TikTokers say titanium dioxide in organic tampons led to severe side effects. Here's what to know about the chemical compound.

• TikTokers are raising concern about titanium dioxide, a whitening agent, in organic tampons.
• The compound is used safely in many foods and cosmetics, but it's still banned in foods in the UK.

TikTokers are raising concern about an ingredient in an organic tampon brand that they say is causing symptoms like heavy bleeding and ovarian cysts.

The brand, L., markets itself as "accessible period care made with ingredients inspired by nature," according to its website. But TikTokers and commenters are questioning why the tampons contain titanium dioxide, a chemical compound often used as a whitening agent.

"Exposure can irritate eyes, nose, and throat, and causes cancer," TikToker monirubio8 reads from a state government webpage on titanium dioxide.

"But not only that, 'such substances may have the potential for causing reproductive damage in humans,'" she continues. "Well what do you know." The video has 630,000 views and nearly 14,00 comments.

Another TikToker, zt0n3r.hippie, responded by saying "now I know" the cause of her own reproductive health problems. "I've been on my period for 13 days, I have ovarian cysts that they have to check for cancer, and I've used five of these," she says holding an empty container of L. tampons.

The TikToker goes on to say she's been told she can't have kids due to "reproductive harm to my uterus and ovaries" and complains of serious pain at night and while trying to sleep. Her video has 3.6 million views.

Environmental and reproductive health experts have mixed views on how safe titanium dioxide in menstrual products is, but there's no evidence the tampons cause reproductive health problems like ovarian cysts or cancer.

Some doctors recommend avoiding tampons until there's more research

Titanium dioxide is a naturally occurring compound that's used in foods — like coffee creamer, salad dressing, and chocolate — and cosmetics, like powders, toothpaste, and sunscreen, usually as a bleach or to block UV damage.

According to the US Food and Drug Administration, the compound is safe in regulated amounts — meaning less than 1% of a food's weight to up to 25% of a sunscreen's concentration.

According to Safe Cosmetics.org, titanium dioxide does not penetrate healthy — or even unhealthy, burnt — skin, and so "poses no local or systemic risk to human health" when used topically.

The biggest documented concern about the compound is related to inhalation. According to the International Agency for Research on Cancer, it's "possibly carcinogenic" since studies have linked lung tumors in rats with inhaling titanium dioxide.

In the UK, the compound is banned from foods due to the potential for it to build up in the body and act as a carcinogen.

A spokesperson for Proctor and Gamble, which manufactures the L. tampons brand, told Insider titanium dioxide is used in the thread that attaches the cord to the absorbent part of the tampon, and represents less than 0.1% of all ingredients in the product.

"It's important to know that our tampons are safe to use," he said. "Our high-quality ingredients are rigorously tested and meet strict safety and government regulations around the world."

But Marianthi-Anna Kioumourtzoglou, an assistant professor of environmental health sciences at the Columbia Mailman School of Public Health, told Insider there's not enough, or really any, research on how the compound in tampons could affect reproductive health.

"We really know very little, or almost nothing really, about something that could impact the health of millions of women," she said. Her team is working on a pilot project analyzing tampons for the presence of metals and pesticides.

Dr. Philip M. Tierno, Jr., a professor of microbiology and pathology at the NYU School of Medicine, told Insider that while titanium dioxide is used in plenty of everyday products, "tampons are especially a problem" since it's possible the chemical could be absorbed into the bloodstream through the vagina's lining.

He added that the vaginal mucosa has lots of blood vessels, which allow it to absorb what's in tampons, leading to complications like toxic shock syndrome.

Tierno said he believed "truly organic tampons" don't, and shouldn't, contain chemicals like titanium dioxide. The safest bet, according to Tierno, is to use pads.

But not all doctors agree. OB-GYN Dr. Jen Gunter posted a response to the controversy on Instagram, calling concerns about it "fearmongering."

"Titanium dioxide is not an issue," she said, adding that "titanium dioxide doesn't cause reproductive harm when it's on a tampon string."