Little about the chemistry of hair coloring has changed since 1909 when a French chemist named Eugene Schuller created the first commercial hair dye. Ammonia has been an ingredient de rigueur for women and men who want to lighten their hair, exposing them to its unpleasant odor. Now, scientists at L’Oréal, which was founded by Schuller, have reinvented the chemistry of hair color and replaced ammonia with an odorless substitute.

The new dye, called INOA for Innovation No Ammonia, is a "revolution" in how hair coloring is formulated, says Jean-Marc Ascione, director for hair color product development worldwide for L’Oréal.

In place of ammonia, INOA relies on a chemical called monoethanolamine, or MEA, which has no odor. But INOA could have some of the same toxicity as ammonia, a scientist for an advocacy group says.

First, here is how it works: MEA is alkaline (as opposed to acidic), like ammonia, so it can accomplish the first step in permanent hair dye, which is to open the hair's cuticles. In fact, L’Oréal already sells ammonia-free permanent hair dyes that contain MEA in the U.S. and Europe. But because MEA does not open the cuticle as efficiently as ammonia, it does not allow the hair coloring ingredients to penetrate the hair strands as well. For this reason, MEA-based permanent hair coloring was only being used to darken the hair one shade, and not to lighten hair or color gray. So the L’Oréal chemists wanted to give MEA a boost.

"We said we like MEA because it doesn't have the strong odor of ammonia but what we needed to do was find a new system that would make the performance of MEA higher," Ascione says.

To boost MEA, L’Oréal chemists added a new component to the hair dye formula: a mineral oil gel that has a high affinity for hair but not for MEA. Right before INOA is put on hair, the oil gel, called oleogel, is mixed together with MEA and the other key components for tinting locks—the oxidative hair dye and the hydrogen peroxide that develops the hair dye. Oleogel contains special emulsifying agents that allow the oil to mix with the other water-based ingredients. But, when the mixture is on hair, the oil coats the outside of hair strands and repulses the MEA, driving it to open the cuticle and penetrate the hair. Adding oil changes the ability of MEA to penetrate the hair. "It's as if you were changing the engine of a car—everything becomes more powerful," Ascione says.

Ascione says it will be no secret to people using INOA that they are not using conventional hair coloring. "We wanted to bring to hair color a pleasure dimension," he says. Besides keeping hair salons and home bathrooms free of ammonia's harsh household cleanser-like smell, Ascione says that the new formula feels more like a thick skin cream than the conventional, more pasty hair dyes.

Smell aside, however, studies have found an increased incidence of work-related asthma in janitors, nurses and office workers that was linked to their exposure to ammonia and MEA, as well as to the bleach and acids in cleaning products, says Rebecca Sutton, a senior scientist at the Environmental Working Group. Hairdressers could also be at greater risk of work-related asthma, she says, adding: "I can't say that replacing ammonia-based dyes with those containing monoethanolamine is an improvement for public health, though it will cut down on the noxious odor."

The L’Oréal scientists have observed that people who have sensitive scalps are not irritated by INOA, although this difference could be attributable to any of the number of modified components in INOA, not just the MEA-for-ammonia swap, Ascione says. He adds that INOA does not upset the hair cuticle as much as conventional hair dyes, preserving hair strength.

While other companies use ammonia in their permanent hair dyes, some have created formulas to soften the hair coloring experience. Aveda's professional line of permanent hair dyes have plant extracts, such as lavender, that help mask the smell of the ammonia and soothe the scalp, says Evan Miller, director of global communications for Aveda Corporation.

So far, INOA has debuted around Europe, but consumers in the United States and Canada should be able to try the new hair coloring within the first three months of 2010, says Pamela Alabaster, senior vice president for corporate communications & external affairs for L’Oréal USA. And the product should eventually be available for home use as well. L’Oréal plans to sell INOA to salons at a 20 percent premium compared to its current professional brand, Majirel, although it is not clear how much more consumers will pay to be part of the new "revolution" in hair coloring.

Image courtesy of iStockphoto/powerofforever