Is Red Dye #40 harmful to most people?

(Red 40, red 3, yellow 5. Make from petroleum? Cancer risk? )

In the US, three dyes compose 90% of dye consumption in the US:  Red 40, yellow 5, yellow 6. In 2010, CSPI published a report stating that most food dyes likely cause cancer, cause allergic reactions in some children, or are not adequately tested. This report mentions:

Red 40, Yellow 5, and Yellow 6 contain benzidene, a human and animal carcinogen permitted in low, presumably safe levels in dyes.2 The FDA calculated in 1985 that ingestion of free benzidine raises the cancer risk to just under the “concern” threshold (1 cancer in 1 million people). Bound benzidene also has been detected in dyes in much greater amounts than free benzidene,7,8 but routine FDA tests measure only free contaminants, overlooking the bound moiety.2 Intestinal enzymes release bound benzidene, “so we could be exposed to vastly greater amounts of carcinogens than FDA’s routine tests indicate,” says Jacobson—especially considering today’s children are exposed to multiple dyes and flavoring agents and other added chemicals in foods.9

Red 40
Red 40 dye, also called Allure Dye (international number E129), or FD&C Red Dye 40, is made from petroleum products but industry claims it's so refined it's not dangerous. It's also called "Azo Dye". It might be listed as "Red 40 Lake" on the ingredients. A "lake" form of a dye is one that water will not wash off, it's not water soluble. This is mostly used in pills where the manufacturer does not want the dye to be washed off if it contacts a bit of water.

In Europe, foods that contain the dyes that might causes sensitivity must be labeled. In 2009 the European Food Safety Authority re-evaluated the use of Red 40 dye. The panel found that red #40 did not have genotoxicity with Salmonella, nor cause cancer. The panel recommends limiting red #40 (Acceptable Daily Intake) to 0-7mg/kg of body weight. But since the weight of red dye in US foods is not listed, this ADI is useless for consumers.


Here are some studies on red dye.

1. 1989. Study abstract here. "The no-adverse-effect levels in this study were 5.19% (2829 mg/kg/day) for male rats, and 1.39% (901 mg/kg/day) for female rats." It is unknown how many mg of dye people eat on average because this information is not on nutrition labels. The ingredients are listed but not the amounts of each ingredient.
2. 1992. Azo dyes are not mutagenic.
3. 1997. Red dye #3 increases growth of human breast cancer cells. 
4. 2002. Red dye #40 found to be most genotoxic.

The results of studies are mixed because they look for different things. But it certainly is within the realm of possibility that some kids will become hyperactive to red #40 if they consume it. When in doubt, avoid it. It does contain benzidine which is a known carcinogen.

Red 40 sources
FD&C red 40 chemical info.