Cancer Warning: Nearly Every Hair Extension Tested Contained Toxic Chemicals

A groundbreaking study reveals that many popular hair extensions may carry hidden cancer-linked chemicals — and sparks calls for urgent regulation.

A sweeping new investigation from Silent Spring Institute has uncovered dozens of potentially dangerous chemicals in widely used hair extensions, including products made from human hair. The findings represent the most detailed analysis so far of this largely unregulated beauty category and add to growing concerns about possible health risks. The issue is especially significant for Black women, who are far more likely to wear hair extensions than other groups.

The research, published today (February 11) in the American Chemical Society journal Environment & Health, comes as questions mount about the long-term health effects of these products. More than 70 percent of Black women say they wore hair extensions at least once in the past year, compared with fewer than 10 percent of women from other racial and ethnic backgrounds. Extensions are often chosen for cultural expression, personal style, and convenience.

“While prior reports have found some chemicals of concern in hair extensions, there’s still much we don’t know about their overall chemical makeup. We wanted to get a better picture of the extent of the problem,” says lead author Dr. Elissia Franklin, a research scientist at Silent Spring Institute. “This is an industry that has long overlooked the health of Black women, who should not have to choose between cultural expression, convenience, and their health.”

Chemical Treatments and Limited Disclosure

Hair extensions are made from synthetic fibers or bio-based materials, including human hair. To improve performance, manufacturers often treat them with chemicals that make the fibers flame resistant, waterproof, or antimicrobial.

“Yet, companies rarely disclose the chemicals used to achieve these properties, leaving consumers in the dark about the health risks from prolonged wear,” says Franklin. Because extensions rest directly against the scalp and neck, users may experience ongoing contact with these substances. Heat styling can also cause chemicals to be released into the air, creating an inhalation risk.

How Researchers Tested 43 Hair Extension Products

For the study, Franklin bought 43 popular hair extension products from online retailers and neighborhood beauty supply stores. The team sorted the products by fiber type, synthetic (mostly plastic polymers) or bio-based (including human, banana or silk), and recorded the claims made on their labels. Among the synthetic products, 19 claimed to be flame retardant, three said they were water resistant, nine advertised heat resistance, and three promoted “green” claims such as “no PVC” or “non-toxic.”

To analyze the samples, researchers used non-targeted analysis, a method designed to detect a broad spectrum of chemicals, including those not routinely tested in consumer goods. Using two-dimensional gas chromatography with high-resolution mass spectrometry, they identified more than 900 distinct chemical signatures, representing both known and unknown compounds. Machine-learning software compared these signatures against a chemical database, allowing scientists to identify 169 specific chemicals grouped into nine major structural classes.

Cancer Linked and Hormone Disrupting Substances Identified

The testing revealed numerous chemicals associated with cancer, hormone disruption, developmental harm, and immune system effects. Among them were flame retardants, phthalates, pesticides, styrene, tetrachloroethane, and organotins.

Key findings include:

• All but two of the 43 products contained hazardous chemicals. The two exceptions were labeled as “non-toxic” or “toxic-free.”
• A total of 48 detected chemicals appear on established hazard lists. Twelve are included under California’s Proposition 65 for causing cancer, birth defects, or reproductive harm.
• Four different flame retardants were present in both synthetic and bio-based products.
• Seventeen chemicals linked to breast cancer were found in 36 samples, including substances known to interfere with hormones in ways that may raise risk.
• Nearly 10 percent of the products contained toxic organotins, in some cases at levels exceeding health-based limits set in the European Union, where those chemicals are regulated.

“We were especially surprised to find organotins,” says Franklin. “These are commonly used as heat stabilizers in PVC and have been linked with skin irritation, which is a common complaint among hair extension users.” Organotins have also been associated with cancer and hormone disruption.

Growing Calls for Stronger Regulation

The global hair extension market is expected to exceed $14 billion by 2028, with the United States leading worldwide imports. Given the widespread use and the chemicals detected, Franklin says regulators need to step in. “These findings make clear that stronger oversight is urgently needed to protect consumers and push companies to invest in making safer products.”

Many of the identified chemicals are listed under Proposition 65, which suggests that clearer warnings and tighter oversight may be warranted for hair extensions.

Lawmakers have begun responding. In New York, proposed legislation would require companies that manufacture synthetic braids and hair extensions to disclose all ingredients. In New Jersey, a bill advancing through the legislature would prohibit certain harmful chemicals in synthetic hair products.

At the federal level, the Safer Beauty Bill Package, introduced in Congress last year, includes provisions directing the Food and Drug Administration to oversee the safety of synthetic braids and hair extensions.

Reference: “Identifying Chemicals of Health Concern in Hair Extensions Using Suspect Screening and Nontargeted Analysis” by Elissia T. Franklin, Kristin Favela, Radonna Spies, Jacqueline M. Ranger and Ruthann A. Rudel, 11 February 2026, Environment & Health.
DOI: 10.1021/envhealth.5c00549

Funding for this project was provided by a Beauty Justice Grant from the Environmental Defense Fund and charitable donations to Silent Spring Institute, including the Institute’s Safer Chemicals Program.

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