Hair dye and cancer
Hair dye is a common cosmetic product used to change or enhance hair color, generally categorized into permanent, semi-permanent, and temporary types. Research has identified several chemicals in hair dyes, particularly in darker shades, that are classified as reasonably anticipated human carcinogens. The primary concerns relate to a potential increase in risks for various cancers, including bladder, breast, and urinary tract cancers, as well as non-Hodgkin lymphoma and blood-related cancers.
While some studies indicate an association between hair dye use and these cancers—especially noting a higher risk among Black women—no direct causal link has been established. Most evidence suggests that the overall cancer risk for hair dye users is similar to that of non-users. It is essential to consider that exposure routes primarily include skin contact and that those most at risk include hairdressers, barbers, and consumers using hair dye in salons or at home. The ongoing discussion around the safety of hair dyes is informed by both historical practices, which date back to ancient civilizations, and modern usage trends, which have increased significantly during the COVID-19 pandemic.
Hair dye and cancer
ROC STATUS: Reasonably anticipated human carcinogens include 2,4-diaminotoluene (since 1981), 2,4-diaminoanisole sulfate (since 1983), 4-chloro-o-phenylenediamine (since 1985), Disperse Blue 1 (since 1998)
ALSO KNOWN AS: Hair color, coloring agent
RELATED CANCERS: Bladder, breast, endometrial, and urinary tract cancers; non-Hodgkin lymphoma; hematopoietic cancers; myelodysplasia; multiple myeloma; leukemia; preleukemia
DEFINITION: Hair dye is a usually soluble substance for staining or coloring to change or enhance the color of hair. Synthetic hair dye falls into one of three categories: permanent, semi-permanent, and temporary. Darker hair dyes have more carcinogens than lighter dyes because more chemicals are used in the dyes.
Exposure routes: Skin contact
Where found: Hair salons, barber shops, hair dye manufacturing plants, individual residences
At risk: Hairdressers, barbers, hair dye manufacturers, and individuals using hair dye either in a salon or at home. Of the three types of synthetic hair dye, permanent, semi-permanent, and temporary carcinogens are more prevalent in permanent and semi-permanent dyes.
Etiology and symptoms of associated cancers: There appears to be an increased risk for those who use darker shades of hair color because darker shades have more chemicals than lighter shades. In addition, the frequency and duration of use may also increase exposure. Older versions of dyes may have a greater risk associated with them than newer versions; however, death rates from all cancers combined appear to be about the same for hair dye users and nonusers.
Most evidence does not show hair dyes to be a significant cancer risk factor, and studies indicating otherwise have been inconsistent. For example, some studies have shown an association between hair dye use and bladder or blood cancers, while others have found no association. Results from the long-running Sister Study appeared to show a 9 percent increase in cancer rates among users of hair dye and chemical straighteners. This risk was markedly higher in Black women. Of all the studies conducted, none has shown a direct link, only an association, although many ingredients in hair dye have been classified as known carcinogens. Potential cancer risk relates mostly to permanent and semi-permanent dyes as opposed to temporary ones.
History: Ancient civilizations used plants to dye hair. The first synthetic dye was created in 1907. It is estimated that between 66 and 74 percent of women and up to 38 percent of men use hair dye. These numbers increased during the COVID-19 pandemic, as did the number of people using at-home hair dyes. Chemicals in hair dye have been shown to cause cancer in lab animals; however, these animals were fed high levels of dye over a long period, leaving the relevancy of these studies to humans unclear.
Alexander, Heather. “Hair Dye, Hair Relaxers and Breast Cancer: What's the Risk?” MD Anderson Cancer Center, Mar. 2020, www.mdanderson.org/publications/focused-on-health/hair-dye--hair-relaxers-and-breast-cancer--what-s-the-risk-.h12-1593780.html. Accessed 13 June 2024.
“Hair Dye, Chemical Straighteners Linked with Breast Cancer in Large Study.” UNC Gillings School of Global Public Health, 19 Dec. 2019, sph.unc.edu/sph-news/hair-dye-chemical-straighteners-linked-with-breast-cancer-in-large-study. Accessed 13 June 2024.
Saitta, Peter, et al. "Is There a True Concern Regarding the Use of Hair Dye and Malignancy Development?: A Review of the Epidemiological Evidence Relating Personal Hair Dye Use to the Risk of Malignancy." The Journal of Clinical and Aesthetic Dermatology, vol. 6, no. 1, 2013, pp. 39-46, www.ncbi.nlm.nih.gov/pmc/articles/PMC3543291. Accessed 13 June 2024.