Hair Dyes, Chemical Straighteners Linked to Breast Cancer: Study
Thu, April 22, 2021

Hair Dyes, Chemical Straighteners Linked to Breast Cancer: Study

Scientists have long suspected that hair dye may be linked to certain types of cancer, but years of various studies showed inconclusive results / Photo by: Olena Yakobchuk via Shutterstock

 

Scientists have long suspected that hair dye may be linked to certain types of cancer, but years of various studies showed inconclusive results. Most research that specifically looked into dye and breast cancer failed to find a connection. The same could be said for hair straighteners as well, in which research showed unclear results.

But now, a recent study has established a link between the two common hair products with an elevated risk for breast cancer.  The study also found that black women who use these products are at a higher risk of the disease compared to white women. While the study provided merit for further work, the researchers noted their findings don't prove that hair dyes and straighteners cause breast cancer.

 

Increased Cancer Risks

The new study involved 46,700 American women aged between 35 to 74 who had no personal history of breast cancer but had a sister diagnosed with the disease. They were asked about their health, demographics, and lifestyle—including the hair product they use—and were tracked for an average of eight years.

More than half of the participants (55%) said they used permanent hair dyes a year before they enrolled in the study while 10% said they used chemical straighteners. The researchers found that these women are more likely to be among the 2,794 participants who later developed breast cancer.

Based on the study, Time reports that women who use hair dye have a 9% increased risk of developing breast cancer compared to those who don't use the product. Black women are at a significantly higher risk (45%) compared to non-users whereas white women have about 7% increased risk.

Frequent use of hair dye of at least once every five to eight weeks was found to increase the risk by up to 8% for white women and 60% for black women. The researchers also looked into the effects of chemical straighteners and found that the product raised the risk by 30% for both populations. 

However, they noted that black women are more likely to use the said product (74%) compared to white women (3%)—meaning they are more exposed to the effects of the products.

Study author Alexandra White said the differences between the two groups could be due to the variety of formulations in the dyes and straighteners they use. Co-author Dale Sandler added that thicker hair in black women may also absorb more dye, thus, increasing its effect.

Additional work needs to be done to confirm the hypothesis, Time says, but Sandler noted that it's important for doctors to understand the differences since black women are at a higher risk of death due to breast cancer—even if the incidence is slightly lower for them than in white women.

Casual Associations

While the study did not determine a direct cause-and-effect relationship between hair products and the risk of hair cancer, there's still a reason to believe the findings. For one, some of the ingredients found in these products have already been described as potential carcinogens or chemicals that can alter hormones like estrogen.

"The associations seen certainly could be causal, especially since there are known carcinogens contained in many of these products," Anne McTiernan, an epidemiologist in the Public Health Sciences Division at the Fred Hutchinson Cancer Research Center, told Forbes.

"One thing that surprised me was that the effects of hair dyes and straighteners were seen in both black and white women," she added, noting that studies don't usually have enough women from different races and ethnic groups to do that.

While the study did establish a connection between the products and breast cancer, oncologist Larry Norton believes this doesn't prove that using hair dyes and chemical strengtheners lead to breast cancer. "There’s a weak association but this association does not equal causation," he said.

The effect could've been underestimated as well, considering that the researchers asked about exposures in the last 12 months prior to the start of the study. This means the effects of these beauty products on the disease may actually be larger than what is established.

Forbes says that the study also cited earlier research that suggests these estrogen-interfering chemicals could be found in higher levels in products marketed to black women. Since the risks were higher in black women, it's possible that the type, amount of dye used, or the application method "varies substantially and influences risk,” according to White.

Calls for Better Regulation

The results of the study serve as a reminder that beauty and self-care products are not regulated properly in the US. A significant number of cosmetic products and ingredients are free from securing approval from the Food and Drug Administration (FDA) nor do they require safety testing before being launched to the market.

Aside from color additives, the FDA doesn't have the authority to recall tainted products—something McTiernan said should be changed, as the government should give the agency the "ability to regulate cosmetic products because we know that they are absorbed, and if there are carcinogens in them, they can be harmful."

"If women are worried about their breast cancer risk, this [hair dyes and chemical straighteners] may be one exposure they could avoid."

However, hair is important for women so swearing off these products would be difficult. The researchers recommend looking at the chemicals used and studying them further to determine if they have any hints of carcinogenicity.

Norton said situations like this would already have a "combination of lab studies to show a potential mechanism and corroborating studies with other populations of people," and that it's only reasonable to conduct these studies to further evaluate the risks.

A significant number of cosmetic products and ingredients are free from securing approval from the Food and Drug Administration (FDA) nor do they require safety testing before being launched to the market / Photo by: Gustavo Frazao via Shutterstock