Elevated formaldehyde concentration in "Brazilian keratin type" hair-straightening products: a cross-sectional study

J Am Acad Dermatol. 2014 Feb;70(2):276-80. doi: 10.1016/j.jaad.2013.10.023. Epub 2013 Dec 9.


Background: Brazilian keratin treatment (BKT) and similar straightening products fix and retain a straight shape even when the hair is wet. Unacceptably high concentrations of formaldehyde have been reported in such products.

Objective: We sought to measure the formaldehyde concentration in all BKT brands marketed in South Africa in 2012.

Methods: We quantified formaldehyde by high-performance liquid chromatography with ultraviolet light detection after derivatization with dinitrophenylhydrazine. All components of 7 identified commercial brands were each tested 3 times.

Results: The maximum safe concentration of formaldehyde set by the US Cosmetic Ingredient Review Expert Panel is less than 0.2%. Of the 7 commercial BKT brands, 6 had formaldehyde levels that ranged from 0.96% to 1.4%, ie, 5 times higher than the recommended level; these included 5 brands labeled formaldehyde-free.

Limitations: The study is limited by not including all internationally available BKT products.

Conclusions: Formaldehyde concentrations in BKT products may exceed recommended levels and serve as a health hazard. Industry monitoring is needed to improve compliance and protection of hairdressers and consumers.

Keywords: BKT; Brazilian keratin treatment; Brazilian keratin treatments; DNPH; DNPHF; HPLC; dinitrophenylhydrazine; formaldehyde; formaldehyde dinitrophenylhydrazone; hair; hairdressing; high-performance liquid chromatography; public health.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Barbering*
  • Chromatography, High Pressure Liquid / methods
  • Consumer Product Safety
  • Cross-Sectional Studies
  • Environmental Monitoring*
  • Formaldehyde / analysis*
  • Hair Preparations / chemistry*
  • Humans
  • Keratins, Hair-Specific
  • Magnetic Resonance Spectroscopy
  • Marketing
  • Maximum Allowable Concentration
  • Occupational Exposure / analysis*
  • Risk Assessment
  • South Africa


  • Hair Preparations
  • Keratins, Hair-Specific
  • Formaldehyde