Is hydrogen peroxide harmful to your hair?

Hair Colouring -Dean Wissing CC-BY-SA

 by Zoë Gamble

Throughout history, people (especially women!) have attempted to change the colour of their hair. There is even evidence suggesting that the Ancient Egyptians used a dye to alter the colour of their locks.

Fashionable hair colours have changed a great deal over the years. Did you know that in the first century BC, the Gauls would dye their hair red as a mark of distinction? Whereas, in the dark ages, red hair was thought to be a sign of witchcraft. Currently, blonde is the most commonly sought after hair colour, followed by brown. To achieve luscious blonde tresses, many people turn to hydrogen peroxide.

What is hair?

Hair is made of a protein called keratin. That’s the same thing that fingernails are made of! Hair starts off inside a hair follicle under the skin, and it’s at that point that pigment is added into granules in the protein, giving your hair its colour. Natural hair colour results from two pigments – eumelanin (found mainly in darker hair) and pheomelanin (found mainly in red hair). Blonde hair results from a lower amount of pigment present, while grey hair occurs when pigment production decreases, or stops.

Changing the natural hair colour

Human hair magnified 200x. Public Domain – Jan Homann

Bleaching hair penetrates the hair shaft and removes the natural pigment of the hair. The bleach we use to lighten hair is ‘hydrogen peroxide’. Hence the phrase ‘peroxide blonde’!

The chemical formula for hydrogen peroxide is H2O2; two hydrogen atoms and two oxygen atoms make one molecule of hydrogen peroxide. But don’t be fooled, this chemical compound is nothing like water, which is H2O! That extra oxygen makes a big difference.

Heated to boiling point, hydrogen peroxide is explosive, not to mention it being used as a disinfectant at room temperature.

To be safer for our skin, the hydrogen peroxide used to bleach hair is diluted many times. This chemical enters the hair shaft and releases oxygen, causing the pigments to be broken down. Another colourant is normally used alongside the hydrogen peroxide, to introduce the desired colour to the hair.

Is it bad for my hair?

To help the hydrogen peroxide to get into the hair to reach the pigment, another chemical, like ammonia, is normally added. Ammonia can cause the hair to lose moisture, and the hair colour to fade. However, there are alternatives that don’t use ammonia.

Hydrogen peroxide itself is a harmful chemical, but it is diluted before being used on the hair so only a small amount goes on your head. As many people associate hydrogen peroxide with damage to the hair, some companies are looking to use alternatives. Bleaching the hair just isn’t possible without an oxidising agent such as hydrogen peroxide, so these alternatives work in the same way as hydrogen peroxide, just have a different name and use a different chemical!

The future

CC-BY FlickrLickr

According to one study, 75% of women dye their hair in some form, and there are more shades to choose from than ever before. Although hair dye is being developed by scientists to be more effective, safer, longer-lasting, there are still these horror stories!

The bottom line is that exposing your hair on a regular basis to strong chemicals is likely to do some damage. But many people are wiling to risk it to achieve their desired hair colour. Are you?

 

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Posted in Chemistry