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Permanent hair dye, straighteners: Worth the risk?

Several women of color with varying hair shades and styles.

Jan. 4, 2020—Do you often dye or straighten your hair? That habit may raise the risk of breast cancer, say scientists at the National Institute of Environmental Health Sciences. And the risks are especially high for African American women, according to a study published in the International Journal of Cancer.

A lopsided risk for hair dye

Researchers looked at data from the Sister Study. It involved more than 46,000 breast-cancer-free women ages 35 to 74 whose sisters had been diagnosed with the disease.

The study found that women who regularly used permanent hair dyes were 9% more likely to develop breast cancer than women who didn't.

But that risk wasn't equal for all women. Black women who used permanent dyes every five to eight weeks or more often had a 60% greater chance of developing breast cancer. By comparison, the increased risk for white women on a similar schedule was just 8%.

One possible reason for that difference? Permanent dyes marketed to black women often contain higher amounts of chemicals that can disrupt the body's natural hormone balance.

Permanent hair dyes are popular because they provide long-lasting color. But these dyes cause chemical changes in the hair shaft. Semi-permanent dyes also penetrate the hair shaft but only last for up to 10 washings. Temporary dyes only cover the hair's surface and last for just one or two washings.

Researchers found little to no increased breast cancer risk for women who use semi-permanent or temporary dyes.

Straighteners linked to breast cancer too

The findings also showed that women who apply chemical straighteners every five to eight weeks or more often were 30% more likely to develop breast cancer.

This risk was about the same in both black and white women who use straighteners. But straightener use is more common among black women, so the increased risk may affect them more often.

Should you stop dyeing or straightening?

That's something only you can decide. It's important to remember that many things contribute to a woman's overall breast cancer risk, not just environment, a study author said. But for women who are concerned about lowering their risk, steering clear of these products may be a reasonable change to make.

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