zlacker

>>Impres+(OP)
From a quick scan the results are a bit surprising. One should know that dying ones hair involves 2 components:

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.

>>except+Ps
I'm confused by your analysis. For black women, it's not just hair dye, but they have hair straightener products that have companies putting some very toxic and carcinogenic stuff into them. So black women can be putting themselves at greater risk, if they use such chemical straighteners (they do have non/less toxic options).

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.