AYESHA RASCOE, HOST:
** You may want to think twice before making your next hair relaxing appointment at the salon. A new study has linked the chemicals that straighten hair to an increased risk of uterine cancer. Alexandra White leads the Environment and Cancer Epidemiology Group of the National Institute of Environmental Health Sciences. She's also the lead author of the study. Welcome.
ALEXANDRA WHITE: Hi. Thank you so much for having me.
RASCOE: The link between hair dyes and straighteners and diseases like breast cancer have been documented in the past. So what did your study find this time?
WHITE: We were interested in expanding this research to consider uterine cancer. And uterine cancer is similar to breast and ovarian cancer in that we know that they are all hormonally mediated outcomes. We looked at over 33,000 women in the U.S. who are part of the sister study cohort, and we asked them about their use of hair products and how often they use them, including hair dyes, straighteners, perms. And so we followed these women, at this point, for almost 11 years. During that time, we had about 378 uterine cancer cases that were diagnosed. And we found that among women who, when they enrolled in the study, told us that they were frequent users of the hair straightening products - meaning that they use them more than four times a year - they had about over double the risk of uterine cancer compared to women who did not say they've used those products.
RASCOE: What motivated you to conduct this study?
WHITE: You know, there's been a lot of concern about the chemicals that are in these products - in particular, the straighteners. We know that certain formulations of straighteners can release formaldehyde when heated, and formaldehyde is an established carcinogen. And we know that these products are relatively commonly used, particularly for Black women. In our study, we found that 60% of those who reported using these products were Black women.
RASCOE: If you are a Black woman right now - I mean, or any woman who would get your hair straightened; but as you said, it's a lot of Black women...
WHITE: Yeah.
RASCOE: ...Should you continue getting your hair relaxed?
WHITE: You know, that's a very personal decision. So it's hard for me to, you know, recommend that. There is this growing evidence base showing that hair straighteners are related to some adverse health outcomes. And I think that it's an important piece of knowledge for women to have when they make decisions. The increase in risk that we observed here is relatively small. So it's doubling, but what we saw is that for women who didn't use these products, their risk of uterine cancer was about 1.6%. So if they doubled, it went up to about 4%. So one thing that may be helpful for people who are trying to make this decision is that we did see that less frequent use was not as strongly related to risk. So one option may be just to reduce the frequency that you use these products if you're not ready to stop using them at all.
RASCOE: How does it happen exactly?
WHITE: So these chemicals can be absorbed through the scalp. And particularly if you're having any abrasions or burns, it might make it easier for them to enter the bloodstream and then travel through your body. But formaldehyde, in particular, is released from the product when it's heated. And that's a gas, so that's something that you're inhaling.
RASCOE: And so the rate of uterine cancer is on the rise lately...
WHITE: Yes.
RASCOE: ...With Black women dying of the cancer more than white women. Could hair straighteners be a contributing factor to that?
WHITE: It's hard to say. We assessed this exposure in the early 2000s. That's when we enrolled women in the study, and then we followed them over time. The challenge in trying to understand if one exposure is driving these larger trends we see in the population is difficult because we know with cancer that things that happened to us, you know, decades prior - even, you know, during our adolescence or childhood - could be contributing to our risk now.
RASCOE: Are there certain products that maybe have less harmful chemicals in them that you could look for, or is it, like, if it's relaxing your hair, it's probably just dangerous?
WHITE: It's really challenging to know because studies have found that when they actually go try to measure the chemicals that are in a hair product, that there's not a lot of concordance with what the label says.
RASCOE: Oh, my gosh. OK.
WHITE: So that's one of the challenges in knowing what products are safe. And it's really not fair to the consumer.
RASCOE: OK. Well, how can authorities like the FDA help?
WHITE: Right. You know, I think the challenge is our study shows this correlation. It's not causation. And I think it often comes down to the fact that it's really hard to prove these things. They have, I guess, a high bar for where they, you know, deem something dangerous. And there are instances of, you know, California passing legislation to reduce chemicals in products or putting warning labels on products. And so that might be one way to at least increase the ability of the consumer to know that there might be something hazardous in this product.
RASCOE: OK. I have a tough question for you.
WHITE: OK.
RASCOE: If you had a dear loved one, and they were like, they want to get their hair relaxed. What would you tell them?
WHITE: I would probably not have them do that.
RASCOE: Yeah. Yeah. Alexandra White is the head of the Environment and Cancer Epidemiology Group of the National Institute of Environmental Health Sciences. Thank you so much for talking to me.
WHITE: Thank you so much for having me. And thank you, you know, for everyone's interest in this research. ** Transcript provided by NPR, Copyright NPR.
