Red Light
Red 40 may cause symptoms of hypersensitivity in some people, including swelling around the mouth, and it may also cause hives. The colorant might contain contaminants that may contribute to cancer in humans and could trigger hyperactivity in children. In a handful of studies, Red 40 damaged the DNA of mice, according to the CSPI.
Go Natural
Many food products contain a mixture of dyes that includes Red 40 and the combined effect is not well-known. Limit your intake of Red 40 and other food dyes. Choose products that contain paprika, beet juice, carotene, red cabbage and turmeric for coloring instead of synthetic dyes."
Credit

Food Red 17, C.I. 16035, FD&C Red 40, E129,2-naphthalenesulfonic acid, 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-, disodium salt, and disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalenesulfonate. It is used as a food dye and has the E number E129. Allura Red AC was originally introduced in the United States as a replacement for the use of amaranth as a food coloring.
It has the appearance of a dark red powder. It usually comes as a sodium salt, but can also be used as both calcium and potassium salts. It is soluble in water; in solution, its maximum absorbance lies at about 504 nm.[3]p.921 Its melting point is above 300 degrees Celsius.
Allura Red AC is one of many High Production Volume Chemicals.
Red AC was originally manufactured from coal tar, but is now mostly made from petroleum. Despite the popular misconception, Allura Red AC is not derived from any insect, unlike the food colouring carmine, which is derived from the female cochineal insect."
See more...
@Wikipedia
More Info...
Is the Red 40 Food Dye Additive Having a Negative Impact on Your Child?
Food Dyes Linked to Cancer, ADHD, Allergies
Snoopes