Hair relaxers straighten the hair by penetrating the cuticle and the cortex layers of the hair shaft to loosen the natural curl pattern. While these products may seem ideal to use if you want to achieve straight hair in the comfort of your own home, some are, in fact, very dangerous to your health, as they often contain toxic chemicals. These harmful substances can enter your bloodstream through the lesions and burns caused by applying hair relaxers. Women who regularly use these products are more than twice as likely to develop uterine cancer as those who do not, according to a recent study from the Journal of the National Cancer Institute.

A class of toxic chemicals present in hair relaxers is phthalates. They are plasticizers used to increase the flexibility and durability of cosmetic products. Phthalates are endocrine disruptors, which means they can interfere with the hormonal system. A highly dangerous phthalate is di-2-ethylhexylphthalate. It is a probable carcinogen that is responsible for endometriosis, reproductive problems, infertility, and various malignancies. Having endometriosis places a woman at a significantly higher risk of developing ovarian cancer, another disease hair relaxers can be responsible for.

The phthalates lurking in hair relaxers also increase the risk of developing uterine fibroids, which is another proof that these chemicals are endocrine disruptors. Fibroids are benign tumors growing in the uterus. According to estimates, they can affect up to 80% of women throughout their lives. Although having uterine fibroids does not increase the risk of uterine cancer, these growths can greatly affect the life of the woman who has this condition, as she can experience heavy and painful periods, as well as miscarriages and infertility. Furthermore, exposure to phthalates can result in liver, kidney, lung, and reproductive system damage.

Chronic exposure to phthalates can adversely influence the endocrine system and functioning of several organs, which has negative long-term impacts on the pregnancy outcome, child growth and development, and reproductive systems in young children and adolescents. In animal studies, it was shown that phthalates have low acute toxicity with a median lethal dose of 1-30 g/kg body weight, and their toxicity was mainly concentrated in the liver, kidneys, thyroid gland tissue, and testis. According to the laboratory experiment on pregnant animals, exposure to di-2-ethylhexylphthalate at 100 mg/kg body weight/day is toxic to fetal development.

When it comes to children, epidemiological studies on phthalate toxicity found that these chemicals affect pregnancy outcomes, genital development, semen quality, precocious puberty, thyroid function, and neurodevelopment. It was shown that exposure to phthalates negatively affected the level of reproductive hormones and thyroid function. Altered thyroid function is associated with thyroid cancer, which makes hair relaxers highly dangerous to children because they often contain phthalates, so they should never use these products. Children are at a higher level of exposure and considerably more vulnerable to phthalates.

Heavy metals such as cadmium and lead are also present in some hair relaxers. Cadmium exposure may increase the risk of endometrial cancer, perhaps due to the effects of estrogen, and it was found that exposure to high cadmium levels increased the risk of endometrial cancer by 22%. Lead and cadmium disrupt the antioxidant properties of many enzymes, consume the resources of antioxidant cells, and participate in the production of oxidative stress, which may result in DNA damage. All of these changes that can occur in the body following exposure make a person more susceptible to developing gynecological cancers.

Lead causes high oxidative stress levels, which damages cellular components in a similar way as other hazardous metals, such as cadmium. The pathogenetic effects of lead are multifactorial. Firstly, singlet oxygen, hydrogen peroxides, and hydroperoxides are produced. Secondly, the cellular pool of antioxidants is depleted. Consequently, two independent but connected mechanisms contribute to free radical damage caused by lead exposure from hair relaxers. These two mechanisms are interrelated, so when oxidative stress levels increase on one side, antioxidant pools are depleted on the opposite side.

Chemicals that can induce estrogenic activity, subsequently causing uterine or ovarian cancer, can be divided into several groups, such as estrogens, xenoestrogens, phytoestrogens, and metalloestrogens. Inorganic heavy metal ions that attach to estrogen receptors and induce their activation are known as metalloestrogens. Cadmium and lead are among these. They have estrogenic properties and have been found to produce a significant estrogen-like effect once inside the body. Hormone-sensitive cancers such as uterine and ovarian cancer are often the result of an imbalance between estrogen and other hormones.

Finally, bisphenol A is another toxic chemical present in many hair relaxers on the market. It exhibits hormone-like properties, which means exposure can eventually cause uterine and ovarian cancer. The estrogenic activity of bisphenol A represents the major endocrine-disrupting effect of this substance and was revealed in 1993 by a study showing that bisphenol A can be released from polycarbonate flasks during autoclaving. Bisphenol A was originally thought to disrupt the estrogen-triggered pathways by forming a transcriptional complex that can bind the estrogen-responsive element. Still, additional studies found that the chemical can also activate non-classical estrogen pathways during bisphenol A-mediated rapid responses.

Considering how many toxic chemicals are lurking in hair relaxers, women who intend to use these products to straighten their hair are advised to find safer alternatives, such as heat styling, keratin treatments, or silicone creams. Although using hair relaxers just occasionally is not associated with a high risk of uterine or ovarian cancer, it is always better to be on the safe side and use non-toxic methods if you want straight hair.

About the Author
Miguel Leyva is a case manager at Atraxia Law. He provides assistance to women injured by toxic hair relaxers. Miguel Leyva helps women with uterine or ovarian cancer gather and organize relevant information about their injuries so they can subsequently file a claim.


  • Ashley Lauer said:

    Would like to try this sample

    May 08, 2024

  • Audrey Sims said:


    December 08, 2023

  • Jennifer said:

    Would love to try a sample

    December 08, 2023

  • Claudia Juarez said:


    November 05, 2023

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