Hair straightening chemicals linked to higher risk of uterine cancer

in the past decadethere is evidence that chemical hair straighteners, relaxers and dyes may contribute to our risk of developing certain cancers.

Previous research has found that hair dyes and straighteners are associated with higher rates of ovarian and breast cancer. While it’s unclear how these products may contribute to cancer, scientists suspect that some chemical ingredients may affect the endocrine system and lead to the formation of cancer cells.

Now, a large study from the National Institute of Environmental Health Sciences is the first to show that these products may also increase the risk of uterine cancer in humans. The study, published Monday in the Journal of the National Cancer Institutefound that the risk of uterine cancer doubled in people who frequently used chemical hair straighteners.

“These findings suggest that [people] should consider their use of hair products in light of the fact that the chemicals in straightening products may affect their risk of developing uterine cancer,” Alexandra White, head of the NIEHS group for environment and cancer epidemiology, told HuffPost. “However, the overall risk is not great and chemical hair products are just one of many factors that can affect a woman’s chances of developing uterine cancer.”

What we know about chemical hair products and cancer

For the study, the researchers tracked the health of more than 33,000 women for 11 years. The research team recorded how often the participants used chemical-based hair products and what health problems they developed.

Of those who did not use chemical hair straighteners in the previous year, 1.6% developed uterine cancer by age 70. About 4% of women who used chemical hair straighteners frequently (i.e. more than four times in the previous year) developed uterine cancer — that’s a two-fold greater risk. The increased risk was already most pronounced in black women disproportionately affected by uterine cancer.

This isn’t the first study to link chemical hair products to a higher risk of cancer. A National Institutes of Health study published in 2020 found that people who regularly use chemical hair dyes and straighteners had a higher risk of breast cancer. That study also found that black women, who are more likely to use these types of hair products, were linked with a 45% higher rate of breast cancer, compared with white women who were associated with a 7% higher rate.

In recent years, study after study has similarly associated frequent use of chemical-based hair products with a higher risk breast cancer, especially in women of color.

Nicole Dezielan associate professor of epidemiology and a member of the Yale Cancer Center for Cancer Prevention and Control, said the new NIEHS study adds to the growing body of research showing that popular beauty products contain harmful ingredients that may contribute to more cancers and other cancers. health outcomes.

“Hair straightening products contain many harsh, toxic and hormone disrupting chemicals, and because they last on the scalp for extended periods and women can use them repeatedly from a young age, it increases the likelihood of exposure,” Deziel said. .

This is why these products can lead to cancer

It’s not yet clear how chemical-based hair straighteners contribute to cancer, as the research is still in its early stages, according to Dr. Oliver Dorigo, the director and associate professor of gynecologic oncology at Stanford University.

Many chemical-based hair straighteners contain: formaldehyde and formaldehyde-releasing chemicals, which are known to be carcinogenic. But the leading theory is that some of the Chemicals, such as metals, phthalates, and parabens, can disrupt estrogen levels in the body and cause hormonal imbalances. we know that excess estrogen is a risk factor for several hormone-mediated cancers, such as breast, ovarian, and uterine cancer. We also know that the uterus is extremely sensitive to hormonal changes.

“At this point, we can hypothesize that some ingredients may have a stimulatory effect on the lining of the uterus, called the endometrium, and the endometrium is very responsive to changes in hormone cycles and especially responds to estrogen,” Dorigo said. . This can cause the endometrium to thicken over time and, in certain cases, become cancerous.

Can you indicate which products are the safest?

Because so little research has been done on the ingredients, it’s too early to make any hard recommendations. That said, it may be worth scaling back how often you use chemical hair straighteners and relaxers, White said, regardless of whether you use them at home or in the salon. She also encouraged doctors to share these findings with their patients so they can make informed decisions about using chemical hair straighteners.

Most product labels don’t accurately list all the chemicals that are in hair straighteners, so it’s hard to know what’s actually in the products. Deziel said the new study highlights the need for stricter regulatory oversight on these types of products and for safer and affordable alternatives.

In the meantime, it is best to proceed with caution.

“At this point, I think it’s fair to say that this is an association we should be aware of – but I wouldn’t draw any other conclusions until further studies provide more data, particularly in terms of explaining the causality of hair straighteners on the development of uterine cancer,” Dorigo said.

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