Hmm...did some research on Ethoxyquin this morning to try to learn more about it. According to the short Wiki article, it's an antioxidant used as a food preservative and a
pesticide! It was the pesticide bit that got me concerned so I did more research and discovered that it's labeled a pesticide but the only use I've been able to find for it is in a product called StopScald where it acts more as a preservative than as a pesticide since scald is not caused by a pathogen. It is however known to kill fish and on the MSDS I was slightly concerned to find that it falls under the category of "Agricultural Chemical Mutagen ".
The fact that the studies mentioned in the Wiki article that led to the FDA asking for a voluntary reduction in pet food levels were never published is frankly a little odd...but from everything I read, the toxic dose is ridiculously high and the cancer risk extremely low. But that doesn't take into account long-term, low-dose feedings so draw from that what you will
And then there's the fact of who developed and manufactured the stuff, which is reason enough for me to avoid it!