Title: Ethoxyquin
CAS Registry Number: 91-53-2
CAS Name: 6-Ethoxy-1,2-dihydro-2,2,4-trimethylquinoline
Additional Names: 1,2-dihydro-6-ethoxy-2,2,4-trimethylquinoline; EMQ
Trademarks: Santoflex; Santoquin (Novus)
Molecular Formula: C14H19NO
Molecular Weight: 217.31
Percent Composition: C 77.38%, H 8.81%, N 6.45%, O 7.36%
Literature References: Prepn: Knoevenagel, Ber. 54, 1722 (1921); Baird et al., GB 505113 (1939 to ICI); C. C. Tung, Tetrahedron 19, 1685 (1963). Structure: Cliffe, J. Chem. Soc. 1933, 1327. Metabolism: R. H. Wilson et al., Agric. Food Chem. 7, 206 (1959); J. U. Skaare, E. Solheim, Xenobiotica 9, 649 (1979). Toxicity data: V. I. Piul'skaya et al., C.A. 90, 4601c (1979).
Properties: Yellow liquid. bp2 123-125°. nD25 1.569-1.672. d2525 1.029-1.031. LD50 orally in rats, mice: 1920, 1730 mg/kg (Piul'skaya).
Boiling point: bp2 123-125°
Index of refraction: nD25 1.569-1.672
Density: d2525 1.029-1.031
Toxicity data: LD50 orally in rats, mice: 1920, 1730 mg/kg (Piul'skaya)
Use: Antioxidant in feed and food; antidegradation agent for rubber.
Ethoxysulfuron Ethoxzolamide Ethybenztropine Ethyl Acetate Ethyl Acetoacetate

CAS number 91-53-2 YesY
PubChem 3293
ChemSpider 3177 YesY
UNII 9T1410R4OR YesY
Jmol-3D images Image 1
Molecular formula C14H19NO
Molar mass 217.31 g mol−1
Melting point < 25 °C
Boiling point 123–125 °C at 2 mmHg
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Ethoxyquin is a quinoline-based antioxidant used as a food preservative (E324) and a pesticide (under commercial names such as "Stop-Scald"). It is commonly used as a preservative in pet foods to prevent the rancidification of fats. Ethoxyquin is also commonly used in spices to prevent color loss due to oxidation of the natural carotenoid pigments.[2]

There has been some speculation that ethoxyquin in pet foods might be responsible for multiple health problems. To date, the U.S. Food and Drug Administration (FDA) has only found a verifiable connection between ethoxyquin and buildup of protoporphyrin IX in the liver, as well as elevations in liver-related enzymes in some animals, but there are no known health consequences from these effects.[3] In 1997, the Center for Veterinary Medicine has asked pet food manufacturers to voluntarily limit ethoxyquin levels to 75 ppm until further evidence is reported.[3] However, most pet foods that contain ethoxyquin have never exceeded this amount.[3]

Ethoxyquin has been shown to be slightly toxic to fish.[4]

Ethoxyquin is not permitted for use in Australian foods nor is it approved for use within in the European Union,[5] it is an accepted additive in the U.S.A (most likely the only reason is due to the FDA approving this pesticide safe for U.S citizens). Other than USA it is also widely used in third world countries (often ones with poor food controls in place)[citation needed], which is in contrast to all other first world countries that have not approved the use of this chemical due to potential health concerns.

Even though it has been approved for use in foods and as a spray insecticide for fruits Eethoxyquin has surprisingly not been thoroughly tested for its carcinogenic potential. For a long time been suggested it is a possible carcinogen, a very closely related chemical 1,2-dihydro-2,2,4-trimethylquinoline has been shown to cause carcinogenic activity in rats, as well as a Manson et al (1987) study suggested Ethoxyquins potential for carcinogenic effect.[6]