Gamma cyhalothrin
CAS No. 76703-62-3


Return to Gamma cyhalothrin Adverse Effects

ACTIVITY: Insecticide (Pyrethroid)

Systematic Name: Cyclopropanecarboxylic acid, 3-(2-chloro-3,3,3-trifluoro-1-propenyl)-2,2-dimethyl-, cyano(3-phenoxyphenyl)methyl ester, (1R-(1alpha(S*),3alpha(Z)))-


Adverse Effects:

Body Weight Decrease
Suspected Disruptor

Regulatory Information
(only comprehensive for the US)
US EPA Registered: Yes (as of April 8, 2004)
US EPA PC Code: 128807 
US Tolerances: CFR 180.438
Registered use in
(includes only a limited list of countries)

US Maximum Residue Levels permitted in food commodities

Lambda-cyhalothrin and its isomer Gamma-cyhalothrin have more than 380 food tolerances, including:

Alfalfa, Egg, Garlic, Barley, Brassica, Cattle, Corn, Cotton, Goat, Hog, Horse, Lettuce, Milk, Onion, Peanut, Poultry, Rice,Sheep, Sorghum, Soybean, Sugarcane, Sunflower Seeds, Tomato, Wheat 

Other Names:

ProAxis 15CS

[1R-[1 ALPHA(S*),3 ALPHA(Z)]]-CYANO(3-
Of special interest:
PAN Data 

April 2003: Proaxis* 15CS Product Launch in Indonesia. Organizer: PT Dow AgroSciences Indonesia. Co-sponsor: PT Bingel Agung.

Brochure in Indonesian
Cheminova manufactures gamma-cyhalothrin on behalf of Pytech Chemicals, which is a 50:50 joint venture between Dow AgroSciences and Cheminova. Pytech Chemicals is responsible for worldwide registration and market development activities.
Products based on gamma-cyhalothrin are marketed by Dow AgroSciences and Cheminova´s local organisations and partners. Gamma-cyhalothrin was launched in 2002. Gamma-cyhalothrin is marketed under the brand names Nexide® and Fentrol®.

Dow AgroSciences Study of Gamma Cyhalothrin:. First year field performance of XDE-225 - Paper presented June 2001.

See also:
Cyhalothrin (76703-62-3)
Lambda-Cyhalothrin (91465-08-6)

Gamma-cyhalothrin is a single, resolved isomer of the pyrethroid insecticide cyhalothrin, and as such shares physical, chemical, and biological properties with both cyhalothrin and lambda-cyhalothrin, which are mixtures of 4 and 2 isomers respectively. Gamma-cyhalothrin is the most insecticidally active isomer of cyhalothrin/lambda-cyhalothrin, and thus the technical gamma-cyhalothrin product may be considered a refined form of cyhalothrin/lambda-cyhalothrin in that it has been purified by removal of less active and inactive isomers. Thus, similar levels of insecticidal efficacy for gamma-cyhalothrin can be obtained with significantly reduced application rates as compared with either cyhalothrin or lambda-cyhalothrin.

-- The tolerance under 40 CFR 180.438 currently identifies lambda-cyhalothrin as a 1:1 mixture of two isomers and their epimers, one of which is the gamma isomer. The gamma isomer is present at 42% in this mixture. By contrast in the proposed tolerance expression the gamma isomer is present at 98% in the mixture.

-- It is noted that in the developmental toxicity study in the rat that the resolved gamma isomer is over an order of magnitude more toxic than in cyhalothrin.

-- B. International Residue Limits
There are currently no Mexican, Canadian, or Codex MRLs (maximum residue limits) for gamma- or lambda-cyhalothrin; however, there are MRLs for cyhalothrin from which lambda-cyhalothrin is derived as an enriched isomer. A Codex MRLs of 0.2 part per million (ppm) has been
established for pome fruits for cyhalothrin, which is inconsistent with the proposed U.S. lambda-cyhalothrin tolerance of 0.3 ppm for pome fruits. It is unclear if harmonization can be achieved because residues up to 0.25 ppm were found in the U.S. trials for apples. Codex MRLs were not established for the other crops presently under consideration.

Ref: US EPA. Lambda-Cyhalothrin and an Isomer Gamma-Cyhalothrin; Tolerances for Residue. FINAL RULE. Federal Register.

US Federal Register
Date Published Docket Identification No. Details
April 8, 2004 OPP-2004-0025

Pytech. Lambda-Cyhalothrin and Gamma-Cyhalothrin. Tolerances for Residues. FINAL RULE. EPA is amending 40 CFR part 180 by promulgating a new tolerance expression for the isomer form of gamma-cyhalothrin. Gamma-cyhalothrin is the isolated active isomer of lambda-cyhalothrin under 40 CFR 180.438. Pytech Chemicals GmbH, 9330 Zionsville Rd., Indianapolis, IN 46268, requested this change in tolerance expression in support of the registration of a pesticide formulation enriched with the gamma isomer of lambda-cyhalothrin.

EPA's previous risk assessment on lambda-cyhalothrin (September 27, 2002, Federal Register) is sufficient to cover gamma-cyhalothrin. Accordingly, a new aggregate risk assessment for gamma-cyhalothrin is not needed.

It is noted that in the developmental toxicity study in the rat that the resolved gamma isomer is over an order of magnitude more toxic than in cyhalothrin.

Excerpts from Table 1.-- Subchronic, Chronic, and Other Toxicity
Study Type Results

13-Week Dietary - Rat
- Gamma cyhalothrin

(Guideline No. 870.3100)

NOAEL: male/female =3.4/4.2 mg/kg/day
LOAEL: male/female = 6.6/8.8 mg/kg/day
(mortality in males, neuromuscular effects in both sexes, dermatitis, and gross and microscopic skin lesions in females).

3-Generation Reproduction - Rat
Lambda cyhalothrin
Gamma cyhalothrin

(Guideline No. 870.3800)

Parental NOAEL: 1.5 mg/kg/day
Parental LOAEL: 5.0 mg/kg/day
(decreased parental body weight and body weight gain during premating and gestation periods).

Reproductive NOAEL: 5.0 mg/kg/day
Reproductive LOAEL: Not established.
Offspring NOAEL: 1.5 mg/kg/day
Offspring LOAEL: 1.5 mg/kg/day (reduced pup weight and weight gain during lactation).

21-Day Inhalation Toxicity - Rat
Lambda cyhalothrin
Gamma cyhalothrin

(Guideline No. 870.3465)

NOAEL: 0.08 mg/kg/day
LOAEL: 0.90 mg/kg/day (clinical signs of neurotoxicity, decreased body weight gains, increased incidence of punctate foci in cornea,
slight reductions in cholesterol in females, slight changes in selected urinalysis parameters).

Gamma cyhalothrin

(Guideline No. 870.3200)

Maternal NOAEL: 0.5 mg/kg/day
Maternal LOAEL: 2.0 mg/kg/day
(clinical signs, reduced body weight and body weight gain and food consumption).
Developmental NOAEL: 2.0 mg/kg/day
Developmental LOAEL: Not established

Gamma cyhalothrin

(Guideline No. 870.3200)

NOAEL: male/female = 4.2/4.5 mg/kg/day
LOAEL: male/female = 8.8/10.2 mg/kg/ day.
(decreased body weight, body weight gain, food consumption, clinical and biochemical effects)

Chronic Toxicity - Dog
Lambda cyhalothrin
Gamma cyhalothrin

(Guideline No. None)

NOAEL: 0.1 mg/kg/day
LOAEL: 0.5 mg/kg/day (clinical signs of neurotoxicity).
Note: For one or two days of dosing, the NOEL is 0.5 mg/kg.

Excerpts from Table 2.-- Summary of Toxicological Dose and Endpoints for Gamma-Cyhalothrin for Use in Human Risk Assessment
Note: No study in this Table references Gamma-cyhalothrin
Exposure Scenario Study and Toxicological Effects
Acute dietary general population including
(infants and children)
Chronic oral study in the dog (lambda-cyhalothrin) Clinical signs of neurotoxicity (ataxia) observed from day 2, 3 to 7 hours post dosing.
Chronic dietary (all populations) Chronic oral study in the dog (lambda-cyhalothrin) Gait abnormalities observed in two dogs.
Short-term dermal (1 to 30 days)
Long-term dermal (< 6 months)
21-Day dermal toxicity study in the rat (lambda- cyhalothrin)
Clinical signs of neurotoxicity
(observed from day 2) and decreased body weight and body weight gain.

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

Commodity PPM Commodity PPM
Alfalfa, forage 5 Pea and bean, dried shelled,(except soybean), subgroup
See Ref. 5
Alfalfa, hay 6 Pea and bean, succulent shelled, subgroup
See Ref. 6
Almond, hulls 1.5 Peanut 0.05
Apple pomace, wet 2.50 Peanut, hay 3.0
Aspirated grain fractions 2.0 Poultry, fat 0.03
Avocados (imported) 0.20 Poultry, meat 0.01
Brassica, head and stem, subgroup
See Ref. 1
0.4 Poultry, meat byproducts 0.01
Canola, seed 0.15 Rice, grain 1.0
Cattle, fat 3 Rice, hulls 5.0
Cattle, meat 0.2 Rice, straw 1.8
Cattle, meat byproducts 0.2 Sheep, fat 3.0
Corn, grain (field and pop) 0.05 Sheep, meat 0.2
Corn, fodder 1.0 Sheep, meat byproducts 0.2
Corn, forage 6.0 Sorghum, grain. 0.20
Corn, grain flour 0.15 Sorghum, grain, forage 0.30
Corn, sweet, kernel plus cob with husks removed 0.05 Sorghum, grain, stover 0.50
Cottonseed 0.05 Soybean 0.01
Dry bulb onion 0.1 Sugarcane 0.05
Egg 0.01 Sunflower, forage 0.20
Fruit, pome, group
See Ref. 2
0.30 Sunflower, seed hulls 0.50
Fruit, stone, group
See Ref. 3
0.50 Sunflower, oil 0.30
Garlic 0.10 Sunflowers, seed 0.20
Goat, fat 3.0 Tomato 0.10
Goat, meat 0.2 Tomato, pomace (dry or wet) 6.0
Goat, meat byproducts 0.2 Vegetables, fruiting, group (except cucurbits)
See Ref. 7
Hog, fat 3.0 Vegetables, legume, edible podded, subgroup
See Ref. 8
Horse, meat 0.2 Wheat, grain 0.05
Horse, meat byproducts 0.2 Wheat, forage 2.0
Lettuce, head 2.0 Wheat, hay 2.0
Lettuce, leaf 2.0 Wheat, straw 2.0
Milk fat (reflecting 0.20 ppm in whole milk 5.0 Wheat, bran 2.0
Nut, tree, group
See Ref. 4
0.05 Hop, dried cone. 10

Ref. 1 broccoli; broccoli, cavalo; broccoli, chinese; brussels sprout; cabbage; cabbage, chinese mustard; cabbage, chinese napa; cauliflower; cavalo broccolo; kohlrabi
Ref. 2 apple; apple, dried pomace;
apple, juice; apple, wet pomace;
crabapple; fruit, pome; loquat;
mayhaw; pear; pear, oriental; quince
Ref. 3 apricot; cherry, sweet; cherry, tart;
fruit, stone; fruit, stone, except plum, prune, dried; nectarine; peach; plum; plum, chickasaw; plum, damson; plum, japanese;
plum, prune; plum, prune, dried;
plum, prune, fresh
Ref. 4 almond; almond, hulls; beechnut; butternut;
cashew; chestnut; chinquapin; filbert;
nut, brazil; nut, hickory; nut, macadamia;
nutmeat, processed, except peanut;
nuts; pecan; pistachio; walnut
Ref. 5 bean, adzuki; bean, broad dry; bean, dry;
bean, kidney; bean, lablab; bean, lima dry;
bean, moth; bean, mung; bean, navybean, pink; bean, pinto; bean, rice; bean, tepary;
bean, urd; catjang; chickpea; cowpea; guar;
lentil; lupin, grain; lupin, sweet; pea, blackeyed; pea, crowder; pea, field; pea, field seed; pea, pigeon; pea, southern
Ref. 6 bean, broad succulent; bean, lima succulent; cowpea; cowpea seed;
pea, blackeyed; pea, english; pea, garden; pea, green; pea, pigeon; pea, southern
Ref. 7 chili, postharvest; eggplant; groundcherry;
pepino; pepper; pepper, bell;
pepper, nonbell; pepper, nonbell, sweet;
tomatillo; tomato; tomato, concentrated products; tomato, dried pomace;
tomato, paste; tomato, puree;
tomato, wet pomace; vegetable, fruiting;
vegetable, fruiting, group
Ref. 8 bean, moth; bean, runner; bean, snap;
bean, wax; bean, yardlong; jackbean;
longbean, chinese; pea, dwarf;
pea, edible podded; pea, pigeon;
pea, snow; pea, sugar snap;
soybean immature seed; swordbean
Feb 25, 2004 OPP-

Pytech. Pesticide tolerance petition; proposal to amend 40
CFR part 180 by adding gamma-cyhalothrin to the tolerance expression of lambda-cyhalothrin. Gamma-cyhalothrin is the isolated active isomer of lambda-cyhalothrin.

Reproductive and developmental toxicity. A developmental
toxicity study in rats given gavage doses of 0, 0.1, 0.5, and 2 mg/kg/day with no developmental toxicity observed under the conditions of the study. The developmental no observed adverse effect level (NOAEL) is greater than 2 mg/kg/day, the highest dose tested (HDT). The maternal NOAEL and lowest observed adverse effect level (LOAEL) are established at 0.5 and 2 mg/kg/day, respectively, based on reduced body weight,
body weight gain, and feed consumption.

Subchronic toxicity. A 90-day feeding study in rats fed doses of 0, 2.5, 10, 50, and 100 parts per million (ppm) with a NOAEL of 50 ppm and a LOAEL of 100 ppm based on mortality, decreased feed consumption, decreased body weights, and increased relative liver and kidney weight at 100 ppm.

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