8 hours ago
Do Tattoos Pose a Cancer Risk?
Over recent decades, tattoos have rapidly gained in popularity, with a Narrative Research survey in 2024 showing that 31% of the adult Canadian population has tattoos. Moreover, women are much more inclined to get a tattoo, including permanent makeup, than men (38% vs 28%). In Canada, the US, and Europe, a patient must be about 18 to start accumulating tattoos.
Stephen A. Hoption Cann, PhD
As tattoos grow in popularity, patients increasingly seek advice from general practitioners and dermatologists about potential health risks. While adverse effects such as infections and allergic reactions are well-documented, the longer-term health implications of tattoos, particularly cancer risks, have only recently begun to receive more attention. Although this commentary centers on Canada, its implications extend globally. Let's explore the key concerns tattoos present in terms of cancer risks and how clinicians should approach them.
A patient may wonder whether injecting all manner of inks into the dermal layers of their skin poses any long-term risks. One might assume, wrongly, that since tattoos have been around for a very long time that cancer risks would have been exhaustively investigated. While there have been many case reports noting the occurrence of various types of cancerous lesions within tattoos, they do not tell us whether this association is causal or coincidental. Epidemiological studies exploring this question are few.
On the surface, it seems like an easy question to explore: Just compare cancer risk in those with tattoos to those without. However, one must remember that there are hundreds of brands and thousands of colors of ink on the market — and individual tattoos often contain many colors. Then there is the question of tattoo size. Moreover, if people stopped at one tattoo, that would make it much easier for epidemiologists; however, individuals who were happy with their first tattoo may go on to get many more over subsequent years, adding complexity to the calculation of an individual's overall exposure risk. Then there are the many confounding factors such as smoking, alcohol, socioeconomic status, etc, which must be accounted for.
Before we get into the epidemiological studies, we might want to know how tattoo inks are regulated. Health Canada has created a list of restricted or prohibited ingredients of tattoo inks. This list includes substances that are considered mutagenic, carcinogenic, toxic to reproduction, skin sensitizers, and irritants. The regulator also samples and tests tattoo inks to check for microbial contamination, heavy metals, and labeling accuracy. The European Union has taken a similar approach, but the FDA does not approve tattoo inks. Its regulation is mostly passive (eg, investigating safety concerns when adverse reactions are reported).
So, what can be found in these tattoo inks? Nonorganic inks can contain a virtual smorgasbord of metals, including barium, cadmium, chromium, cobalt, iron, nickel, lead, titanium, and mercury, though the latter largely has been phased out due to toxicity concerns. Some nonorganic inks contain acrylics or synthetic pigments. All these substances aid in long-term color retention. In contrast, organic inks are often made from plant-based or carbon-based pigments but tend to fade faster as they lack the metallic or synthetic stabilizers found in nonorganic inks. While the FDA requires accurate labeling of these products, a recent US study found that 83% of tattoo inks tested (45 of 54) had major label discrepancies — not that clients getting a tattoo would even read the label.
Many of the metals used are known carcinogens (eg, cadmium, chromium, lead, mercury, and nickel) or possible carcinogens (eg, cobalt and titanium), depending on the chemical species. Additionally, some of the pigments used, such as azo dyes, can decompose into carcinogenic aromatic amines. Other harmful substances in inks include polycyclic aromatic hydrocarbons, which have been proven to be carcinogenic to animals and humans.
What about cancer risks? Most studies to date have examined lymphomas, as it has been demonstrated in animal and human studies that most of the pigment from tattoos will be transported to regional lymph nodes. In this mostly final resting place, it could cause chronic inflammation and carcinogenic processes over time. A couple of case-control studies have found a significant increase in lymphoma risk in tattooed subjects relative to comparison groups (see Table). A well-designed twin study noted a higher risk, particularly for large tattoos (ie, bigger than the palm of the hand, which may not seem so large today). While another study from Sweden noted an elevated risk for lymphoma and lymphoma subtypes, no finding was significant. In contrast, a Canadian study found no trend for non-Hodgkin lymphoma, although tattoos were uncommon (around 5%) in the population studied.
Several studies have examined risks for various types of skin cancer. A study on cosmetic tattoos showed a nonsignificant elevated risk for basal cell carcinoma. Clemmensen et al, who conducted a case-control and a cohort study, showed significantly elevated risk for skin cancer associated with large tattoos in the former study and elevated risks for skin cancer and basal cell carcinoma in the latter study. In contrast, a recent study by Liljedahl et al found no evidence of risk for cutaneous squamous cell carcinoma. Aside from lymphomas, a few other hematologic cancers have been studied, but nothing significant has been found.
Table: Research into tattoos and cancer risk.
Download Table as PDF
Ultimately, many uncertainties about cancer risks remain, and thus it is not surprising that some larger cohort studies have been established to answer these questions. A couple of examples include Tattoo inK, a cohort study of about 18,000 tattooed individuals and 160,000 untattooed controls within the German National Cohort, and Cancer Risk Attributable to the Body Art of Tattooing, a cohort study of about 13,000 tattooed individuals and 100,000 untattooed controls, which is integrated into the French Consultants des Centres d'Examens de Santé (Constances) cohort. While these are ample cohorts, one may have to wait one or more decades for findings to accrue.
A patient who smokes or drinks can quit to reduce his or her cancer risk. But what about a patient with a tattoo? The most common removal technique is laser therapy, which uses high-intensity light pulses to break down tattoo ink particles. Can this process remove the potentially hazardous particles? Well, not exactly, as these fragments end up being funneled into the draining lymph nodes. Sending more pigment into this region could increase risk, but we don't know for sure. Dermabrasion, chemical peels, or surgical removal can remove the ink but can also produce significantly more scarring and thus are usually reserved for smaller tattoos.
So, you have a patient with a new tattoo who is eager to hit the beach to show it off. What do you tell them? First, they should be warned that sun exposure will accelerate fading. And those degraded pigments don't just disappear, they release potentially harmful substances into the body. There is also a possible increased risk for skin cancer, so they're better off displaying their tattoos indoors or using sun-protective clothing or sunscreen. Beyond skin issues, tattoos may also increase the risk of lymphomas, but we do not know this for sure. Nor do we know much about risks for other types of cancer. Finally, tattoo removal is not the quick fix that works for other risky habits. Thus, for the patient considering their first tattoo, or more tattoos, one might say that if they can hold off for just another 10 to 20 years, we should be able to give a more definitive answer. Alternatively, given the current evidence, it would be premature to assure patients that tattoos are entirely risk-free.
