A study from the U.S. National Institutes of Health (NIH) has raised serious concerns about the long-term use of permanent hair dyes and chemical hair straighteners. According to the research, women who use these products regularly may face a higher risk of developing breast cancer.
The study, published in the International Journal of Cancer, analyzed medical data from more than 46,000 women who took part in the Sister Study. The women were aged between 35 and 74, and all had at least one sister diagnosed with breast cancer.
Over an average follow-up of eight years, nearly 2,800 cases of breast cancer were reported among the participants. Researchers then compared lifestyle patterns, product use, and chemical exposures to determine if any clear connections existed.
The results were alarming. Women who frequently used permanent hair dye were found to be nine percent more likely to develop breast cancer compared to women who avoided it. But the risk was not the same for everyone.
The findings showed that African American women who dyed their hair every five to eight weeks had up to a 60 percent higher risk of developing breast cancer. In contrast, white women who dyed their hair with the same frequency had only about an eight percent higher risk.
Experts suggest that part of the difference could be due to the way products are marketed and used in different communities. Some hair dyes and straighteners aimed at Black women may contain stronger or more harmful chemicals, including endocrine disruptors that can affect hormone levels in the body.
Dr. Stephanie Bernik, Chief of Breast Surgery at Mount Sinai West in New York, commented on the findings. “Black women are already at an increased risk of breast cancer, and drawing a clear line to hair products is difficult.
Having said that, I believe the study provides sufficient evidence to warrant a prospective trial specifically designed to examine this one factor. In the meantime, I would caution patients that there is a possible link between hair dyes and cancer, although more research is needed.”
The study also found similar concerns with chemical hair straighteners. Women who used straighteners every five to eight weeks were about 30 percent more likely to develop breast cancer. This increase was consistent across all races, but researchers note that straightener use is more common among African American women, making them more likely to be affected.
The chemical ingredients inside permanent hair dye are another reason for concern. Most dyes contain more than 5,000 chemicals, including ammonia, hydrogen peroxide, and a compound called p-phenylenediamine (PPD). PPD is already restricted in the European Union due to links with birth defects, allergic reactions, and possible toxicity in the liver and blood.
Many dyes also contain aromatic amines, which have been shown in laboratory studies to cause cancer. When hair is dyed, small amounts of these chemicals are absorbed through the scalp and can also be inhaled in salons, creating repeated exposure over time.
Dr. Otis W. Brawley, medical oncologist at the Johns Hopkins Kimmel Cancer Center, said the findings did not surprise him. “Many of us have worried that the chemicals in especially the permanent hair dyes and hair straighteners, have the potential to cause cancer,” he told Newsweek.
At the same time, experts stress that hair products are only part of the bigger picture. Dr. Brawley pointed out that lifestyle choices such as obesity, lack of exercise, and poor diet carry an even greater impact on cancer risk. “I would also point out that the combination of obesity, consuming too many calories, and lack of physical activity has a much higher relative risk for breast cancer in both Black and white women,” he explained.
Michael Jones, Senior Staff Scientist in Epidemiology at The Institute of Cancer Research, also urged caution. He said, “It is too early to make a firm recommendation on the basis of one study, and further research is needed. The Sisters Study is a good prospective cohort study, but women were recruited because they had a sister with breast cancer. The conclusions wouldn’t necessarily hold true for women in the wider population.”
The Food and Drug Administration (FDA) regulates hair dye in the United States, but its oversight is limited. The FDA does not pre-approve every ingredient before it reaches the market. Instead, manufacturers are responsible for ensuring their products are safe. The agency can only step in if there is strong evidence that a product is harmful, which leaves gaps in consumer protection.
For now, researchers say the findings should be seen as a warning sign, not a reason to panic. Women who choose to dye or straighten their hair may want to limit how often they use these products, especially permanent ones, or switch to semi-permanent or temporary alternatives. Experts also recommend balancing beauty routines with healthier lifestyle choices, which remain the strongest defense against breast cancer.
Dr. Dale Sandler, who led the study at the NIH, said women need to be aware of chemical exposures in their everyday lives. “While hair dye is one piece of the puzzle, overall lifestyle choices and limiting unnecessary exposures are the best way to lower cancer risk,” she explained.
The debate over beauty products and cancer risk is far from over. This study does not prove that hair dye or straighteners directly cause breast cancer, but it shows a strong association that cannot be ignored.
