Hair dyes raise the risk of breast cancers especially among black women says study

By Dr. Ananya Mandal, MDDec 5 2019

A new study has confirmed that permanent hair dyes and chemical hair straightener use are associated with breast cancers especially among African American women. There have been animal studies that reveal that these hair dyes and chemicals used for straightening the hair are associated with cancers. Human studies however have not shown consistent results establishing the relationship between the chemicals and the cancers.

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This large group study is thus the first that shows that there is a real relationship between these chemicals and cancer. The study was published this week in the International Journal of Cancer. The study was titled, “Hair dye and chemical straightener use and breast cancer risk in a large US population of black and white women.”

The study called the Sister’s Study looked at 46,709 women from their medical records and lifestyle questionnaires. The participants were between ages 35 and 74 years of age and were enrolled between 2003 and 2009. The study population comprised of 9 percent African American women. All the women were asked about their use of hair dyes and straighteners. They found that women who used these hair dyes and chemicals had a higher risk of breast cancer. Alexandra White, one of the authors of the study and part of the National Institute of Environmental Health Sciences said, “The association was notably higher among black women.”

The team followed up the women and their records for eight years. White explained that permanent hair dye was associated with a 7 percent higher risk of breast cancers among white women and among black women the risk was around 45 percent. Black women who dyed their hair more frequently (once every one or two months) were at a greater risk of breast cancers.

The study authors wrote that the specific chemical found in the hair dyes that could be carcinogenic has not been detected yet. There are over 5,000 chemical ingredients present in various hair dyes. Some of these are known to be carcinogenic and some are capable of damaging the genes and cause mutations. The team wrote, “Hair dye use is very common; it has been estimated that more than one-third of women above the age of 18 in the United States use hair dye.” White explained that there are several chemicals in these products that contain aromatic amines which can affect hormonal balance and lead to an increased risk of cancers. The team wrote, “Many hair products contain endocrine-disrupting compounds and carcinogens potentially relevant to breast cancer. Products used predominately by black women may contain more hormonally-active compounds.”

The team wrote in explanation, “Dye constituents, such as 2, 4-diaminoanisole sulfate and para-phenylenediamine, have been found to induce tumors in the mammary gland of rats... Chemical treatments used to permanently or semi-permanently straighten or relax hair (henceforth referred to as straighteners) contain a mixture of chemicals, including formulations in which the carcinogen formaldehyde is an active ingredient.”

They also explained that these women were all at a greater risk of breast cancer because they had sisters with breast cancer. It has been found that women whose mothers or sisters or maternal relatives had breast cancer had a greater risk of the cancer. They also wrote that non-Hispanic black women are at a generally greater risk of being diagnosed with a more aggressive form of breast cancer that is more advanced at diagnosis and is more difficult to treat.

They wrote, “Fifty-five percent of participants reported using permanent dye at enrolment...Among all participants, personal straightener use was associated with breast cancer risk; with higher risk associated with increased frequency.”

Moving on to chemical hair straighteners, the team noted that all women had a raised risk of getting cancers irrespective of their racial origin. Black women were however more likely to use these products with 75 percent of the women participants of African American origin using the chemical straighteners. Women who used these straighteners had a 30 percent raised risk of getting breast cancers compared to women who did not use these products.

Authors wrote in conclusion, “We observed a higher breast cancer risk associated with any straightener use and personal use of permanent dye, especially among black women. These results suggest that chemicals in hair products may play a role in breast carcinogenesis.”

White added, “For the chemical straighteners one of the big concerns there is formaldehyde, which is a known carcinogen.” She explained that Brazilian keratin treatments called Brazilian blowouts used formaldehyde which is a known carcinogenic. This was not used before 2000s, she explained.