What is Blue 1?
Blue 1 also known as Brilliant Blue FCF is an artificial colorant used in food.
It is a synthetic dye derived from coal tar. 
Synthetic food dyes have been suspected of disrupting children's behavior since the 1970s, when Dr. Ben Feingold, a San Francisco allergist, reported that his patients improved when their diets were changed. Numerous controlled studies conducted over the next three decades in the United States, Europe, and Australia proved that some children’s behavior is worsened by artificial dyes, but the government did nothing to discourage their use and food manufacturers greatly increased their reliance on them.