Those obvious extensions in your hair may also come with harmful chemicals; is the fake look really worth it?
A study by the Silent Spring Institute has revealed dozens of potentially harmful chemicals in widely sold hair extensions, even including human hair products.
This represents the most comprehensive chemical review to date (2026) of a largely unregulated beauty product category.
The study was published in Environment & Health. 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.
But the chemical toxicity plays no favorites as far as skin color and natural hair texture of the user.
Chemical Treatments and Hidden Ingredients
Hair extensions are made from synthetic fibers or bio-based materials, including human hair.
Manufacturers commonly treat these fibers with chemicals to make them flame resistant, waterproof or antimicrobial.
You can even smell the chemical treatment; take a good whiff of your hair extensions.
You may be wondering why there are no warnings on the packaging. The paper says that companies rarely disclose this information.
Because extensions sit directly against the scalp and neck, users may experience extended skin contact, and heating the extensions during styling can release chemicals into the air.
How the Study Tested Hair Extensions
The researchers purchased 43 popular hair extension brands from online retailers and beauty supply stores.
They grouped the products by fiber type — synthetic (mostly plastic polymers) or bio-based (including human, banana or silk) — and noted claims on packaging.
Among synthetic products, 19 claimed flame retardant properties, three were labeled water resistant, nine advertised heat resistance, and three promoted “green” claims like non-toxic.
Researchers used a method called non-targeted analysis, combining two-dimensional gas chromatography with high-resolution mass spectrometry, to detect over 900 chemical signatures, both known and previously unidentified.
Machine learning helped identify 169 chemicals across nine major structural classes.
The study found numerous substances associated with cancer, hormone disruption, developmental harm and immune system effects.
* All but two of the 43 samples contained hazardous chemicals. The only exceptions were labeled “non-toxic” or “toxic-free.”
* Forty-eight identified chemicals appear on major hazard lists, including 12 under California’s Proposition 65 for cancer, birth defects or reproductive harm.
* Four flame retardants were detected in both synthetic and bio-based products.
* Seventeen chemicals linked to breast cancer were found in 36 samples, many of which disrupt hormones.
* Nearly 10 percent of products contained toxic organotins, sometimes at levels exceeding EU safety limits.
Everyone These Days Seems to Wear Hair Extensions
It’s understandable when a woman with really thin, sparse hair decides to volumize it with extensions.
It’s a trade-off: risking chemical exposure for having a healthier looking, younger looking head of hair.
And sometimes, a home extension job is done very well, making the entire head of hair look natural rather than supplemented.
On the other hand, some extension users already have a pretty decent head of hair, but want it to appear longer.
In many such cases, it’s visibly obvious where the natural hair ends and the extensions begin. Are these sloppy jobs really worth the chemical exposure?
