Whether it’s the neon hues found in a bag of Skittles or the fiery orange of a Dorito, you’ve probably guessed that the colors in a lot of products you buy aren’t natural.

But while many things we consume contain synthetic dyes, the safety data on some of them isn’t exactly black and white. Some dyes, such as Blue 1 and Yellow 5, can cause allergic reactions, like hives.

And others, like Red 40, might even exacerbate ADHD symptoms. And a couple of dyes have been in the news lately as some U. S. states are attempting to ban them entirely.

Titanium dioxide, which gives products like toothpaste their gleaming white, and Red number 3, found in many things pink, have both been linked to cancer in animal studies. But the human implications of those studies are about as clear as your strawberry milk. [♪ INTRO] Let’s start with titanium dioxide. It’s a chemical compound that’s often used to help pigment things bright white.

And if you do a little inventory of your house and peruse the ingredients, you’ll probably find a lot of items with titanium oxide, including makeup, sunscreen, toothpaste, and even food. Things like muffins, queso, and milk can include titanium dioxide, though it’s more commonly found in sweets, like chewing gum or candy. And that could be problematic because titanium dioxide has wreaked some pretty serious havoc on lab rats.

Some products, like eye shadow, utilize titanium dioxide in a powder form, so a study conducted in 1985 focused on whether inhalation of such a product was dangerous in rats. The study found that chronic exposure to high doses of titanium dioxide powder led to cancerous tumors in the lungs of the rats. Subsequent studies determined this was due to a build up of titanium dioxide particles in the lungs, which led to deposition of particles faster than immune cells could clear them out.

While we may scarf down our food, most of us don’t literally inhale it. So maybe our digestive systems have a better chance at combating these dyes than our lungs do? Well, to assess this, a 2012 study sought to estimate how much titanium dioxide the average person consumed through their diet each day.

These estimates varied widely depending on age. The average adult, for example, consumed around .5 milligrams of titanium dioxide per 1 kilogram of body weight. Toddlers, on the other hand, consumed more like 1-2 milligrams per kilogram of body weight.

But those were just the averages. They found that some kids could consume several hundred milligrams of titanium dioxide in a day, which translates to 13 mgs per kilogram of body weight or more. In 2017, a research team studying how eating titanium dioxide would affect rats split the difference and settled on a dose of 10 milligrams per kilogram of body weight: higher than the average person would consume, but still in the ballpark.

The good news: No lung cancer. But bad news: Colon cancer. See, the rats eating the titanium dioxide had a bunch of changes in their intestines, including an increased presence of dendritic cells, decreased number of regulatory T cells, and fewer T helper cells.

Essentially, it really messed with the immune system, leading to increased inflammation. Plus, it decreased the amount of a protein called interferon gamma, which helps kick the immune system into action when you get sick and inhibit tumor growth. Less interferon gamma means a less effective immune system.

The titanium dioxide also made the gut environment somewhat of a precancerous cell nursery, damaging healthy cells while largely sparing the precancerous ones. And these cellular changes had other consequences too as well. A normal colon has many small crevices in the tissue called crypts, which are important for absorption of nutrients and water, among other things.

After exposure to titanium dioxide, the rats developed aberrant crypts, which means their crypts got misshapen, enlarged, or otherwise messed up. They also had lesions, which can be an early warning sign for cancer. Further studies on titanium dioxide showed that it not only accumulates in the body, but may also damage DNA and compromise chromosomal integrity.

And I don’t know about you, but I prefer my chromosomal integrity uncompromised. In May 2021, the European Food Safety Authority seemed to agree, as they announced that titanium dioxide was no longer safe to consume as a food additive. They’ve even been working on banning it entirely, though this has been challenged in the courts.

And in the United States, several states, including California, have introduced legislation to ban titanium dioxide from food. The Environmental Defense Fund has officially petitioned the FDA to repeal the regulation that allows titanium dioxide in the things we eat. And a lawsuit filed against Skittles for including titanium dioxide in their candy made headlines in 2022.

But the FDA isn’t just ignoring this data because they love Little Debbies Fudge Rounds more than the health of the United States. The real reason why it’s still an approved food dye is because lots of studies haven’t found the same dangerous health effects. For example, a study published in June 2023 gave rats up to 1000 milligrams of titanium dioxide per kilogram of body weight for 90 days, and even at this extremely high dose, they found no indication of toxicity or increased presence of wacky colonic crypts.

Another study out of Michigan State University gave rats between 1 and 374 milligrams of titanium dioxide per kilogram of body weight per day for as many as 100 days. Again, they found no significant problems. Even inhalation of the stuff has studies suggesting no difference in lung cancer development.

So altogether, titanium dioxide safety is definitely still up for debate, and worthy of continued research. So now let’s look at erythrosine 127, AKA Red number 3, which has an eerily similar story to titanium dioxide. Except, instead of dying things white, it dyes things pink, like Nesquik strawberry milk which I have right here.

A 2011 study found that Red 3 inhibited a lot of different proteins, which is generally a problem because our proteins have jobs to do. And one of the proteins it inhibited was tumor necrosis factor, which is responsible for killing cancer cells, among other things. A separate study found that Red 3 consumption could affect the amount of bilirubin, HDL cholesterol, and vitamin C in the blood, contributing to liver cirrhosis and cancer development.

And rat studies from decades ago suggest that exposure to Red 3 could significantly promote thyroid tumor growth in animals with other risk factors. And we can’t forget to mention that the FDA banned Red 3 from cosmetic products based on that thyroid cancer study. That’s right!

You can eat it in your Carvel ice cream cake or Betty Crocker loaded mashed potatoes, but you can’t use it for that perfect pink blush. Which is a big reason why many organizations have begun petitioning the FDA to reconsider Red 3’s safety in food. The FDA even released a statement in May 2023 confirming that they were currently reviewing petitions to revoke both Red 3 and titanium dioxide from their approved list.

So yeah, we might have a problem with our pink and white pigments here. But the good news is that alternatives are already being worked on for both. Calcium carbonate, for example, is a safe alternative derived from limestone that can pigment food white.

While some argue it affects the texture of the food and may not be as bright as titanium dioxide, it sure beats colon cancer. And it’s used in Lucky Charms, so it clearly gets the job done. Plus, there are some proprietary titanium dioxide alternatives available, like Avalanche, which has different formulas for applications like baking, condiments, and pet food.

Though we may not know exactly what’s in these, it does highlight the interest in moving away from titanium dioxide. As for Red 3, carmine offers a safe pink alternative, and it’s heat-stable for those of us worried about our pasteurized strawberry milk. It’s already used in foods like Yoplait Strawberry Yogurt and rainbow Mentos, which we couldn’t find.

But carmine is technically a powder made from the pulverized bodies of the cochineal scale insect, though, so it’s not a vegetarian option. For those folks, plants like beets can be a great alternative when aiming for that perfectly pink look. Similarly, Starbucks turned to a tomato extract when their use of carmine gave customers the heebeegeebees.

And since a lot of these alternatives are already used in foods, it would just be a matter of getting the brands still holding out to accept the slight color difference in their drinks and make the switch. Dunkin Donuts actually already phased out using titanium dioxide in its powdered donuts, so it can be done, and apparently pretty discreetly, too. So even if the FDA does revoke their approval of titanium dioxide or Red 3 and companies remove these dyes from their products, you’ll still be able to get a refreshing glass of strawberry milk.

It will just look a little different. Now you know who tends to like strawberry milk? Kids.

And you know what else they might like? SciShow Kids, our YouTube channel for children! A few times a month, our host Jessi and her friends learn about magnets, the weather, weird animals, and all kinds of experiments you can do at home.

So if you have a kid in your life who’s curious about science, you can visit YouTube.com/SciShowKids and join the fun. [♪ OUTRO]