Hair Extensions May Contain Cancer-Causing Chemicals, Study Finds

• A new study has found that many types of hair extensions contain chemicals linked to cancer.
• A chemical banned from boat paint because it’s too toxic for fish is allowed in products worn by millions of Black women.
• The beauty industry has no federal safety standards, no testing requirements, despite mounting evidence of harm.
• All but two of the 43 hair extension products tested contained harmful chemicals linked to cancer, fibroids, hormone disruption, and metabolic disease.

A first-of-its-kind study found high levels of dangerous known chemicals and mystery chemicals in widely used hair extensions. Of the over 900 chemicals detected, researchers could identify only 169.

Many are linked to early puberty in girls, cancer, and conditions like uterine fibroids.

The Silent Spring Institute study, published on February 11 in Environment & Health, analyzed the chemical composition of 43 hair extension products and found nearly all products tested contained at least one cancer-causing chemical.

About 10% had plastic stabilizers called organotins at levels higher than what European regulators consider safe.

This is especially concerning for Black women and children, who make up the overwhelming majority of hair extension users — more than 70% of Black women report wearing extensions at least once a year compared to less than 10% of other groups — and typically keep them in for weeks at a time.

Here’s what you need to know.

Researchers went shopping at beauty supply stores in Houston and online for a variety of synthetic, plant-fiber-based, and human-hair extensions.

They tested hair used for eyelash extensions, bundles of loose hair that are installed directly on the head or used in wigs and braiding hair for styles like box braids and cornrows.

Elissia Franklin, PhD, lead author and research scientist at Silent Spring Institute, told Healthline that they chose a method that would “let the data tell us what’s in the sample” instead of looking for something specific.

That method resulted in a key finding of the study.

“When the fiber was not disclosed, those had some of the most hazardous chemicals in them,” Franklin said.

Products that don’t disclose what type of synthetic fiber they’re made from were the most dangerous. All but one sample without fiber disclosure contained significantly more hazardous chemicals than the products that disclosed their materials.

Researchers couldn’t identify more than 80% of the chemicals they detected because those substances aren’t in scientific databases, leaving users exposed to unknown toxins.

• Skin and scalp irritants — cause immediate burning, itching, rashes, and allergic reactions
• Hormone disruptors — interfere with your body’s natural hormones, causing weight gain, diabetes, early puberty, and metabolic problems
• Carcinogens — cause or increase cancer risk
• Reproductive toxins — harm fertility, fetal development, or can cause fibroids
• Neurotoxins and developmental hazards — damage the brain and nervous system, especially harmful to children

• Organotins— plastic stabilizers that cause skin reactions and hormone disruption
• Acrylonitrile — used in fibers like Kanekalon, harmful to skin and nervous system
• Phthalates — plasticizers that disrupt hormones and reproductive health
• Styrene — linked to leukemia and lymphoma

Many chemicals cause multiple types of harm. For example, organotins disrupt both hormones and reproductive health.

While allowed to be used in beauty products, researchers detected a type of organotin, tributyltin chloride, in the hair samples that the EPA and international bodies have banned from being used in the paint used on the bottom of boats for being extremely toxic to marine life.

This list represents just 20% of the chemicals found in the hair extensions. The other 80% of the chemicals were unidentifiable.

While skin irritation is one of the more immediate concerns with hair extensions, the risks go beyond the scalp.

The identifiable chemicals are linked to cancer, hormone disruption, immune system effects, and developmental problems, according to the study.

Cherie C. Hill, MD, OB-GYN, is an associate professor of gynecology and obstetrics at Emory University School of Medicine who treats patients with uterine fibroids. She wasn’t involved in the study, but told Healthline these products are especially concerning because fibroids impact Black women disproportionately.

One reason is their exposure to endocrine-disrupting chemicals (EDCs) found in hair extensions and other beauty products.

Hair extensions can rest on the scalp, face, neck, and back. The stylists who install the extensions on clients have heavy exposure as well.

Hill said once these EDCs are absorbed, they impact the hormonal balance.

“Fibroids respond to estrogen and progesterone. So, there may be a link between what we’re putting in and on our body and then fibroid tumor growth,” she said.

Hanna McCaskey, a hairstylist in Atlanta, told Healthline the study’s results weren’t surprising because she’s seen many people have skin reactions to braids.

“I know I struggled for a long time when I was younger and wearing sew-ins,” she said.

McCaskey said it’s frustrating to feel like the industry doesn’t care about the harm these products are causing.

“I just wonder if they would be keen to have those types of chemicals in products that their families, [themselves], their daughters would use,” she said.

McCaskey, like many Black women, has spent the majority of their life using these products and has also seen women her age experience uterine cancer and uterine fibroids.

Fibroids are often found in people who are in their reproductive years, yet exposure to these chemicals in beauty products begins in childhood. The EDCs are also linked to early puberty and obesity in girls.

Franklin pointed to research on how EDCs exposure can extend across generations.

“There are some studies… that support that the chemicals that a grandmother is exposed to do impact her grandchild,” Franklin said. That’s because females are born with all of their eggs. “That’s 3 generations right there affected by the same exposure,” she said.

That fact is especially concerning since many Black women choose to get hair extensions during and after pregnancy because of the convenience.

A 2024 Consumer Reports study tested popular synthetic braiding hair products and found all 10 contained cancer-causing chemicals, and 9 out of 10 had lead levels exceeding California safety limits — with some products containing over 600% of the allowable dose.

The beauty industry remains largely unregulated despite mounting evidence of harm. There are no safety requirements, testing standards, or recalls for harmful products primarily marketed to and used by Black people.

There’s a generation of millennial Black women who had chemical hair relaxer treatments nearly a dozen times a year for more than a decade to make their naturally curly or coily hair bone straight.

Those relaxers are now the subject of thousands of lawsuits over their link to uterine and other reproductive cancers.

Formaldehyde is a primary chemical of concern in hair straightening and smoothing treatments. Formaldehyde is a chemical used in pesticides and to preserve dead bodies, yet it is commonly found in hair relaxers.

Despite the known hazards, formaldehyde remains largely unregulated in the U.S. cosmetics market.

The FDA was scheduled to propose a ban on using the products in hair products, but has continually missed deadlines to do so. In a statement, the FDA told Healthline that the proposed rule remains a priority and that they “may adjust the anticipated publication date.”

Several bills have been introduced at the federal and state levels to regulate beauty products, but aside from California’s Prop 65, most haven’t passed or taken effect. Washington State has gone furthest, banning PFAS, phthalates, and formaldehyde by 2025-2026.

Despite these efforts, hair extensions remain federally unregulated, leaving Black women to navigate a market filled with untested products.

For Black women and girls, hair extensions are cultural, convenient, and essential for maintaining hair health while navigating discrimination rooted in white-centered beauty standards that equate sleek hair with cleanliness and professionalism.

The Silent Spring study found two products with no hazardous chemicals identified. One was Latched & Hooked’s Pre-Stretched Braiding Hair in color 1B, an American brand marketed as nontoxic.

Several American brands are entering the market long dominated by Asian manufacturers, but there’s a significant price barrier. Enough hair for a style using conventional synthetic braiding hair costs $3–$5, while safer alternatives run $15–$25 or more for the same style.

McCaskey said her clients are looking for convenient styles at affordable prices.

“A lot of our demographic can’t afford the better options because it is more expensive to use human hair and it is more expensive to use those products that are healthier for you,” she said.

When women sit down in her chair, she said she takes the opportunity to share what she’s learned about safer products. “When we get our hair done, that’s our time to gossip, to have little therapy sessions…I educate my clients along the way,” she said.

One method Black people have used to reduce irritation is rinsing or soaking the hair in apple cider vinegar (ACV). Franklin, who is Black, decided to test whether the science backed up this common practice.

“We have some support that the apple cider vinegar rinse can have very limited protection in that it does reduce the number of chemicals by a bit, but it doesn’t completely eliminate the hazard,” Franklin said.

While the ACV rinse can help, Franklin said it shouldn’t be Black women’s responsibility to try and detoxify dangerous products before using them.

“These companies should not make products that harm their consumers,” she said. The beauty industry needs regulation because “people should not be allowed to sell these products without testing them for safety and making sure that they do not cause harm… I don’t think we should have to choose between beauty or our culture.”

As awareness grows among stylists and consumers, the demand for transparency and safer choices is putting pressure on an industry that has not faced regulatory accountability.

Hill said regulatory oversight is essential because “these endocrine disrupting chemicals, they’re in everything.” She encourages using “our collective voice to push those in positions of power to make changes.”

Franklin said she hopes women use this information to make informed decisions about their overall chemical exposure.

“It’s not even about not wearing the braids,” she said. “It’s about — OK, if I’m going to wear the braids, do I need the edge control and the gel and the mousse and the other products on top of that that also contain these harmful chemicals?”

McCaskey agreed, “I think we just need to get away from thinking we have to put so much stuff on our hair, because we don’t.”