Hair relaxers are used by millions of black women, possibly exposing them to various chemicals through scalp lesions and burns. In the Black Women’s Health Study, the authors assessed hair relaxer use in relation to uterine leiomyomata incidence. The study published in the American Journal of Epidemiology found that women who used hair relaxers were two to three times more likely to develop uterine fibroids. The study tracked more than 23,000 African-American women between 1997 and 2009.
Uterine fibroids (leiomyomata) are tumors of the uterine muscle that are responsive to estrogens and progesterone. Although benign, uterine leiomyomata are associated with significant gynecologic morbidity and are the leading indication for hysterectomy in the United States. The incidence of uterine leiomyomata is 2–3 times higher in US black women than in US white women, and the lifetime risk of uterine leiomyomata based on ultrasound evidence of preclinical and clinical disease—is estimated to be as high as 80% in US black women.
The black-white disparity in uterine leiomyomata risk is not explained by established risk factors. Hair relaxers (straighteners) have been used by millions of US black women, often for long periods of time. Hair relaxers can cause burns and lesions in the scalp, facilitating entry of hair relaxer constituents into the body.
Ingredients of hair relaxer:
The main ingredient of “lye” relaxers is sodium hydroxide; no-lye relaxers contain calcium hydroxide and guanidine carbonate, and “thio” relaxers contain thioglycolic acid salts. No-lye relaxers are advertised to cause fewer scalp lesions and burns than lye relaxers, but there is little evidence to support this claim. Products may also contain hormonally active compounds, such as phthalates, which are not required to be listed separately as ingredients and are often reported under the term “fragrances” or “perfume”.
Beauty products and the FDA:
Cosmetic products are not subject to premarket approval by the Food and Drug Administration, and a complete list of ingredients is not mandatory, making it unclear what types of chemicals they contain. However, because the vast majority of hair relaxers list “fragrance” as an ingredient, and 100% of popular fragrances tested in a 2002 study were found to contain phthalates, most hair relaxers likely contain these chemicals. In addition, some hair relaxer products directly list phthalates as one of their chemical ingredients. association between hair relaxer use and uterine leiomyomata risk in a large population of premenopausal black women.
Chemicals in hair products:
Hair products may contain chemicals that can disrupt hormones and increase the risk of fibroids. These chemicals include:
- Cyclosiloxanes
- Nonylphenols
- Phthalates
- Formaldehyde
- Di-2-ethylhexylphthalate (DEHP)
- Parabens
- Volatile organic compounds (VOCs)
