A new peer-reviewed analysis by the Silent Spring Institute found dozens of potentially hazardous chemicals in popular hair extensions, including products made from human hair. Researchers detected substances associated with cancer, hormone disruption and other health concerns in nearly all of the 43 products tested, raising renewed questions about safety and ingredient transparency in a largely unregulated market.
Researchers at the Silent Spring Institute analyzed 43 hair extension products purchased from online retailers and local beauty supply stores, including synthetic fibers and bio-based materials such as human hair as well as other plant- or silk-based fibers.
The study, published in the American Chemical Society journal Environment & Health, used non-targeted chemical screening and two-dimensional gas chromatography with high-resolution mass spectrometry to map what was inside the products. The team reported detecting more than 900 chemical “signatures,” and said it was able to identify 169 chemicals across nine major structural classes.
According to the institute’s summary of the findings, all but two of the tested products contained chemicals flagged as hazardous in the researchers’ framework. The analysis identified 48 chemicals that appear on major hazard lists, including 12 chemicals listed under California’s Proposition 65 as linked to cancer, birth defects, or reproductive harm.
The researchers also reported finding 17 chemicals connected to breast cancer in 36 of the products tested, and four flame retardants in both synthetic and bio-based samples. In addition, the institute said nearly 10% of samples contained organotin compounds, and that some measurements were above health-based concentration limits used in the European Union, where such chemicals are regulated.
“We were especially surprised to find organotins,” said Dr. Elissia Franklin, a research scientist at Silent Spring Institute and lead author of the study. “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.”
The institute said manufacturers often treat hair-extension fibers to achieve properties such as flame resistance, water resistance, or antimicrobial effects, but that companies rarely disclose what chemicals are used. Because extensions can rest directly against the scalp and neck and may be heated during styling, the researchers said there is potential for exposure through skin contact and inhalation of released chemicals.
The findings are likely to be of particular interest for public-health and consumer-safety debates involving products disproportionately used by Black women. The institute cited survey data indicating that more than 70% of Black women report wearing hair extensions at least once in the past year, compared with fewer than 10% of women from other racial and ethnic groups.
Franklin argued that stronger oversight is needed, saying the industry has historically overlooked the health concerns of Black women. “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,” she said.
The institute also pointed to growing policy attention. It said the global hair extension market is projected to surpass $14 billion by 2028, and noted that New York has introduced legislation that would require ingredient disclosure for synthetic braids and hair extensions, while New Jersey lawmakers are advancing a bill that would restrict certain harmful chemicals in synthetic hair products. At the federal level, the institute said the Safer Beauty Bill Package introduced in the previous year includes a proposal that would direct the Food and Drug Administration to regulate the safety of synthetic braids and hair extensions.
