Cyhalothrin

Pesticide -> EPA IRIS

Insecticides

Active substance -> EU Pesticides database: Not approved

Pesticides -> Pyrethrins/Pyrethroids

Environmental transformation -> Pesticides (parent, predecessor)

Pesticide

log Kow = 6.8

6.9

6.02

1.25 at 25 °C

Relative density (water = 1): 1.2

In acetone, dichloromethane, methanol, diethyl ether, ethyl acetate, hexane, toluene, all >500 g/L (20 °C)

In water, 5.0X10-3 mg/L, temp not specified

Solubility in water: none

Does not boil at atmospheric pressure

BP: 187-190 °C at 2 mm Hg

HAZARDOUS DECOMPOSITION PRODUCTS: Carbon monoxide, hydrogen chloride, hydrogen fluoride, nitrogen oxides, hydrogen cyanide, and various chlorinated and fluorinated organic compounds. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

Decomposes at 275 °C

When heated to decomp it emits toxic vapors of /nitrogen oxides, fluoride, chloride/.

275 °C

0.00000001 [mmHg]

Vapor pressure, Pa at 20 °C:

Cyhalothrin is a colorless solid. Insoluble in water. Used as a wide spectrum insecticide.

Yellow-brown viscous liquid (technical product); [ICSC]; [HSDB] Colorless solid; [CAMEO]

YELLOW-BROWN VISCOUS (TECHNICAL-GRADE PRODUCT) LIQUID WITH CHARACTERISTIC ODOUR.

Danger

H301 (98.6%): Toxic if swallowed [Danger Acute toxicity, oral]

P260, P261, P264, P264+P265, P270, P271, P272, P273, P280, P284, P301+P316, P302+P352, P304+P340, P305+P351+P338, P316, P317, P320, P321, P330, P332+P317, P333+P317, P337+P317, P362+P364, P391, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 70 reports by companies from 6 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Hazard Traits - Developmental Toxicity; Endocrine Toxicity; Environmental tox; Neurotoxicity; Other Toxicological Hazard Traits; Reproductive Toxicity

Commission Regulation (EU) No 188/2011

Cyhalothrin is listed in the dataset of EPA Human Health Benchmarks for Pesticides under the Safe Drinking Water Act (40 eCFR 141)

94/643/EC

Cyhalothrin: HSNO Approval: HSR002832 Approved with controls

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

Combustible. Liquid formulations containing organic solvents may be flammable. Gives off irritating or toxic fumes (or gases) in a fire.

Commercial product is 95% cis isomer; A synthetic pyrethroid; [Merck Index] A skin, eye, and respiratory tract irritant; May cause skin sensitization; The substance may cause effects on the nerve terminals of the skin , resulting in subjective facial skin sensation characterized by tingling, burning or numb sensation. [ICSC] Caused weight loss in rats fed 250 mg/kg/day for 90 days; [HSDB] A moderate skin sensitizer in guinea-pig testing; [Reference #1] See Pyrethrum.

WHO; Environmental Health Criteria 99: Cyhalothrin (1990). EHC are designed for scientists and administrators responsible for the establishment of safety standards and regulations and provide basic scientific risk evaluations of a wide range of chemicals and groups of chemicals.[Available from, as of February 16, 2011: http://www.inchem.org/documents/ehc/ehc/ehc99.htm]

WHO; Health and Safety Guide (1990). This is a companion volume to Environmental Health Criteria 99: Cyhalothrin.[Available from, as of Februray 16, 2011: http://www.inchem.org/documents/hsg/hsg/hsg038.htm]

ATSDR; Toxicological Profile for Pyrethrins and Pyrethroids (2003)[Available from, as of February 16, 2011: http://www.atsdr.cdc.gov/toxprofiles/tp155.pdf]

National Poisons Information Service; UKPID Monograph - Cyhalothrin. This monograph was commissioned and funded by the UK Departments of Health, and was designed as a source of detailed information for use by poisons information centers.[Available from, as of February 16, 2011: http://www.inchem.org/documents/ukpids/ukpids/ukpid59.htm]

Tolerances are established for the combined residues of the pyrethroid lambda-cyhalothrin, 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and its epimer expressed as epimer of lambda-cyhalothrin, a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate, on plants and livestocks, as indicated in the following table. /lambda-Cyhalothrin/ [Table#6286]

Tolerances are established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer of lambda-cyhalothrin) ( S )-'-cyano-3-phenoxybenzyl ( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate)) and its epimer ( R )-'-cyano-3-phenoxybenzyl ( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate in/on the following commodities: /gamma-Cyhalothrin/ [Table#6287]

A tolerance ... is established for residues of the insecticide lamba-cyhalothrin and an isomer gamma-cyhalothrin in or on all food commodities (other than those already covered by a higher tolerance as a result of use on growing crops) in food-handling establishments where food products are held, processed, or prepared. /lambda-Cyhalothrin, gamma-Cyhaloathrin/

Time-limited tolerances are established for combined residues of the insecticide lambda-cyhalothrin (a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and (R)-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and its epimer a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl -( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclo-propanecarboxylate in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. The tolerances will expire and are revoked on the dates specified in the following table: /lambda-Cyhalothrin/ [Table#6288]

For more FIFRA Requirements (Complete) data for CYHALOTHRIN (6 total), please visit the HSDB record page.

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

Use alcohol-resistant foam, dry sand, powder, carbon dioxide. NO water.

Fresh air, rest.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Do NOT induce vomiting. Refer for medical attention .

EXTINGUISHING MEDIA: Dry chemical or carbon dioxide for small fires, and water spray or foam for large fires. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

FIRE AND EXPLOSION HAZARDS: Foam fire extinguishing system is preferred because uncontrolled water can spread possible contamination. Toxic irritating gases may be formed under fire conditions. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

FIRE-FIGHTING EQUIPMENT: Use a positive-pressure self-contained breathing apparatus or positive-pressure airline with auxiliary self-contained air supply and full protective equipment. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

Extinguish fire using agent suitable for type of surrounding fire. /Pyrethrins/

Keep away from food, feedstuffs, and water supplies. Store in original container with the lid tightly closed. Avoid extremes of cold and hot temperatures. Prolonged storage can cause a slight settling, lightly shake container before use. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

Store in original containers only. Keep container closed when not in use. Do not store near food or feed. .. Do not allow product to freeze. /Warrior II with Zeon Technology, 22.8% lambda-Cyhalothrin/

Do not store near feed, food or within reach of children.

Pyrethrins with piperonyl butoxide topical preparations should be stored in well-closed containers at a temperature less than 40 °C, preferably between 15-30 °C. /Pyrethrins/

Absorb small spills with materials such as sand, sawdust, Zorball, or dirt. Wash exposed body areas thoroughly after handling. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

In case of spill or leak on floor or paved surfaces, soak up with sand, earth, or synthetic absorbent. Remove to chemical waste area. /Warrior II with Zeon Technology, 22.8% lambda-Cyhalothrin/

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal and plant life; and conformance with environmental and public health regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Pesticide wastes are acutely hazardous. Improper disposal of excess pesticide, spray mixture, or rinsate is a violation of Federal law. If these wastes cannot be disposed of by use according to label instructions, contact your State Pesticide or Environmental Control Agency, or the Hazardous Waste Representative at the nearest EPA Regional Office for guidance. /Warrior II with Zeon Technology, 22.8% lambda-Cyhalothrin/

Container Handling [less than 5 gallons]: Non-refillable container. Do not reuse or refill this container. Offer for recycling if available. Triple rinse container (or equivalent) promptly after emptying. Triple rinse as follows: Empty the remaining contents into application equipment or a mix tank and drain for 10 seconds after the flow begins to drip. Fill the container 1/4 full with water and recap. Shake for 10 seconds. Pour rinsate into application equipment or a mix tank or store rinsate for later use and disposal. Drain for 10 seconds after the flow begins to drip. Repeat this procedure two more times. Then offer for recycling if available or puncture and dispose of in a sanitary landfill, or by incineration, or, if allowed by state and local authorities, by burning. If burned, stay out of smoke. /Warrior II with Zeon Technology, 22.8% lambda-Cyhalothrin/

Container Handling [Bulk/Mini-Bulk]: Refillable container. Refill this container with pesticide only. Do not reuse this container for any other purpose. Cleaning the container before final disposal is the responsibility of the person disposing of the container. Cleaning before refilling is the responsibility of the person refilling. To clean container before final disposal, empty the remaining contents from this container into application equipment or mix tank. Fill the container about 10 percent full with water. Agitate vigorously or recirculate water with the pump for 2 minutes. Pour or pump rinsate into application equipment or rinsate collection system. Repeat this rinsing procedure two more times. Then offer for recycling if available or puncture and dispose of in a sanitary landfill, or by incineration, or, if allowed by state and local authorities, by burning. If burned, stay out of smoke. /Warrior II with Zeon Technology, 22.8% lambda-Cyhalothrin/

Use protective clothing chemically resistant to this material. Selection of specific items such as face shield, boots, apron, or full body suit will depend on the task. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

Remove contaminated clothing immediately, wash skin area with soap and water, and launder clothing before reuse or dispose of properly. Items which cannot be decontaminated, such as shoes, belts and watchbands, should be removed and disposed of properly. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

Wash thoroughly with soap and water after handling and before eating, chewing gum, using tobacco, using the toilet or smoking. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

FIRST AID. EYE: Hold eyes open and rinse slowly and gently with water for 15-20 minutes. Remove contact lenses, if present, after the first 5 minutes, and then continue rinsing eyes. Call a poison control center or doctor for treatment advice. /Declare Insecticide, 14.4 % gamma-Cyhalothrin/

For more Preventive Measures (Complete) data for CYHALOTHRIN (23 total), please visit the HSDB record page.

Following oral exposure, the 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. Following inhalation exposure, 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 inhaled beta2 agonist and oral or parenteral corticosteroids. In case of eye exposure, irrigate exposed eyes with copious amounts of room temperature water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility. If the contamination occurs through dermal exposure, 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. Vitamin E topical application is highly effective in relieving parenthesis. (L363)

/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/

The objective ... study was to analyze the reproductive toxicity caused by lambda-cyhalothrin (LCT) in male rabbits, and to evaluate the possible protective effect of vitamin E (Vit. E) as antioxidant. Animals were orally administered their respective doses of LCT every other day and given drinking water supplemented with vitamin E for 16 weeks. ...Semen quality was deteriorated following treatment with LCT. Also, testosterone levels, body weight (BW), feed intake (FI), and relative testes (RTW) and epididymis (REW) weights were significantly decreased. Concentrations of thiobarbituric acid-reactive substances (TBARS) were significantly increased in seminal plasma of rabbits treated with LCT compared with control. Activities of glutathione S-transferase (GST), transaminases and acid phosphatase (AcP) were significantly decreased. Vitamin E alone significantly increased testosterone levels, BW, FI, RTW, REW, semen characteristics and seminal plasma enzymes, and decreased the levels of TBARS. ... It was suggested that LCT exerted a significant adverse effect on reproductive performance of male rabbits. Furthermore, vitamin E antagonized the toxic effects of LCT and improved semen quality of male rabbit. /lambda-Cyhalothrin/

For more Interactions (Complete) data for CYHALOTHRIN (6 total), please visit the HSDB record page.

At high doses, signs of poisoning attributable to cyhalothrin include profuse salivation and pulmonary edema, clonic seizures, opisthotonos (i.e., the spine is bent forward such that a supine body rests on its head and heels), coma, and death. At lower doses, commonly observed effects include paresthesia and erythema. (L863)

LD50; Species: Anas platyrhynchos (Mallard duck) oral >3950 mg a.i./kg bw /lambda-cyhalothrin/

LD50; Species: Anas platyrhynchos (Mallard duck) oral >5000 mg/kg

LC50; Species: Anas platyrhynchos (Mallard duck) diet 3948 mg a.i./kg diet for 8 days /lambda-cyhalothrin/

LC50; Species: Anas platyrhynchos (Mallard duck) diet >4430 mg a.i./kg diet for 8 days /gamma-cyhalothrin/

For more Ecotoxicity Values (Complete) data for CYHALOTHRIN (32 total), please visit the HSDB record page.

TERRESTRIAL FATE: Based on a classification scheme(1), Koc values of >80,000 to 182,000(2,3) indicate that cyhalothrin is expected to be immobile in soil(SRC). Volatilization of cyhalothrin from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 1.4X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(4). However, adsorption to soil is expected to attenuate volatilization(SRC). Cyhalothrin is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.1X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(5). Biodegradation half-lives for cyhalothrin have been reported as 4-12 weeks in soil(6), suggesting that biodegradation may be an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), Koc values of >80,000 to 182,000(2,3) indicate that cyhalothrin 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 1.4X10-5 atm-cu m/mole(SRC), developed using a fragment constant estimation method(5). Using this Henry's Law constant and an estimation method(4), volatilization half-lives for a model river and model lake are 6 and 50 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is 48 to 110 years if adsorption is considered(5). According to a classification scheme(6), a BCF of 19 reported in bluegill(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Cyhalothrin was found to be stable to hydrolysis at pH 5 and 7, and had a half-life of 7 days at pH 9(8). Loss of cyhalothrin in the light was <10% after 20 months(8). Biodegradation half-lives in soil for cyhalothrin have been reported as 4-12 weeks(8), suggesting that biodegradation may be an important environmental fate process in water(SRC).

AQUATIC FATE: To investigate the influence of aquatic plants on the fate and behavior of the pyrethroid insecticide lambda-cyhalothrin, two laboratory experiments (to assess adsorption and degradation) and an indoor microcosm study (to assess fate under semirealistic conditions) were conducted. In the laboratory studies, adsorption to macrophytes was extensive and essentially irreversible, and degradation occurred rapidly by cleavage of the ester bond. In the indoor microcosm, which contained water, sediment, and macrophytes from a pond, degradation was also rapid, with DT50 and DT90 values of less than 3 and 19 hr, respectively, for dissipation from the water column and of less than 3 and 56 hr, respectively, for the whole system. For ... readily degraded pesticides like lambda-cyhalothrin ... macrophytes have considerable influence on fate and behavior in surface waters. /lambda-Cyhalothrin/

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), cyhalothrin, which has an estimated vapor pressure of 1.1X10-6 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase cyhalothrin is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 12 hours(SRC), calculated from its rate constant of 3.1X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). The rate constant for the vapor-phase reaction of cyhalothrin with ozone has been estimated as 1.6X10-18 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). This corresponds to an atmospheric half-life of about 7 days at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(4). Particulate-phase cyhalothrin may be removed from the air by wet or dry deposition(SRC). Cyhalothrin does not contain chromophores that absorb at wavelengths >290 nm(5) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

Cyhalothrin residues have been detected in domestic apples (16 out of 2,464 samples) at a maximum concn of 0.4 ppm, imported apples (6 out of 735 samples) at a maximum concn of 0.50 ppm, domestic pears (14 out of 571 samples) at a maximum concn of 0.4 ppm, imported pears (5 out of 816 samples) at a maximum concn of 0.5 ppm, and imported oranges (4 out of 474 samples) at a maximum concn of 0.5 ppm in a survey of domestic and imported foods which may be eaten by infants/children during 1985-1991(1). Cyhalothrin concns were measured by means of capillary gas chromatography using extraction with ethyl acetate and dichloromethane from an assortment of vegetable and fruit samples(2). Cyhalothrin concns ranged from 68.2 to 91.6 ppm for those samples measured with ethyl acetate extraction(2), while concns ranged from 61.2 to 94 ppm for those samples measured with dichloromethane extraction(2). Cyhalothrin was detected, concn unreported, in one out of 18 dried bean samples in the 1995-1996 Danish National Pesticide Monitoring Program(3). The compound was detected at an avg concn of 0.07 ug/g in peas from farms in Delhi, India during 1992-93(4).

Cyhalothrin was detected in garlic, potato, turnip, mint, spinach, chilies, lady fingers, peas, tomato, cabbage and cauliflower but not detected in carrot, ginger, onion, radish, sugar beet, Brassica leaves, coriander, methi, salad, brinjal, bitter gourd, french beans, Indian squash, cucumber and pumpkin, Lady's fingers, luffa, cabbage and cauliflower, in a study conducted in Karachi, Pakistan 2000 to 2003(1). Of 173 agricultural products analyzed in 2006 in Japan, one was reported to contain cyhalothrin at 8.9 ng/g(2).

The substance can be absorbed into the body by inhalation of its aerosol and by ingestion.

Inhalation (L857) ; oral (L857) ; dermal (L857) ; eye contact (L857).

Metabolic studies have been carried out on /various mammalian species/. In rats and dogs, cyhalothrin has been shown to be well absorbed after oral administration, extensively metabolized, and eliminated as polar conjugates in urine. ... Residues in rats were eliminated with a half-life of 23 days. ... In all mammalian species investigated, cyhalothrin has been found to be extensively metabolized as a result of ester cleavage to the cyclopropanecarboxylic acid and 3-phenoxybenzoic acid, and eliminated as conjugates. In fish, the main residue in tissues consists of unchanged cyhalothrin, and there are lower levels of the ester cleavage products. Under laboratory conditions of constant toxicant concentrations, cyhalothrin and lambda-cyhalothrin are highly toxic to fish and to aquatic invertebrates. ... Accumulation studies conducted under laboratory conditions with constant concentration show that rapid uptake takes place in fish ... Since the compound is rapidly absorbed and degraded under natural conditions, there will not be any practical problems concerning the accumulation of residues or the toxicity of cyhalothrin or lambda-cyhalothrin in aquatic species. Cyhalothrin and lambda-cyhalothrin are virtually non-toxic to birds ... Under laboratory conditions, cyhalothrin and lambda-cyhalothrin are toxic to honey bees ... However, in the field the hazard is lower ... Cyhalothrin and lambda-cyhalothrin are type II pyrethroids; clinical signs /of toxicity/ include ataxia, unsteady gait, and hyperexcitability. In the rabbit, cyhalothrin is a moderate eye irritant and lambda-cyhalothrin is a mild eye irritant; both are mild skin irritants. /Cyhalothrin/ is a moderate skin sensitizer in the guinea pig. Lambda-cyhalothrin is not a skin sensitizer. ... Cyhalothrin and lambda-cyhalothrin gave negative results in a range of in vivo and in vitro assays designed to detect gene mutations, chromosomal damage, and other genotoxic effects. When orally administered to the rat and rabbit during the period of major organogenesis, cyhalothrin was neither embryotoxic or teratogenic at dose levels that elicited maternal toxicity ... In manufacturing, formulation, laboratory work and field usage, /human/ symptoms of subjective facial sensation have been reported. ... Subjective facial skin sensations, which may be experienced by people who handle cyhalothrin and lambda-cyhalothrin are believed to be brought about by repetitive firing of sensory nerve terminals in the skin. They may be considered as an early warning signal indicating that overexposure of the skin has occurred. ... The exposure of the general population to cyhalothrin and lambda-cyhalothrin is expected to be very low and is not likely to present a hazard under recommended conditions of use. ... Cyhalothrin and lambda-cyhalothrin are unlikely to present a hazard to those occupationally exposed. ... Under laboratory conditions cyhalothrin and lambda-cyhalothrin are highly toxic to fish, aquatic arthropods, and honey bees. However, under field conditions, lasting adverse effects are not likely to occur under recommended conditions of use.

Both type I and type II pyrethroids exert their effect by prolonging the open phase of the sodium channel gates when a nerve cell is excited. They appear to bind to the membrane lipid phase in the immediate vicinity of the sodium channel, thus modifying the channel kinetics. This blocks the closing of the sodium gates in the nerves, and thus prolongs the return of the membrane potential to its resting state. The repetitive (sensory, motor) neuronal discharge and a prolonged negative afterpotential produces effects quite similar to those produced by DDT, leading to hyperactivity of the nervous system which can result in paralysis and/or death. Other mechanisms of action of pyrethroids include antagonism of gamma-aminobutyric acid (GABA)-mediated inhibition, modulation of nicotinic cholinergic transmission, enhancement of noradrenaline release, and actions on calcium ions. They also inhibit calium channels and Ca2+, Mg2+-ATPase. (T10, T18, L857)

/BIRDS and MAMMALS/ In an 8-day dietary study with mallard duck, the LC50 = 3948 (2868-7602) mg ai/kg diet, and sublethal effects included subdued behavior and unsteadiness in the 2030-5040 mg ai/kg diet treatment levels.

/BIRDS and MAMMALS/ ...Studies were conducted with the bobwhite quail (Colinus virginianus). The study conducted on the technical grade active ingredient (100%) resulted in an LD50 >2000 mg a.i./kg bw during a 14-day observation period, based on mortality. Decreased body weight and food consumption were observed in the treatment birds on days 0-3 compared to the control, but these difference were not observed on days 7 and 14. In another study with a formulated product (XR-225, 14.7% a.i.), the LD50 was also >2000 mg a.i./kg bw during a 14-day observation period, based on mortality. Food consumption in the 1400 and 2000 mg a.i./kg bw treatment group was significantly lower on days 0-3 compared to the control. However, these differences were not observed on days 7 and 14. No significant effects on bodyweight were observed during the study. All dosed groups displayed head twitching behavior indicative of intoxication during the first two days of the study. /gamma-cyhalothrin/

/BIRDS and MAMMALS/ Two avian 8-day dietary studies have been conducted on gamma-cyhalothrin technical. In the dietary study with the mallard duck, after 5 days on treated diets, there were 20 and 40% mortality in the 2400 and 4430 mg a.i./kg diet treatment groups, respectively. The controls and other treatment groups had no mortalities. There were significant reductions in body weight change for all treatment groups during the exposure period. Food consumption decreased as the treatment concentrations increased during the test period. The food consumption improved over the recovery period. The sublethal effects of ataxia, swollen/weepy right eyes, and/or hyporeactivity were observed in the 933, 1430, 2400, and 4430 mg a.i./kg diet treatment groups. The gross pathological findings observed in the 2400 and 4430 mg a.i./kg diet treatment groups were emaciation, lesion/growth on intestines, and/or discoloration of internal organs. The 8-day acute dietary LC50 was >4430 mg a.i./kg diet. The NOAEC was <617 mg a.i./kg diet, based on reductions in body weight. In a dietary study with the bobwhite, quail, after 5 days on treated diets, there was 10, 10, 30, and 90% mortality in the 933, 1430, 2400, and 4430 mg a.i./kg diet treatment groups, respectively. The controls and 617 mg a.i./kg diet treatment group had no mortalities. Significant reductions in body weight change for all treatment groups occurred during the exposure period and these reductions were not apparent during the recovery period. Food consumption decreased as the treatment concentrations increased during the test period. The food consumption improved over the recovery period. The sublethal effects of ataxia, hyporeactivity, and moribundity were observed in the 1430, 2400, and 4430 mg a.i./kg diet treatment groups. No significant gross pathological findings were observed. The 8-day acute dietary LC50 was 2794 mg a.i./kg diet. /gamma-cyhalothrin/

/BIRDS and MAMMALS/ Two avian 8-day dietary studies have been conducted on gamma-cyhalothrin technical. In the dietary study with the mallard duck, after 5 days on treated diets, there were 20 and 40% mortality in the 2400 and 4430 mg a.i./kg diet treatment groups, respectively. The controls and other treatment groups had no mortalities. There were significant reductions in body weight change for all treatment groups during the exposure period. Food consumption decreased as the treatment concentrations increased during the test period. The food consumption improved over the recovery period. The sublethal effects of ataxia, swollen/weepy right eyes, and/or hyporeactivity were observed in the 933, 1430, 2400, and 4430 mg a.i./kg diet treatment groups. The gross pathological findings observed in the 2400 and 4430 mg a.i./kg diet treatment groups were emaciation, lesion/growth on intestines, and/or discoloration of internal organs. The 8-day acute dietary LC50 was >4430 mg a.i./kg diet. The NOAEC was <617 mg a.i./kg diet, based on reductions in body weight. In a dietary study with the bobwhite, quail, after 5 days on treated diets, there was 10, 10, 30, and 90% mortality in the 933, 1430, 2400, and 4430 mg a.i./kg diet treatment groups, respectively. The controls and 617 mg a.i./kg diet treatment group had no mortalities. Significant reductions in body weight change for all treatment groups occurred during the exposure period and these reductions were not apparent during the recovery period. Food consumption decreased as the treatment concentrations increased during the test period. The food consumption improved over the recovery period. The sublethal effects of ataxia, hyporeactivity, and moribundity were observed in the 1430, 2400, and 4430 mg a.i./kg diet treatment groups. No significant gross pathological findings were observed. The 8-day acute dietary LC50 was 2794 mg a.i./kg diet. /gamma-cyhalothrin/

For more Ecotoxicity Excerpts (Complete) data for CYHALOTHRIN (18 total), please visit the HSDB record page.

Burning sensation. Cough. Sore throat.

Numbness. Tingling sensation. Redness.

Redness. Pain.

Following dermal exposure to cyhalothrin, feelings of numbness, itching, burning, stinging, tingling, or warmth may occur, that could last for a few hours. Dizziness, headache, nausea, muscle twitching, reduced energy, and changes in awareness can result from inhalation or ingestion of large amounts of cyhalothrin. Paralysis can occur after exposure. (L857)

Tolerances are established for the combined residues of the pyrethroid lambda-cyhalothrin, 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and its epimer expressed as epimer of lambda-cyhalothrin, a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate, on plants and livestocks, as indicated in the following table. /lambda-Cyhalothrin/ [Table#6286]

Tolerances are established for the combined residues of the pyrethroid [gamma-cyhalothrin (the isolated active isomer of lambda-cyhalothrin) ( S )-'-cyano-3-phenoxybenzyl ( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate)) and its epimer ( R )-'-cyano-3-phenoxybenzyl ( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate in/on the following commodities: /gamma-Cyhalothrin/ [Table#6287]

A tolerance ... is established for residues of the insecticide lamba-cyhalothrin and an isomer gamma-cyhalothrin in or on all food commodities (other than those already covered by a higher tolerance as a result of use on growing crops) in food-handling establishments where food products are held, processed, or prepared. /lambda-Cyhalothrin, gamma-Cyhaloathrin/

Time-limited tolerances are established for combined residues of the insecticide lambda-cyhalothrin (a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and (R)-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and its epimer a 1:1 mixture of ( S )-a-cyano-3-phenoxybenzyl-( Z )-(1 S ,3 S )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclopropanecarboxylate and ( R )-a-cyano-3-phenoxybenzyl -( Z )-(1 R ,3 R )-3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2-dimethylcyclo-propanecarboxylate in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. The tolerances will expire and are revoked on the dates specified in the following table: /lambda-Cyhalothrin/ [Table#6288]

For more FIFRA Requirements (Complete) data for CYHALOTHRIN (6 total), please visit the HSDB record page.

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/

For more Mechanism of Action (Complete) data for CYHALOTHRIN (10 total), please visit the HSDB record page.

Major metabolic reactions are ester hydrolysis and hydroxylation at the alcohol moiety. The metabolic fates of the alcohol moiety, alpha-cyano-3-phenoxybenzyl alcohol, was the same as those of pyrethroid insecticides having the same alcohol moiety. ... The cyano group of the alcohol moiety of cyhalothrin is expected to undergo conversion to SCN ion. The major metabolites of the acid moiety are cyclopropylcarboxylic acid and its glucuronide and those from the alcohol moiety is PBacid, 4'-OH-PBacid and sulfate of 4'pOH-PBacid.

The comparative metabolism of gamma-cyhalothrin with or without enantiomer pari A and cyhalothrin revealed that enantiomer pair A had little or no effect on the absorption, distribution, tissue retention, or metabolic profiles, implying that enantiomers of cyhalothrin behave independently.

In common with other structurally related pyrethroids, the main routes of metabolism of cyhalothrin in the cow have been found to be similar to those observed in rats and dogs, i.e cleavage of the ester bond with subsequent excretion of the cyclopropyl carboxylic moiety, either free, hydroxylated, or as a glucuronide conjugate. The phenoxybenzyl moiety was further metabolized by loss of the nitrile group and excreted as free 3-phenoxybenzoic acid and its amino acid conjugate, or after aromatic hydroxylation probably at the 4'position. Cyhalothrin itself gives rise to residues in fats; this is consistent with lipophilic properties of cyhalothrin compared to those of its more polar metabolites.

Identification of the metabolites produced in the rat studies revealed that, following oral administration, unabsorbed cyhalothrin was eliminated unchanged via the feces. The absorbed material was rapidly and extensively metabolized and no unchanged cyhalothrin was present in urine or bile. The main route of metabolism was, as anticipated, via hydrolysis of the ester linkage. The cyclopropanecarboxylic acid moiety was subsequently excreted via the urine as the glucuronide conjugate. This material accounted for about 50% of the radioactivity in urine following dosing with (14)C-cyclopropyl-labelled cyhalothrin. The 3-phenoxybenzyl moiety was further metabolized by loss of the nitrile group, oxidation of the aldehyde formed to a carboxylic acid, aromatic hydroxylation at the 4'-position, and formation of the 4-O-sulfate conjugate of 3-(4-hydroxyphenoxy)benzoic acid. This conjugate accounted for approximately 75% of the urinary radioactivity following dosing with (14)C-benzyl-labelled cyhalothrin. No metabolite containing the ester function was detected.

For more Metabolism/Metabolites (Complete) data for CYHALOTHRIN (6 total), please visit the HSDB record page.

Cyhalothrin has been shown to be well absorbed after oral administration, extensively metabolized, and eliminated as polar conjugates in urine. The main route of metabolism is, as anticipated, via hydrolysis of the ester linkage. The cyclopropane-carboxylic acid moiety is subsequently excreted via the urine as the glucuronide conjugate. The 3-phenoxybenzyl moiety is further metabolized by loss of the nitrile group, oxidation of the aldehyde form to a carboxylic acid, aromatic hydroxylation at the 4' position, and formation of the 4- O-sulfate conjugate of 3-(4-hydroxyphenoxy)benzoic acid. (L871)

Chemicals that kill or inhibit the growth of fungi in agricultural applications, on wood, plastics, or other materials, in swimming pools, etc.

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.

In rats, following oral admin, cyhalothrin is rapidly eliminated in urine & feces. The ester group is hydrolyzed, both moieties forming polar conjugates.

After twice daily oral ingestion of (14)C-benzyl- or (14)C-cyclopropyl-labelled cyhalothrin (1 mg/kg/day for 7 days), absorption of the insecticide by cows was apparently slow and incomplete. Approximately 50% of the dosed radioactivity was excreted in the feces, mainly as unchanged cyhalothrin, but only small amounts were detected in the bile. With both labelled forms, most of the radioactive material was rapidly eliminated in the urine (27%) and feces (49%) within 24 hr of each daily dose. Only a very small proportion of the dose was secreted in the milk (0.8%) and this was found to be unchanged cyhalothrin. Tissue residues of radioactive material were low and were in the following order: fats> liver> blood> muscle. Residues in fat consisted of unchanged cyhalothrin. The liver and kidney contained small amounts of cyhalothrin, but the residues were largely due to a number of ester-cleavage metabolites that were probably present because the animals were still actively metabolizing and eliminating a significant fraction of the most recent day's intake of cyhalothrin. The almost two-fold difference in the plasma levels of total radiolabelled components obtained with the different labelled forms suggests that little cyhalothrin was present in blood. The ester link must therefore be hydrolysed very rapidly, apart from a small fraction that is distributed into fatty tissues.

The absorption,distribution, excretion, and metabolism of cyhalothrin have been studied in the dog using cyhalothrin labelled either in the acid (14)C-cyclopropyl or alcohol (14)C-benzyl moieties of the molecule. Groups of three male and three female beagle dogs were given a single oral dose of cyhalothrin (1 mg/kg or 10 mg/kg) and, after a 3-week interval, a further single intravenous administration of 0.1 mg/kg. Samples of blood and excreta were collected for 7 days after dosing and were analysed for total radioactivity. The proportions of unchanged cyhalothrin and of metabolites in urine and feces were determined by thin-layer chromatography. The identity of major metabolites was confirmed by mass spectrometry. The absorption of cyhalothrin after oral administration was variable. The degree of absorption was difficult to assess but was within the range 48%-80%. Excretion of radioactivity after both oral and intravenous dosing was initially rapid, with most of the administered radioactivity being excreted in the first 48 hr after dosing. After 7 days, a mean of 82-93% had been excreted.

Groups of six male and six female Alderly Park rats received a single oral dose (1 or 25 mg/kg) of radiolabelled cyhalothrin in corn oil. As it was known that the metabolism of related pyrethroids involves extensive cleavage of the ester bond, duplicate experiments were performed using two forms of cyhalothrin labelled with (14)C in the acid (14)C-cyclopropyl or alcohol (14C-benzyl) portions of the ester. ... Following oral administration of cyhalothrin, absorption was variable but accounted for about 55% of the dose. The proportions absorbed were similar at both dose levels. Excretion was rapid for both (14)C-cyclopropyl- and (14)C-benzyl- labelled cyhalothrin at both dose levels, although excretion rates were faster with the (14)C-benzyl label than with the (14)C-cyclopropyl label. Urinary excretion accounted for approximately 20-40% of the dose and fecal excretion for 40-65% of the dose during the first 7 days. Peak blood concentrations of radioactivity were reached within 4-7 hr, and by 48 hr these concentrations had declined to 10% or less of peak values. A small proportion of an oral dose (2-3%) was retained in the animals after seven days; analysis of twelve different tissues indicated that this radioactivity was present mainly in white fat.

For more Absorption, Distribution and Excretion (Complete) data for CYHALOTHRIN (13 total), please visit the HSDB record page.

Used as insecticide and acaricide; [Merck Index] Used in agriculture and for public and animal health; [ICSC]

Not registered as a pesticide for use in the US; [HSDB] Banned in the EU for use as pesticide for plant protection; [eChemPortal: ESIS]

Farming (Pesticides) [Category: Industry]

For gamma-cyhalothrin (USEPA/OPP Pesticide Code: 128807) 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./ /gamma-Cyhalothrin/

For lambda-cyhalothrin (USEPA/OPP Pesticide Code: 128897) 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./ /lambda-Cyhalothrin/

Acaricides (pyrethroid ester acaricides), insecticides (pyrethroid ester insecticides) (Compend Pest Common Names at

Prepared by esterification of 3-(2-chloro-3,3,3-trifluoroprop-1-enyl)-2,2- dimethylcyclopropanecarboxylic acid chloride with alpha-cyano-3-phenoxybenzyl alcohol.

Lambda-cyhalothrin is manufactured by crystallization of the more active pair of enantiomers from cyhalothrin. The less active pair of enantiomers is recycled. /lambda-Cyhalothrin/

PREMIX PARTNERS: Acetamiprid; Buprofezin; Chlorantraniliprole; Chlorpyrifos; Diazinon; Fenitrothion; Piperonyl Butoxide; Pirimicarb; Tetramethrin; Thiamethoxam. /lambda-Cyhalothrin/

PRMIX PARTNERS: Chlorpyrifos /gamma-Cyhalothrin/

Emulsifiable concentrate, ULV, wettable powder. /lambda-Cyhalothrin/

Technical grade cyhalothrin contains more than 90% of the pesticide and is formulated in 5%, 10%, and 20% emulsifiable concentrates. Technical grade lambda-cyhalothrin also contains more than 90% active ingredient. It is formulated as 2.5%, 5.0%, 8.3%, and 12% emulsifiable concentrates and as a 0.8% ultra-low volume concentrate.

For more Formulations/Preparations (Complete) data for CYHALOTHRIN (150 total), please visit the HSDB record page.

Veterinary Drug -> INSECTICIDE -> JECFA Functional Classes

Environmental transformation -> Pesticides (parent, predecessor)

Natural pyrethrins, the insecticidal ingredient occurring in the flowers of Tanacetum cinerariaefolium (also known as Chrysanthemum cinerariaefolium or Pyrethrum cineratiae-folium), have been used widely for human and animal health protection by controlling indoor pest insects such as cockroaches, houseflies, and mosquitoes. Natural pyrethrins consist of six compounds (pyrethrin I and II; jasmolin I and II; and cinerin I and II). ... Extensive efforts on modification of chemical structures have been made ... to improve chemical properties in terms of stability in the environment (air, light, and heat) as well as better biological performance (higher selective toxicology). From these investigations, many synthetic pyrethroids have been elaborated ... . They can be classified into the so-called first-generation pyrethroids, which are esters of chrysanthemic acid and alcohols having furan ring and terminal side chain moieties, is to be he highly sensitive to light, air, and temperature. Therefore, these pyrethroids have been used mainly for control of indoor pests. On the other hand, the second generation pyrethroids, which commonly have 3-phenoxybenzyl alcohol derivatives in the alcohol moiety, have excellent insecticidal activity as well as sufficient stability in outdoor conditions by replacement of photolabile moieties with dichlorovinyl, dibromovinyl substituent and aromatic rings. Thus, the second generation pyrethroids are used worldwide for agricultural pests.

The WHO Recommended Classification of Pesticides by Hazard identifies cyhalothrin (technical grade) as Class II: moderately hazardous; Main Use: ixodicide (for tick control).

Synthetic pyrethroid insecticide

Cyhalothrin has two asymmetric centres in the acid moiety and one in the alcohol moiety, as well as Z and E forms. Thus, there are 16 possible isomeric forms (eight enantiomeric pairs). However, in practice cyhalothrin is produced only in the Z and cis forms, reducing the number of isomers to four. These comprise two cis enantiomeric pairs: Enantiomer pair A: (Z), (1R, 3R), R-a-cyano (Z); Enantiomer pair B: (Z), )1R, 3R), S-a-cyano (Z), (IS, 3S) R-a-cyano.

/Pyrethroids/ are modern synthetic insecticides similar chemically to natural pyrethrins, but modified to increase stability in the natural environment. /Pyrethroids/