New research featuring over 46,000 women in the United States has revealed potentially worrying links between the use of certain hair products and the risk of developing breast cancer.
The study, published last month in the International Journal of Cancer, suggests that women who use products such as permanent hair dyes and chemical straighteners could be increasing their risk of breast cancer by up to 60%.
“Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent,” said Alexandra White, Ph.D., head of the National Institute of Environmental Health Sciences Environment and Cancer Epidemiology Group and senior author of the study.
As well as warning of an overall increase in risk of breast cancer for women who use these hair products, the paper reports huge differences in the risks posed by various products to black women and white women.
For white women dying their hair regularly the risk of developing breast cancer seemed to increase by 7%, but for black women, this was far higher at 45%. For ‘heavy’ usage of hair dye, defined as at least once every 5-8 weeks, the increased risk was 8% for white women and 60% for black women.
“In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African American women, particularly those who are frequent users,” said White.
The incidence of breast cancer in black women is slightly lower than in white women, but black women are likely to be diagnosed at a later stage of disease than white women and are far less likely to survive their cancer.
The new study is correlative and does not describe a direct cause-and-effect relationship between hair products and breast cancer risk, but considering some of the components of these products have been described to be potential carcinogens or chemicals that can interfere with hormones such as estrogen, there is reason to believe the conclusions of the study.
“The associations seen certainly could be causal, especially since there are known carcinogens contained in many of these products,” said Dr. Anne McTiernan, an epidemiologist in the Public Health Sciences Division at Fred Hutchinson Cancer Research Center in Seattle. “One thing that surprised
me was that the effects of hair dyes and straighteners were seen in both black and white women. Often, studies don’t have enough numbers of women from diverse race and ethnic groups in order to do that,” she added.
“Obviously this topic is useful to look at,” said Dr Larry Norton, medical oncologist and medical director, Evelyn H. Lauder Breast Center at Memorial Sloan Kettering Cancer Center in New York. “Does this work merit further study? Yes, absolutely. Does this prove hair straighteners and hair dyes cause breast cancer? No. There’s a weak association but this association does not equal causation,” he added.
The research looked at women between the ages of 35 and 74 recruited between 2003 and 2009, who had no personal history of breast cancer, but had a sister diagnosed with the disease.
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