Uterine fibroids, hair relaxers, and why some evidence is better than others

There's a story making the rounds right now suggesting that the use of hair relaxers—products that are used more often by African American women than women of other ethnicities—might cause uterine fibroids—a painful condition experienced more often by African American women than women of other ethnicities.

Nobody really knows why African American women seem to be more prone to uterine fibroids, and, on the surface at least, this connection seems like it might make sense. Relaxers and other products contain hormones and chemicals that act like hormones. So, maybe, those things are getting absorbed into the body and leading to the growth of fibroids.

Trouble is: That's just speculation. And the evidence used to back it up is pretty flimsy. The study this story is based on looks at nothing but broad correlations: African American women have more fibroids and African American women use more of these hair care products. That's a problem, because broad correlations can be really, really misleading.

At The Urban Scientist blog, Danielle Lee (a scientist who has experience with both fibroids and hair relaxers) talks about why the "evidence" being presented in this case isn't even close to the same thing as "proof".

Parabens and phthalates can do some funky things. (I don’t trust these chemicals.) They are problematic and should be evaluated for safety, especially by the US Food and Drug Administration. Parabens can be an estrogen mimic – but only slightly it seems. But it’s everywhere – not just in Black hair care products like shampoos and perms. Parabens are preservatives in cosmetics and pharmaceuticals, so it’s in lotions, shaving gel, KY Jelly, makeup, even in food. Phthlates are what make plastics flexible, transparent, durable and strong. Exposure to these chemicals is coming from who-knows-how-many-sources: those dissolving plastic pill caplets, adhesives in bandages, toys, food packaging, even textiles, and paint.

My problem with this study is that it doesn’t eliminate all of these confounding and possibly conflicting variables. Again, what was the reason for hypothesizing hair care products for the disparity? It’s a leap – a huge leap and the data just doesn’t convince me. In my opinion, finding strong correlations of relaxer use among African-American women who happen to have fibroids is an artifact. Culturally, getting relaxers is a very typical hair-care regime among adult black women today. It’s a cultural phenomenon. So is being ashy and using lotion — which potentially has the same possible EDC risks as hair care products. These studies fall far short in making a connection between high occurrence of uterine fibroids and hair care rituals of Black women.

I see Lee pointing out a couple of problems here. One: A correlational study like this doesn't account for many, many other ways women might come into contact with the hypothetical causal agent. So it doesn't make much sense to tie causality to one, single source. Two: In a correlational study with this many variables, the connection you see might not mean what you think it means. The authors of this paper wonder whether hair care products might be causing fibroids. Okay. But it could be just that women who are more likely to have fibroids also, coincidentally, are part of a culture that uses a lot of these hair care products.

Correlational studies are important. They're a good first step in noticing patterns that can tell us something important about human health. But correlational studies can't be thought of as "proof" of anything. They're a way to notice a problem exists. But they aren't a good way of solving problems.

Unfortunately, correlational studies, like this one, make the news a lot. And, when they do, they're treated as though they represent scientific proof. That's a problem. Even if you don't have fibroids or use hair relaxers, you should read Danielle Lee's full post on this study. It'll give you a better idea about the sorts of questions you should be asking every time you see a scary science headline in the newspaper.

The the full story at The Urban Scientist

Image: Conditioning Lourdie's Hair 1002132, a Creative Commons Attribution (2.0) image from stevendepolo's photostream


  1. Correlation isn’t even correlation, here!

    Someone I knew well also experienced uterine fibroids. After careful investigation, it was found to be that she was allergic to alcohol (poor her!) and the fibroids were an allergic reation!

    If you ask me, generally, people put too many unnecessary chemicals on and in their bodies – especially women. Hair dye, fingernail varnish, makeup, fake tanning spray, etc.
    Let me paraphrase myself: “What’s wrong with these people? What’s so wrong with women that you have to mask/mould/lose their character by combining them with chemicals?

    Women are perfect all by themselves.”

    1. It’s not that there is anything wrong with women, but rather something wrong with society and society’s beauty standards.  Also, women aren’t perfect; they are just as flawed as men.

      1. I dunno.  I’m inclined to think they’re less flawed than men.  Or at least, if allowed to overgeneralize: women’s flaws seem more self-destructive.  Men’s flaws are just generally destructive.

        1. “I’m inclined to think they’re less flawed than men.”

          You’re not doing women any favors by putting them on a pedestal.

        2. This is not helpful at all, and you’re only going off of vague feelings that you, if I must remind you, have garnered from a rather sexist, patriarchal society.  A society that tries to put women into a special category, different from men… just like you are.  Women aren’t special creatures — we’re no worse, or better, than men.

          Of course this is a nuanced issue, and it has a lot to do with the fact that they are generally the primary care givers, even in 2012,and therefore the primary recipient of the stress involved of care-giving, but did you know that moms are more likely to kill their children than dads?


          People suck, all around, male or female, and trying to make women seem somehow “special” quite frankly, skeeves me out a bit.  I don’t want to be “special”.  I’m just as fucked up* as the next guy, and my vagina doesn’t really have anything to do with it.

          *Not that I’m a terrible human or anything.  We just all have our issues, including women.

          1. I’m not trying to change your mind, nor do I feel as though I put women on a pedestal.  It’s just that the character traits that strike me as “flaws” do not apparently manifest themselves in the women I know as much as they do in the men I know.  And that the flaws of men, in my experience, more often adversely affect other people more egregiously than do the flaws of women.  Don’t think for a minute that I consider you particularly “special.”  No doubt you’re all kinds of fucked up, just like I am.  Except, not like I am.  We are each our own uniquely fucked-up little snowflake.  But, statistically speaking, my problems and flaws, as a man, are more apt to compel me to rape someone, murder someone, declare war on someone, subjugate someone, pollute someplace, blackmail someone, extort, pillage, loot, or simply to fart in a crowded elevator.  ‘Cause I’m a guy, and though most guys don’t do those things, most people who do those things are guys.  

            Also, that “sexist, patriarchal society” you mentioned?  Do you suppose that was created and enforced by the flaws of women as much as by the flaws of men?  It seems to me that making the women of the world complicit in their own subjugation smacks overmuch of victim-blaming, but your mileage may certainly vary.

          2. ” It’s just that the character traits that strike me as “flaws” do not apparently manifest themselves in the women I know as much as they do in the men I know. ”

            You cannot be serious.  Anecdotal evidence, as a way to explain an entire group of people, in this case women, which take up over 50% of the population?


            “But, statistically speaking, my problems and flaws, as a man, are more apt to compel me to rape someone, murder someone, declare war on someone, subjugate someone, pollute someplace, blackmail someone, extort, pillage, loot, or simply to fart in a crowded elevator. ”

            I see no statistics.  Just feelings and conjecture.  Women are more likely to kill their children than men. I provided actual statistics.  Where are yours?  Saying “statistically speaking” without any actual statistics … I honestly have nothing to say to that, except, are you shittin’ me here?

            Regarding your last paragraph:  Sarah Palin.  Michelle Bachmann.  Etc.  Plenty of women hurt women.  This is nothing new, and it’s not victim-blaming.  People are assholes, no way around it.  Regardless of gender.
            Seriously, trying to claim that women are somehow “better” or “less flawed” IS PART OF THE PROBLEM.We are not special snowflakes in need of coddling and protection, okay?  So stop it, @boingboing-096f32c997988c54d6d7c09ff0be4d32:disqus .

          3. I can be (on occasion), and am (this time) serious.  But I’m not trying to proclaim my own opinion as the factual law of the land.  You certainly have a point that you have cited an actual, referrable statistic whereas I, in my intellectual poverty, have not.  But what exactly does that mean?  Since the Arizona Department of Health Services finds that a mother is more likely to kill her children than a father, your sweeping conclusion is that women are precisely as flawed as men.  And that, marilove, does not follow.

            Last year’s report found authorities suspected the mother in nearly half of the 70 child-abuse deaths in 2010, the most recent year with available data.  Authorities found fathers responsible a quarter of the time. Stepfathers or new boyfriends of the mothers were at fault 9 percent of the time, and investigators blamed only one death on a foster parent.

            Looks damning at a glance, but it doesn’t necessarily imply that women are equally vicious and violent as men.  

            Child-welfare experts say the statistics make sense: Mothers often get overwhelmed from the stress of caring for newborns and toddlers, many of whom die from neglect. Older children are more likely to be beaten to death, often by men.

            And there’s also the fact that in too many cases where a mother is overwhelmed from stress, she may not have a father or stepfather figure around to share the burden.  I don’t mean to imply that single motherhood is a problem in and of itself; that’s a separate argument altogether.  But I have to wonder, in the cases where the child perished of neglect or even at the violent hands of an overstressed mother, in how many of those cases had a father or boyfriend simply skipped out on the responsibility, or otherwise contributed to the problem?

            I see no statistics.  Just feelings and conjecture.  Women are more likely to kill their children than men. I provided actual statistics.  Where are yours? 

            You’re kinda misrepresenting the statistics through oversimplification, though your initial post avoided that.  In Arizona, during that year, mothers were more likely to cause the deaths of their children than anyone else.  “Nearly half,” as I quoted above.  Fathers were to blame 25% of the time, boyfriends and stepfathers 9%, and the rest were presumably “other.”  And as you mentioned, mothers are actually the primary, present caregivers the vast majority of the time.  If nothing else, they have far more opportunity to wring their kids’ necks, even if we’re supposed to disbelieve that a mother could ever have a motive to do so.

            But it’s the motive we’re discussing, and the capability to act on it (even if it’s through inaction, as I suspect most children’s death by neglect would entail, though once again I haven’t a statistic to support that suspicion).  

            Saying “statistically speaking” without any actual statistics … I honestly have nothing to say to that, except, are you shittin’ me here?

            I see you are unfamiliar with the word “statistical.”  “Of, relating to, based on, or employing the principles of statistics.”  It doesn’t actually mean citing statistics, though of course those would always be desirable, wouldn’t they?  I honestly don’t know where to find elevator-farting statistics (perhaps somebody at Otis commissioned a study some years back), but if you honestly need someone to provide numbers on how many more men per male capita commit the crimes I enumerated in my prior post than women per female capita, then you’re gonna have to browbeat somebody with more time and patience for your disingenuousness.

            Yes, women hurt women.  And they hurt men, and children too.  Women are flawed.  Not one of them is perfect.  I never said or implied any of them were.  But there are degrees of evil, sez I, and though any given woman is potentially capable of evil as profound as that of any man, in practice we don’t see it.  And it’s not because women are special, precious little angels in need of coddling and protection.  I never said women were better.  I certainly like them better, but I never labored under the misapprehension that how I feel about them has anything whatsoever to do with their objective value and qualities as people.  I did say, and continue to maintain, that I believe that the flaws of the female gender, in aggregate, do far less damage to the world and the people and creatures and habitats therein, than the flaws of men do.  Never mind statistics.  Want empirical evidence?  Live in this world for a little while.  Consult history.  Ask your mother.

            If I wanted to be completely anecdotal, I’d simply ask if you weren’t simply a better person than I am and call it a day.

    2. Thank you so much for blaming women for doing the best we can in a patriarchal society that values us only for our looks. Maybe you ought to go out and say something to your fellow men, instead of presuming to scold women for being “vain.”

    3. Are you aware that some women are subject to workplace dress codes that give them a choice between maintaining a “standard of appearance” that mandates a lot of these things and losing their jobs? Standards that, to put it mildly, are much more strict than those for men?

  2. Should be easy enough to tease out the effects of hair relaxer use among African-American women, since many African-American woman don’t use hair relaxer: Do those women have fewer fibroids? 

      1. That may have been true 10 years ago. The return to natural hair and relaxer backlash has pretty much become a revolution, as has hair weave and microbraids. I bet the majority of black women you see with slick straight hair are wearing someone else’s rather than having straightened their own. Not to mention flat ironing, which has been around since well before relaxers and is used by many women with unrelaxed hair for temporary straight styles.

        1.  10 years is not nearly enough time to get a significant population who have never been exposed to hair relaxers AND who have lived long enough to have had a reasonable chance to get fibroids in the first place. 16 year old girls just aren’t like to have fibroids, regardless of what ethnic group they come from.

          If the current trend stays for another 50-60, so we can look at a whole cohort who reach menopause without using relaxers, we can have a really REALLY firm comparative study.

    1.  I’m married to a black women (PC police: she’s Canadian, so that’s how she refers to herself, not ‘African-American’) who doesn’t use hair relaxers (she has beautiful dreadlocks) and since I have many black friends, nieces, and in-laws, I am all-too-well-acquainted with the many mysteries of black hair (though I am pasty pink myself). I personally know many black women who don’t use hair relaxers. It could be a Canadian thing.

      But in any case, our anecdotes and personal opinions are beside the point. All that would be needed for the study is that there are _some_ African-American women who don’t use hair relaxers. I Googled for the actual data and found Rosenberg, Boggs, Adams-Campbell, Palmer (2007). Hair Relaxers Not Associated with Breast Cancer Risk: Evidence from the Black Women’s Health Study. Cancer Epidemiol Biomarkers Prev, 16, 1035. These guys actually have the numbers: “Women <45 years of age were more likely to use hair relaxers than older women (94% versus 89%)."

      So there we are: case closed. At worst we would need to draw from the 6% of young black Americans who don't use hair relaxers- or conduct the study with non-Americans, if the relevant ratios are more favorable in other countries where the relaxer craze is not as entrenched as it is in the USA.

      I can see the title already: 'Dreadlocks are protective against fibroids'.

  3. Your posts are such a breath of fresh air Maggie. Everytime I see a headline like this on the web, I instinctively expect to see some bullshit scaremongering nonsense.
    Your posts never fail to make me pleased that Boing Boing employs someone with a critical mind and good understanding of science.

  4. I will look forward to a proper study on this, since I know a white woman who has fibroids and uses relaxers.

    Well, really she’s a sort of pinkish tan, with millions of darker brownish tan spots.

    1. This is a total topic fork but:

      Well, really she’s a sort of pinkish tan, with millions of darker brownish tan spots.

      My mother, a kindergarten teacher, would confound students who made comments on “other!student does !thing because they are black/white” with comments like “Actually, !student1 is light brown and !student2 is dark brown. I’m not white, I’m beige! !student3 is pink with orange spots!” and so forth.

      It really blows a four year olds mind, and it seems to be a reasonably good way to short-circuit the early stages of stereotyping – same/different is a really common educational game to play with little kids, and works great for getting them to see other people as individuals.

      1. I agree with your mother!

        Little Kid:  “Mister, is your daughter Black?”

        Me: “Yes, and White too!  And a little bit of Red Indian.”

        -pause for consideration-

        Little Kid: “That’s cool!”

        Awright, back to the topic then.  Sorry.

  5. If it can be shown that black women who do not use hair relaxers are less prone to fibroids, that might be interesting. Otherwise, since most women who use hair relaxers are  black, all you’ve done is restated the fact that black women are more prone to fibroids, which is already known.

    Anyone who doesn’t understand “correlation does not imply causation” has no business doing, or reporting on, science. Did you know that more than 90% of the proven murderers in this country have eaten tomatoes?

    1. Did you miss that that was the point of the article or are you replying to the author of the original study? I mean this in a sincere and non sarcastic way.

      1.  Replying to the original author; seconding the opinion of the article, and grousing about sloppy studies breeding disrespect for _real_ science.

  6. I was told I had fibroids late last year, and last month I had my hair relaxed. So I am complete and irrefutable proof that fibroids cause hair relaxation and not the other way round.  

    By the way, PaulR, there’s nothing “wrong with me*” for getting my hair straightened. I just did, that’s all. What’s “wrong” with all those people who have tattoos or use Axe deodorant or paint their houses pink? Nothing. People do stuff with chemicals. (Shrug.)

    *Except for fibroids.

  7. I find it interesting that when there is some causal relationship between a product or chemical of some sort and women’s health, there is always a group of nay-sayers who leap out to pooh-pooh the claim. But when it comes to men’s health and a causal relationship, generally there seems to be more of an embracing of the link. Now, I have no scientific proof of such a claim – it just seems as if women are alarmed about something w/o 22 peer reviewed scientific studies, double-blinds, etc etc proof, then we must be overacting, or being unscientific, etc. I’m just saying….. As for me, the fewer chemicals I put in or on or near my body, the better. (0f course already I can hear someone tapping the keyboard to remind me that everything is chemical, etc, etc and I should stop being so emotional). 

    1. I think if you read here regularly, you’ll find that I poo-poo a lot of health scares that are supported by only crappy evidence. Some apply to men, some to men and women, and I think this is the first time we’ve poo-poo’d a particularly woman-centric thing. 

      1. I wasn’t necessarily speaking about boing-boing. The nay-sayers are out there nonetheless and I’ve seen them post here. 

  8. The active chemical in relaxer is sodium hydroxide or another alkaline substance. As such I would expect the effect to be local and if absorbed it would be neutralised quickly and not cause problems other than the usual ones of damage to the scalp and hair.

  9. The real problem here is why so little research is being done into fibroids. Is that because it’s a problem that only affects women – and mainly black women?  
    BTW I’m white, have never used relaxers on my hair and have fibroids. My theory is that they were caused by a particular brand of Pill – anyone want to research that?

    1. I am also white (actually the pinkish-tan mentioned earlier, but without the brownish dots) and have never used relaxers.  My hair is stick-straight and baby fine.  I, too, have fibroids.  I’m a lesbian, so I never used any brand of Pill for birth control.  I am overweight.  My doctor seems to think it has to do not so much with amounts of hormones as ratios of hormones.  My estrogen levels are very high for my age (I am ten years post-menopausal), especially relative to progesterone.  One doctor had prescribed the progesterone-only “minipill” to me for this, but it made me very ill.  My current doctor has me use transdermal progesterone cream 28 days a month, and this has helped balance my estrogen and progesterone levels.

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