Can tattoos damage health? This was the question tackled by a Swedish study conducted by researchers at Lund University and published in the European Journal of Epidemiology. They investigated the link between tattoo exposure and the risk of developing cutaneous melanoma, one of the more aggressive skin tumours.
Over the past 30 years, the number of cutaneous melanomas has increased, especially those caused by exposure to ultraviolet radiation. It is believed, however, that certain chemicals - such as polycyclic aromatic hydrocarbons - can also contribute to the development of the disease.
At the same time, tattoos have become more common in recent years, and the choice to have at least one is today very widespread, especially among young people. In Sweden, about one adult in five is tattooed, and the percentage is even higher among the under 40s.
These two factors have led to research into the possible health impact over time associated with tattoos.
Cutaneous melanoma is a tumour that originates in the melanocytes, cells that produce melanin, the pigment responsible for the colour of the skin. Although it accounts for a relatively small proportion of skin tumours, it is considered one of the more aggressive types owing to its ability to spread to other organs.
Melanoma develops when the melanocytes accumulate genetic changes that modify their behaviour, leading them to spread uncontrollably. Risk factors include exposure to ultraviolet rays, sunburn, the use of sunlamps and family and genetic predisposition, all of which can contribute to an increased risk of developing the condition (Slominski, R. M et al. 2024).
The theory that tattoos may have a biological impact is based on already well-established findings. The inks used in tattoos can contain blends of chemicals, including heavy metals, polycyclic aromatic hydrocarbons and aromatic amines, some of which are believed to be carcinogenic. Once
injected, a portion of the pigments can migrate to the lymph nodes; it's not yet clear for how long and to what extent certain substances can spread through the body.
The cutaneous trauma associated with tattoos, the scarring processes and the interaction with sunlight are also some of the possible mechanisms discussed by the researchers.
To compare the risk of melanoma in people with tattoos and in those without, the authors of the study compared about 1,600 people with melanoma, or precancerous lesions, with over 4,000 people from the general population, selected by age and gender. Information was collected from all subjects on their tattoos, if any, and on factors that increase the risk of tumours, such as sunburn, sun exposure, sunlamps, smoking, and type of skin.
Results suggest that people with tattoos showed a 29% greater risk of melanoma, compared to those without tattoos. The greatest risk was observed in those tattooed 10-15 years prior to the study: according to the authors of the study, this could indicate that the length of exposure to a tattoo could be a factor, but requires corroboration.
It seems the risk does not depend on tattoo size: the probability of disease is no greater for those with larger tattoos. In only 30% of those examined was the tattooed area of the skin affected by the onset of melanoma. On the other hand, the estimated risk was higher for tattoos with mixed black/grey and coloured pigments.
An interesting aspect concerned the fact that tattooed individuals with greater UV exposure did not show an increased risk of melanoma. The accelerated breaking down of pigments caused by sun rays doesn't appear to increase the risk of melanoma, beyond that associated with the tattoo itself.
To conclude, the study does not show that tattoos cause melanoma, but that they could be a risk factor for its development. It has also contributed to an ongoing area of research, given that precise EU regulations on pigment ingredients were only introduced in 2022.
It is not yet clear for how long the ingredients in the ink may circulate around the body, and the way these substances behave once injected is an area that has been little studied. Such substances could act locally on the immune system, at the site of the tattoo and in the nearby lymph nodes, with potentially wider consequences. Broader research with longer observation periods will thus be needed to better understand how ink behaves in the body and any role it has as a risk for melanoma.