Research Gone Viral: Hair Products & Breast Cancer

UPDATE

June 2022 brought us more information on the way that hair care products interact with breast cancer in Black women. According to this study, parabens (chemicals found in lots of personal care products) were found to have more of an influence on a breast cancer cell line more commonly found in Black women compared to a different breast cancer cell line more commonly found in white women. What we can understand from this is that breast cancer in Black women and white women can look different, and can react differently to the same environmental influences. This is a new take on a frequently studied question and one that warrants further research. For more information on clinical trials, please visit our page on the subject. For more information on issues of health equity in breast cancer, check out this article.

A study was recently published in the International Journal of Cancer that indicated a stronger correlation than previous studies between the use of permanent hair dye and hair straighteners with the diagnosis of breast cancer, and it has been getting a lot of attention. Because it is sometimes difficult to get the full picture of a scientific study from a non-scientific news outlet, we read the journal article and want to provide you with our take (Read the full journal article here).

According to this study, all of the participants were already at higher risk of developing breast cancer because they all had a sister who had been diagnosed with breast cancer, so the results can’t necessarily be applied to the general, average-risk population. 

Imagine it like a scale, with one side labeled “breast cancer” and the other side labeled “no breast cancer.” Having a family history of breast cancer, particularly a first degree relative (like a parent or sibling), places a heavier weight on the breast cancer side of the scale. So one person can have smaller weights like alcohol use, dense breasts, lack of sleep, and these factors won’t “tip the scale” into developing breast cancer, but if a person has a family history of breast cancer, maybe just one of those other smaller weights will “tip the scale.” These participants already had a higher risk, so what has a strong relationship with their breast cancer diagnoses may not have a substantial effect on those with an average risk. For more about when and how to broadly apply results from scientific studies, read this.

Studies like this one also show that there is a possible relationship between hair straighteners/dyes and breast cancer diagnosis, not that the use of hair dyes/straighteners causes breast cancer. There have been a lot of studies on this topic, so this one is hardly definitive, especially because all of the previous studies were mostly inconclusive. You have probably heard the saying “correlation does not equal causation,” or perhaps the statistic that when ice cream sales go up, so do rates of violence. Does eating ice cream make someone more likely to cause harm? No, ice cream sales and rates of violence both increase when it gets hot outside. Ice cream sales and rates of violence have a relationship; they are correlated, but one does not cause the other. If you want to learn more about correlation and causation, read this.

Does this mean the results of this study aren’t important? Well, no. This study has a lot of participants, over 47,000, which means that it is more relevant than a study with just 47 participants. When it comes to ethnic breakdown, 9% of the participants identifying as black is a small number, but it is pretty close to the percentage of total US population that is black or African American (13.4%). That number is also (unfortunately) a better ratio than many scientific studies out there. The journal article also states they “noticed” a relationship, though not strong enough to “count,” between the use of hair straighteners/dyes and estrogen receptor-negative breast cancer, which is more common (and deadly) in black women. They found no significant difference in risk between non-Hispanic white and black participants when it comes to the use of straighteners. However, there is a difference when it comes to hair dyes. This study showed a 45% increase in risk in black women who use permanent hair dyes, much greater than the risk increase for non-Hispanic white women. Here’s a quote from the journal article:

“The strength of association observed for permanent dye use among black women is consistent with toxicological assessments that report higher concentrations of estrogens and endocrine-disrupting compounds in hair products marketed to black women. Previous studies on hair dye use and breast cancer risk, including most that found no association, have largely been limited to white women.” 

Overall, more studies need to look at this issue. Questions need to be asked like: Is there a higher risk for using both hair straighteners and permanent hair dye? What kind of chemicals are in the products used, and are there any of them that could be the main “culprits” in breast cancer risk? A higher percentage of the participants in those future studies should be black (if not all participants) and/or of average breast cancer risk in order to get a fuller picture of the effect of these products. 

In conclusion, doctors aren’t treating this information as revolutionary, but as a stepping stone to getting more information. If you read the full journal article, the study’s authors list multiple limitations and why their findings add to the discussion around hair dyes and hair straighteners, but should also not be taken as the final answer on the subject.

Photo by Guilherme Petri on Unsplash.