Breast Cancer

Permanent Hair Dyes and Chemical Hair Straighteners May Increase the Risk of Breast Cancer, Especially in Black Women

A new and important study showed that the use of hair dyes and chemical straighteners may significantly increase a woman’s risk of breast cancer, especially for African-American women.
February 2020 Vol 6 No 1
Chevon M. Rariy, MD
Endocrinologist, Cancer Treatment
Centers of America (CTCA), Chicago, Illinois

A new and important study showed that the use of hair dyes and chemical straighteners may significantly increase a woman’s risk of breast cancer, especially for African-American women.1 It is estimated that about one-third (33%) of American women use such hair products, which on average contain more than 5,000 chemicals.

Previously published studies have been inconclusive about the potential link between hair dyes and breast cancer, but much of the previous research involved only white women. This new study included African-American women, although they made up only a small percentage (9%) of the study participants.

The study included 46,709 American women (aged 35 to 74) living in the United States and Puerto Rico and was conducted between 2003 and 2009.1 It was published in December 2019 in the International Journal of Cancer, and was supported by a grant from the National Institute of Environmental Health Sciences, a part of the National Institutes of Health.1

More than half (55%) of the women said that they had used permanent hair dyes regularly during the 12 months before the start of the study.

When the study started, none of these women had been diagnosed with breast cancer, but they all had at least 1 sister diagnosed with breast cancer, which is considered a family history of breast cancer.

Study Findings

Overall, the study results showed that:

  1. During the 8 years of the study, 2,794 of the women were diagnosed with breast cancer
  2. Using permanent hair dyes increased the risk of breast cancer
  3. Black women who used a permanent hair dye had a 60% higher risk of breast cancer than white women
  4. Black women used hair dye more frequently than white women; 74% of black women said they used these products every 5 to 8 weeks compared with only 3% of white women who used them as frequently
  5. Women who straightened their hair with chemicals were mostly black and had a 30% higher risk of breast cancer
  6. Although use of semi-permanent dye was not associated with increased risk, non-professional use of semi-permanent dye did increase the risk of breast cancer.

Hair Products & Estrogen Function

Permanent hair dye and chemical straighteners may contain hormone-disrupting chemicals and carcinogens that may be linked to the development of breast cancer. Hair products that are designed for African-American hair may contain even more endocrine-disrupting compounds than other products.

According to this study, hair straighteners may contain more than 5,000 chemicals and are used more often in hair products for African-American women than for white women.

Chemicals, such as formaldehyde, which is a known carcinogen, are active ingredients in many common hair-smoothing solutions. These products may contain hormone-disrupting compounds, including chemicals that are able to imitate the action of estrogen, and may be involved in certain types of breast cancer, as well as other carcinogens that may be connected to the development of cancer.

Family History of Breast Cancer

It’s important to note that this study consisted of women with a family history of breast cancer, who were therefore at increased risk of the disease to begin with. All study participants had at least 1 sister who had had breast cancer, which places them at an increased risk for breast cancer.

This study was what scientists call a prospective observational study, meaning that none of the women had breast cancer before the beginning of the study, follow-up studies to confirm these findings are needed, but all women should be aware of the potential risks associated with hair dye products available freely on the market.

People should be aware that these products are not monitored by the FDA for safety. Talk to your physician about how using hair dyes or chemical straighteners may affect your specific risk of breast cancer, especially if you have a family history of breast cancer.

As an endocrinologist specializing in treating patients with cancer, I aim to provide a unique expert perspective on medical news and its impact on our patients’ health. As a black woman and a doctor, this study is particularly important to me: ever since childhood, my family members, friends, and I have made regular visits to the hair salon.

Make Informed Decisions

Our sisters, nieces, aunts, mothers, grandmothers, and daughters are using these products regularly. It is important to know the risks that may exist with the use of these products, so we can make better-informed decisions based on our individual situations and family history.

Ironically, adhering to beliefs that resist the natural process of aging may have adverse medical consequences. For black women, hair and its straightening has had a complex history, steeped in cultural pressures of conforming and political undertones rooted in race and gender debates. If you were looking for another good reason to embrace your age and your natural hair color and texture, this study may just be it.


  1. Eberle CE, Sandler DP, Taylor KW, White AJ. Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women. International Journal of Cancer. Published online Dec 3, 2019.

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Last modified: March 11, 2020

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