If you’re looking at an invasion of grey hairs and/or dark roots, you might well be tempted to get out the hair dye. An estimated 53% of women in the UK – and an increasing number of men – use hair dye at home, according to Mintel. Of those, 70% choose permanent hair colour, which raises the most concern in terms of cancer risk.

Should you really be worried? It’s a confusing area so I want to decode it and give you the headlines.

There are three main types of hair dye:

• Temporary dyes (tints) cover the surface of the hair but don’t penetrate into the hair shaft. They generally last for 1 to 2 washings.
• Semi-permanent dyes do penetrate into the hair shaft. They typically last for 5 to 10 washes.
• Permanent (oxidative) hair dyes bring about chemical changes in the hair shaft, which last until new growth comes through. They contain substances such as aromatic amines and phenols, which are colourless until hydrogen peroxide comes on the scene when chemical reactions cause them to become dyes.
• Darker permanent hair dyes have a higher concentration of ingredients so are of greatest potential concern, particularly for people who use them frequently.

Hair dyes are complex to study because they can contain any of thousands of different chemicals. The concern centres on the fact that some chemicals used in hair dyes are ‘reasonably anticipated to be human carcinogens’, according to the US National Toxicology Program.

However, many of the potential problem chemicals have now been discontinued, with the biggest shift happening from 1980 after ingredients called aromatic amines were found in the late 1970s to cause cancer in animal tests. (It’s significant to note that the animals were fed large amounts of the dyes over a long period, rather than having it on their skin – and yes, I hate animal testing…)

There has been continuous research and monitoring of hair dyes over the three decades I’ve been writing about health and beauty. The latest big study was the US Nurses Health Study, which followed 117,200 (mostly white) women for 36 years to ‘evaluate the associations between personal use of permanent hair dyes and cancer risk and mortality’.

Before we go on to the results, the key word here is ‘association’. There is no direct causal link between using any form of hair dye and cancer. As Cancer Research UK says: ‘Links have been suggested between hair dyes and a variety of cancers including bladder cancer, breast cancer, leukaemias and lymphomas. But there is no clear evidence that hair dyes could cause any of these cancers.’ They add that any increase in risk would only be very small in comparison to other risk factors, principally smoking.

The Nurses Study researchers concluded that ‘No positive association was found between personal use of permanent hair dye and risk of most cancers and cancer related mortality.’

However, there was a slight increased risk of non-malignant skin cancer (basal cell carcinoma) with a higher risk in women with naturally light hair (and thus lighter skins more prone to burning; the researchers did control for this but it is still a possible factor).

Cumulative dose, in other words using permanent dye often over years, was linked to a higher risk of some types of breast cancer and ovarian cancer. Also, an increased risk of Hodgkin’s lymphoma was seen in women with naturally dark hair in a small sample. The researchers emphasise that their greatest concern is about the risk of dark coloured, permanent hair dyes.

In the Sister Study from 2019 where the subjects were women whose sisters had been diagnosed with breast cancer, women who used permanent hair dye were more likely to get breast cancer than those who didn’t. The risk was significantly higher in African American women who used hair dye every five to eight weeks. Chemical hair straighteners also increased the risk, according to this study.

Legislation and regulation of ingredients in hair dye formulations differ from country to country. In the US, permanent hair dyes do not need pre-market approval by the FDA (although they monitor safety concerns): manufacturers are responsible for the safety of ingredients. However, the FDA did ban lead acetate in hair colour although dark hair dyes containing this compound can still be found on the international market – see below for more on US regulation of hair dye.

For the time being, the UK is still regulated under the European Union’s Reach laws (Registration, Evaluation, Authorisation and Restriction of Chemicals) and the regulations for all cosmetics are much more stringent and reassuring for consumers than in the US. In 2006, the EU Commission announced that it would ban 22 different hair dye substances, which did not have ‘adequate safety files’. As of February 2020, the EU banned a common ingredient known as PPD (paraphenylenediamine) in all hair, eyebrow and eyelash dye product, although a somewhat less troubling sibling, PTD, is still permitted at a low concentration. (What happens after we leave the EU we don’t know.)

Because they work with hair dye every day, colourists may have an increased risk of cancer (and also skin conditions) not just through contact – that’s why gloves are so important – but also from airborne particles.

There are some general safety guidelines:

• Use a good quality brand of hair dye; you may want to ask your hairdresser for a recommendation.
• Skin irritation is a concern and allergy can build up over time so experts recommend carrying out an Allergy Alert Test 48 hours in advance, every time you colour your hair even if you have used the product before. For details of how to do this, click here.
• Always follow the directions to the letter, particularly about the length of time you leave the product on your scalp; this also helps avoid the risk of skin irritation
• Always wear gloves and make sure the room you are in is well ventilated.
• If you’re concerned about the risk of permanent dyes, use them infrequently and camouflage roots, eg with a mineral powder such as Color Wow.
• People going through cancer treatment are generally advised to wait six months before using permanent or semi-permanent hair dye because hair is likely to be more fragile. More information here.

Other options:

Several leading hair care brands offer lovely temporary tints and colour glosses to shampoo in at home, often stuffed with hair-nourishing botanicals.

Meanwhile, expert colour companies are exploring the potential of truly natural ingredients in professional formulas, some already used in salons. So it’s a likely bet that truly natural, high quality, at home formulations will be available before too long.

Remember, however, that the word ‘natural’ has no legal definition and some brands use the word ‘organic’ to mean something quite different from what we presume it to mean (check an ‘organic’ product is certified organic by a reputable organisation such as the Soil Association.)

If you choose to use ‘natural’ products, do be aware that, with the exception of henna, hair colour virtually always needs some synthetic chemicals to work and also that these DIY products may not have been subject to stringent scrutiny and regulations. If you want to go more natural, I suggest you go to a specialist salon at least for a consultation and initial process.

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