These ingredients “can be very drying, stripping, and irritating for the scalp,” Dr. Marshall says. Sulfates, as they’re known, are common in everything from beauty products to food. The FDA doesn’t consider sulfates harmful — but certain concentrations have been found to cause “mild to moderate” irritation in some people. So if you’ve got sensitive skin, it might be worth limiting your exposure to sulfates.
Similar to mineral oil and petrolatum, Benzene is an immune-signaling disrupter, Dr. Marshall says. And it’s also got a pretty clear link to cancers, including leukemia. The chemical “is known to cause cancer, based on evidence from studies in both people and lab animals,” according to the American Cancer Society. “The link between benzene and cancer has largely focused on leukemia and other cancers of blood cells.”
Benzene is still used in many consumer products. In fact, it’s one of the 20 most common chemicals in the U.S. So vigilance is key.
These chemicals “secretly make their way into products under the non-regulated term “fragrance,” Dr. Marshall says, “and have been found to be endocrine hormone disruptors.” As she explains, “Our hair cycle is very sensitive to changes in our endocrine hormones like estrogen, progesterone, cortisol, testosterone, insulin, and thyroid hormones.”
Similar to phthalates, parabens are also “endocrine disruptors,” Dr. Marshall says. They can pop up on an ingredients list as methylparaben, ethylparaben, propylparaben, butylparaben and isobutylparaben, etc. What’s more, parabens are present not only in beauty products but also in household products. This means that people may become exposed to parabens even if they avoid them in the beauty aisle, according to Scientific American.
These are rife in beauty products, and can “harm the hair cuticle, leaving it susceptible to oxidative damage,” Dr. Tess says. This is doubly undesirable if you color your hair.