A new study by Swedish researchers found that tattoos can increase your risk of lymphoma by 21%. Lymphoma is term for a group of blood cancers that begin in the lymphatic system.  

According to Metro News, the scientists from Lund University said that further studies need to be done to verify their results and determine how tattoos can trigger this form of cancer. Out of 11,905 people ages 20 to 60 in the study, 2,938 were diagnosed with lymphoma. Study participants answered questionnaires and after adjusting for age and smoking factors, the researchers determined that the risk for developing lymphoma was 21% higher for those who had tattoos.

The risk associated with tattoos was mostly noted in diffuse large B-cell lymphoma, which is a fast-growing, curable form of cancer and follicular lymphoma, a slow-growing, incurable cancer, says the New York Post. While no specific cause-and-effect was determined, Christel Nielsen, the lead author of the study, speculated that tattoos cause inflammation that could lead to cancer.

“One can only speculate that when the tattoo ink is injected into the skin, the body interprets this as something foreign that should not be there and the immune system is activated,” she said in a statement. “A large part of the ink is transported away from the skin to the lymph nodes where it is deposited.”

A study presented to the American Association for Cancer Research last year said there was a “potential association” between having “several large tattoos” and the risk of blood cancers. The risk increased when people were tattooed at a very young age.

The Pew Research Center says that 32% of Americans have a tattoo, including 22% who have more than one. Surprisingly, 38% of women have at least one tattoo, compared to 27% of men. This includes 56% of women ages 18 to 29 and 53% of women ages 30 to 49.  The majority of those surveyed said they had tattoos inked to commemorate a person or an event. While most people with tattoos said they don’t regret getting them, 24% reported regretting their decision.

The Swedish researchers assert that further investigation is needed to clarify the association between tattoos and other types of cancer.

“People will likely continue to express their identity through tattoos, and therefore it is very important that we as a society can make sure that it is safe,” said Nielsen. “For the individual, it is good to know that tattoos can affect your health and that you should turn to your healthcare provider if you experience symptoms that you believe could be related to your tattoo.”