Is Hair Dye "Toxic"? Our Guide To More Natural Hair Color

This way, you can make a more informed decision on what's right for you. Here, what to know about hair dye, some myths to bust, and more.

 Here are the main ingredients that come up and what to know about them: 

However, Thompson notes that modern formulas have significantly less of these dyes than the past versions. "Back in the day, the color was much different dye than what we use today. You can see the difference: Past hair dyes used to be so opaque and harsh, but now formulas are softer and look much more natural. As we've learned more, we know what molecules we need to minimize and at what concentrations," she says, noting that while many of the hair color formulas still use these dyes, they do so at much lower levels—swapping out the ingredient for safer dyes. 

Used as a preservative and stabilizer, these are tricky. Research shows that even trace amounts of formaldehyde are enough to trigger dermatitis in humans5. Few products are going to outright say they contain formaldehyde, yet several preservatives release6 the irritant over time, with temperature variations, or when it comes into contact with other actives. One of those is quaternium-15, which is a common hair dye ingredient. 

Ammonia is a highly alkaline substance, so it is used in hair color to open up the cuticle7. Once the cuticle is lifted, the pigment can be deposited or the lightning agents can lift the color. It's also what gives hair color the strong, overpowering odor. Ammonia is a respiratory and asthma irritant, so the issues arise when you breathe it in through the air. Thompson notes, however, that if you know your formula has ammonia in it, but you can't smell it, that might actually be a bad sign: "That means the product is filled with fragrances to mask the smell—the ammonia is still there," says Thompson. "That's why natural-leaning dyes actually have a more potent ammonia smell—because they're not trying to mask it."

So if you want to color your hair safely, it really comes down to how you color your hair. 

And a few color brands offer better-for-you professional formulas, like Aveda and Biolage, so ask your colorist what brands they offer. 

"Some of my clients are very sensitive to the smell, so sometimes we even color their hair outside in one of the salon's gardens," notes Thompson. While this may not be realistic for most salons, you should at the very least find one that has good airflow. 

While you're coloring the hair, be mindful to follow instructions: Wear gloves, follow the time limits, and so on. Oh, and the same goes for ventilation here: Most people probably color their hair in their bathroom, but that likely doesn't have the same airflow. Try the kitchen and open up a window. Check out our favorite at-home dyes here.

If you decide to do all-over color, ask that your colorist use foils instead. When a colorist uses foils, they are painting just the strand rather than applying the dye directly to the skin. "I tell my clients that when I use foils, the only exposure they're getting from the dye is through inhalation; you're not absorbing it into the body as it's not touching the skin," says Thompson, and so we'll refer to the ventilation point again. 

Another way to prolong hair color is to opt for glosses or glazes in between appointments, as these can color-correct, add depth, and increase shine.

Or, says Thompson, embrace gray. "Often people who have been dyeing their grays for years are scared to transition to gray, not because they don't like the look of gray but because they are afraid of the grow-out process. But there are colorists who specialize in this transition phase who can help you go gray in a really beautiful, natural way."  

"The EPA reports, a large portion of the world's fresh water resides underground, stored within cracks and pores in the rock that make up the Earth's crust. Half of the U.S. population relies on groundwater for domestic uses as local water waste management can decontaminate only 50% of the water waste. In many parts of the United States, people rely on groundwater for drinking, irrigation, industry, and livestock. This is particularly true in areas with limited precipitation, limited surface water resources, or high demand from agriculture and growing populations. Some ecological systems, such as wetlands or surface waters fed by springs and seeps, also rely on groundwater," says Bill Deliman, the director of business development at Green Circle Salons, a nonprofit organization that educates salons on how to be more eco-friendly (they currently have a partnership with Biolage salons to educate hair stylists and colorists on best practices.)

Let's say you just want a slight tweak to your natural color: A toner might be your best bet. Here's our guide to toning your hair naturally.