If you search for hair dye on social media, you’ll mostly see inspo photos of women with brightly colored locks. But you’ll also find clips warning you that dying your hair isn’t so fun — it could cause cancer or reproductive health problems.
If you’re one of the up to 80% of women in the U.S. who color your hair, you might see these headlines and wonder: What’s really in my hair dye, and is it safe to use?
“There’s still a lot that we have to learn, but the data that exists so far, I think, is enough for us to be worried about what we’re being exposed to,” says Samantha Schildroth, PhD, MPH, a postdoctoral associate in environmental epidemiology at Boston University.
How Risky Is Hair Dye?
The concern with hair dyes isn’t what they do to your hair — it’s what happens when they enter the skin around it.
“The scalp has a very rich blood supply,” says Melanye Maclin, MD, a research and development dermatologist. “Those chemicals absorb into the scalp and enter the main bloodstream.”
In fact, hair dye users have significantly different levels of at least 11 metabolites circulating in their blood compared to those who don’t use it, according to research published in Scientific Reports.
What does that mean for your health? It’s hard to say for sure because there are no clinical trials that prove that one product or another increases risk. However, cohort and case-control studies have shown associations between hair dye use and some negative health outcomes.
A recent study review of 96 articles suggests that women who use permanent or semi-permanent hair dye just once or twice have a 7% increased risk of breast cancer, while those who use it 35 to 89 times have a 31% increased risk. Permanent dye was also associated with a 250% increased risk of bladder cancer in people with certain genetic factors.
“There can be health risks with using these chemicals, especially if you’re continually exposing your body to them over time,” says Maclin. “It’s a progression.”
Permanent dyes penetrate hair to its middle layer — the cortex — to strip existing pigment and leave new color behind. Semipermanent and temporary dyes tint the outer layers of the hair and wash out over time.
Researchers point to aromatic amines in permanent dyes, chemicals that help hair color stick to your strands, as potential culprits that might increase cancer risk. These substances can bind to DNA and lead to cancerous mutations. They can also affect reproductive health by mimicking or blocking the sex hormone estrogen.
A recent cohort study from Schildroth’s research group suggests that women who use hair dyes might have an increased risk of uterine fibroids, which are noncancerous growths that can cause pain or reduce fertility. Black women who used temporary hair color rinses the past 12 months had a 98% increased risk of fibroids.
“Fibroids are typically very responsive to estrogen, so if you have a chemical that mimics estrogen in the body, it could then, in turn, influence the way fibroids grow and develop in the body,” she says.
Schildroth also notes that temporary hair colors are usually thought to be safer than permanent dyes, since they contain fewer aromatic amines. However, her study’s results raise questions about their safety.
What’s the Safest Way to Use Hair Dyes?
Knowing which hair dyes are safer than others is not easy. “We can’t really point and say this is the particular type of dye that is really bad that we should avoid,” Schildroth says. Studies are often based on surveys about hair dye use, and they don’t drill down to exactly which brands or formulas users applied.
However, there are steps you can take to lower potential health risks.
Read the labels on your products. Look for hair dyes without PPD or other aromatic amines, such as m-Aminophenol. Plant-based or vegetable dyes often contain fewer of these substances, says Maclin. She also recommends looking for products free of sensitizing ingredients such as ammonia and sodium lauryl sulfate.
“The Environmental Working Group has an online database where they go through products and give them scores based on the ingredient lists,” says Schildroth. “That’s a really great resource for consumers who are trying to stay up to date.”
Credit: webmd
