In a study published in the International Journal of Cancer, researchers warned of the link between hair coloring products and an increased risk of developing breast cancer.
Although these are preliminary results that require further research, they are of concern.
In a study published in the International Journal of Cancer, researchers at the National Institute of Environmental Health Sciences (NIEHS) and the University of North Carolina highlight the increased risk of developing breast cancer in people who use hair chemicals.
“Researchers have long studied the possible link between hair dye and cancer, but the results so far have been inconsistent,” said Alexandra White, lead author of the NIEHS Environmental and Cancer Epidemiology Group, in a press release. “In our study, we see an increased risk of breast cancer associated with the use of hair dyes, and the effect is stronger in African-American women, especially those who use hair dyes frequently.”
9% additional risk
To reach this conclusion, the researchers used data from the Sisters’ Study cohort: 46,709 women aged 35 to 74 were studied who, although they had not developed breast cancer themselves, were considered at risk because their sister had developed the disease.
Looking at the results, the researchers then found that women who regularly used permanent hair dyes in the year prior to entering the study were 9% more likely than women who did not use hair dyes to develop breast cancer.
African-American women more at risk
The risk is greater for African-American women. For them, the use of permanent dyes every five to eight weeks or more was associated with a 60% higher risk of breast cancer, compared with an 8% higher risk in white women. This increased risk is explained, according to researchers, by the fact that “the products used by black women sometimes contain more hormonal substances”. They also found a slightly higher risk of breast cancer associated with the use of semi-permanent or temporary dyes.
The use of hair relaxers is also incriminated. Dr. White and her colleagues found that women who used them every five to eight weeks had a 30% higher risk of developing breast cancer. Again, although the association between hair relaxers and breast cancer was similar in African-American and white women, the use of smoothing products were much more common though among African-American women.
Although worrying, these preliminary results require further research to substantiate the link between breast cancer and hair chemicals. “We are exposed to many factors that can contribute to breast cancer, and it is unlikely that a single factor explains a woman’s risk. Although it’s too early to make a firm recommendation, avoiding these chemicals may be another thing women can do to reduce their risk of breast cancer,” said Dr Dale Sandler, head of the NIEHS Epidemiology Division and co-author of the study.