Originally published May 12, 2008. Updated August 17, 2017.
An estimated 75 percent of women over age 18 and 10 percent of men over 40 in the U.S. color their hair, so the issue of whether this practice can be harmful is important. Until recently, no definitive evidence has shown that coloring your hair can lead to any type of cancer. However, a study published this year (2017) looked at the effects of hair dyes, hair relaxers and cholesterol-based hair products on breast cancer risk. First, the researchers, from Rutgers University, accounted for other possible breast cancer risks, such as family and personal health history, hormone use, alcohol consumption and physical activity among the study’s 4,285 participants: African American and Caucasian women ranging in age from 20 to 75.
The researchers found that using dark brown or black hair dyes was linked to a 51 percent increased risk of breast cancer among African American women and a 72 percent increased risk that the cancer would be estrogen receptor positive. The study also linked use of chemical relaxers or hair straighteners to a 74 percent increased risk of breast cancer among Caucasians.
These findings indicate that we need to know more about the short and long-term health implications of using these hair products. Prior to the new results, the strongest evidence we had for a link between hair dye and cancer came from epidemiological studies showing an increased risk of bladder cancer among hairdressers and barbers with high occupational exposure to these products. But even that evidence was not conclusive. According to a review published in January 2013 in the Journal of Clinical and Aesthetic Dermatology, the bulk of available data did not strongly support a link between occupational exposure to hair dye and bladder cancer. However, based on results of a previous study that found a significant relationship between hair-dye use and bladder cancer, the International Agency for Research on Cancer (IARC) concluded in 2008 that working regularly with hair dyes in salons and barbershops probably increases the risk of cancer and that long-term employment in these establishments is “probably carcinogenic to humans.” At the same time, the IARC, an arm of the World Health Organization, reported that there is not enough evidence to conclude that occasional personal use of hair coloring raises the risk of any type of cancer.
Other studies on the association of hair dyes with non-Hodgkin’s lymphoma and leukemia have shown no increased risks among people who color their hair using today’s dyes. Some increased risk had been seen among women who applied darker tints before 1980, when hair dyes commonly contained aromatic amines and other agents known to cause cancer in animals. Those chemicals are not present in today’s products.
In general, I discourage use of hair dyes containing artificial coloring agents, which to my mind are as suspect in cosmetic products as they are in food. More than 5,000 different chemicals – some of them carcinogenic in animals – are used in hair dyes; these can be absorbed through the scalp, with its rich blood supply, and be carried throughout the body.
The latest evidence from the Rutgers study confirms my suspicions about the risks of hair dyes and other commonly used hair products.
Andrew Weil, M.D.
Adana A.M. Llanos et al, “Hair product use and breast cancer risk among African American and White women.” Carcinogenesis June 9, 2017, doi.org/10.1093/carcin/bgx060
Peter Saitta et al “Is There a True Concern Regarding the Use of Hair Dye and Malignancy Development?” Journal of Clinical and Aesthetic Dermatology. January 2013