Since ancient times, most people have been coloring and dyeing their hair. However, little is known about the chemistry of the dye and its health implications. It generally causes an itchiness and irritating allergic reaction or even make it worse. And those people, who become allergic to the hair dye, can develop reactions to many other common substances, transforming even a simple cosmetic treatment into a big problem. But now, a range of permanent hair dyes without the itchiness and other allergic problems have been developed, as reported by researchers in ACS Sustainable Chemistry & Engineering.
‘This article proposes that new hair dyes have better outputs when compared to the old ones when it comes to allergic reactions.’
A common ingredient in permanent dyes paraphenylenediamine (PPD) When used as an hair color undergoes a chemical reaction, which turns the hair into a dark color that will not wash out over time. However, this reaction can also produce compounds that bind proteins in the people’s skin, causing allergic reactions, such as eczema, facial swelling, wheezing, stomach pain, vomiting, and so on. PPD can also sensitize the users to other substances, such as some chemicals in sunscreens and cosmetics. Some alternatives have been proposed, but generally they are not water soluble, and the safety of some of the compounds is not up to the mark. To avoid these problems, some research has been done, and a new method of a perfect hair dye has been proposed. The results indicate that the new hair dyes have less allergic reactions when compared to the traditional ones.
The research team prepared seven dyes based on PPD with modifications to the aromatic amine core. The modifications were chosen to make the compounds less reactive toward proteins and less able to be absorbed into skin. All seven compounds were permanently colored hair samples, and were producing a range of hues from rosy pinks to deep blacks that did not fade, even after three weeks of daily washing. The team then examined the dyes in a test commonly using a test in the cosmetics industry to determine if a product is a skin sensitizer or not. Five of the modified dyes were “weak” sensitizers, whereas PPD was “moderate.” Another test showed that the new compounds generated a reduced inflammatory response in cells compared to PPD. These results suggest that the new dyes can effectively color hair and can also avoid the potential allergenic and sensitization risks compared to more traditional dyes.
The researchers acknowledge funding from the National University of Singapore.