Dyes are not a chemical and not a definite toxin. Feeding actual poisons to an animal like the ones mentioned in the above post will affect the animal eating said prey. But dyes may be an exception to that rule. People have been feeding dog food to rats for a long time and many have never seen any difference. Without scienctific research into the matter there is no way to tell for sure.
You obviously didn't even look at the studies I linked to. Most dyes used today ARE a chemical that is created in a lab. The studies I posted are SCIENTIFIC studies that have determined the toxicity of many food dyes, including Red 40, which is commonly found in dog food, along with many other dyes that those studies have ALSO proven to be toxins.

Some of the studies on that page not only examine the toxicity of dyes on rats and mice, but also on people.

http://www.feingold.org/Research/dye-studies.html

I'm basing my "irrational and potentially unfounded fear" and "opinion" on FACTS.