Whether it’s a chic cherry red or a striking blonde, changing your hair colour can be an exciting way to refresh your look. But, a new study raises questions about the potential health risks linked to permanent hair dyes and chemical straighteners. Scientists at the National Institutes of Health (NIH) have found that these products could increase the risk of breast cancer, especially with frequent use.
Key findings from the study
A study published in the International Journal of Cancer analysed data from 46,709 women enrolled in the Sister Study, which investigates risk factors for breast cancer. Researchers from the National Institute of Environmental Health Sciences (NIEHS), a division of NIH, found that:
Women who used permanent hair dye in the year before the study were 9% more likely to develop breast cancer than those who did not use these products.
Among African American women, frequent use of permanent dyes (every five to eight weeks or more) was linked to a 60% higher risk of breast cancer, compared to an 8% increased risk among white women.
In contrast, the study found little to no increase in breast cancer risk associated with the use of semi-permanent or temporary hair dyes.
"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 NIEHS Environment and Cancer Epidemiology Group. "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."
Chemical hair straighteners impact on breast cancer
Another finding from the study was the association between chemical hair straighteners and breast cancer. Women who reported using straighteners at least every five to eight weeks faced a 30% increased risk of developing breast cancer. While the risk linked to straightener use appeared similar for African American and white women, African American women were found to use these products more frequently.
Co-author Dale Sandler, PhD, chief of the NIEHS Epidemiology Branch, pointed out that while there is some evidence supporting the link between chemical straighteners and breast cancer, further research is needed to confirm these findings. "We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk," said Sandler.
What can be done?
The study's findings may encourage women to rethink their use of chemical hair products. Research advice to minimise exposure to these chemicals could be a step toward reducing breast cancer risk. "While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer," Sandler added.