In the most comprehensive analysis to date, a new study by Silent Spring Institute identified dozens of hazardous chemicals in hair extensions, including products made from human hair, providing the strongest evidence yet of the potential health risks associated with this largely unregulated category of beauty products that disproportionately affect Black women.
Published in the American Chemical Society journal Environment & Health , the study arrives amid growing concern about the health impacts of hair extensions, which are widely used by Black women. More than 70 percent of Black women report wearing hair extensions at least once in the past year, compared with less than 10 percent of women from other racial and ethnic groups. Many wear them for cultural and personal reasons, as well as for 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."
Hair extensions can be made from synthetic fibers and bio-based materials, including human hair, and are often treated with chemicals to make them 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. The fibers sit directly on the scalp and neck, and when heated and styled, they can release chemicals into the air that wearers may breathe in.
For the study, Franklin purchased 43 popular hair extension products online and from local beauty supply stores. She categorized the products by fiber type—synthetic (mostly plastic polymers) or bio-based (including human, banana or silk)—and then coded them by their claims. Nineteen of the synthetic samples claimed to be flame retardant, three were water resistant, nine heat resistant, and three carried "green" claims such as "no PVC" or "non-toxic."
The researchers used a technique called non-targeted analysis to screen the samples for a wide range of chemicals, including compounds that are not typically tested for in products. Using two-dimensional gas chromatography with high-resolution mass spectrometry, the team detected over 900 chemical signatures, capturing both known and unknown substances. Machine-learning software was then used to match these signatures to a chemical library, ultimately identifying 169 chemicals across nine major structural classes.
The analysis revealed dozens of hazardous substances linked with cancer, hormone disruption, developmental problems, and effects on the immune system. These included flame retardants, phthalates, pesticides, styrene, tetrachloroethane, and organotins.
Key findings:
- All but two samples contained hazardous chemicals, and both of those were labeled as "non-toxic" or "toxic-free."
- 48 chemicals appeared on major hazard lists, including 12 listed under California's Proposition 65 for causing cancer, birth defects, or reproductive harm.
- Four flame retardants were found in both synthetic and bio-based samples.
- 17 chemicals related to breast cancer were found across 36 samples, including compounds known to alter hormones in ways that increase risk.
- Nearly 10 percent of samples contained toxic organotins, some at concentrations exceeding health-based levels set in the European Union, where the 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 linked with cancer and hormone disruption.
With the global hair extension market projected to surpass $14 billion by 2028, and the United States leading in global imports, "these findings make clear that stronger oversight is urgently needed to protect consumers and push companies to invest in making safer products," says Franklin.
In particular, many products contained chemicals listed under Proposition 65, suggesting that hair extensions should be more closely regulated and carry consumer warnings.
Momentum for policy change is building. New York recently introduced legislation that would require manufacturers of synthetic braids and hair extensions to disclose all ingredients. In New Jersey, a bill that would ban harmful chemicals from synthetic hair products is also advancing through the legislature.
At the federal level, the Safer Beauty Bill Package, introduced in Congress last year, includes legislation that would direct the Food and Drug Administration to regulate the safety of synthetic braids and hair extensions.
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.
Reference: Franklin, E.T., K. Favela, R. Spies, J.M. Ranger, R.A. Rudel. 2026. Identifying chemicals of health concern in hair extensions using suspect screening and non-targeted analysis. Environment & Health. DOI: 10.1021/envhealth.5c00549
