If your mother needs yet another reason to be horrified that you have a tattoo – or a few – here’s a big one: a new study links tattoos to lymphatic cancer.

The study found people with tattoos were 21% more likely to get lymphoma. But the number of tattoos or the amount of the body covered by tattoos did not seem to affect lymphoma risk.

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Lymphatic cancer is cancer of the cells of the lymphatic system, which is part of the body’s immune system that helps fight germs and disease. There are two types: non-Hodgkin lymphoma, which accounts for about 90% of all lymphoma cases, and Hodgkin lymphoma.

Previous research has shown that when tattoo ink is injected into the skin, it activates the immune system, and ink particles travel away from the skin into the lymph nodes.

Last year, a Pew Research survey found that 32% of Americans have tattoos, with 22% having more than one.

The new research about tattoos and lymphoma, out of Lund University in Sweden, included 11,905 people. Nearly 3,000 of them had lymphoma between ages 20-60. Of them, 54% answered a questionnaire about tattoos, while 47% of participants in the group without lymphoma also responded. In the group with lymphoma, 21% were tattooed, compared to 18% who were tattooed in the group without a lymphoma diagnosis.

“People will likely want to 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,” lead researcher Christel Nielsen said in a statement. “For the individual, it is good to know that tattoos can affect your health, and that you should turn to your health care provider if you experience symptoms that you believe could be related to your tattoo.”

According to the Mayo Clinic, lymphoma symptoms include:

• Fever
• Night sweats
• Fatigue
• Itchy skin
• Painless swelling of lymph nodes in the belly, neck, armpits or groin
• Pain in the chest, abdomen or bones
• Losing weight without trying

The study results were published in the medical journal eClinicalMedicine. More research is needed to learn if there is any link between tattoos and other types of cancer, the researchers said.