A recent lawsuit has grabbed the headlines and sparked consumer concern with its claim that the popular multi-colored Skittles candy contained “known toxin»: chemical titanium dioxide. A lawsuit filed by a consumer in July against the maker of Skittles Mars notes that the European Union is prohibition titanium dioxide as a food additive.
But in the US, Canada and many other countries, titanium dioxide is still considered safe for use in regulated amounts. So what does science really say about a chemical that’s also used in cosmetics and sunscreens? Scientific American reached out to several toxicologists who have studied whether titanium dioxide can cause harm for answers. (We also reached out to Mars for comment, but did not hear back by the time of publication.) It turns out there is no conclusive research showing that this chemical used in food poses a risk to humans. Some clues from animal studies have prompted European countries to proceed with extra caution. Still, “saying we’re not sure it’s safe is a lot different than saying it’s dangerous,” says Agnes Oomen, a senior researcher at the Netherlands National Institute for Public Health and the Environment who has studied the chemical substance
What products contain titanium dioxide and why do they use it?
Titanium dioxide it is a natural, odorless white powder used as a pigment in many candies, including Skittles, as well as a number of other products such as cosmetics and even house paint. It perfectly scatters visible light, which gives what it is added a brighter and more saturated color. Titanium dioxide is also popular in sunscreens because of its effectiveness against skin-damaging UV rays.
How is titanium dioxide regulated in the US?
Domestically, the Food and Drug Administration deems the chemicals safe in foods, drugs, and cosmetics. As a color additive in food products The FDA requires it titanium dioxide meet certain requirements. One of them is that its amount cannot exceed 1 percent of the weight of the food to which it is added.
Why is this chemical banned in the EU?
In Europe, titanium dioxide is being phased out as a food additive alongside what are predicted to be thousands of other chemicals in various products. These efforts are sometimes referred to as “great detox.”
The current ban on titanium dioxide is the result of the European Food Safety Authority (EFSA) – agency which issues scientific advice on food risks –safety assessment of a chemical as a food additive in the 2021 report. EFSA noted that it cannot say unequivocally that titanium dioxide is toxic. But it also cannot rule out the possibility that the substance may be genotoxicis a term that indicates that something can alter genetic material, including DNA, or establish a safe level for daily consumption. Because of this uncertainty, EFSA concluded that titanium dioxide can no longer be considered safe for use as a food additive.
Omen, who co-authored the EFSA report on the potential toxicity of titanium dioxide, says the decision “is cautious”. For the past 15 years, she has worked on assessing the risks of nanoparticles to human health. These are particles between one and 100 nanometers in size, and some dietary titanium dioxide particles fall into this range. Respiration of nanoparticles have long been recognized as dangerous to human health, but when it comes to their ingestion, there is less scientific consensus. Still, Omen, who is also a professor at the University of Amsterdam, wonders, “If it’s just used as a colorant, is it really necessary in your food?”
“I think the main issue around titanium dioxide right now is not the science; the point is that the European Union really wants to get rid of nanomaterials in food products,” says Norb Kaminsky, director of the Institute of Integrative Toxicology at Michigan State University. (Kaminsky has previously been a consultant to the Titanium Dioxide Manufacturers Association.)
Were there any problems with the toxicity studies?
According to Kaminsky, most studies evaluating the toxicity of titanium dioxide have been conducted in animal models, primarily rats. U 2017 study prominently mentioned in the EFSA safety assessment – the very study to which it is credited which prompted France to ban the chemical in food in 2020— The researchers added titanium dioxide to the rats’ drinking water. After 100 days, the researchers found that these rats were more likely to develop aberrant crypt foci-clusters of abnormal glands in the mucous membrane of the colon and rectum – than rats given ordinary drinking water. Abnormal glands can be a sign of colon cancer.
But according to some researchers, the study has a critical experimental flaw: titanium dioxide is insoluble in water, so it likely settled and collected in large quantities near the opening of the bottle the rats drank from. “So we have absolutely no idea how much titanium dioxide these animals were exposed to,” says Kaminsky. “Remember that enough of anything—even things like water and oxygen—can be harmful.”
Eric Houdo, one of the authors of the 2017 study and the scientific director of France’s National Research Institute for Agriculture, Food and the Environment, says that he and his colleagues replaced the titanium dioxide-infused drinking water two to three times a week and that the bottles were shaken repeatedly. once a day. So they weren’t bothered by the excessive amount collecting at the bottom of the bottle.
Kaminsky and others are unconvinced by this argument, and are also perplexed by the fact that Goudot and his colleagues used water as a test. “The irony is that people are not exposed to titanium dioxide,” he says. “We are exposed to it in food.”
Joe Zagorski, a toxicologist at Michigan State University’s Center for Ingredient Safety Research, says it’s critical to properly define the route of exposure in a study to draw meaningful conclusions. “You have to ask, ‘Is this type of human impact achievable?'” he says. “Will it ever happen?”
In 2019, Kaminsky and his colleagues published a copy of the 2017 study, but instead of water, titanium dioxide was added to the rats’ food. They found no aberrant crypt foci or other indicators of toxicity in animals. The scientists did get some support from industry to carry out the research, but the funders couldn’t see the results until they were published in a peer-reviewed journal Food and chemical toxicology. And the researchers didn’t know which animals had been exposed to titanium dioxide until their analysis was complete.
Back in 1979, so did the National Cancer Institute evaluated the potential toxicity of titanium dioxide in food in rats and mice by exposing them to large amounts of the chemical for two full years, which is most of a rat’s lifetime. They found no evidence that titanium dioxide in food can cause cancer.
Why might a chemical be less toxic in food than in water? Recent works of a nanotoxicology researcher Saji George McGill University, published in the journal Nanoscale, provided some information. George’s lab discovered that proteins and other molecules are contained in food bind to titanium dioxide nanoparticles by encapsulating their surface, and this makes it difficult for the particles to interact with cells and cause damage.
Hudo says he and his colleagues are currently working on a new study looking at chronic dietary exposure to titanium dioxide in mice and plan to publish it later this year.
What about titanium dioxide in sunscreen?
Over the past few years, the FDA has evaluated 16 active sunscreen ingredients, including titanium dioxide. In 2021, the agency concluded that it was a chemical and zinc oxide safe and effective. (The remaining 14 ingredients required more data to draw any conclusions or were completely unsafe, the FDA said.)
Are there better ways to estimate titanium dioxide in food?
Research evaluating the acute toxicity of titanium dioxide is important, but it’s not everything, George says. “You’re missing other important parts of the picture,” he says. “There are so many other things that can happen with small, consistent amounts of titanium dioxide in the diet over a long period of time.” For example, George and his colleagues recently found that titanium dioxide – and nanoparticles more broadly – can enhance allergies to proteins in food. This result may not be as striking as the research that mentions the possibility of causing cancer, but it can still be important for human health.
George also says that most toxicology studies only consider the toxicological effects on healthy animals, which, again, is not the full picture. “We don’t know how titanium dioxide might make certain diseases worse—for example, inflammatory bowel disease in people with pre-existing conditions,” he says.
Why do different countries come to different conclusions on security?
There are different approaches to weighting risk. In order to ban titanium dioxide from food, regulators in countries like the US require factual evidence of increased risk. This is also true for Canada, where a recent assessment scientific evidence has concluded that titanium dioxide as a food additive is safe. In the EU, however, the uncertainty about safety – the inability to rule out potential harm – is enough to trigger regulatory action.
While Omen believes the EU’s cautious response to titanium dioxide is justified, she says the methods used to study the chemical need to be improved to lead to more definitive conclusions about human health. For example, she notes, research should provide dietary titanium dioxide in amounts comparable to what humans ingest.
Kaminsky agrees that better research methods are needed, but for now he’s not worried. “I don’t think titanium dioxide in the amount it’s used in Skittles and food is a toxicological concern or a public health problem,” he says. “At this point, there’s just no evidence to support that.”