, 55 fields added/edited/deleted.
Field Update on 08/08/2001, 1 field added/edited/deleted.
Field Update on 05/16/2001, 1 field added/edited/deleted.
Complete Update on 09/12/2000, 1 field added/edited/deleted.
Complete Update on 06/12/2000, 1 field added/edited/deleted.
Complete Update on 03/13/2000, 1 field added/edited/deleted.
Complete Update on 02/08/2000, 1 field added/edited/deleted.
Complete Update on 02/02/2000, 1 field added/edited/deleted.
Complete Update on 09/21/1999, 1 field added/edited/deleted.
Complete Update on 08/27/1999, 1 field added/edited/deleted.
Complete Update on 06/08/1999, 7 fields added/edited/deleted.
Field Update on 03/17/1999, 1 field added/edited/deleted.
Field Update on 06/03/1998, 1 field added/edited/deleted.
Field Update on 11/01/1997, 1 field added/edited/deleted.
Field Update on 05/09/1997, 1 field added/edited/deleted.
Complete Update on 03/17/1997, 2 fields added/edited/deleted.
Complete Update on 02/28/1997, 1 field added/edited/deleted.
Complete Update on 10/20/1996, 1 field added/edited/deleted.
Complete Update on 05/14/1996, 1 field added/edited/deleted.
Complete Update on 03/26/1996, 1 field added/edited/deleted.
Complete Update on 03/21/1996, 1 field added/edited/deleted.
Complete Update on 02/01/1996, 1 field added/edited/deleted.
Complete Update on 08/21/1995, 1 field added/edited/deleted.
Complete Update on 04/05/1994, 1 field added/edited/deleted.
Complete Update on 03/01/1994, 72 fields added/edited/deleted.
Record Length: 156160