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Can Dying Your Hair Raise Your Risk for Breast Cancer? Experts Explain

Here's what you need to know about the potential dangers of touching up your roots and straightening your hair.

hair dye and breast cancer risk
Edgardo ContrerasGetty Images

When you dye your hair — whether at home or in a salon — your biggest concerns may be covering those stubborn grays, getting as close to your original strawberry-blond as possible or creating the perfect rainbow hue to match your mood that month. But a couple of large studies published in the last few years have brought this question back to the forefront: Can the chemicals used to change the color of your hair — as well as those used to straighten, relax, or curl it — increase your risk for developing breast cancer?

In the past, the literature on hair dye and breast-cancer risk has been "all over the place," says Marisa C. Weiss, MD, the director of breast radiation oncology at Lankenau Medical Center in Wynnewood, PA, and the founder and chief medical officer of BreastCancer.org. While some of the more than 5,000 different chemicals that are used to make permanent hair dye — plus other chemical processes, such as straightening, relaxing and perming hair — have been found to carry a relatively small risk, every product uses a different mix of chemicals, so it has been difficult to accurately compare them, she says. A large review by the Institute of Medicine in 2011 found "no strong evidence" that the personal use of hair dyes was associated with an increased risk of breast cancer.

But in the last few years, two very large, long-term studies show a stronger association between the use of permanent hair dye and hair relaxers/straighteners and breast cancer riskespecially among Black women. Does this mean you should completely rethink how you treat your hair? Here's what you need to know, and how to maintain your color and style as safely as possible:

What do the studies show?

In a 2019 study in the International Journal of Cancer, researchers from the National Institutes of Health crunched the numbers from the Sister Study, which followed more than 46,000 women who had at least one sister who had been diagnosed with breast cancer but who had no history of breast cancer themselves. “Our findings for any use of permanent hair dye in the past year suggested a slight increase in risk for breast cancer, although associations were stronger for chemical straightener use and for hair dye use among Black women,” says the study’s co-author, Alexandra J. White, PhD, an investigator in the Epidemiology Branch of the National Institute of Environmental Health Sciences.

To break it down:

  • The risk is higher for Black women: Permanent hair dye use was associated with a 9% higher risk of breast cancer in all women, but among Black women, there was a 45% increase in risk; among white women, the increase was just 7% (if you're wondering how those two figures average out to 9%, there were far more white women in the study than Black women).
  • Straightening your hair may be an even riskier activity: The use of chemical hair straightener at all over the previous 12 months was associated with an 18% higher risk of breast cancer among all women, and the more frequent the use, the higher the risk: Women who used straighteners at least every 5 to 8 weeks had a 31% higher breast cancer risk.
  • The shade of the dye may (or may not) matter: Among Black women, there was an increase in risk with both dark and light dye; in white women, risk was associated with light-colored permanent dye but not dark dye.
  • Adolescents are particularly vulnerable: In a separate report on the same Sister Study, the researchers found that there was an increase in premenopausal breast cancer among women who had frequently used hair straighteners or perms between the ages of 10-13.

    Though these numbers may have you tossing your box of hair dye into the nearest trash can, Dr. Weiss points out that the statistics should be put into perspective. “The overall risk of any woman getting breast cancer in her lifetime is about 12%," she explains. So when you say use of permanent hair color increases risk by 9%, we're looking at relative risk, meaning an increase of 9% to that original 12%, which brings your risk up to around 13%, Dr. Weiss explains— which is obviously still something to be concerned about, but not the dramatic leap it appears at first. In addition, risk can vary depending on your race, the type of products, and the age when you start using them. Also, it is important to note that since all the women in the study had a first-degree relative with a history of breast cancer, their risk was already elevated.

    “While they can’t say definitively that these products cause breast cancer, the results are very compelling and they show a correlation,” says Ryland Gore, MD, a surgeon specializing in breast cancer oncology at North Atlanta Breast Care, who is particularly concerned about the larger numbers for Black women: “Hair is a huge thing in our community, it’s almost like a religion, going to the beauty shop every week or two weeks.” Dr. Gore says the results are even more alarming considering that Black women are 40% more likely to die of breast cancer than white women.

    Less than a year after the NIH study hit the headlines, researchers from the Harvard T.H. Chan School of Public Health and Brigham and Women's Hospital published a large study that looked at more than 117,000 women in the decades-long Nurses’ Health Study and concluded that while there was no association between hair dye use and most cancers, there was an increase in the risk of one form of breast cancer (estrogen receptor negative, progesterone receptor negative, hormone receptor negative). However, it should be noted that the women in this study started reporting about their hair dye use in 1976; assessments of hair dye exposures stopped in 1982; and many companies changed their formulas since then based on what we now know about carcinogens. In addition, the study’s authors point out that 96% of the women in the Nurses’ Health Study were of European (white) ancestry.

    black plastic brush for hair coloring
    pepifotoGetty Images

    How exactly do these products put you at risk?

    To permanently change the color of your hair, chemicals need to penetrate the hair cuticle and react with the melanin in your hair. These chemicals include everything from ammonia and hydrogen peroxide to some that are considered carcinogens, and others that are hormonally active.

    “You absorb products through your skin — that’s why we have birth control and medications that are delivered through a patch on your skin — and your scalp has a very high rate of absorption because there is a large blood supply,” Dr. Weiss explains. In addition to absorbing chemicals through your scalp, you also breathe in the chemicals while you sit in the chair having the process done, especially if you are in a small, poorly ventilated space (like your bathroom at home) for several hours. Dr. Weiss points out that though you only absorb a small amount of chemicals each time you dye or straighten your hair, many women repeat this process every month, adding up to accumulated exposure over many years.

    Why are Black women at higher risk?

    In the Sister Study report, the risk of breast cancer was found to be higher in Black women than in white women, even though the frequency of use was similar between both groups, says White. “It’s possible that the type of dye or application of dye is different for Black women compared to white women,” White says. “It’s also possible that hair texture plays a role in how much dye is needed or absorbed.”

    As for the risk for Black women from straighteners and relaxers, many of those products — particularly those marketed to and used by Black women, according to research —contain hormonally active chemicals, such as phthalates, parabens and cyclosiloxanes. One study found that of 18 hair products used by Black women that they tested, 11 contained chemicals prohibited under the European Union Cosmetics Directive based on their risk of cancer, female reproductive toxicity and developmental toxicity, and/or regulated by California's Propostion 65.

    "Hair care for women who are Black or biracial is a huge business," says Dr. Gore. "But the issue is that in the middle of mass production, the ingredients that are going into those products include a lot of chemicals that disrupt the normal endocrine process. These ingredients include chemicals that are used to fragrance products as well as preservatives that increase the shelf life. Some of these chemicals are linked to breast cancer risk and pregnancy complications. You can't say for certain that these chemicals like parabens or phthalates cause breast cancer, but you can see there is a correlation."

    So what should I do?

    • Consider going gray If you've been debating whether to give up the cost and time commitment of dying your hair every month, this may be the incentive to take the leap to a natural salt-and-pepper or silvery style — especially if you're already at higher risk because of a family or personal history of breast cancer. “There are a lot of famous women who are rocking gray hair,” points out Dr. Weiss.
    • Consider going natural: If you've been straightening or perming your hair for years or even decades, perhaps it's time to let your curls, coils or stick-straight locks show off their natural style. “For a long time, there was pressure to change the texture of your hair to fit into a certain mold,” says Dr. Gore. “But there is a big cultural shift right now toward the beauty of embracing your natural hair.”
    • If you have a tween or teen daughter, encourage her to wait a few years: “When you're an adolescent, exposure to certain chemicals can have an impact on the development of breast tissue,” Dr. Weiss says. “You are laying down the foundation for your future breast health, so you should be particularly careful what goes in and around you—it makes sense to avoid products that might be associated with issues later on.” Dr. Weiss recommends tweens and teens experiment with non-permanent dyes and using different hairdos, accessories, blow-dryers or flat irons rather than chemicals to create fun looks.

      If you choose to continue using hair dye and other products, then do it as safely as possible with these tips:

      • Read the labels: Though it can be difficult for anyone without a chemistry degree to interpret the labels of some of these products, there are certain names that should give you pause, such as “placental extracts,” says Dr. Weiss. You can also check out the Environmental Working Group's hair color database, which ranks products based on the safety of the ingredients.
      • Use temporary rather than permanent treatments: As anyone who has ever decided to experiment with a streak of purple that washes out in a few days knows, there are many different types of hair dye, though permanent dye is by far the most popular, accounting for 80% of the dyes used in America. “Permanent, or oxidative, hair dyes include higher concentrations of oxidizing agents such as aromatic amines, which have been classified as carcinogens,” says White. “Semipermanent dyes, which stain the hair but do not cause lasting chemical damages to the hair shaft, are nonoxidative and contain lower levels of these compounds.”
      • Consider plant-based dyes: Hair color made from natural ingredients such as henna, chamomile, bark, or flowers, and containing no synthetic chemical ingredients, are a lower-risk option, says Dr. Weiss.
      • Touch up your color less often: If you switch to a lighter shade, you won't have to touch up your roots every 3 to 4 weeks to avoid the telltale skunk stripe at your part when you're coloring dark brown or black over gray. You can also stretch out your time between hair-color appointments by touching up your roots with a brush-on powder. And the less time you spend with chemical dye in your hair, the lower the risk.
      • Reduce your chemical exposure as much as possible. Choose a hair salon with good ventilation and plenty of space between clients — or even consider dying your hair yourself outdoors, when the weather permits. If you dye your hair at home, be sure to wear gloves and follow the directions closely.
      • Dilute the effects. “I always like to say, Dilution is the solution to pollution,” says Dr. Weiss, who recommends you give an extra thorough rinse out to your hair after applying any process to make sure there is no residue left sitting on your scalp. And drink plenty of water during and after the procedure.

        Bottom line:

        While these findings are certainly worth noting, they are just one small piece of a larger puzzle. “The overall risk, particularly for permanent hair dye, is not large, and chemical hair products are just one of the many factors that may influence a woman’s chances of getting breast cancer,” says White. Dr. Gore agrees, pointing out that reducing your risk for breast cancer is more complex than simply switching up your hair-color routine. “Taking care of your health, reducing alcohol intake, eating fruits and vegetables of many different colors, exercising and minimizing exposure to radiation are all things you can do to decrease your risk of breast cancer,” she says.

        But if you are concerned about your risk, rethinking how often you change your hair's natural color and texture, and which products you use to do it is one positive step you can take in that direction. "We can’t change certain risk factors, like our genetics or the air we breathe," says Dr. Weiss. "But there are things we can modify, like how we treat our hair.”

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