1. developer. Some liquid that breaks open your hair follicles, containing usually 3%/6%/9% hydrogen peroxide. This is the aggressive stuf.
2. hair dye. The stuff that contains the color pigments.
The more you have to bleach the hair, the more aggressive the developer formulation needs to be. If you have perfectly black hair and you want to go blond, you basically going for the nucleair scenario: aggressively breaking open your hair follicles so that the existing dark pigments will fall out of it (bleach) so that the new pigments can enter eventually.
It suggests that black women have higher risks than white women. But also that semi-permanent dyes do incur way less risk. Semi-permanent dyes work different as in that the developer is way less aggressive, as a trade of with doing a less thorough job in getting the hair follicles to open.
The strange this is that for black women, the color of the permanent dye makes a more drastic difference in cancer risk compared to white women.
"The association with permanent dye use among black women was evident for both dark-colored dye (HR = 1.51, 95% CI: 1.12–2.05) and, although less precise, light-colored dye (HR = 1.46, 95% CI 0.91–2.34). Among white women, breast cancer risk was associated with use of light-colored permanent dye (HR = 1.12, 95% 1.01–1.23) but not dark dye (HR = 1.04, 95% 0.94–1.16)."
For me, this leaves the question open if one is comparing apples with apples, as I don't see the formulation for the developer accounted for.
It also indicates that black women are less likely to get breast cancer than white women, but when they do, they are more likely to die from it for a whole bunch of reasons. To include factors like time of diagnosis, quality, or cost of medical care.
> For me, this leaves the question open if one is comparing apples with apples, as I don't see the formulation for the developer accounted for.
Here, I agree with you. Clearly what the companies are putting into the products vary significantly. That by itself, might be worthy of more study as to what's gong on. Dumping more toxic and carcinogenic chemicals into the product, would seem to clearly increase risk. For consumers, they need a guide as to what products and ingredients are safer or more dangerous. Looks like certain ingredients arguably need cancer warnings or some kind of warning on the label.
I think we agree that we still have no idea about what has been measured here.
It doesn't look like they corrected for this, unless I missed it.
In 2015 my (now ex) girlfriend was diagnosed with TNBC. I obviously researched the hell out of it to gain as much of an understanding as I possibly could as a non-medical professional as I'm sure anyone would, and most of my reading suggested that it was mostly African American women and youngish white ladies who tend to get this.
As far as I know, she had used permanent die at least once in her early twenties. Thankfully less than a year later and after chemo and surgery, she fully recovered.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7783321/
Edit: added space after comma, fixed grammo
In many cases, it could even be a cancer "from some other organ" that winds up in the breast and happens to, even by chance (not growing in the breast because it's a favorable environment), grow there.
[0] could explain why TNBC is more common in African American women -- less research done in those populations
> In many cases, it could even be a cancer "from some other organ" that winds up in the breast and happens to, even by chance (not growing in the breast because it's a favorable environment), grow there.
That would imply metastasis, would it not? By which, the originating organ of the tumour could be determined by examining the samples from the initial biopsy. The doctor said that in the case of TNBC there is no hormone expression, which makes it differ from other BC types, and why a more aggressive chemo regime is required for this diagnosis.
I was there, at her second-opinion encounter. Nothing was mentioned about it possibly originating from another organ. She had had repeated body scans, blood work, all that one can imagine. I'm not saying you are wrong, I am saying there was not a single mention in any part of the treatment nor received "coping" literature that this could have come from another organ.
So yeah, it could have caused it. Is it the likely cause? Maybe not.
With skin cancer, getting a sunburn every two years triples your risk of developing melanoma. With the fairest skin types, even a single severe burn can increase risk if melanoma. Other skin cancers tend to result from constant exposure over time.
I don’t know much about this scenario with hair product. But if you have some other risk factors, it’s not unreasonable that a single exposure may result in a bad outcome.
Dyes have electron delocalization. That's why they're optically active. Those bonds will gladly participate in chemical reactions within your body. (One of the cited chemicals was a biphenyl, and looked particularly nasty.)
Chemical straightener is even worse. They're intended to break disulfide bonds, which are of critical importance in biochemical structure.
This stuff could percolate to your DNA and introduce deleterious changes.
You might find my work based on the HN front page of interest: <https://toot.cat/@dredmorbius/110437783957361794>. Note that this is a subset of total HN activity, though a significant subset.
There's also Whaly.io's retrospectives based on the HN API:
<https://whaly.io/posts/hacker-news-2021-retrospective>
<https://whaly.io/posts/top-10k-commenters-of-hacker-news-in-...>
Really interesting analysis. Thanks for sharing this!
I must be too active on HN when my username is showing up in these lists.
What do you mean by that?
When electrons are tightly bound into nodes in and between the vertices, they are energetically ‘stable’. They, therefore, do not like change.
When electrons are shared equally between all nodes and are mobile, they could be considered to be ‘more active’. As the electrons are not tightly bound, it is ‘all to play for’ and some change in state may be accommodated.
The optical activity described occurs because the equally shared, ‘central node’ electrons are ‘free-er’ and have the flexibility to accept unusual states. This is because in the multi-node model, the electrons may be considered tightly bound to each node and so any the effect of any change in the state of a given electron is highly concentrated and local.
In the shared electron central node model the electrons are ‘more mobile’ and so any change in state has a distributed and shared effect across all electrons, rather than only those in a given node of the multi modal model.
To emit light, an electron must absorb enough energy to reach ‘the next level’. In the multi nodal model, the next level is extremely far away and may require so much energy that the molecule will disintegrate rather than emit light.
In the equally shared central node model, the next level is ‘accessible’ in that, whilst unstable, the mobile bulk of electrons in the molecule can accommodate the change and radiate the excess away.
The exact colour of light is determined by the energy required to reach the next level, in most cases. This is a consequence of the delocalisation of electrons in dyes, which may be considered as following the shared central node model. A further consequence is increased reactivity.
This explanation should be considered poor and ignores a lot of nuance and theory (whilst relying on a hazy memory). Likewise, it neglects to explain intriguing phenomena such as the anion-pi interaction. In any case, I hope it is not ‘too wrong’ and helps!
>We observed a higher breast cancer risk associated with any straightener use and personal use of permanent dye
