Three in 10 Americans have at least one tattoo, according to a 2016 Harris Poll, and of these, 69 percent have two or more tattoos. Rather than being the stuff of drunken sailors and lovesick men far from home, tattoos are now commonplace. Still, they may not be safe. The ink used in tattoos and permanent makeup may be harmful--even years later, reports WebMD of a study conducted by the European Commission's Joint Research Centre.

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The ink that was studied was imported from the United States, so this isn't just a European problem. The commission found that the tattoo inks contained hazardous chemicals, including carcinogens. In addition heavy metals were found in the inks--arsenic, lead, nickel, preservatives, organic compounds and bacteria.

These substances can cause cancer, genetic mutations and allergies, as well as have toxic effects on reproduction, according the European Chemicals Agency.

What about the United States? The U.S. Food and Drug Administration has also raised concerns about tattoo ink. Specifically, it has warned about the following:

• Allergic reactions.

• Itchiness and inflammation when exposed to summer sunlight.

• Granulomas, or small knots or bumps that form around areas where the body senses foreign material, such as the pigments in tattoo ink.

• The spread of tattoo ink to the body's lymphatic system. It's unknown whether this has health consequences.

Perhaps even more important, the FDA admits it knows little about the tattoo inks that are currently used in the United States. Why? While tattoo inks are classified as cosmetics and their color additives are subject to regulatory authority, the FDA has not been using that authority to monitor tattoo inks due to other, more pressing public health priorities.

The takeaway: There is minimal regulation of tattoo inks in the United States. As a consumer, you can't even discern if the bottle of ink is sterile. (In the European study as many as 10 percent of the bottles contained bacteria.) In addition, new organic inks are being used that have never been tested and have a far higher risk of complications, reports WebMD. And while there is no established link between tattoo inks and cancer, there is concern because the ingredients may contain carcinogens.

You won't believe who has a tattoo--and what it says about them!