41 popular hair extensions have toxic chemicals linked to cancer and other health risks

The global market for hair extensions is booming, and projected to hit $14 billion by 2028. What was once a niche luxury item for women is now widely available.

Now, a new study from Silent Spring Institute says many hair extensions—including products made from human hair—contain dozens of hazardous chemicals, some linked to cancer.

The research, published in the American Chemical Society journal Environment & Health, provides the strongest evidence to-date about the potential health risks associated with these beauty products, which are largely unregulated. The risks disproportionately affect Black women: The study found over 70% of Black women report wearing hair extensions at least once in the past year, compared with “less than 10% of women from other racial and ethnic groups.”

The findings come at a time when many women’s beauty products are under scrutiny, with a growing number of studies finding cancer-causing chemicals in products ranging from shampoo and conditioner, to soap and lotion, to skin lightener, eyeliner, eyelash glue, and even lipstick.

Many hair extensions are made from synthetic fibers and bio-based materials, which are often treated with toxic chemicals to ensure they are flame resistant, waterproof, or antimicrobial.

Researchers analyzed chemicals in 43 popular hair extension products, including compounds that are not typically tested, and using machine-learning software, were ultimately able to identify 169 of the more than 900 compounds. According to the study, all but two of the samples tested contained hazardous chemicals.

Those chemicals included flame retardants, phthalates, pesticides, styrene, tetrachloroethane, and organotins, which are linked with cancer, hormone disruption, developmental problems, and disrupting the immune system. (In girls, they are also linked to early puberty and uterine fibroids.)

“Companies rarely disclose the chemicals used . . . leaving consumers in the dark about the health risks from prolonged wear,” Dr. Elissia Franklin, scientist at Silent Spring Institute, said. “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.”

The study concludes more industry regulation is needed. “The findings make clear that stronger oversight is urgently needed to protect consumers and push companies to invest in making safer products,” said Franklin.