CAS No. 153233-91-1

Return to Etoxazole Adverse Effects

ACTIVITY: Acaricide, Ovicide (unclassified)

CAS Name: 2-(2,6-difluorophenyl)-4-[4-(1,1-dimethylethyl)-2-ethoxyphenyl]-4,5-dihydrooxazole


Adverse Effects:

Body Weight Decrease
Endocrine: Adrenal
Endocrine: Prostate
Endocrine: Testicular


Environmental Effects:

Very highly toxic to aquatic invertebrates

Regulatory Information
(only comprehensive for the US)
US EPA Registered: Yes
US EPA PC Code: 107091
US Tolerances: CFR 180.593
Registered use in
(includes only a limited list of countries)

France, Israel, Japan, Korea, Taiwan, Turkey, South Africa, US
Japan's Maximum Residue Levels (MRLs) Apple, Beans (dry), Cherry, Cotton seeds, Cucumber, Eggplant, Grapefruit, Hop, Lemon, Lime, Loquat, Melons, Natsudaidai (whole), Orange, Other Citrus fruits, Peach, Pear, Strawberry, Tea, Tomato, Unshu orange, Watermelon
Note high level - 15 ppm - for Tea (Green, Black, Oolong, Wulung)
US Maximum Residue Levels permitted in food commodities

Tolerances for 25 food commodities, including: Apple, Cattle, Cotton, Goat, Horse, Milk, Pear, Sheep, Strawberry, Tangerine

Existing tolerances for Ornamental plants grown in greenhouses, shadehouses, and lathhouses.

Other Information
Molecular Formula: C21H23 F2 NO2
Manufacturers: Valent
Yashima Chemical Industry
Sumitomo Chemical
Other Names: YI-5301, TETRASAN,
Baroque, Virk, Zoom
Of special interest:
PAN Data
April 27, 2005 - U.S. Congresswoman Ellen Tauscher (D-CA) introduced a bill "to suspend temporarily the duty on Etoxazole" up to December 31, 2008. The bill was referred to the House Committee on Ways and Means.
November 29, 2004. Review report for the active substance etoxazole. European Commission. SANCO/4054/2001 - rev. 3.
August 2003 - Summary of Toxicology Data. California EPA.
August 2002 - Pesticide Fact Sheet. US EPA.
2001 - IR-4 New Products/Transitional Solution List - This list contains brief descriptions of numerous new pest control materials that have been introduced over the last several years. Additionally, it contains information on some "older" crop protection chemicals that are believed to have room for new uses. This List includes Etoxazole
2001 - Glossary of Pesticide Chemicals. A listing of pesticides subject to analysis of residues in foods and feeds by the US Food and Drug Administration. Also available at:

US Federal Register

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Date Published Docket Identification Number Details
June 27, 2007 EPA-HQ-OPP-2007-0309

IR-4. Pesticide Petition. PP 6E7150. Proposal to establish a tolerance for residues of the insecticide etoxazole in or on food commodities:

hop, dried cones 7.0 ppm

melon, subgroup 9A

This subgroup includes 6 commodities.
cantaloupe • citron melon • melon • melon, citron • muskmelon • watermelon

0.15 ppm
cherry 0.70 ppm

Practical analytical methods for detecting and measuring levels of etoxazole have been developed and validated in/on all appropriate agricultural commodities and respective processing fractions. The LOQ of etoxazole in the methods is 0.02 ppm which will allow monitoring of food with residues at the levels proposed for the tolerances.

July 20, 2005 OPP-2005-0170

VALENT. Pesticide Tolerance. FINAL RULE.

Parts per million
Almond, hulls
2.0 ppm
0.50 ppm
Grape, raisin
1.5 ppm

Nut, tree, group 14

This group includes 16 commodities.

almond • almond, hulls • beechnut • butternut • cashew • chestnut • chinquapin • filbert • nut, brazil • nut, hickory • nut, macadamia • nutmeat, processed, except peanut • nuts • pecan • pistachio • walnut

0.01 ppm
0.01 ppm

A summary of the toxicological endpoints for etoxazole used for human risk assessment is discussed in Unit III.B. of the final rule published in the Federal Register of September 26, 2003

Excerpts from the Sept. 26, 2003, Federal Register:
-- 90-Day oral toxicity rodents (rat). NOAEL = 61.8/69.0 milligrams/kilogram/ day (mg/kg/day) Male/Female (M/F) LOAEL = 183.7/204.8 mg/kg/day (M/F), based upon increases in hepatic enzyme levels, increased liver weights and centrilobular hepatocellular swelling in both sexes and liver enlargement in females only
-- 90-Day oral toxicity rodents (mouse). NOAEL = 213.6/250.5 mg/kg/day (M/F) LOAEL = 878.4/994.5 mg/kg/day (M/F), based upon periportal hepatocellular necrosis, increased alkaline phosphatase levels, accompanied by increased relative liver weight, liver enlargement, and centrilobular hepatocellular swelling
-- 90-Day oral toxicity nonrodents (dog). NOAEL = 5.33/5.42 mg/ kg/day (M/F) LOAEL = 53.7/55.9 mg/ kg/day (M/F), based upon clinical signs (vomiting foamy fluid and mucous stool), clinical chemistry, increased liver weights, and centrilobular swelling in the liver and acinar cell atrophy in the prostate.
-- Prenatal developmental toxicity in nonrodents (rabbit). Maternal NOAEL = 200 mg/kg/day LOAEL = 1,000 mg/kg/day based upon
liver enlargement and decreased body weight gains and food consumption. Developmental NOAEL = 200 mg/kg/day LOAEL = 1,000 mg/kg/ day based upon increased incidences of 27 presacral vertebrae and 27 presacral vertebrae with 13th ribs in the fetuses.
-- Reproduction and fertility effects (rat). Parental/Systemic NOAEL = 20 mg/kg/ day LOAEL = 100 mg/kg/ day (M/F), based upon increased liver weights in the P and F1 males and increased adrenal weights in the P females Offspring/Systemic NOAEL = 20 mg/kg/ day LOAEL = 100 mg/kg/ day (M/F), based upon pup mortality Reproductive NOAEL = 100 mg/kg/day LOAEL = not determined.
-- Combined chronic toxicity/ carcinogenicity rodents (rat). NOAEL = 64 mg/kg/day (M/F). LOAEL = not determined Equivocal evidence of carcinogenicity.
-- 2-Year feed/ carcinogenic (rat) . NOAEL = 1.83/2.07 mg/kg/day (M/F) LOAEL = 187/216 (M/ F), based upon
effects on the incisors including abnormal amelogenesis. No evidence of carcinogenicity
-- Chronic toxicity nonrodents (dog). NOAEL = 4.62/4.79 mg/kg/day (M/F). LOAEL = 23.5/23.8 mg/ kg/day (M/F), based upon increased alkaline phosphatase activity, increased liver weights, liver enlargement (females), and incidences of centrilobular hepatocellular swelling in the liver.
-- 78-Week carcinogenic mouse. NOAEL = 242/243 (M/ F). LOAEL = 484/482 (M/ F), based on a slight increase in the incidence of a fatty change in the centrilobular hepatocytes in males.
Gene mutation - in vitro forward gene mutation assay in mouse lymphoma cells. When tested up to cytotoxic levels, mutagenic in the presence of S9 activation and
equivocal for mutagenicity in the absence of S9 activation.
-- Cancer. EPA has determined that etoxazole is not likely to be a human carcinogen and EPA therefore, does not expect it to pose a cancer risk. As a result, a quantitative cancer dietary exposure analysis was not performed.

From the July 20, 2005, Federal Register.
Prenatal and postnatal sensitivity.
There is qualitative evidence of increased susceptibility following exposure to etoxazole in the rat reproduction study. Therefore, EPA performed a Degree of Concern Analysis to determine the LOC for the effects observed when considered in the context of all available toxicity data, and to identify any residual uncertainties after establishing toxicity endpoints and traditional UFs to be used in the risk assessment of this chemical. If residual uncertainties are identified, EPA examines whether these residual uncertainties can be addressed by a special FQPA safety factor and, if so, the size of the factor needed. In performing the Degree of Concern Analysis, EPA noted that the effects in the pups in the rat reproduction study are well-characterized with a clear NOAEL. In addition, the pup effects occur at the same dose as maternal toxicity. Furthermore, the doses selected for various risk assessment scenarios are lower than the doses that caused off spring toxicity. There are no residual uncertainties for prenatal/postnatal toxicity in this study. Therefore, although there is evidence of increased qualitative susceptibility in the rat reproduction study, the concern is low. For the reasons stated above, EPA has concluded that there is low concern for prenatal and/or postnatal toxicity resulting from exposure to etoxazole.
EPA determined that the 10X SF (safety factor) to protect infants and children should be removed.
Acute exposure... EPA evaluated the suitability of the developmental toxicity study in rabbits in which the developmental NOAEL of 200 milligram/kilogram/day (mg/kg/day) is based upon increased incidences of 27 presacral vertebrae and 27 presacral vertebrae with 13th ribs (skeletal variations) in the fetuses at the LOAEL of 1,000 mg/kg/day (limit dose). Although these developmental effects may be attributed to a single dose, EPA concluded that these effects are minor in magnitude and were observed only at the limit dose (1,000 mg/kg/day).
Therefore, quantitation of the acute risk was not performed.

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