Going for Hair Dye or Chemical Straigthening? Beware of Breast Cancer risks, says study

Chemical treatments used in hair dye or to permanently or semi-permanently straighten or relax hair (referred to as straighteners) contain a mixture of chemicals, including formulations that contain the carcinogen formaldehyde as an active ingredient.

USA: Products such as hair dye and hair straightener are widely used. Now a recent study in the International Journal of Cancer has found a link between frequent use of these chemical hair products and breast cancer risk. The findings are of deep concern keeping in mind the increasing use of such products by women.

Hair products are known to contain more than 5,000 chemicals including some having mutagenic and endocrine-disrupting properties. Some dye constituents such as 2,4-diaminoanisole sulfate and para-phenylenediamine have been found to induce tumours in the mammary glands of rats.

Chemical treatments used to permanently or semi-permanently straighten or relax hair (referred to as straighteners) contain a mixture of chemicals, including formulations that contain the carcinogen formaldehyde as an active ingredient.

Prior studies on the association of hair dye use and breast cancer have yielded inconsistent results. While some established a positive relationship, many concluded that there is no elevated risk.

Alexandra J. White, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC, and colleagues evaluated the relationship specifically between breast cancer risk and hair dye and chemical straightener use in a prospective cohort of women ages 35-74.

For the purpose, the researchers used data from 46,709 women in the Sister Study who were enrolled between 2003 and 2009. The women had a sister with breast cancer but were cancer-free themselves. Enrollment questionnaires included past 12‐month hair product use.

Read Also: Hormonal contraceptives, hair dyes linked to increased breast cancer risk

Key findings of the study include:

• During follow‐up (mean = 8.3 years), 2,794 breast cancers were identified. Fifty‐five per cent of participants reported using permanent dye at enrollment.


• Permanent dye use was associated with 45% higher breast cancer risk in black women (HR = 1.45), and a 7% higher risk in white women (HR = 1.07).


• Among all participants, personal straightener use was associated with breast cancer risk (HR = 1.18); with higher risk associated with increased frequency.


• Nonprofessional application of semipermanent dye (HR = 1.28) and straighteners (HR = 1.27) to others was associated with breast cancer risk.


• A higher breast cancer risk was associated with any straightener use and personal use of permanent dye, especially among black women.

The researchers found that women who used hair straighteners at least every 5 to 8 weeks were about 30% more likely to develop breast cancer. While the association between straightener use and breast cancer was similar in African American and white women, straightener use was much more common among African American women.