Candy corn, cocktail cherries, and cancer. Oh my!
Candy corn on a black background. Photo by liz west. CC BY 2.0 via Wikimedia Commons.
Do candy corn, cocktail cherries, and Tylenol cause cancer? If you’ve been reading news outlets like Vice or CBS News, you’ve probably seen reporting that suggests that Red Dye 3, a common food additive that creates a bright, artificial red color, causes cancer. That claim is true, but only if you’re a lab rat treated with other drugs, missing part of your thyroid, and consuming truckloads of the stuff.
Despite the sweeping claims about the dangers of the chemical, the actual research tying it to any specific health outcome is extremely limited.
The study linking Red Dye 3 to thyroid cancer used a rat model for their experiments. Usually, an animal model is a helpful tool to study how cancer develops in a body. Animal models for diseases like cancer give scientists an idea of how different systems of the body will interact when one tissue is diseased. For example, scientists can observe that the immune system response for bone cancers or pancreatic cancers are different, and this could inform treatment strategies. This is not the case for cancers that develop in fundamentally different ways between humans and animals.
Humans do not develop thyroid cancer in the same way that rats do. Studies using rats to model thyroid cancer induce the cancer with chemicals that increase the amount of Thyroid Stimulating Hormone (TSH) in the rats’ bloodstreams. Increases in TSH cause thyroid cells to grow very quickly, leading to cancer in both rats and humans. However, the problem with applying these studies to humans is the chemicals researchers use to increase TSH in rats do not increase TSH in humans, indicating that they likely would not increase the risk of thyroid cancer.
Because this process of cancer development does not exist in people, it’s not clear how or whether the rat studies can be applied to humans. On top of this, the Food and Drug Administration has evaluated the safety of Red Dye 3 several times and found no reason to revoke the approval for use in foods or ingested drugs. All of this suggests that Red Dye 3 will not increase any person’s risk for cancer.
Red Dye 3 is far from the only chemical that gets an entire media cycle dedicated to its purported cancer risks, sourced from a handful of flimsy research articles. Diet Coke, sunscreen, and titanium dioxide, another color additive, have all received similar treatment by the media. While there are animal studies that link all of these to cancer risks, mainstream reporting excludes the nuances of these studies, like differences between humans and animal models or the quantity of the chemical being tested, that limit their applicability to human health.
Because all these studies are presented as equally valid, it becomes difficult for readers to parse through the information and make decisions about their health. Any toxicologist will tell you that the dose makes the poison, meaning that in high enough quantities, any chemical can become dangerous to human health. Few media outlets will tell you how much of a chemical was used in a study linking it to cancer, let alone how that compares to the amount of chemical any person could reasonably expect to encounter.
It is up to reporters to end these media frenzies and inject nuance into their articles to help their readers make informed decisions. Reporters are far from perfect, so next time you read an article that makes you panic about your own health, remember to take it with a grain of salt – or maybe Red Dye 3.
References
Gawley, P. Candy Corn and Other Halloween Candy Found to Contain Cancer-Causing Red Dye 3. Vice. 24 Oct 2024. Accessed 25 Nov 2024.
Picchi, A. Some Halloween candy still includes carcinogen Red Dye 3, Consumer Reports warns. Here's a list. Moneywatch, CBS News. 24 Oct 2024. Accessed on 25 Nov 2024.
Hiasa, Y. et al. The promoting effects of food dyes, erythrosine (Red 3) and rose bengal B (Red 105), on thyroid tumors in partially thyroidectomized N-bis(2-hydroxypropyl)-nitrosamine-treated rats. Jpn J Cancer Res 79(3):314-319 (1988).
Bartsch, R. et al. Human relevance of follicular thyroid tumors in rodents caused by non-genotoxic substances. Regul Toxicol Pharmacol 98:199-208 (2018).
US Food and Drug Administration. FD&C Red No. 3. Accessed 25 Nov 2024.