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  • Permethrin
Name:Permethrin
CAS No:52645-53-1

PRODUCT DESCRIPTION

【Name】

Permethrin (3-(2,2-Dichloroethenyl)-2,2- dimethylcyclopropanecarboxylic acid, (3-phenoxyphenyl)methyl ester)

 Permethrin
【CAS Registry number】
52645-53-1
【Synonyms】
Corsair
Spartan (pesticide)
Mitin BC
Coopex
InsomniaInsorbcid MP
Ecsumin
Dragnet
Ectiban
Cyclopropanecarboxylic acid,3-(2,2-dichloroethenyl)-2,2-dimethyl-,(3-phenoxyphenyl)methyl ester
Riapan A
NIA 33297
S 3151
FMC 41655
Exmin
SBP 15131TEC
Damminix
Ipitox
Perigen
Perigen W
KaleCollards are also indexed at this headingKaleait
Pounce
Stomoxys calcitransStablefly is also indexed at this headingStomozan
Efmethrin
MP 79
KestrelThis heading is used only when the specific taxonomycannot be established from the original documentKestrel (pesticide)
NRDC 143
Chinetrin
Pertrin E
Stomoxin
SBP 1513
Imperator
Kavil
Bematin 987
JF 7065
ICI-PP 557
Cooper
(3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethyl-cyclopropane-1-carboxylate
Anomethrin N
WL 43479
Kudos
Permasect
FMC 33297
Permanone
PP 557
Diffusil H
Adion
m-phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate
NDRC-143
AI3-29158
D-Tetramethrin
Permethrin 95%TC, 25%WP, 50%WP, 25%EC
Permethrin
【EINECS(EC#)】
258-067-9
【Molecular Formula】
C21H20Cl2O3 (Products with the same molecular formula)
【Molecular Weight】
391.29
【Inchi】
InChI=1/C21H20Cl2O3/c1-21(2)17(12-18(22)23)19(21)20(24)25-13-14-7-6-10-16(11-14)26-15-8-4-3-5-9-15/h3-12,17,19H,13H2,1-2H3/t17-,19-/m0/s1
【InChIKey】
RLLPVAHGXHCWKJ-UHFFFAOYSA-N
【Canonical SMILES】
CC1(C(C1C(=O)OCC2=CC(=CC=C2)OC3=CC=CC=C3)C=C(Cl)Cl)C
【Isomers smiles】
CC1([C@H]([C@H]1C(=O)OCC2=CC(=CC=C2)OC3=CC=CC=C3)C=C(Cl)Cl)C
【MOL File】
52645-53-1.mol

Chemical and Physical Properties

【Appearance】
colourless crystals (but the technical productis normally supplied as a pale brown liquid)
【Density】
1.19
【Melting Point】
34-35℃
【Boiling Point】
465.9°Cat760mmHg
【Flash Point】
159.4°C
【Water】
insoluble
【Solubilities】
insoluble
【Color/Form】
Water white to pale yellow; colorless crystals to a viscous liquid
【Stability】
Stable. Incompatible with strong oxidising agents.
【Storage temp】
0-6°C
【Computed Properties】
Molecular Weight:391.2877 [g/mol]
Molecular Formula:C21H20Cl2O3
XLogP3:6.5
H-Bond Donor:0
H-Bond Acceptor:3
Rotatable Bond Count:7
Exact Mass:390.07895
MonoIsotopic Mass:390.07895
Topological Polar Surface Area:35.5
Heavy Atom Count:26
Formal Charge:0
Complexity:521
Isotope Atom Count:0
Defined Atom Stereocenter Count:2
Undefined Atom Stereocenter Count:0
Defined Bond Stereocenter Count:0
Undefined Bond Stereocenter Count:0
Covalently-Bonded Unit Count:1
Feature 3D Acceptor Count:2
Feature 3D Hydrophobe Count:1
Feature 3D Ring Count:2
Effective Rotor Count:7.6
Conformer Sampling RMSD:1
CID Conformer Count:356

Safety and Handling

【Hazard Codes】
Xn: Harmful;N: Dangerous for the environment;T: Toxic;F: Flammable;
【Risk Statements】
R20/22
【Safety Statements 】
13-24-36/37/39-60-61-45-36/37-16-7-26
【Safety】

Poison by inhalation, intravenous, and intracerebral routes. Moderately toxic by ingestion. Experimental reproductive effects. Mutation data reported. A skin irritant. When heated to decomposition it emits toxic fumes of Cl?. See also ESTERS.
Hazard Codes:?HarmfulXn,DangerousN,ToxicT,FlammableF 
Risk Statements: 20/22-43-50/53-39/23/24/25-23/24/25-11-51/53-36-20/21/22?
R20/22:Harmful by inhalation and if swallowed.?
R43:May cause sensitization by skin contact.?
R50/53:Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.?
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed.?
R39:Danger of very serious irreversible effects.?
R11:Highly flammable.?
R51/53:Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.?
R36:Irritating to eyes.?
R20/21/22:Harmful by inhalation, in contact with skin and if swallowed. 
Safety Statements: 13-24-36/37/39-60-61-45-36/37-16-7-26?
S13:Keep away from food, drink and animal foodstuffs.?
S24:Avoid contact with skin.?
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection.?
S60:This material and its container must be disposed of as hazardous waste.?
S61:Avoid release to the environment. Refer to special instructions / safety data sheets.?
S45:In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.)?
S36/37:Wear suitable protective clothing and gloves.?
S16:Keep away from sources of ignition.?
S7:Keep container tightly closed.?
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
RIDADR: UN1230 3/PG 2 
RTECS: GZ1255000

【Skin, Eye, and Respiratory Irritations】
Mild irritant to skin and eyes. /Technical permethrin/
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. /Pyrethroids/
【Transport】
UN1230 3/PG 2
【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/
【Formulations/Preparations】
USEPA/OPP Pesticide Code 109701; Trade Names: Permanone 10, Ambush. Permanone 40, pounce, Matadan, NRDC 143, PP 557, Ectiban, Indothrin, Pramex, AI-29158, Diffusil H, Anomethrin N, Kavil, Perigen.
Emulsifiable concentrate; wettable powder; ULV liquid; fumigant; aerosol; dustable powder; water-dispersible granules.
It is used as a broad-spectrum insecticide in a variety of formulations. The cis/trans ratio varies depending on conditions of manufacture and can also vary with time due to differential rates of hydrolysis and photolysis. A common ratio is 40:60 for agricultural use, with veterinary preparations having lower ratios.
Mixtures (permethrin +) dimethoate; pyrethrins; malathion; tetramethrin; heptenophos; bioallethrin + piperonyl butoxide; primiphos-methyl; chloropyrifos-methyl+pyrethrins; bioallethrins S-cyclopentenyl isomer; bioallethrin S-cyclopentenyl isomer + piperonyl butoxide.
Premixes: Pyra Perm (+ pyrethrins), Tetra Perm (+ tetramethrin), Per Super (+ S-bioallethrin), Tennin (+ tetramethrin), Chinetrin (+ piperonyl butoxide + tetrametrhin), Killout (+ piperonyl butoxide + tetramethrin), Mobeesol (+ piperonyl butoxide + tetramethrin) Duracide P, Super Duracide P (+ piperonyl butoxide + tetramethrin), Permethrin K (+ fenitrothion), Phinoco-T22 (+ piperonyl butoxide + tetramethrin)
【Other Preventative Measures】
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/
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/
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.
【Protective Equipment and Clothing】
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/
【Specification】

? Ambush (CAS NO.52645-53-1), its Synonyms are Cyclopropanecarboxylic acid, 3-(2,2-dichloroethenyl)-2,2-dimethyl-, (3-phenoxyphenyl)methyl ester ; Cyclopropanecarboxylic acid, 3-(2,2-dichlorovinyl)-2,2-dimethyl-, 3-phenoxybenzyl ester, (+-)-, (cis,trans)- ; Permethrin ; m-Phenoxybenzyl 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate ; Ambushfog ; Anomethrin N . It is crystalline solid.

【Octanol/Water Partition Coefficient】
log Kow= 6.50
【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.
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/

Use and Manufacturing

【Use and Manufacturing】
Methods of Manufacturing

3-Phenoxybenzy alcohol + (1RS)-cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboylic acid (esterification)
Consumption Patterns

In 1992, the estimated agricultural use of permethrin in the United States was about 1,055,097 pounds.
【Usage】

Synthetic pyrethroid insectide, more stable to light and at least as active as the natural pyrethrins and with low mammalian toxicity

Biomedical Effects and Toxicity

【Pharmacological Action】
- Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
- Pesticides designed to control insects that are harmful to man. The insects may be directly harmful, as those acting as disease vectors, or indirectly harmful, as destroyers of crops, food products, or textile fabrics.
【Therapeutic Uses】
MEDICATION (VET): ectoparasiticide
Permethrin is a synthetic pyrethroid that has low mammalian toxicity and an insecticidal effectiveness higher that of the natural pyrethrins. Because of its high ovicidal activity and persistence on hair, a properly applied 1% cream rinse preparation eliminates head lice infestation after a single application. Fewer than 1% of patients have required retreatment after seven days.
Permethrin is stressed as a photostable insecticide that is very effective against a large variety of insects and mites with low mammalian toxicity and virtually no allergic side effects. Only 10-20 min after application, permethrin (1% cream rinse or 0.5% in ethanol) proved to be safe, reliable and cosmetically acceptable in the treatment of infestations with head lice and the prevention of reinfestations, and also in failures with lindane owing to the development of tolerance in the lice. The same was true of 5% permethrin cream (2.5% in children below 5 yr of age) used in the treatment of scabies. Permethrin is absorbed percutaneously in only small amounts, is metabolized rapidly in the skin and excreted in the urine. A single "head to toe" application is ideal for eradication programs allowing lice to be targetted and the prevalence of secondary bacterial infections decreased at the same time. [Haustein UF; Hautarzt 42 (1): 9-15 (1991)]
【Biomedical Effects and Toxicity】
Lactating cows (three/group) fed permethrin at dose levels of 0, 0.2, 1.0, 10, 50 mg/kg diet for 28 days showed no mortality, & growth & milk production were normal. Permethrin residues were observed in the milk within 3 days at the two highest dietary levels; levels appeared to reach a plateau rapidly & not to incr with time. Analysis of individual cis & trans isomers showed that the ratio of permethrin isomers in milk appeared to change during the course of the study with the cis isomer predominating. Permethrin residues were not found in the tissues of animals that received doses of 1 mg/kg or less. At dose levels of 10 or 50 mg/kg, residues were detected in the tissues, predominantly in the fat. Low levels were also present in the muscle & kidney at the highest dose level. Permethrin did not appear to accumulate in the fat but to reach a plateau rapidly.
(14)C-cis-Permethrin was applied to the clipped skin of mice at a level of 1 mg/kg body weight in 0.1 ml of acetone. The mice were restrained until the solvent had evaporated and then placed in mouse metabolism cages. They were sacrificed at 1, 5, 15, 50, 480, and 2880 min after treatment and examined for absorption, distribution, and excretion of the insecticide. About 40% of the applied permethrin had moved from the site of application within 5 min and appeared to move rapidly to other parts of the body.
When ten consecutive oral doses of (14)C-trans- or (14)C-cis- permethrin (labelled in the acid or alcohol moieties) at 0.2-0.3 mg/kg bw/day were given to lactating goats, they excreted 72-79% & 25-36% of the trans & cis isomer doses, respectively, in urine & 12-15%, respectively, in the feces. The amounts of the radiocarbon appearing in the milk were 0.04 mg/kg for the trans isomer or 0.25 mg/kg for the cis isomer.
Two human volunteers, who consumed about 2 and 4 mg of permethrin (25:75), respectively, excreted 18-37% and 32-39% of the administered dose, detected as the metabolite Cl2CA, after acid hydrolysis of their urine collected over 24 hr.
To assess the human tolerance, absorption, & persistence of permethrin when used against human lice, ten adult volunteers (four men, six women) were treated with 15-40 ml of permethrin (25:75) (1%) head louse solution. Their hair was allowed to dry naturally & then washed with baby shampoo. Urine samples were collected at 0-24, 24-48, 120-144, & 336-360 hr to measure dermal absorption. Permethrin excretion during the first 24 hr was only about 1% of the applied dose, while the cumulative maximum over 14 days was only about 5.5 mg.
To assess the safety of permethrin dusts for the control of human body lice, approximately 350 people were individually dusted with 50 g of powder containing either 2.5 or 5.0 g permethrin/kg. Urine samples, taken at the time of treatment and subsequently, indicated that maximal absorption of permethrin was 39 ug/kg, 24 hr after treatment.
Ten scabies patients (five men and five women) had about 25 g (range 21-32 g) of a 5% permethrin cream applied to the skin of the whole body, with the exception of the head and neck. Dermal absorption of permethrin was calculated from the quantity of conjugated and nonconjugated cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (CVA) metabolites of permetherin determined in the urine. In samples of urine collected by seven patients one and two days after application of the permethrin cream, 414 and 439 ug mean total CVA were found, respectively. The mean total CVA in the urine of three patients who collected their urine in the same container for two days was 1435 ug. The urinary concentration of trans-CVA varied during the first 48 hours from 0.11 to 1.07 ug/ml and that of the cis-isomer form 0.02 to 0.21 ug/ml. CVA was still detectable in the urine of three patients after a week and in the urine of one patient, reported to be an alcoholic, after two weeks. The absorption of permethrin over the first 48 hours after application was estimated from the urinary CVA excretion levels to be 6 mg (range, 3-11 mg), i.e., 0.5% of the dose applied.
Penetration of pesticides through the GI tract compound: permethrin; species: mouse; application site: oral; solvent: emulfor; penetration parameter: 39%, 1 hr; Method: GI content. /From table/
Dermal penetration of pesticides. Compound: permethrin; species; mouse; Application site: dermal; Solvent: acetone; Penetration-parameter: 80%, 1 hr; Method: patch. /From table/
Dermal penetration of pesticides. Compound: permethrin; species: roach; application site: dermal; solvent: acetone; penetration: 24%, 1 hr; Method: patch. /From table/
Dermal penetration of pesticides. Compound: permethrin; species: hornworm; application site: dermal; solvent: acetone; penetration parameters: 15%, 1 hr; Method: patch. /From table/
Dermal penetration of pesticides. Compound: permethrin; species: frog; Applicaton site: dermal; Solvent: acetone; Penetraton parameters: 20%, 1 hr; Method: patch. /From table/
A 25% water-wettable powder formulation of permethrin was applied as an indoor residual spray at a target dosage of 0.5 g/sq m. One bagger, one mixer, and three spraymen treated a village in 2 days. Each man wore overalls (washed daily) shoes, and a hat. The mixer wore a cartridge-type respirator and rubber gloves. The bagger wore the same plus an apron. The spraymen did not wear masks. All practiced good personal hygiene. The men were examined before and 1 day after exposure. No complaints were received, and no abnormalities were detected. Based on the measurement of metabolites in the urine, it was estimated that one sprayman absorbed from 1 to 2 mg in each 12-hour period of work, but that the other men absorbed 
Whereas permethrin is relatively stable to air and light, rats readily metabolize both the [1R-trans]- and [1C-cis]-esters by ester cleavage, by hydroxylaton of a geminal dimethyl group in the acid or the pheoxy group of the alcohol, and by conjugation of the resulting carboxylic acids and phenols. The metabolites are quickly excreted and do not persist significantly in the tissues. In spite of the rapid metabolism of each dose, residues of unmetabolized compound did persist 12 or 13 days in mild fat and in other fat of cows that received (14)C-permethrin by mouth at a rate of about 1 mg/kg for 3 consecutive days.
Less than 2% of an applied topical dose is absorbed systemically. The compound is rapidly metabolized by ester hydrolysis to inactive metabolites that are excreted in the urine. Permethrin persists on hair for at least 10 days.
A study was conducted to define permethrin toxicokinetics in Sprague-Dawley rats after iv (iv) administration and to assess its oral bioavailability. Orally dosed rats received a single dose of 460 mg/kg by gastric intubation. Injected rats received 46 mg/kg iv. All animals were sacrificed at 0.25, 0.5, 1, 2, 3, 4, 6, 8, 12, 24, or 48 hr after dosing. For permethrin the elimination half life and the mean residence time from plasma were 8.67 and 11.19 hr after iv and 12.37 and 17.77 hr after oral administration. The total plasma clearance was not influenced by dose concentration or route and reached a value of 0.058 l/hr. After a single oral dose permethrin was absorbed slowly. The maximum plasma concentration was 49.46 ug/milliliter. The oral bioavailability of permethrin was 60.69%. The plasma concentration time data for permethrin metabolites as well as the tissue concentration time data for permethrin and its metabolites after an oral dose of permethrin were found to fit a one compartment open model. The maximum amounts of permethrin in cerebellum, hippocampus, caudata putamen, frontal cortex, hypothalamus, and sciatic nerve were about 1.5, 2, 2, 2.7, 4.8, and 7.5 times higher than in plasma, respectively, suggesting an accumulation of pyrethroids by nervous tissue itself. The metabolites of permethrin, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, were detected in plasma and in all selected tissues for 48 hr after dosing, suggesting that a combination of metabolism by the tissues and diffusion into it from the blood may be present. [Anadon A et al; Toxicol Appl Pharmacol 110 (1): 1-8 (1991)] PubMed Abstract
/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/ [MIYAMOTO J; ENVIRON HEALTH PERSPECT 14: 15-28 (1976)] PubMed Abstract
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/
In spraying trials in Kenya it was estimated that permethrin absorption did not exceed 2 mg per 12 hr period. After oral dosage of 2 or 4 mg permethrin, urinary excretion accounted for 18 or 35% of the dose, with most being excreted over the first 12 hr.

Environmental Fate and Exposure Potential

【Environmental Fate/Exposure Summary】
TERRESTRIAL FATE: Based on a classification scheme(1), Koc values ranging from 10,471 to 86,000(2,3), indicates that permethrin is expected to be immobile in soil(SRC). Volatilization of permethrin from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.9X10-6 atm-cu m/mole(SRC), derived from its vapor pressure, 2.18X10-8 mm Hg(2), and water solubility, 6.00X10-3 mg/l(2). However, adsorption to soil is expected to attenuate volatilization(SRC). Permethrin is not expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(2). The biodegradation half-life of permethrin in aerobically incubated soil was less than 4 weeks, and the degradation of the trans-isomer is more rapid than the cis-isomer(4). In two Japanese soils, both the 1R, trans- and 1R, cis-isomers were rapidly degraded under dry conditions with half-lives of less than 2 days(5). Under anaerobic conditions in flooded silt loam soils, degradation half-lives were 32-34 days for 14C-labeled trans-permethrin and greater than 64 days for 14C-labeled cis-permethrin(4). Field dissipation half-lives for permethrin range from 6 to 106 days(2).
AQUATIC FATE: Based on a classification scheme(1), Koc values ranging from 10,471 to 86,000(2,3), indicates that permethrin is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(4) based upon an estimated Henry's Law constant of 1.9X10-6 atm-cu m/mole(SRC), derived from its vapor pressure, 2.18X10-8 mm Hg(2), and water solubility, 6.00x10-3 mg/l(2). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 26 days and 289 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column(SRC). The estimated volatilization half-life from a model pond is 336 years if adsorption is considered(5). At pH 5 and pH 7, permethrin is stable towards abiotic hydrolysis(2); at pH 9, the abiotic hydrolysis rate constant is 0.0139 per day at 25 deg C(2) which corresponds to a half-life of 50 days(SRC). According to a classification scheme(6), BCF values of approx 560 and 480 for rainbow trout (Oncorhynchus mykiss) and sheepshead minnow (Cyprinodon vagiegatus), respectively(7,8), suggests the potential for bioconcentration in aquatic organisms is high(SRC). In water, the photolysis rate constant is 0.021 per day(2); this corresponds to photodegradation half-life of 33 days(SRC). Photolysis half-lives of 27.1 and 19.6 hrs were determined for respective cis- and trans-isomers in 800 ml pond water exposed to sunlight(9). The photolysis half-life of permethrin in seawater exposed to outdoor light was determined to be 14 days(8). The biodegradation half-life of permethrin in a sediment-seawater solution was less than 2.5 days; under sterile conditions there was no significant change in permethrin concn(8).
ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), permethrin, which has a vapor pressure of 2.18X10-8 mm Hg at 25 deg C(2), will exist in both the vapor and particulate phases in the ambient atmosphere(SRC). Vapor-phase permethrin is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone(SRC); the half-life for reaction with hydroxyl radicals in air is estimated to be 9.8 hours(SRC), calculated from its rate constant of 3.9X10-11 cu cm/molecule-sec at 25 deg C(3); the half-life for reaction with ozone in air is estimated to be 49 days(SRC), calculated from its rate constant of 2.3X10-19 cu cm/molecule-sec at 25 deg C(4). Particulate-phase permethrin may be removed from the air by wet and dry deposition(SRC). Permethrin absorbs light in the environmental spectrum(5) and has the potential for direct photolysis(SRC).

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