Dying your hair is a fun way to mix up your look. You can brighten things up with a few highlights, or even channel your inner rainbow and dye your hair blue, purple, or pink! It's estimated that 33% of women over the age of 18 use some sort of hair dye product (1). However, dyes contain thousands of chemicals, including endocrine‐disrupting compounds, carcinogens, and aromatic amines (2). To determine the health effects of hair dyes, scientists first experimented on rats. These studies found that exposure to hair dyes resulted in induced tumors among the rats (3). Because of the detrimental effects of hair dye on animals, researchers are now investigating whether there is a connection between these products and cancer in humans.
What Do the Studies Show?
A recent paper published in 2019 provided strong evidence that connected hair dye and chemical hair straightener use to breast cancer (2). This study collected responses from 47,000 women on:
- how often they used permanent, semi-permanent, or temporary hair dye and hair straighteners before they joined the study,
- how often hair dye and straightener was applied at home, and
- whether the dye used was a dark color or a light color or both.
After following these women for over 8 years, permanent hair dye was found to be associated with a 45% increased risk in breast cancer among black women and 7% increased risk in white women (2). It was found that black women were at greater risk for breast cancer because hair products marketed to them had higher concentrations of estrogens and endocrine-disrupting compounds. Chemical hair straighteners were also found to increase risk of breast cancer.
Despite these stark findings, there is no definitive evidence that the use of hair dyes cause cancer. While there are multiple studies like the one described above that link hair dyes with an increased risk of breast cancer, there are others that fail to produce similar results. Research on the association between hair dyes and other cancers such as non-Hodgkin lymphoma, leukemia, and bladder cancer have yielded equally inconclusive results (4). This discrepancy has made it difficult for regulatory agencies to take a side on this debate.
Looking to the Future
While dying your hair with traditional synthetic permanent hair dyes may be a fun way to spruce up your look, these products may be harmful to your health. Because of the mixed results from the scientific literature, it is too early to make a firm recommendation on how to handle permanent hair dyes. However, in the interim, those who are concerned for their health or who are at a high risk for cancers should think about using natural, non-toxic hair dyes. These products include henna, which can be used to dye hair a darker color, and lemon juice for highlights.
- Huncharek, Michael, and Bruce Kupelnick. "Personal Use of Hair Dyes and the Risk of Bladder Cancer: Results of a Meta-Analysis." Public Health Reports (Washington, D.C. : 1974), Association of Schools of Public Health, 2005, www.ncbi.nlm.nih.gov/pubmed/15736329.
- Eberle, Carolyn E., et al. "Hair Dye and Chemical Straightener Use and Breast Cancer Risk in a Large US Population of Black and White Women." Wiley Online Library, John Wiley & Sons, Ltd, 3 Dec. 2019, onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738.
- "Permanent Hair Dyes, Straighteners Linked to Higher Breast Cancer Risk." Breastcancer.org, 21 Jan. 2020, www.breastcancer.org/research-news/hair-dye-and-straighteners-linked-to-higher-risk.
- "Hair Dyes and Cancer Risk." National Cancer Institute, www.cancer.gov/about-cancer/causes-prevention/risk/myths/hair-dyes-fact-sheet.