Q: Are the dyes in foods safe to be ingested? - Layperson

A: No, but their effects can be minimized if taken in moderation. Other then to make foods more attractive to the consumer and possibly hide damage from expiration, dyes serve no useful purpose. A case in example, is certain dog foods. Dogs see no or almost no colors, but some dog foods contain multi-colors to attract dog owners into buying them.

Originally, food producers used colored dyes to hide poor quality products or spoiled products. Though typically the colors came from nature, as the 20th century approached, scientists came up with ways of creating different colors in the lab. Some of these new colors were dangerous to the public's health.

In the 1800's, toxic chemicals and metal-based compounds were used to make some color dyes. Arsenic and similar poisons were used to color hard candies and pickles. There are records of injuries and deaths because of these colors.

Over time, more than 80 different artificial colors have been used in common foods such as jellies, wine, candies, mustard, and ketchup. Some of these colors were intended for use in the textile industry, not the food industry.

Likewise, in the United States, there appears to have been little organized opposition to the adulteration of foods and beverages until after the Civil War. Until this time in the United States, it was virtually impossible to find any food, drink, or medicine that had escaped extensive contamination. For example, cod liver oil was adulterated, almost to substitution, with train oil mixed with iodine. Yellow tinged milk, colored with lead(II)chromate (PbCrO₄), was so common that people refused to purchase white milk, thinking that the latter had been doctored. In 1856, the English chemist, William Perkin (1838–1907) prepared the first synthetic organic dye, “aniline purple” or “mauve”. Within a few years, a variety of these potentially safer organic dyes began to replace mineral pigments as food colorants. However, in the United States, toxic colored metal salts of arsenic, mercury, lead, chromium, and copper continued to be used as food colorants until the beginning of the 20th century. In the United States, it was common to color pickles and canned vegetables with copper sulfate until about 1905.

Laws prohibiting the coloration of foods and beverages with toxic metal salts were enacted in 1906, when Congress passed the Pure Food and Drug Act which created the F.D.A., the Food and Drug Administration and was signed into law by President Theodore Roosevelt. This law was the foundation for the Federal Food Drug and Cosmetic Act of 1938, which required the testing and the safety certification of the 15 aniline-based organic food colors that were in use at that time. Presently, in the United States, there are six certified artificial colors that are allowed in foods and beverages.These are all derived from carbon compounds rather than from inorganic minerals. The safety of food additives—food colors in particular—continues to interest the health-conscious public. 

This was the beginning of several laws that allowed the government to control the use of food and color additives. In 1938, the government passed an act that also allowed them to control the colors used in cosmetics. This included the following new designations that consumers can still see on package labels: FD&C (colors allowed to be used in food, drugs and cosmetics), D&C (colors to be used in drugs and cosmetics), and Ext. D&C (colors only to be used only in external-use drugs and cosmetics).

In the years after 1938, regulations were created that gave color dyes numbers to separate them and make it easier to tell which colors are used in food, drugs, cosmetics and textiles. Only F.D.A. certified colors have these numbers.

In 1960, the law created in 1938 was changed to broaden the government's control of not just which colors were used, but also how much of each color could to be used.

Many colorings that are legal for use in foods in one country are banned in another; conversely, those dyes allowed in the latter country may be banned in the former. In the US, the list of legal synthetic food dyes is short:

dye name	F D & C food dye number	Color Index number	European additive number
allura red	red dye #40	16035	E129
brilliant blue FCF	blue #1	42090	E133
sunset yellow FCF	yellow #6	15985	E1 10
indigotine	blue #2	73015	E132
fast green FCF	green #3	42053	INS 143
erythrosine	red #3	45430	E127
tartrazine	yellow #5	19140	E102

All other food colorings in the US, aside from a few natural dyes such as annatto, turmeric (spice), beet extract, and carmine (red insects, used to color yogurt and other foods), are composed of different combinations of the above.

As of now there are only seven dyes that have been approved by the F.D.A. for safe use in food, drugs and cosmetics. These are known as the FD&C dyes. These dyes are yellows #5 and #6, reds #3 and #40, blues #1 and #2, and green #3. The most popular of these dyes is Red #40. The second most popular is Yellow #5. The table on the next page summarizes the seven FD & C dyes.

Lakes- These are a form of the certifiable colors that are water-insoluble. These forms are more stable than the straight dyes and are ideal for products where the makers do not want the color to bleed. Such products are hard candies and coated tablets.

Straight Dyes- These are a form of the certifiable colors that dissolve in water. They are manufactured as powders, granules, liquids, or other forms. These dyes are used in baked goods and beverages.

In short, the ingestion of large amounts of, and/or long term use of, dyed foods has definitely been linked to allergic reactions, behavior disturbances, cancer, DNA/other genetic damage, fertility/fetal damage, growth [pattern damage, and immune system damage.  Food dyes are not as harmless as the public has been lead to believe.