6 ms·

Breast Cancer Linked to Permanent Hair Dye and Chemical Hair Straighteners

123 points by goshx 7y ago

velcrovan 7y ago
> “The research was based on the medical records of more than 46,000 women aged 35 to 74 from the Sister Study, meaning all women involved had a close relative who had died of breast cancer.” Can someone explain to me how this isn’t a huge problem for this study?
- draw_down 7y ago
  Can you explain? If they all came from that set, and the ones who used straighteners/dyes developed cancer more often than the ones who didn't... what exactly am I missing here?
- natalyarostova 7y ago
  It means they researchers hypothesized that the cost of generalizing to the population was less than the benefit from increased statistical power.
- UnFleshedOne 7y ago
  If you want to be careful, you can say the study found that among cohort with increased cancer risk due to genetics, using those hair products increased cancer risk even further.
- tinco 7y ago
  Can you explain why it would be?
- btilly 7y ago
  You go with the data that you have, not the data you wish you could get. It would be nice to redo the study with a large population that is randomly selected. However there is also no reason to believe that the results will be significantly different in direction. Therefore it would also be unwise to discount this result.
- jcutrell 7y ago
  Depends on the goal. If the risk factor is homogenized, then the variable researched can be isolated theoretically. However, this doesn’t allow you to test for interaction between those variables. In the study for example, they identify an apparent interaction between ethnicity and the chemicals mentioned; we don’t know what the effect size would be (whether additive, multiplicative, or something else entirely). (This is without any domain knowledge of the mechanisms of breast cancer to be fair.)
tptacek 7y ago
Is there a source for this that isn't Newsweek? Newsweek isn't really a trustworthy source; they are, as I understand it, a publication several tiers below Buzzfeed (which does good work sometimes) that has acquired and turned Newsweek into a Newsweek Suit, Buffalo-Bill-style, and wears it around the Internet.
- draw_down 7y ago
  Linked in the first sentence of the article https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738 https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738
- clumsysmurf 7y ago
  https://medicalxpress.com/news/2019-12-permanent-hair-dye-straighteners-breast.html https://medicalxpress.com/news/2019-12-permanent-hair-dye-st...
  - tptacek 7y ago
    Thanks!
- brutal_chaos_ 7y ago
  From the article: https://www.sciencedirect.com/science/article/pii/S0013935118301518 https://www.sciencedirect.com/science/article/pii/S001393511...
nbrempel 7y ago
Direct link to the research article: https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738 https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738
Animats 7y ago
Breast cancer, but not head skin cancer?
- notacoward 7y ago
  Just guessing here, but I suppose it's because the effect has less to do with where the chemicals get into the body than where they accumulate and/or have an effect. As it turns out, scalp tissue is not sensitive to those chemicals but breast tissue is. Could have been the liver or the prostate instead, but it wasn't.
  - Scipio_Afri 7y ago
    This is due to the tendency for bioaccumulation in lipids, which breast tissue and organs tend to have a high percentage of. I'm not an expert, just what I remember reading, so someone please chime in for the exact mechanisms. Likely to be some other contributing factors, like their role in producing breast milk biochemistry related to that (speculating: accumulates in the mother but doesn't get passed on to the child).
  - elliekelly 7y ago
    And if a woman has long hair at least some of the chemicals from the hair dye will wash off over their breasts when they shower. Also guessing here, but home hair dye is usually quickly washed off in the sink while a salon will not only wash your hair more thoroughly but they tend to wash it twice after dying. So I would assume that when a person showers after home hair dye a lot more of the chemicals are rinsed off over their breasts when compared to after a salon dye.
tropo 7y ago
The only thing surprising here is that it isn't scalp cancer. Hair straighteners work by breaking and reforming the disulphide bonds in proteins. Proteins perform many important roles related to DNA repair, chromosome formation, DNA replication, and other cancer-relevant actions. It can't be good to have bonds in those proteins getting changed somewhat randomly.
- dsfyu404ed 7y ago
  Skin has millions of years of incremental improvement at keeping stuff out. It is not unheard of for a carcinogen applied to the body to not cause skin cancer directly but to cause cancer elsewhere because being on the body makes it likely to get in through the various holes where it then finds its way to some more susceptible tissue.
btilly 7y ago
I am glad that they have statistical evidence, however it has been believed for a long time. Beauty salons use a wide variety of products that are biologically active and unregulated. Many are known carcinogens, and working at a beauty salon puts you at increased risk of cancer. See https://www.ncbi.nlm.nih.gov/pubmed/19755396 https://www.ncbi.nlm.nih.gov/pubmed/19755396 for random verification. The question is what it does to the customers. It has long been suspected that increased cancer rates among blacks are tied to the fact that they are more likely to use beauty salons than whites. And if they do use them, they use them more often.
thdrdt 7y ago
The most important part of the article: "While the paper is based on patterns and trends and, as such, doesn't confirm a direct cause, ..." Please be carefull jumping into conclusions. Further research is needed for that.
pithymaxim 7y ago
Slide summary from the authors: https://bcerp.org/wp-content/uploads/Session3-AlexandraWhite_hair-dye-and-straightener-use-and-bc-BCERP.pdf https://bcerp.org/wp-content/uploads/Session3-AlexandraWhite...
modeless 7y ago
> 7% higher risk in white women (HR = 1.07, 95% CI: 0.99–1.16) The confidence interval clearly includes 1.0. I'm tired of all these studies being uncritically reported on in the press with no mention of the giant error bars. IMO medical researchers need to raise their standards. 95% is way too low. Also, journalists should be ashamed at the state of science and medical reporting. It's ironic that you can read articles blaming tech for the spread of fake news and then turn the page to the health section and read garbage like this article.
- icegreentea2 7y ago
  Won't argue about the validity 95% confidence interval here, but the 95% CI of HR of women as a whole excludes 1, and for African Americans clearly also excludes one. The overall conclusion is still sound (if you accept the validity of 95% CI as a measurement).
  - modeless 7y ago
    Only for dye, not for straighteners, and only for "Nonprofessional application of semipermanent dye to others", and black women. If you count up the specific claims made in the article, a majority are not actually supported by the study. And unless the study was preregistered for the cohorts they analyzed, the statistical analysis is suspect even at the 95% level which I still contend is too low.
    - gus_massa 7y ago
      It's interesting to see the supplementary tables (that are free). In the supplementary table 1, classified by menopausal status, they report 55 results. The intervals that exclude 1.00 are: 1.30 (1.04, 1.62) 1.35 (1.08, 1.69) 1.41 (1.10, 1.79) 1.26 (1.02, 1.55) 1.51 (1.17, 1.94) 0.68 (0.47, 0.99) (Some are very correlated.) Anyway, they get 6 interesting results, slightly more than the expected number of false positive cases with a 95% CI interval with 55 cases. Moreover, in the last case, 1.00 is excluded because the interval is too low, i.e. in this study in the premenopausal women that applied hair dye to other person between 1 and 3 times a year got less cancer that the women that didn't. This is probably just noise, but note that this case is not highlighted in the abstract in spite they highlight a few cases where the 95% interval includes 1.00. In the supplementary table 2, classified by estrogen reception, they report also 55 results. The intervals that exclude 1.00 are: 0.78 (0.63, 0.97) 0.82 (0.70,0.95) Both are below 1.00, and neither is highlighted in the abstract. This number is close to the expected number of false positive cases with a 95% CI interval with 55 cases. I guess there is another table in the paper where they classify the women black or white, and perhaps even more classifications. So the evidence looks weak and close to the noise level.
perspective1 7y ago
It's a plausible mechanism but a bogus study. With most of their confidence intervals including hazard ratios of 1.0 (or very close to it), they need to rule out even slight correlations like smoking and (low) income. Recall bias of the survey participants is another major factor in cancer cases. Overall this reads like they collected data of a bunch of chemical exposures setting their p to < 0.05 and found this one that they could publish on.
- carlmr 7y ago
  >need to rule out even slight correlations like smoking and (low) income. Especially with hair dying, since looking at my environment at least early usage (before graying) is very much correlated with low income/education.
  - romdev 7y ago
    I'd like to see antiperspirant usage as a variable, but it seems like it would be hard to find a control. Having tried several times to buy deodorant without antiperspirant for my wife, I can say how hard it is to find an armpit product without aluminum oxide. It's not so hard to find masculine scented deodorants.
    - carlmr 7y ago
      Yeah, I'm wondering why we're not erring on the side of caution there and banning them until proven safe.
nostromo 7y ago
Silly question: did they control for age? Please tell me they did, because, duh... older women have more cancer and dye their hair more. I don't have access to the full paper, but the abstract makes no mention of this, and states they included women from 35-74.
- mmmrtl 7y ago
  Fortunately, yes
DemonicTitLord 7y ago
God. The comments here in this thread on HN are so fucking stupid, it begs disbelief. Meanwhile, sometimes I had considered that maybe there was a broad medical experimentation program, designed to gather lots of women, drop a fabricated diagnosis on them, and double-blind them into things healthy women would never do. The main idea stemming from the fact that, in an age when shoe size flouroscopes are banned out of fear of ionizing radiation, we encourage frequent mammograms, to cast dragnet for wild tumor goose chases. Mammogram x-rays that mostly don't even work, to the point that Malcom Gladwell pontificates pop culture junk food fluff for air port book stores that conflate them with LANTIRN pods scanning for SCUD missiles. Mammograms that scan for "tumors you can't feel" and thus have no means of verifying beyond the single-source proof of the mammogram itself. Maybe mammograms were the original deep fakes? Maybe eventually, all those extra x-rays shot directly into breast tissue eventually induced breast cancer in some sort of Nietzschean "find the monster you sought" outcome. If the statistic is 1 in 8, lifetime, all women in first world countries, it would seem pretty strange that such a statistic is even possible, when cancer is usually seen in highly fatigued tissues that are abused and suffer high turnover rates. You'd think boobs would endure a period of chronic pain and injury to erupt into cancer, no? My other hypothesis has been birth control horomones, since they're both uniquely feminine, and implicated in glandular targets.

123 points by goshx 7y ago

> “The research was based on the medical records of more than 46,000 women aged 35 to 74 from the Sister Study, meaning all women involved had a close relative who had died of breast cancer.” Can someone explain to me how this isn’t a huge problem for this study?

draw_down 7y ago
Can you explain? If they all came from that set, and the ones who used straighteners/dyes developed cancer more often than the ones who didn't... what exactly am I missing here?
natalyarostova 7y ago
It means they researchers hypothesized that the cost of generalizing to the population was less than the benefit from increased statistical power.
UnFleshedOne 7y ago
If you want to be careful, you can say the study found that among cohort with increased cancer risk due to genetics, using those hair products increased cancer risk even further.
tinco 7y ago
Can you explain why it would be?
btilly 7y ago
You go with the data that you have, not the data you wish you could get. It would be nice to redo the study with a large population that is randomly selected. However there is also no reason to believe that the results will be significantly different in direction. Therefore it would also be unwise to discount this result.
jcutrell 7y ago
Depends on the goal. If the risk factor is homogenized, then the variable researched can be isolated theoretically. However, this doesn’t allow you to test for interaction between those variables. In the study for example, they identify an apparent interaction between ethnicity and the chemicals mentioned; we don’t know what the effect size would be (whether additive, multiplicative, or something else entirely). (This is without any domain knowledge of the mechanisms of breast cancer to be fair.)

tptacek 7y ago

Is there a source for this that isn't Newsweek? Newsweek isn't really a trustworthy source; they are, as I understand it, a publication several tiers below Buzzfeed (which does good work sometimes) that has acquired and turned Newsweek into a Newsweek Suit, Buffalo-Bill-style, and wears it around the Internet.

draw_down 7y ago
Linked in the first sentence of the article https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738 https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738
clumsysmurf 7y ago
https://medicalxpress.com/news/2019-12-permanent-hair-dye-straighteners-breast.html https://medicalxpress.com/news/2019-12-permanent-hair-dye-st...
- tptacek 7y ago
  Thanks!
brutal_chaos_ 7y ago
From the article: https://www.sciencedirect.com/science/article/pii/S0013935118301518 https://www.sciencedirect.com/science/article/pii/S001393511...

nbrempel 7y ago

Direct link to the research article: https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738 https://onlinelibrary.wiley.com/doi/abs/10.1002/ijc.32738

Animats 7y ago

Breast cancer, but not head skin cancer?

notacoward 7y ago
Just guessing here, but I suppose it's because the effect has less to do with where the chemicals get into the body than where they accumulate and/or have an effect. As it turns out, scalp tissue is not sensitive to those chemicals but breast tissue is. Could have been the liver or the prostate instead, but it wasn't.
- Scipio_Afri 7y ago
  This is due to the tendency for bioaccumulation in lipids, which breast tissue and organs tend to have a high percentage of. I'm not an expert, just what I remember reading, so someone please chime in for the exact mechanisms. Likely to be some other contributing factors, like their role in producing breast milk biochemistry related to that (speculating: accumulates in the mother but doesn't get passed on to the child).
- elliekelly 7y ago
  And if a woman has long hair at least some of the chemicals from the hair dye will wash off over their breasts when they shower. Also guessing here, but home hair dye is usually quickly washed off in the sink while a salon will not only wash your hair more thoroughly but they tend to wash it twice after dying. So I would assume that when a person showers after home hair dye a lot more of the chemicals are rinsed off over their breasts when compared to after a salon dye.

tropo 7y ago

The only thing surprising here is that it isn't scalp cancer. Hair straighteners work by breaking and reforming the disulphide bonds in proteins. Proteins perform many important roles related to DNA repair, chromosome formation, DNA replication, and other cancer-relevant actions. It can't be good to have bonds in those proteins getting changed somewhat randomly.

dsfyu404ed 7y ago
Skin has millions of years of incremental improvement at keeping stuff out. It is not unheard of for a carcinogen applied to the body to not cause skin cancer directly but to cause cancer elsewhere because being on the body makes it likely to get in through the various holes where it then finds its way to some more susceptible tissue.

btilly 7y ago

I am glad that they have statistical evidence, however it has been believed for a long time. Beauty salons use a wide variety of products that are biologically active and unregulated. Many are known carcinogens, and working at a beauty salon puts you at increased risk of cancer. See https://www.ncbi.nlm.nih.gov/pubmed/19755396 https://www.ncbi.nlm.nih.gov/pubmed/19755396 for random verification. The question is what it does to the customers. It has long been suspected that increased cancer rates among blacks are tied to the fact that they are more likely to use beauty salons than whites. And if they do use them, they use them more often.

thdrdt 7y ago

The most important part of the article: "While the paper is based on patterns and trends and, as such, doesn't confirm a direct cause, ..." Please be carefull jumping into conclusions. Further research is needed for that.

pithymaxim 7y ago

Slide summary from the authors: https://bcerp.org/wp-content/uploads/Session3-AlexandraWhite_hair-dye-and-straightener-use-and-bc-BCERP.pdf https://bcerp.org/wp-content/uploads/Session3-AlexandraWhite...

modeless 7y ago

> 7% higher risk in white women (HR = 1.07, 95% CI: 0.99–1.16) The confidence interval clearly includes 1.0. I'm tired of all these studies being uncritically reported on in the press with no mention of the giant error bars. IMO medical researchers need to raise their standards. 95% is way too low. Also, journalists should be ashamed at the state of science and medical reporting. It's ironic that you can read articles blaming tech for the spread of fake news and then turn the page to the health section and read garbage like this article.

icegreentea2 7y ago
Won't argue about the validity 95% confidence interval here, but the 95% CI of HR of women as a whole excludes 1, and for African Americans clearly also excludes one. The overall conclusion is still sound (if you accept the validity of 95% CI as a measurement).
- modeless 7y ago
  Only for dye, not for straighteners, and only for "Nonprofessional application of semipermanent dye to others", and black women. If you count up the specific claims made in the article, a majority are not actually supported by the study. And unless the study was preregistered for the cohorts they analyzed, the statistical analysis is suspect even at the 95% level which I still contend is too low.
  - gus_massa 7y ago
    It's interesting to see the supplementary tables (that are free). In the supplementary table 1, classified by menopausal status, they report 55 results. The intervals that exclude 1.00 are: 1.30 (1.04, 1.62) 1.35 (1.08, 1.69) 1.41 (1.10, 1.79) 1.26 (1.02, 1.55) 1.51 (1.17, 1.94) 0.68 (0.47, 0.99) (Some are very correlated.) Anyway, they get 6 interesting results, slightly more than the expected number of false positive cases with a 95% CI interval with 55 cases. Moreover, in the last case, 1.00 is excluded because the interval is too low, i.e. in this study in the premenopausal women that applied hair dye to other person between 1 and 3 times a year got less cancer that the women that didn't. This is probably just noise, but note that this case is not highlighted in the abstract in spite they highlight a few cases where the 95% interval includes 1.00. In the supplementary table 2, classified by estrogen reception, they report also 55 results. The intervals that exclude 1.00 are: 0.78 (0.63, 0.97) 0.82 (0.70,0.95) Both are below 1.00, and neither is highlighted in the abstract. This number is close to the expected number of false positive cases with a 95% CI interval with 55 cases. I guess there is another table in the paper where they classify the women black or white, and perhaps even more classifications. So the evidence looks weak and close to the noise level.

perspective1 7y ago

It's a plausible mechanism but a bogus study. With most of their confidence intervals including hazard ratios of 1.0 (or very close to it), they need to rule out even slight correlations like smoking and (low) income. Recall bias of the survey participants is another major factor in cancer cases. Overall this reads like they collected data of a bunch of chemical exposures setting their p to < 0.05 and found this one that they could publish on.

carlmr 7y ago
>need to rule out even slight correlations like smoking and (low) income. Especially with hair dying, since looking at my environment at least early usage (before graying) is very much correlated with low income/education.
- romdev 7y ago
  I'd like to see antiperspirant usage as a variable, but it seems like it would be hard to find a control. Having tried several times to buy deodorant without antiperspirant for my wife, I can say how hard it is to find an armpit product without aluminum oxide. It's not so hard to find masculine scented deodorants.
  - carlmr 7y ago
    Yeah, I'm wondering why we're not erring on the side of caution there and banning them until proven safe.

nostromo 7y ago

Silly question: did they control for age? Please tell me they did, because, duh... older women have more cancer and dye their hair more. I don't have access to the full paper, but the abstract makes no mention of this, and states they included women from 35-74.

mmmrtl 7y ago
Fortunately, yes

DemonicTitLord 7y ago

God. The comments here in this thread on HN are so fucking stupid, it begs disbelief. Meanwhile, sometimes I had considered that maybe there was a broad medical experimentation program, designed to gather lots of women, drop a fabricated diagnosis on them, and double-blind them into things healthy women would never do. The main idea stemming from the fact that, in an age when shoe size flouroscopes are banned out of fear of ionizing radiation, we encourage frequent mammograms, to cast dragnet for wild tumor goose chases. Mammogram x-rays that mostly don't even work, to the point that Malcom Gladwell pontificates pop culture junk food fluff for air port book stores that conflate them with LANTIRN pods scanning for SCUD missiles. Mammograms that scan for "tumors you can't feel" and thus have no means of verifying beyond the single-source proof of the mammogram itself. Maybe mammograms were the original deep fakes? Maybe eventually, all those extra x-rays shot directly into breast tissue eventually induced breast cancer in some sort of Nietzschean "find the monster you sought" outcome. If the statistic is 1 in 8, lifetime, all women in first world countries, it would seem pretty strange that such a statistic is even possible, when cancer is usually seen in highly fatigued tissues that are abused and suffer high turnover rates. You'd think boobs would endure a period of chronic pain and injury to erupt into cancer, no? My other hypothesis has been birth control horomones, since they're both uniquely feminine, and implicated in glandular targets.