Is Red Dye 3 Really Worse Than Red Dye 40? What We Know

On January 15, 2025, the FDA officially announced it has banned the use of Red No. 3 in all food products. Although the use of the dye in cosmetics was banned in 1990, after it was found to cause cancer in rats, companies could still use it in food. So they did. Red No. 3 wasn't only used to give food and beverages a bright, unnatural red color, but the synthetic dye was even used to alter the coloring of food products that aren't red.

"People think that 'I know which foods have dyes and which don't,' but no you do not," environmental health consultant Lisa Lefferts told CBS News. "White foods can contain dyes, foods marketed as healthy and natural can contain dyes, egg noodles can contain dyes, it's just very hard to know and avoid them, unless you look at the label." In other words, we should all be reading the ingredients of everything we put in our bodies.

However, while the decision, which gives companies until January 15, 2027, to come up with a healthier option for their products, is a step in the right direction, it does leave a lingering question: What about Red No. 40? Like Red No. 3, Red No. 40 is used liberally in products when trying to create and maintain a certain color. Considering they're both made from petroleum and serve no purpose other than to colorize food, one would think Red No. 40 would be banned too. However, the reason it's not comes down to the fact that Red No. 3 has been linked to cancer in rats, while Red No. 40 hasn't (per ABC News). 

While the FDA's banning of Red No. 3 and not Red No. 40 might lead you to believe that the latter is harmless or at least less problematic, that's not exactly the case. According to a 2012 study published in the International Journal of Occupational and Environmental Health, Red No. 40 contains benzidine and other cancer-causing substances. The same study also found that Red No. 40 was capable of causing hypersensitivity reactions. But without the definitive evidence that Red No. 40 causes cancer in living things, the FDA sees no need to ban it.

Although the FDA hasn't banned Red No. 40 at the federal level, it doesn't mean states can't make a different decision for their residents. In 2024, California passed the California School Food Safety Act in which, among other things, Red No. 40 is banned from being used in school foods. The decision was based on a 2021 report by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) that found that Red No. 40, along with other synthetic food dyes, were "associated with adverse neurobehavioral outcomes in some children."

Unless you're eating whole and organic food at all times, you're likely to run into synthetic dyes and preservatives that aren't exactly good for you. But as long as those ingredients haven't been found to cause cancer (yet), the FDA is going to give them a pass. Because of this, if you're genuinely concerned about Red No. 40, you need to advocate for yourself. Read the labels of every food product you buy and try to limit your consumption of it.