Return to Cyhalothrin Index Page

ACTIVITY: Acaricide, Insecticide (pyrethroid)
Structure:

Adverse Effects:
Ataxia
Body Weight Decrease
CNS
Endocrine: Suspected Disruptor
Endocrine: Testicular
Eye
Liver
Tremors/Convulsions
Environmental

Ataxia (click on for all fluorinated pesticides)

Cyhalothrin administered orally (in capsules) to dogs at 10 mg/kg/day for 26 weeks produced occasional disturbances of the nervous system (unsteadiness and/or muscular trembling). The NOEL for these effects was not defined. In a 1-year dog study, ataxia, muscle tremors, and convulsions were observed following oral administration at 3.5 mg/kg/day. Abnormal gait and convulsions were observed at 0.5 mg/kg/day. The LOEL of the study was 0.5 mg/kg/day and the NOEL was 0.1 mg/kg/day. EPA believes that there is sufficient evidence for listing cyhalothrin on EPCRA section 313 pursuant to EPCRA section 313(d)(2)(B) based on the available neurological toxicity data.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.

Body Weight Decrease (click on for all fluorinated pesticides)

-- Cyhalothrin. 13-Week feeding - rat. 00154805. NOAEL: 2.5 mg/kg/day LOAEL: 12.5 mg/kg/day decreased body weight gain in males.
-- Cyhalothrin. 28-Day feeding - rat. 00153029. NOAEL: 2 mg/kg/day LOAEL: 10 mg/kg/day clinical signs of neurotoxicity. At higher doses, decreases in body weight gain and food consumption and changes in organ weights.
-- cyhalothrin. 28-Day feeding - rat. 00154806. NOAEL: 1.0 mg/kg/day LOAEL: 2.0 mg/kg/day decreases in mean body weight gain in females.
-- cyhalothrin. 4-Week feeding - mouse. 43241901. NOAEL: 64.2/77.9 mg/kg/ day LOAEL: 309/294 mg/kg/ day mortality, 64.2, 309 mg/kg/day clinical signs of toxicity, decreases in bodyweight gain and food consumption. changes in hematology and organ weights, minimal centrilobular hepatocyte enlargement.
-- cyhalothrin. 28-Day feeding - rat. 00153029. NOAEL: 2 mg/kg/day 1984/Acceptable LOAEL: 10 mg/kg/day nonguideline. clinical signs of 0, 2, 10, 25, 50, 75 mg/ neurotoxicity. At kg/day. higher doses, decreases in body weight gain and food consumption and changes in organ weights.
-- cyhalothrin. 21-Day dermal toxicity -rabbit. 00154869. NOAEL: 100 mg/kg/day LOAEL: 1,000 mg/kg/day significant weight loss
-- cyhalothrin. Developmental toxicity - rat. 00154800. Maternal NOAEL: 10 mg/kg/day. Maternal LOAEL: 15 mg/ kg/day. uncoordinated limbs, reduced body weight gain and food consumption. Developmental NOAEL: 15 mg/kg/day, the highest dose tested (HDT) Developmental LOAEL: >15 mg/kg/day
-- cyhalothrin. Developmental toxicity - rat. 00154801. Maternal NOAEL: 10 mg/kg/day. Maternal LOAEL: 30 mg/ kg/day. reduced body weight gain and food consumption. Developmental NOAEL: 30 mg/kg/day (HDT) Developmental LOAEL: >30 mg/kg/day
-- cyhalothrin. 3-Generation Reproduction - rat. 00154802. arental/Offspring NOAEL: 1.5 mg/kg/day. Parental/Offspring LOAEL: 5.0 mg/kg/day. decreased parental body weight and body weight gain during premating and gestation periods and reduced pup weight and weight gain during lactation). Reproductive NOAEL: 5.0 mg/kg/day (HDT).
-- cyhalothrin. Carcinogenicity - mouse. 00150842. NOAEL: 15 mg/kg/day. LOAEL: 75 mg/kg/day. increased incidence of piloerection, hunched posture; decreased body weight gain in males. Not oncogenic under conditions of study. HDT inadequate. New study not required at this time. [FAN Note: The study cited was performed in 1984.]
-- cyhalothrin. 00154803. Chronic/Carcinogenicity - rat. NOAEL: 2.5 mg/kg/day. LOAEL: 12.5 mg/kg/day. decreases in mean body weight. Not oncogenic under conditions of study.
Ref: Federal Register: September 27, 2002. Lambda-cyhalothrin; Pesticide Tolerance. Final Rule.
http://www.fluoridealert.org/pesticides/Lambda.Cyhalot.FR.Sept27.02.htm

CNS (click on for all fluorinated pesticides)

Rationale for US EPA to add Cyhalothrin to the Toxic Release Inventory. Cyhalothrin administered orally (in capsules) to dogs at 10 mg/kg/day for 26 weeks produced occasional disturbances of the nervous system (unsteadiness and/or muscular trembling). The NOEL for these effects was not defined. In a 1-year dog study, ataxia, muscle tremors, and convulsions were observed following oral administration at 3.5 mg/kg/day. Abnormal gait and convulsions were observed at 0.5 mg/kg/day. The LOEL of the study was 0.5 mg/kg/day and the NOEL was 0.1 mg/kg/day. EPA believes that there is sufficient evidence for listing cyhalothrin on EPCRA section 313 pursuant to EPCRA section 313(d)(2)(B) based on the available neurological toxicity data.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.

-- Cyhalothrin. 28-Day feeding - rat. 00153029. NOAEL: 2 mg/kg/day LOAEL: 10 mg/kg/day clinical signs of neurotoxicity. At higher doses, decreases in body weight gain and food consumption and changes in organ weights.
-- cyhalothrin. 28-Day feeding - rat. 00154806. NOAEL: 1.0 mg/kg/day LOAEL: 2.0 mg/kg/day decreases in mean body weight gain in females.
-- cyhalothrin. 26-Week feeding - dog. 00154795. NOAEL: 1.0 mg/kg/day LOAEL: 2.5 mg/kg/day increase in liquid feces. At 10.0 mg/kg/ day, clinical signs of neurotoxicity.
-- cyhalothrin. 28-Day feeding - rat. 00153029. NOAEL: 2 mg/kg/day 1984/Acceptable LOAEL: 10 mg/kg/day nonguideline. clinical signs of 0, 2, 10, 25, 50, 75 mg/ neurotoxicity. At kg/day. higher doses, decreases in body weight gain and food consumption and changes in organ weights.
-- cyhalothrin. Developmental toxicity - rat. 00154800. Maternal NOAEL: 10 mg/kg/day. Maternal LOAEL: 15 mg/ kg/day. uncoordinated limbs, reduced body weight gain and food consumption. Developmental NOAEL: 15 mg/kg/day, the highest dose tested (HDT) Developmental LOAEL: >15 mg/kg/day
Ref: Federal Register: September 27, 2002. Lambda-cyhalothrin; Pesticide Tolerance. Final Rule.
http://www.fluoridealert.org/pesticides/Lambda.Cyhalot.FR.Sept27.02.htm

Endocrine: Suspected Disruptor (click on for all fluorinated pesticides)

Suspected Endocrine Disruptor
Ref: PAN Pesticides Database

Endocrine: Testicular (click on for all fluorinated pesticides)

The physical and behavioral effects of cyhalothrin were studied in rats. Pregnant Wistar rats were administered 0 or 0.018% cyhalothrin topically throughout pregnancy. After delivery the neonates were monitored for development of fur, testes descent, and ear, eye, and vaginal opening. Body weights were recorded on postnatal days 2, 7, 14, and 21. The effects on locomotor activity and inhibitory avoidance behavior were evaluated on postnatal days 21 and 90. The number of head dips occurring in a hole board test was recorded on postnatal day 90. Development of fur and times to testes descent and ear and eye opening were significantly delayed in cyhalothrin exposed pups. Time to vaginal opening was not affected. Body wt of cyhalothrin exposed pups were significantly increased at postnatal days 2, 7, and 14, but not at postnatal day 21. Cyhalothrin did not significantly affect locomotor activity or inhibitory avoidance behavior. Cyhalothrin exposed rats had a significantly smaller number of head dips in the hole board test. The authors conclude that prenatal exposure to cyhalothrin delays development of fur, eye and ear opening, and testes descent and affects motivational behavior. The delays induced in fur development and eye and ear opening suggest that cyhalothrin interferes with maternal or neonatal epidermal growth factor activity. The delay in testes descent suggests that prenatal cyhalothrin exposure induces changes in male sexual development. [da Silva Gomes M et al; Vet Human Toxicol 33 (4): 315-7 (1991)]
Ref: TOXNET profile from Hazardous Substances Data Base for Cyhalothrin.
http://www.fluoridealert.org/pesticides/Cyhalothrin.TOXNET.HSDB.htm

Eye (click on for all fluorinated pesticides)

The physical and behavioral effects of cyhalothrin were studied in rats. Pregnant Wistar rats were administered 0 or 0.018% cyhalothrin topically throughout pregnancy. After delivery the neonates were monitored for development of fur, testes descent, and ear, eye, and vaginal opening... The authors conclude that prenatal exposure to cyhalothrin delays development of fur, eye and ear opening, and testes descent and affects motivational behavior. The delays induced in fur development and eye and ear opening suggest that cyhalothrin interferes with maternal or neonatal epidermal growth factor activity. The delay in testes descent suggests that prenatal cyhalothrin exposure induces changes in male sexual development. [da Silva Gomes M et al; Vet Human Toxicol 33 (4): 315-7 (1991)]
Ref: TOXNET profile from Hazardous Substances Data Base for Cyhalothrin.
http://www.fluoridealert.org/pesticides/Cyhalothrin.TOXNET.HSDB.htm

Liver (click on for all fluorinated pesticides)

Long term toxicity and carcinogenicity Target / critical effect: Liver Lowest relevant NOAEL: NOEL 1.7 mg/kg bw/d, 2 y rat (cyhalothrin) Carcinogenicity: Negative
Ref: European Commission. Review report for the active substance lambda-cyhalothrin. Finalised in the Standing Committee on Plant Health at its meeting on 19 October 2000 in view of the inclusion of lambda-cyhalothrin in Annex I of Directive 91/414/EEC. 7572/VI/97-final. 25 January 2001.
http://europa.eu.int/comm/food/fs/ph_ps/pro/eva/existing/list1-24_en.pdf

Tremors/Convulsions (click on for all fluorinated pesticides)

Cyhalothrin administered orally (in capsules) to dogs at 10 mg/kg/day for 26 weeks produced occasional disturbances of the nervous system (unsteadiness and/or muscular trembling). The NOEL for these effects was not defined. In a 1-year dog study, ataxia, muscle tremors, and convulsions were observed following oral administration at 3.5 mg/kg/day. Abnormal gait and convulsions were observed at 0.5 mg/kg/day. The LOEL of the study was 0.5 mg/kg/day and the NOEL was 0.1 mg/kg/day. EPA believes that there is sufficient evidence for listing cyhalothrin on EPCRA section 313 pursuant to EPCRA section 313(d)(2)(B) based on the available neurological toxicity data.
Ref: USEPA/OPP. Support Document for the Addition of Chemicals from Federal Insecticide, Fungicide, Rodenticide Act (FIFRA) Active Ingredients to EPCRA Section 313. U. S. Environmental Protection Agency, Washington, DC (1993). As cited by US EPA in: Federal Register: January 12, 1994. Part IV. 40 CFR Part 372. Addition of Certain Chemicals; Toxic Chemical Release Reporting; Community Right-to-Know; Proposed Rule.