• Laura Chaparro, science journalist

    Tattoos: what are the risks for the skin?

    28 Nov

    Tattoos are fashionable; even children get henna tattoos. However, medical studies indicate that they are not entirely harmless and health authorities warn of the risks.


    Tattooing, popular as a mark of individuality, as a cultural practice or to indicate affection or admiration, is on the increase, especially among younger people. Although tattoo parlours in Western countries observe strict health safeguards, the most important question still remains to be answered: are tattoos harmful to the skin?

    Increasing numbers of people are turning to their dermatologists with tattoo-related problems and many studies have shown that tattoos are not harmless artwork. A recent study by researchers at the San Gallicano Dermatological Institute in Rome reveals that tattoos can cause skin allergies such as dermatitis, eczema, itching and flaking. Experts link these reactions to metals in the pigment fixing agent, maintaining that adverse reactions associated with tattoos – both the permanent kind and henna tattoos that last just a few days – have doubled in the past five years.

    This same study demonstrated that inks used in the Italian tattoo market have very high concentrations of chromium and nickel and smaller amounts of cobalt. According to the researchers, these three colour-generating chemicals are responsible for allergic reactions.

    Some henna tattoos use para-phenylenediamine (PPD), a product typically used in hair dye, to extend the life of tattooed artwork. PPD too can cause allergies.

    It is also thought that tattoos may be associated with different kinds of skin cancer, although as yet there is no consensus in this regard in the scientific community. Scientists at New York University have concluded that there is no link between tattoos and cancer, as the ink is confined to cells known as macrophages that absorb foreign material. However, according to experts, what could happen is that the tattoo dye could mask the presence of melanoma, the most aggressive kind of skin cancer.


    Children are especially vulnerable
    Allergies and cancer occur mainly in tattooed adults, but what about children? Permanent tattoos are rare in children, but the henna tattoos offered on beaches and the tattoo stickers that come free with various snacks are popular among the younger population. Their safety is uncertain: although they have been approved, they are apparently not entirely risk-free.

    The tattoo stickers sold with food must pass health controls and the resins, polymers, coatings and inks used in these stickers have all been approved by authorities such as the US Food and Drug Administration (FDA). Their safety is therefore theoretically guaranteed.

    Regarding henna tattoos, however, a number of studies  have demonstrated reactions to the PPD in black and pre-mixed hennas, often used in children’s tattoos. Research by scientists at the Reina Sofía General University Hospital in Murcia (Spain) has pointed to the absence of legislation to regulate this kind of tattoo in Spain.
    The Spanish Medicines and Health Products Agency (AEMPS) has also issued an alert warning against the risks associated with the use of temporary black henna tattoos.


    Undoing the tattoo
    Growing numbers of people are deciding to remove permanent tattoos to avoid developing an allergy or because their tattoo is no longer fashionable. Laser technology developed in the cosmetic surgery sector eliminates 90%-95% of any design, although several sessions of treatment are necessary.

    The very short-pulsed laser light is selectively absorbed by the tattoo ink, which is broken it into small particles that are eliminated by the immune system. There are various types of lasers available, so anyone wishing to remove a tattoo should seek advice and consult an experienced specialist before undergoing the 'undo' procedure.


    Mathematical models to predict distortions
    Before removing the tattoo, it makes good sense to see how it may change in shape and colour over time. Professor Ian Eames of University College London has developed a mathematical model that simulates how a tattoo ages.
    This theoretical model forecasts long-term changes in dye particle movement in skin cells over a period of 20 years. Skin type, age, sun exposure, the type of pigment used and the kind of tattoo itself all have a bearing on image distortion. Larger tattoos and thicker lines age better, whereas finer lines and details will fade within ten years.



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