dye straighteners linked to cancer
Julie Hambleton
Julie Hambleton
July 2, 2024 ·  5 min read

Is coloring hair safe? Dye, straighteners may increase breast cancer risk, study finds

Breast Cancer is terrifying. It is the most commonly diagnosed cancer for women across the globe, and the second-most prevalent cancer overall. (1) This statistic rings true in the United States, where 1 in every 8 American women are expected to develop breast cancer in their lifetime. (2)

Naturally, many resources have been put into researching breast cancer to better help fewer women from becoming part of this statistic. A recent study reported by the Department of Epidemiology at the University of North Carolina has found another potential contributor to breast cancer risk that thousands of women use regularly. (3) The culprit? Hair dye.

The Sister Study

Beautiful young woman doing breast self-examination on light grey background
Source: Shutterstock

Researchers from the University of North Carolina (UNC) have recently published results from The Sister Study, a study that looked at 50,000 women in America and Puerto Rico between the ages of 35 and 74 whose sisters had breast cancer. (3, 4)

At the beginning of the study, participants filled in an enrollment questionnaire, which asked them about their daily habits including hair product use in the last 12 months. The scientists at UNC specifically looked at those women who said they colored their hair, used chemical straighteners, or both. In the follow-up between 8 and 9 years later 2, 974 of these participants were found to have developed breast cancer themselves. (3) The researchers found a (3):

  • 45% increased risk of breast cancer related to permanent hair dye in black women
  • 7% increased risk of breast cancer related to permanent hair dye in white women
  • The use of hair straightening product use was associated with an increased breast cancer risk.
  • The use of both hair dye and straightening chemicals increased breast cancer risk, particularly for black women.

Read More: 6 Beverages With Anti-Cancer Properties

Hair Dyes, Straighteners, and Breast Cancer

Hair Coloring In A Beauty Salon. Professional wizard paints the hair in the salon. Beauty concept, hair care. Hairdressing Services
Source: Shutterstock

Other studies have similarly found that the chemicals in hair dyes and straighteners may be a contributing factor to the development of breast cancer in some women. (9, 10, 11) Several cosmetics, including hair dyes, have come under fire in recent years for the long line-up of chemicals in their ingredients list. These products are known as endocrine-disrupting chemicals (or hormonally-active compounds) and carcinogens. (3)

What are endocrine disruptors?

Hairdresser is applying bleaching powder on woman's hair and wrapping into the foil.
Source: Shutterstock

Endocrine disruptors are both naturally occurring and man-made substances that interfere with your body’s endocrine system, aka the system responsible for making hormones. Interference with this system can affect many aspects of the body (8):

  • Developmental
  • Neurological
  • Immunity
  • Reproduction 

There are over 5000 different chemicals found in permanent hair dyes and hair-straightening products. (7)They can be both absorbed through the skin or inhaled from the fumes they create in the air. (5) Hair stylists and women who dye their hair regularly are frequently exposed to these chemicals, and endocrinologists are concerned that this may be affecting their health.

Hair dyes are not regulated

Hairdresser holding bowl with hair dye closeup
Source: Shutterstock

While the FDA does regulate the overall safety of all cosmetics in the United States, they don’t actually approve each ingredient in the dyes before they go to market. This responsibility falls to the manufacturers. 

The FDA is left to have a reactionary approach: if products are determined to be unsafe, they can then request (though not require) a recall by the company. If the company is not compliant, the FDA can then take federal or criminal action. 

Read More: ‘When I Got Cancer, Everyone Brought Food. I Finally Told Them what I Really Wanted’

How to protect yourself

Attractive brunette hairdresser thoroughly dyeing hair of female client while she is sitting in chair in beauty salon
Source: Shutterstock

Now before you start panicking about how many years you or someone you know has been coloring their hair, remember this: correlation does not equal causation. In other words, this information does not mean that you have to stop coloring your hair immediately and let yourself go grey if you are not ready to do that.

There are many things you can do to decrease your risk of developing breast cancer and still have the hair you want.

  1. Use natural hair dyes
    If you are only high-lighting or covering up a few early grey strands, then some of these temporary solutions might work for you. You probably never thought about using coffee or beet juice as hair dye, but not only are they natural and chemical-free, but they are inexpensive.
    If you’re not ready to jump straight to vegetable juice as hair dye, consider some of these non-toxic natural hair dye products instead.
    Organic buyers beware: Just because a product says it uses organic ingredients, does not mean it is completely safe! Read all packaging and do your research first!
  2. Lead a healthy lifestyle
    The best way to protect yourself against breast cancer (and other cancers as well) is to live healthfully. This means eating a well-balanced diet with plenty of fruits, vegetables, and healthy fats; getting at least 30 minutes of moderate-intensity exercise every day, getting proper sleep, and limiting alcohol consumption to no more than one drink per day. Click here for more tips to lower your risk of breast cancer.
  3. Early detection is key
    If you have a family history of breast cancer, you should be getting regular screenings from an earlier age than the rest of the population. Speak with your doctor about what your screening schedule should look like.
    Whether you have a family history or not, all women should know how to perform a self-exam and complete them regularly. If you find any abnormalities, visit your doctor right away.

So what does this mean for you?

Dyeing gray hair. Brush in hand with paint dyes black hair. White background.
Source: Shutterstock

Should you stop coloring or using chemical straighteners? That is for you to decide. We always encourage women to embrace their true selves in whatever way makes them feel confident and beautiful. For some, this means rocking their silver or natural hair with pride. For others, coloring and/or straightening their hair gives them confidence and makes them feel like themselves.

Whatever your style, be sure to live as healthfully as possible, pay attention to your body, and do your research to stay up-to-date with the latest information on cosmetics and cancer. Knowledge and prevention can save your life.

Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.

Read More: Do Vitamin B12 Supplements Cause Acne, Bone Fractures, and Lung Cancer?


  1. https://www.wcrf.org/dietandcancer/cancer-trends/breast-cancer-statistics
  2. https://www.breastcancer.org/symptoms/understand_bc/statistics
  3. https://onlinelibrary.wiley.com/doi/epdf/10.1002/ijc.32738
  4. https://sisterstudy.niehs.nih.gov/English/about.htm
  5. https://www.cancer.org/cancer/cancer-causes/hair-dyes.html
  6. https://www.fda.gov/cosmetics/cosmetic-products/hair-dyes
  7. https://www.cancer.gov/about-cancer/causes-prevention/risk/myths/hair-dyes-fact-sheet
  8. https://www.niehs.nih.gov/health/topics/agents/endocrine/index.cfm
  9. https://www.researchgate.net/profile/Dede_Teteh/publication/337744995_The_Black_identity_hair_product_use_and_breast_cancer_scale/links/5de80f1f92851c8364628830/The-Black-identity-hair-product-use-and-breast-cancer-scale.pdf
  10. https://www.karger.com/Article/Abstract/496447
  11. https://ar.iiarjournals.org/content/38/2/707.short