Concerns about Hair Dye

The origins of hair dye may date back further than we may have anticipated, as even the ancient Egyptians, Greeks, and Romans were interested in changing the colors of their hair! Ancient Egyptians would mix lead oxide with calcium hydroxide and water to form a paste that they would rub on their hair. This originated from the idea that dark-colored hair was beautiful and therefore widely desired. On the other hand, ancient Greeks valued light-colored hair and so mixed wood ash with vinegar or lye soap. The ancient Romans showed the results of being on the two extremes-- they would use gold dust to obtain gold hair and leeches for black hair. Fast forward centuries later into the medieval times when light-colored hair was also idealized, and it has been found that a mixture of honey, wine, herbs and roots was used.

Fast forward a few more centuries, and now it is rather common, especially in the U.S., to see hair dyed all sorts of colors. While hair dye can give us the colors we dream of, exactly how safe is hair dye? The dangers of hair dye actually stem from consumer demand-- the majority of those using hair dye to cover up grey or white hairs want full coverage, and so manufacturers push forward with the chemicals used. Common ingredients used in hair dye are ammonia, hydrogen peroxide, resorcinol, diaminobenzene, p-phenylenediamine and more, all of which are dangerous to one’s health. Ammonia breaks down the outer cuticle of the hair shaft and allows other chemicals to enter the hair and cause the changes in hair color. Hydrogen peroxide bleaches out the natural hair color and releases oxygen to allow chemical reactions to occur. Side effects of these chemicals include eye, skin and lung infections, immunotoxicity, chemical burns, blistering of the scalp, hair breakage and hair loss. In addition to the ingredients used to produce all shades and tones of colors, there are additional chemicals used to cover up any odors. These are usually artificial fragrances that carry their own set of safety hazards.

There has been concern over whether hair dye is a potential cause for cancer. However, it is definitely not a causal relationship. There has been some cases in which increased use of hair dye has led to cancer prevalence, but there are also cases in which there is no relationship to cancer. This concern is therefore for now not supported with scientific evidence and would require further research. Additionally, just because hair dye usage and cancer are not causally related does not mean that the chemicals used are not toxic-- they are still dangerous to one’s health. For example, resorcinol is suspected to be an endocrine-disrupting chemical.

In addition to the chemical effects of hair dye, there are also physical effects that can be seen. For example, mistakes or slips made when dying hair can cause the skin around the hairline to discolor. Although this is usually not a severe and major concern because the skin should naturally heal itself within a few weeks, it is still better to avoid getting hair dye on adjacent skin. Hair quality is also affected with the use of hair dye, especially if it is a stronger and more permanent type. Hair loss is therefore a common consequence, as well as the hair becoming dry, brittle and dull in color. Allergic reactions are also something to be aware of, with the colorant PPD causing allergic reactions in 1.5% of those who use hair dye. As a safety precaution, a patch test should be performed before applying the hair dye.

Of course, these chemical and physical drawbacks to hair dye has not stopped us from changing hair colors, which seems to have grown in popularity. Trends and fads for hairstyles now include various hair colors or dying only certain parts of one’s hair. While hair dye may seem fun and all, it may be worthwhile to spend some time looking into potential health hazards and how it may impact your health in the future.


Stephanie Chan