Is dyeing your hair bad for your health?

Q. I color my hair regularly, but I have heard that permanent hair dye can increase the risk of cancer. Do I have to worry?

Scientists have been investigating the link between hair dye and cancer for decades. And while some studies suggest a connection, the findings are mixedmaking it difficult to make foolproof recommendations, says Alexandra White, an epidemiologist at the National Institute of Environmental Health Sciences.

Still, a closer look at the research can help you make an informed decision about what's best for you and your hairstyle.

What studies suggest

Much of the research on hair dye has focused on its possible link with bladder cancer, especially bladder cancer hairdressers exposed at work to permanent dyes created before the 1980s, said Dr. David J. Goldberg, a researcher and dermatologist in New York City. The longer the hairdressers worked and were exposed through their skin or lungs, the more likely they were to develop bladder cancer.

But other studies not found this increased riskThis could be because manufacturers began producing less toxic formulations after the 1970s.

However, breast cancer appears to be linked to permanent hair dye, said Dr. White. In a 2019 study In more than 46,000 women, Dr. White and her colleagues found that those who used permanent hair dye regularly (every five to eight weeks) had a 9 percent higher risk of breast cancer than those who did not use hair dye.

That may sound like a big jump, but it's actually “a very small increase in breast cancer risk” when contextualized with a woman's lifetime risk, said Dr. White. On average, women have about a 13 percent chance of developing breast cancer, so a 9 percent increase in that value increases her lifetime risk only one percentage point to about 14 percent.

However, when broken down by race, the risk was significantly higher for black women, Dr. White said. Black women who frequently colored their hair with permanent dye had a 60 percent higher risk of breast cancer, increasing their lifetime risk to nearly 21 percent – ​​compared to about 14 percent for white women.

This link between permanent hair dye and the risk of breast cancer in black women has been demonstrated in other studies, at. Although it is unclear what may be causing these racial and ethnic differences, said Dr. Nada Elbuluk, associate professor of dermatology at the Keck School of Medicine of USC.

One possibility is that other hair products popular among black women, such as chemical straighteners, relaxers and leave-in oils, may also play a role. But more research is needed.

Different types of dye

According to Dr. Goldberg, the research results may be mixed because the chemical combinations used in hair dyes can vary significantly between products, and they have evolved over the years. This makes it impossible to generalize about all hair dyes.

Unlike pharmaceuticals, said Dr. White, his hair products do not strictly regulated. Manufacturers don't have to prove their products are safe before putting them on the market, and because their formulations are often proprietary, it can be difficult to know what's in them.

One finding, however, is fairly consistent. Temporary and semi-permanent hair dyes, which wash out over time, appear to be safer than permanent hair dyes, which cause long-lasting hair coloring chemical changes in the hair shaft.

It's challenging to know which specific chemicals might be causing the increase in cancer risk, said Dr. White. But research suggests so aromatic amines And phenolsfound in permanent hair dyes, have carcinogenic effects.

Safer strategies

Since no research has shown that hair dye itself causes cancer, it is up to you to decide whether you want to continue with your coloring routine, taking into account any other possible risk factors you may have.

If you want to play it safe, consider these strategies:

Color your hair less often. While it's not definitive that the more you color your hair, the greater your risk of breast cancer, “it's a good precaution to reduce the frequency of use,” said Dr. White.

Avoid permanent hair dye during pregnancy. It is not certain that carcinogenic chemicals in hair dye can increase a developing fetus's risk of cancer in the long term, but there is some evidence that the chemicals may increase the chance of developmental problems. So it's best for pregnant women to avoid using hair dye “at least during the first trimester,” said Dr. Goldberg.

Follow the color instructions carefully. If you are dying at home, wear protective gloves, apply the dye in a well-ventilated area, do not leave it on your head longer than directed in the instructions, and rinse your scalp thoroughly when you are done. This should help minimize chemical absorption and reduce the risk of skin irritation.

Try dyes with gentler ingredients. Unlike permanent hair dye, semi-permanent and temporary hair dyes contain chemicals that are less aggressive and do not penetrate the hair shaft. Even safer: Try a plant-based dye, such as henna, said Dr. Goldberg. Although these dyes do not have the lasting power of permanent dyes, they do not appear to be linked to cancer and are less likely than chemical dyes to irritate the skin.