Do hair dye and straighteners raise your breast cancer risk? An expert answers

So let’s see what research from December 2019 had said. The Sister Study, which used data from nearly 47,000 women, found that women who regularly used permanent hair dye in the year before enrolling in the study were nine per cent more likely to develop breast cancer than women who did not use the products. It also found that women who used hair straighteners at least every five to eight weeks were about 30 per cent more likely to develop breast cancer.

So what are specific chemicals in hair dyes and straighteners that increase the risk of breast cancer?

Permanent dye, aromatic compound intermediates and formaldehyde used in straightening or curling creams are carcinogenic (a substance capable of causing cancer).

Research has shown that hair products contain over 5,000 chemicals, some of which are hormone disruptors. These can affect how estrogen and other hormones act in the body, by blocking them or mimicking them, which throws off the body’s hormonal balance. Because estrogen can make hormone-receptor-positive breast cancer develop and grow, many women choose to limit their exposure to these chemicals that can act like estrogen. Other chemicals in hair dyes have been found to cause mammary gland tumours in rats.

Straighteners contain formaldehyde, which is considered a carcinogen. Formaldehyde, when absorbed by the body, causes changes in the DNA of cells. It attaches to the DNA of cells, then the cell divides uncontrollably and results in cancer of specific organs.

Should women consider avoiding these products altogether to minimize their risks?

There is no study yet to recommend the exact safe frequency of dyes. However the risk is more if one’s profession involves hair colouring and straightening compared to personal use, where exposure window is less. Ensure safety protocols are followed during application, like wearing gloves, rinsing properly. Do not leave it on than the time intended. Otherwise, go for vegetable-based dyes.

Are women with a family history of breast cancer more vulnerable to these risks, and what precautions should they take?

No. Mutations associated with hereditary syndrome are different. No study has been done separately in these populations. They inherently have a very high risk of breast cancer without any exposure to dyes or relaxers.

(Dr Gupta is unit head and consultant, gynaecologic oncology, Rajiv Gandhi Cancer Institute, New Delhi)