Ethoxyquin - Avian Nutrition with Dr McWatters
Ethoxyquin @ theaviary.com
Ethoxyquin @ avianweb.com
http://www.noahsark2by2.org/ethoxyquin.htm
http://www.fda.gov/cvm/index/updates/dogethox.html
http://www.purelypets.com/articles/whatsinfood.htm
http://www.feathersnpaws.com/whatsinpetfood.htm
http://www.api4animals.org/doc.asp?ID=79
http://www3.sk.sympatico.ca/riverien/nutribag.htm
http://www.canine-epilepsy-guardian-angels.com/Ethoxyquine.htm
http://www.listservice.net/wellpet/ethoxyqu.htm
http://www.homevet.com/petcare/foodbook.html

http://www.fauna-art.com/pets-eat.htm
http://www.groomers.com/tidbits/food.html

http://ntp-server.niehs.nih.gov/htdocs/Chem_Background/ExecSumm/Ethoxyquin.html
Here's a quote from that last one:

"This compound is a mild skin and eye irritant in test animals. Ethoxyquin was found to significantly decrease body weight, food intake, and occasionally growth rate in rats, cows, dogs, chickens, and mice exposed to prechronic and chronic doses in animal feed. In these studies, ethoxyquin caused a significant increase in liver and kidney weights in test animals. In male rats, adverse effects observed included scars on kidneys, inclusions in hepatic cells, and kidney lesions in the higher dosed groups (500-4000 ppm). Effects characteristic of chronic glomerulus nephrosis in male rats exposed to 4,000 ppm ethoxyquin were observed. In dogs fed doses of ethoxyquin ranging from 10-100 mg/kg, adverse effects observed included anorexia, abdominal pain, and increased liver and kidney weights. Dose-dependent exogenous pigment was seen in all groups. These animals also exhibited an increased fat content in the collecting tubules of kidneys, suggestive of fatty nephrosis. Limited data were found on the carcinogenic potential ofethoxyquin. This chemical has been found to be a weak bladder carcinogen in rats.

In mice, ethoxyquin administration caused an increase in solitary adenomas and Iymphomas; however, this was not concluded to be indicative of carcinogenicity. A number of studies of the carcinogenic promoting capabilities of ethoxyquin indicated that it enhanced tumor formation induced by other compounds in the forestomach, bladder, glandular stomach, esophagus, distal colon, and kidney in rats. In reproductive studies conducted on rats and rabbits, ethoxyquin was not found to have adverse effects. However, at high doses in chickens, ethoxyquin caused an increased frequency of resorption, and a significant increase in anomalous features in fetuses. A decrease in fertility was seen in ethoxyquin-treated chickens."

Another interesting snippet:
http://ntp-server.niehs.nih.gov/htdocs/Chem_H&S/NTP_Chem9/Radian91-53-2.html

"It is also used as an antidegradation agent for rubber, insecticide, antioxidant, flex-cracking inhibitor, post-harvest dip to prevent scald on apples and pears, fungicide and plant growth regulator."