http://en.wikipedia.org/wiki/Tartrazine

Tartrazine (otherwise known as E102 or FD&C Yellow 5) is a synthetic lemon yellow azo dye used as a food coloring. It is derived from coal tar.

Tartrazine appears to cause the most allergic and intolerance reactions of all the azo dyes, particularly among those with an aspirin intolerance and asthmatics.[3] Symptoms from tartrazine sensitivity can occur by either ingestion or cutaneous exposure to a substance containing tartrazine.[citation needed]

A variety of immunologic responses have been attribute to Tartrazine ingestion, including anxiety, migraines, clinical depression, blurred vision, itching, general weakness, heatwaves, feeling of suffocation, purple skin patches, and sleep disturbance.[citation needed] Some claim to experience symptoms of tartrazine sensitivity even at extremely small doses, and up to 72 hours after exposure.[citation needed] In children, asthma attacks and hives in children have been claimed, including supposed links to thyroid tumors, chromosomal damage, hives, and hyperactivity. [4]

The mechanism of sensitivity is obscure and has been called pseudoallergic. The prevalence of tartrazine intolerance is estimated at roughly 360,000 Americans affected, about 0.12% of the general population.[citation needed] According to the FDA, tartrazine causes hives in fewer than 1 in 10,000 people, or 0.01%.[5]

Some researchers have linked tartrazine to childhood Obsessive-compulsive disorder and hyperactivity.[6] A study commissioned by the UK's Food Standards Agency found that when used in a mixture of other colors and preservatives, increased levels of hyperactivity in children were observed.[7]

It is not clear to what extent these problems can be specifically linked to tartrazine in affected individuals. The existence of a sensitivity reaction is well-known, but the existence of more extreme effects remain controversial. The incidence of tartrazine intolerance is fairly low as as indicated above, and there is much controversy about whether tartrazine has ill effects on individuals who are not clearly intolerant.

Total avoidance is the most common way to deal with tartrazine sensitivity,[8] but progress has been made in reducing people’s tartrazine sensitivity in a study of people who are simultaneously sensitive to both aspirin and tartrazine.[9]

Why do we put this crap in our food again anyway?