Reference summary — not medical advice or a personal risk estimate.
Hair straightening / relaxer
Chemical treatments to straighten hair. Formaldehyde-releasing formulations are the highest-risk category.
Also known as: keratin treatment, Brazilian blowout, chemical straightener
IARC-classified factors documented in this product
- Contains · Source: US FDA
Keratin and "Brazilian blowout" treatments release formaldehyde during application; FDA has issued warnings.
How to read this page
A factor appearing on this page means it has been documented in this product category — through EPA / FDA testing, IARC monographs, or regulatory recall records. Whether it presents a meaningful personal risk depends on the specific formulation, dose, and how you're exposed. Click any factor to read what science actually says about it, and where.