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The Link Between Hair Relaxer and Uterine Cancer

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In October 2022, the Journal of the National Cancer Institute linked using chemical hair relaxer to an increased risk of developing uterine cancer. To reach this discovery, the JNCI observed the findings of the Sister Study, a long-term womens’ medical study run by the National Institute of Environmental Health Sciences (NIEHS). 

According to the Sister Study, women who regularly use hair relaxer are over TWICE as likely to develop uterine or endometrial cancer compared to women who don’t use them. Currently, there are two theories pointing to why chemical hair relaxers may be causing women to develop uterine cancer:

  1. The presence of endocrine-disrupting chemicals (EDCs) in hair relaxers.
  2. The presence of formaldehyde (a known carcinogen) and other chemicals that release formaldehyde when applied to the scalp.

What are EDCs, and how are they linked to uterine cancer?

Endocrine-disrupting chemicals (EDCs) are a group of natural and synthetic chemicals known to negatively interfere with the human body’s endocrine system, which produces hormones that control many essential bodily functions. According to the NIEHS, EDCs can mimic, block, or interfere with the body’s hormones, which can lead to a hormonal imbalance and cause a variety of health concerns.

Those health concerns include, but are not limited to:

  • Weakened immune system
  • Lowered fertility, or infertility
  • Increased risk of endometriosis
  • Disrupted nervous system function
  • Metabolism disruption
  • Increased risk of type II diabetes
  • Obesity in children and adults
  • Early puberty development
  • Increased risk of premature birth
  • Higher neurological disorder risk

As the list of symptoms above shows, EDCs can cause several complications in the female reproductive system. Many well-known EDCs are estrogenic, which means they can mimic the hormone estrogen in the human body. This is a huge problem, because the NIEHS and other health organizations have identified excess estrogen to be a known risk factor for uterine cancer. Even worse, many at-home hair relaxers available for sale contain estrogenic EDCs.

In 2018, the Silent Spring Institute and the Battelle Memorial Institute published a study in a peer-reviewed academic journal called Environmental Research about the presence of EDCs in different chemical hair relaxers. In this study, researchers discovered that several hair relaxer products marketed towards black women contained EDCs, including parabens, phthalates, cyclosiloxanes, unsafe fragrance chemicals, bisphenol A, and other substances. Most of these EDCs are estrogenic.

How do EDCs get into the body when using hair relaxer?

EDCs can be found in many cosmetic and personal care products, including makeup, shampoo, toothpaste, cleaning wipes, and other household goods. Millions of people are regularly exposed to EDCs, which is a major health concern in its own right, but they’re even more dangerous when added to hair relaxers. This is because of the activating chemicals used to make relaxers straighten hair effectively, such as sodium hydroxide and guanidine carbonate.

When hair relaxer is left on for too long, its activating chemicals can cause burns and lesions to form on the scalp. These chemicals are not cancerous, but the wounds they leave behind give estrogenic EDCs like parabens and phthalates an easy opening to be absorbed into the bloodstream.

What is formaldehyde?

Formaldehyde is a pungent, colorless, and flammable gas that’s commonly used for industrial manufacturing purposes. It can be found in building materials, glues, disinfectants, foam insulation, and many other products. Some foods contain formaldehyde in tiny amounts, but it can also be found in the human body while converting food into energy. Though this chemical is widespread and prevalent, significant exposure to formaldehyde can cause troublesome side effects.

Here are some (but not all) of the common symptoms that can occur because of formaldehyde exposure:

  • Eye or skin irritation
  • Respiratory issues
  • Skin rashes or scalp burns
  • Drowsiness
  • Diarrhea or constipation
  • Vomiting
  • Contact dermatitis
  • Chronic headaches
  • Hormone disruption
  • Cellular toxicity

How is formaldehyde connected to uterine cancer?

Formaldehyde is considered to be a known carcinogen by the International Agency for Research on Cancer (IARC). In 2004, the IARC classified formaldehyde as “carcinogenic to humans” after finding sufficient evidence of frequent exposure causing nasopharyngeal cancer in workers. Formaldehyde exposure has also been linked to an increased risk of leukemia, sinonasal cancer, and reproductive toxicity.

Many professional-grade hair relaxers contain either formaldehyde or methylene glycol, a chemical that releases formaldehyde when applied to the scalp and heated. Over-the-counter relaxers don’t typically contain these chemicals, but they are prominent in relaxer solutions used in salons, including keratin treatments and Brazilian blowouts. Like with EDCs, the presence of formaldehyde, methylene glycol, and other formaldehyde-releasing chemicals in hair relaxers is a major concern for medical researchers. 

Though scientists have not directly connected formaldehyde exposure to an increased risk of developing uterine cancer, formaldehyde’s link to reproductive toxicity and status as a carcinogen is worrying. Reproductive toxicity in women can lead to infertility and abnormal menstrual cycles, as well as an increased risk of birth defects, premature birth, stillbirth, childhood cancer, and developmental disorders in infants. When combined with estrogen-mimicking EDCs often found in hair relaxers, formaldehyde’s reproductive effects could potentially cause even worse of a hormonal imbalance than EDCs could alone.

Which hair relaxer brands contain EDCs or formaldehyde?

Unfortunately, most chemical hair relaxer products available today either contain EDCs, formaldehyde, or a formaldehyde-releasing substance like methylene glycol. If you’re concerned that your favorite relaxer may not be safe to use, here are some of the most popular hair relaxer brands at risk:

  • Creme of Nature, Revlon
  • Olive Oil No-Lye, ORS
  • African Pride, Olive Miracle
  • Africa’s Best, House of Cheatham
  • Motions, Strength of Nature
  • Just for Me, Strength of Nature
  • Ultra Sheen Supreme, Strength of Nature
  • Soft & Beautiful, Strength of Nature
  • Dark & Lovely, Softsheen-Carson, L’Oréal
  • Bantu, Softsheen-Carson, L’Oreal
  • Optimum, Softsheen-Carson, L’Oreal
  • ULTRA precise, Softsheen-Carson, L’Oreal
  • Butter Blend, Mizani, L’Oreal
  • Olive Oil No-Lye, TCB Naturals
  • Pink conditioning no-lye, Luster’s
  • Smooth Touch no-lye, Luster’s

Join the hair relaxer lawsuit

If you or a family member was diagnosed with uterine cancer after frequently using a hair relaxer product, you may be eligible for a hair relaxer settlement.

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See if you qualify for the hair relaxer lawsuit.

Referenced Articles

The references used by our writers at FreeLegalReviews.com are deemed to be from credible and reputable sources, including peer-reviewed studies, court records, non-profit organizations, government agencies, highly regarded news media, and legal subject experts. Before making any medical or financial decisions, please seek the opinion of a qualified professional.
  1. Chang, C., O’Brien, K., et al. (2022 December). Use of Straighteners and Other Hair Products and Incident Uterine Cancer. Journal of the National Cancer Institute, 114 (12), pp. 1636–1645. Retrieved from https://doi.org/10.1093/jnci/djac165

  2. National Institute of Environmental Health Sciences. (2024, July 22). Endocrine Disruptors. Retrieved from https://www.niehs.nih.gov/health/topics/agents/endocrine

  1. Endocrine Society. (2022, January 24). Endocrine-Disrupting Chemicals (EDCs). Retrieved from https://www.endocrine.org/patient-engagement/endocrine-library/edcs

  2. PDQ® Screening and Prevention Editorial Board. (2024, March 15). Endometrial Cancer Prevention (PDQ®)–Health Professional Version. National Cancer Institute. Retrieved from https://www.cancer.gov/types/uterine/hp/endometrial-prevention-pdq

  3. Helm, J., Nishioka, M., et al. (2018, August). Measurement of endocrine disrupting and asthma-associated chemicals in hair products used by Black women. Environmental Research, 165, pp. 448–458. Retrieved from https://doi.org/10.1016/j.envres.2018.03.030

  4. National Cancer Institute. (2024, August 6). Formaldehyde. Retrieved from https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/formaldehyde

  5. Environmental Working Group. (2011, April). Brands that hide formaldehyde. Retrieved from https://www.ewg.org/hair-straighteners/our-report/hair-straighteners-that-hide-formaldehyde/

  6. International Agency for Research on Cancer. (2006). Formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans (Vol. 88). Retrieved from https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Formaldehyde-2-Butoxyethanol-And-1–Em-Tert-Em–Butoxypropan-2-ol-2006

About the Hair Relaxer Lawsuit

Products at-risk
  • Store-bought chemical hair relaxers that have endocrine-disrupting chemicals, or EDCs.
  • Professional, in-salon relaxing treatments that release the chemical formaldehyde.
Who's being sued?
  • L’Oreal
  • Revlon
  • Softsheen-Carson
  • Strength of Nature
  • Original Root Stimulator (ORS)
  • Luster’s
  • Olive Miracle
  • TCB Naturals
  • House of Cheatham
  • Mizani
  • and other hair relaxer companies.
Which illnesses are eligible?
Further Reading
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