Evidence suggests, but does not prove, that Blue 1, Blue 2, Green 3, Red 40, and Yellow 6 cause cancer in animals. The three most widely used dyes -- Red 40, Yellow 5, and Yellow 6 -- are contaminated with known carcinogens.Read the full story at SFGate.com.
The granddaddy of them all, Red 3, is recognized by the Food and Drug Administration as a carcinogen. The law requires it to be illegal, but pressure from Ronald Reagan's Secretary of Agriculture, John R. Block, scuttled the required ban. About 200,000 pounds annually of Red 3 go into foods including Betty Crocker's Fruit Roll-Ups and ConAgra's Kid Cuisine frozen meals.
This article available online at:
http://www.theatlantic.com/health/archive/2010/07/colorful-carcinogens-why-we-should-ban-food-dyes/59944/