What Was in My Hair Products? Rethinking 40 years of Chemical Exposure

For approximately 40 years, chemical hair relaxers and permanent hair dyes were simply part of my normal hair-care routine. I never thought of relaxing or coloring my hair as an environmental exposure. It was grooming, beauty, and something I routinely did without questioning what was actually in the products being placed directly on my hair and scalp. Like many consumers, I assumed that products readily available and commonly used for years were reasonably safe.

Then, in 2022, I was diagnosed with breast cancer. At the time, I did not connect my diagnosis with the hair products I had used for decades. However, learning more about environmental exposures has caused me to look at that history differently. Can I say that 40 years of chemical relaxers and permanent hair dyes caused my breast cancer? No. Breast cancer is a complex disease with many contributing risk factors. What I cannot ignore, however, is research showing associations between certain chemical hair products and breast cancer risk.

What Does the Research Show?

Research from the National Institute of Environmental Health Sciences (NIEHS) particularly caught my attention. The NIEHS Sister Study investigates environmental and genetic factors that may influence breast cancer risk. Eberle et al. (2020) analyzed data from 46,709 women enrolled in the Sister Study who were breast cancer-free at enrollment and examined their use of permanent hair dyes and chemical straighteners.

Overall, permanent hair dye use was associated with a 9% higher breast cancer risk. However, the association differed by race. Any permanent dye use was associated with a 45% higher risk among Black women compared with a 7% higher risk among White women. Frequency also mattered. Black women who used permanent dye every five to eight weeks or more had a 60% higher breast cancer risk. Frequent chemical straightener use was associated with a 31% higher breast cancer risk overall (Eberle et al., 2020). These percentages represent relative increases in risk compared with women who did not use the products; they do not mean that 60% or 31% of users developed breast cancer.

Those findings immediately caught my attention because my exposure was not occasional. I consistently used both chemical relaxers and permanent hair dyes for more than four decades before my breast cancer diagnosis. The NIEHS has also reported research examining possible associations between hair products and hormone-related cancers, including breast, ovarian, and uterine cancers (ECU Libraries Catalog, n.d.). This does not mean everyone who uses these products will develop cancer, but it raises legitimate questions about repeated exposure over many years.

What Are We Being Exposed To?

One of the biggest changes in how I now view hair products is recognizing that the relaxer or permanent hair dye itself is not the toxin. These products are mixtures of chemicals, some of which have raised health concerns. Personal-care and hair products may contain phthalates, parabens, formaldehyde or formaldehyde-releasing chemicals, and p-phenylenediamine (PPD),among other substances (Lin et al., 2024; National Institute of Environmental Health Sciences [NIEHS], 2025).

These chemicals are concerning for different reasons. Phthalates and parabens have been studied for their potential endocrine-disrupting effects, meaning they may interfere with normal hormone signaling. Formaldehyde is a known human carcinogen, and exposure may occur when certain hair products release formaldehyde into the air during use. PPD, an ingredient commonly used in permanent oxidative hair dyes, is particularly known for its potential to cause skin irritation and allergic contact dermatitis (Lin et al., 2024).

How these products are used also matters. Hair relaxers and permanent dyes are applied directly to the hair and scalp and remain there while processing. I remember the burning and scalp irritation I sometimes experienced when getting my hair relaxed. At the time, that burning was almost accepted as part of the process. Looking back, I now question what repeated exposure to chemical mixtures may have meant, particularly when my scalp was already irritated.

After approximately 40 years of using these products, I cannot determine which chemicals were present in every relaxer or permanent dye I used or how much exposure I received. Product formulations also differ and have changed considerably over time. Therefore, it would not be scientifically accurate for me to say that I was exposed to a particular chemical for exactly 40 years. What I can say is that my long-term use of these products created repeated opportunities for exposure to chemical mixtures that researchers continue to investigate for potential health effects. More Importantly, these chemicals should not be interpreted as the explanation for the breast cancer associations identified by Eberle et al. (2020). Researchers have not established that any one chemical in hair relaxers or permanent dyes causes breast cancer. 

Association Is Not Causation

This distinction is especially important when discussing my own diagnosis. It would be easy for me to say, I used these products for 40 years and then developed breast cancer, so they caused my cancer. Science does not support that conclusion.

A better question is: Could decades of repeated exposure have contributed to my overall risk?

I may never know that answer. Eberle et al. (2020) identified an association between certain hair-product practices and breast cancer, but observational research cannot establish that these products caused an individual woman's cancer. NIEHS (2025) makes the same point, explaining that many factors influence whether cancer develops. Association does not equal causation, but an association involving products used repeatedly by millions of women deserves continued research.

Making More Informed Choices

My experience has changed how I view personal-care products. Reducing exposure does not mean becoming afraid of every chemical or giving up hair care. It means becoming a more informed consumer. Research suggests that changing personal-care products can reduce exposure to certain chemicals, including some endocrine-disrupting compounds (Yang et al., 2023).

So, what can we choose instead? Reducing exposure does not necessarily mean giving up hair color or changing how we want to wear our hair. For those who color their hair, semi-permanent or temporary dyes may be reasonable alternatives to permanent dyes. In the Sister Study, personal use of semi-permanent or temporary dyes was not associated with increased breast cancer risk, although this does not mean these products are completely risk-free (Eberle et al., 2020). When selecting personal-care products, look for options labeled phthalate-free and paraben-free when possible. Intervention studies have shown that replacing products containing these chemicals with alternatives can lower measurable levels of phthalate and paraben metabolites in the body, sometimes within only a few days (Yang et al., 2023).

For hair straightening, consider reducing the frequency of chemical relaxers or choosing styles that do not require chemical straightening. It is also reasonable to avoid applying chemical treatments to an already irritated or damaged scalp. Most importantly, becoming an informed consumer means reading ingredient labels and recognizing that “natural” or “clean” on the front of a package does not automatically establish that a product is safer. Research also shows how difficult it can be for consumers to completely eliminate these exposures, which is why safer product formulations and greater transparency from manufacturers are just as important as individual choices (Yang et al., 2023).

My breast cancer diagnosis in 2022 cannot tell me what caused my cancer, and I cannot say that approximately 40 years of chemical relaxers and permanent hair dyes were responsible. But I also cannot dismiss research showing associations between products I used for decades and breast cancer risk. For me, the message is not about fear. It is about awareness, asking better questions, and having enough information to make informed decisions about products we may use for a lifetime.

References

Eberle, C. E., Sandler, D. P., Taylor, K. W., & White, A. J. (2020). Hair dye and chemical straightener use and breast cancer risk in a large US population of Black and White women. International Journal of Cancer, 147(2), 383–391. https://doi.org/10.1002/ijc.32738

Lin, R. R., Lin, D. A., & Maderal, A. D. (2024). Toxic ingredients in personal care products: A dermatological perspective. Dermatitis, 35(2), 121–131.

National Institute of Environmental Health Sciences. (2025). Cosmetics and your health. U.S. Department of Health and Human Services, National Institutes of Health. https://www.niehs.nih.gov/health/topics/agents/cosmetics

Yang, T. C., Jovanovic, N., Chong, F., Worcester, M., Sakhi, A. K., Thomsen, C., et al. (2023). Interventions to reduce exposure to synthetic phenols and phthalates from dietary intake and personal care products: A scoping review. Current Environmental Health Reports, 10(2), 184–214. https://doi.org/10.1007/s40572-023-00394-8