Does Hair Dye Cause Cancer?

Does Hair Dye Cause Cancer
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Does Hair Dye Cause Cancer?

The fine line between beauty and health has long been blurred in the name of fashion. Sacrifices have been made for centuries in the pursuit of vanity and short-term gains despite them having damaging consequences over time. But could hair dyes be the latest trend to follow the tight corsets, impossibly small shoes, lead-based face powders and various other treatments which have gone before?

Although artificially changing hair color is something which has been practiced since the ancient Egyptians reigned supreme, it’s a treatment which was for a long time borderline taboo. In the same way that a lady doesn’t reveal her age, she most certainly never revealed the fact she hid her graying hair.

The Dying Roots

The first bottle-blonde’s were introduced to the public through Hollywood in the post-depression years of the 1930’s. With dust storms and financial problems ravishing the country during this period, the clean glamor of Jean Harlow’s “platinum blonde” offered exactly the type of escapist fantasy people needed to sink into.

The early methods used to obtain blonde locks invariably came at a price. Mixtures of peroxide, Clorox, and ammonia were used directly on their scalps to literally bleach the color out of the hair.

This process was incredibly painful, producing hydrochloric acid and toxic gases as a by-product. When Harlow dies at the tender age of 26 through ill-health, her weekly hair treatments were one of the chief culprits for her premature demise.


It wasn’t until 1956 that the first home-dying kits became readily available. The eponymously titled “Miss Clairol” product provided a one-stop package which allowed women across the nation to change their hair color from the sanctity of their own bathrooms.

For decades, hair dye was only ever used as a way of concealing grey hair. The convenience offered by these new set of products in the mid-twentieth century saw an explosion in the number of people regularly dying their hair.

Unlike the ancient processes which employed natural pigments, these modern products contained an array of potently strong chemicals. Whether they were aimed at restoring a natural color or creating the vivid effect such as that sported by Harlow years earlier, coloring quickly became common practice.

How do permanent hair dyes work?

With the rise of the hair colorant industry came its own set of problems. To make permanent dyes effective, they needed to use chemicals which were powerful enough to change the composition of human hair.

The first stage of dying hair is to separate the outer layers of protein (the cuticle) in the hair strands. This allows the dye to penetrate each fiber and mix with the natural pigment at their core. Unlike dying other protein fibers such as wool, it’s impossible to boil your hair in an acid solution for an hour to achieve this.

For this reason, Ammonia is one of the key ingredients found in most products. This is also the reason why the process of dying hair takes a minimum of half an hour.

Does Ammonia cause a health risk?

While ammonia may not be carcinogenic, it is a corrosive substance. The diluted amounts present in hair dye products cause no great danger, however, repeated and regular use of ammonia-based, permanent hair dyes can degrade your hair’s overall appearance.

Known to cause dry, brittle and dull-looking hair, this rarely occurs from occasional dyes and can generally be considered a safe process. Similarly, exposing your hair to too much heat through hair straighteners or blow-drying can also have a similar dulling effect. As such, moderation should be your key takeaway from any such processes.

Despite the public conception that Ammonia can cause an allergic reaction, this almost never happens. The human body naturally creates ammonia and although high concentrations can cause burns to the skin, the levels present in hair dye products are unlikely to do anything more than cause irritations.

Allergic reactions to Hair dyes

While it’s possible to have an allergic reaction to any number of different chemicals and substances, most reactions to hair dyes are caused by the colorants.

para-phenylenediamine (PPD) and para-toluenediamine (PTD) are the two most effective, and therefore most common, dye molecules used in permanent hair dyes. Between 0.5 to 1% of the population has an allergy to these substances which can result in the formation of swelling and blisters.

Often referred to as sensitizers, these compounds can develop allergies between themselves and your skin through repeated exposure to them. If you’ve ever seen and read a news article warning of the effects hair dyes can pose, it most probably uses a photo of a reaction to PPD. Because these remain relatively rare and due to no other known substance working as well to color hair, this chemical remains a key part of the vast majority of coloring products.

A Colored Controversy

So why the link between hair dyes and cancer you may ask.

One of the main ingredients used in early products was 4-methoxy-m-phenylenediamine - often shortened as 4-MMPD. This is a type of aromatic amine which was the dying agent used to color hair. While it is similar to PPD, it was found to have mutagenic properties.

With the backing of scientific evidence, the FDA (the American Food and Drug Administration) proposed in 1979 that all products containing 4-MMPD should carry an official government health warning.

Warning: Contains an ingredient that can penetrate your skin and has been determined to cause cancer in laboratory animals.”

The major cosmetics companies who manufactured hair dyes at the time heavily disputed these claims, threatening lawsuits if these rules were to be applied. As such, these warnings were never officially enforced.

Within a few years, however, these carcinogenic substances were completely phased out of cosmetic products. Although pharmaceutical companies refused to publicly acknowledge the dangerous consequences 4-MMPD carried, the image of hair dye products was to be badly tainted.

What are the risks?

Anyone who has experienced a dyeing, highlighting, toning, balayaging, or glossing process on their hair will testify to the slight annoyance which accompanies them. Beyond a minor discomfort, an irritating smell and the expense of undergoing such a treatment, there remains very little tangible risk.

The modern world is becoming preoccupied with increasing health concerns, something underlined by rises in the number of confirmed cases of cancer. Instances of bladder cancer have increased by over 50% during the last two decades, however, much of this can be placed on an aging population.

The seeds of distrust sown by pharmaceutical companies over the years combined with the idea that chemicals are bad while nature is good have stigmatized the industry. With sensitizers being the only major risk present in modern beauty products, the industry does have a slight problem it still needs to overcome. However, this is more true of the fragrance markets than that of hair-care products.

Do Modern Hair Dyes Cause Cancer?

With an ever-increasing range of hair dye products on the market, it’s easy to imagine that at least some contain unsafe substances. It’s believed there are now well in excess of 5,000 different chemicals used between the different coloring agents, chemical relaxers, and deep conditioning creams currently occupying shelf space.

To help ensure consumer safety, many independent organizations now assess the findings of scientific research in this area. Although the European Union currently has a stricter set of guidelines than their American counterparts, both strive to protect consumers interests.

While permanent hair dyes are still questioned regarding potential links to cancer, the general consensus amongst experts is that the risk is negligible within regular usage. Hairdressers generally do have a slightly above-average chance of developing bladder lung, or larynx cancer, however, this does not take into account any other potential causes within the group as a whole. More importantly, studies made of women who dye their hair have not shown any major reason for concern with the exception of consumers who used products prior to the early 1980’s.

Is It Safe To Color Your Hair During A Pregnancy?

Because the chemicals used to dye your hair can be absorbed into your skin through your scalp, this means they can enter your bloodstream too. While this is something of concern to everyone, it’s particularly worrisome for women who are pregnant.

As with all other aspects of using bleaches and chemical’s to change your hair color, scientific evidence is not conclusive. The expert view on this remains that the chemicals are not highly toxic and as such, they pose no immediate danger to either mother or child through using either permanent or semi-permanent hair dyes.

Because there is so little residual dye absorbed into your bloodstream, only a negligible amount could potentially come into contact with the unborn baby.

For any mothers-to-be who wish to tread a more cautious path, experts advise waiting until the start of the second trimester before using a hair dye.

Growing market

Fueled by our natural desire for self-improvement, the global hair color market is now huge. It’s been estimated that around a third of American women aged 18 or over currently use some form of dye product on their hair. Other reports put this figure much higher, some claiming as many as 75% of adults have used some form of hair colorant to enhance their looks at some point in their lives.

Whatever the actual figure, the current market is clearly booming. Continuing to record an annual growth rate of around 8%, new fashion trends and the increasing ease to color your hair means this is unlikely to change.

With no clear evidence that hair dyes cause cancer, the industry has never been as safe as it is today. Rumors will continue to persist, however, normal use of these products in-keeping with manufacturers instructions will leave you with nothing other than a great new look.

(Last Updated On: March 19, 2021)

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