Most of us have contemplated getting a tattoo — from the design we want to the ink color — as a means to highlight our self-expression. The decision to ink ourselves is difficult, and riddled with potential tattoo regret. Although we might've weighed a tattoo's artistic and social merits, chances are we haven't given the health aspects much thought.

In the U.S., one in five adults have at least one tattoo, according to a Harris poll. Americans between the ages of 25 and 29 account for 30 percent of the tattooed population, while those aged 18 to 24 made up 22 percent. With such a large demographic getting tatted, especially a young population, there are many health risks to consider that can affect us into old age.

Before getting your next tattoo, keep the these questions in mind:

What's in a tattoo?

Each color and each brand of ink has completely different ingredients, so it’s impossible to know what’s in tattoo ink. A study published in the journal Nature found some inks have high levels of lead, as well as the presence of lithium. The blue inks had too much copper in them; they went right off the scale.

There’s still a lot to be learned about how these pigments interact with the body. Ink breakdown products may disperse throughout the body with unknown affects.

Is tattoo ink regulated?

Inks and ink pigments used for tattoos are subject to regulation by the FDA as cosmetics and color additives, but just barely. The FDA states because of “a previous lack of evidence of safety concerns, FDA has not traditionally regulated tattoo inks or the pigments used in them.” The agency has received reports of bad reactions to tattoo inks right after tattooing or even years later. Common side effects include itchy or inflamed skin around their tattoos in the summer when they’ve been out in the sun. Moreover, researchers found tattoos can actively remodel collagen, the body’s main connective tissue.

What pigments may cause abnormal skin reactions?

Chronic reactions tend to be more common among people with more colors in their tattoos. A study published in the journal Contact Dermatitis found 10 percent out of 300 people with tattoos developed abnormal reactions, including pain, itching, and infection that would warrant antibiotics. Six percent of those experienced symptoms for much longer, and were more likely to have shades of red in their tattoos.

Red pigments lead to delayed tattoo reactions. A separate study found interface dermatitis was the primary problem that led to an allergic response. Pink and purple colors were also commonly involved in reactions.

Does tattoo ink contain carcinogens?

Tattoo inks, specifically black pigments, have been found to contain nanoparticles that could be carcinogenic. These particles are small in size, which allows them to easily penetrate the skin and seep into underlying blood vessels and the bloodstream. Some nanoparticles may cause toxic effects in the brain and nerve damage, according to a study published in the British Journal of Dermatology. This suggests ink particles are leaving the surface of your skin and traveling throughout the body where they could enter organs and other tissues.

Does the tattoo place use an autoclave; individual packages; and single-use cups?

The tattoo parlor should have and use an autoclave — equipment that sterilizes the necessary tools. Without an autoclave, there should be no procedure, according to the University of Michigan Health Service. Needles and other sharps should only be used once and be opened from individual packages in front of you before beginning the procedure. Lastly, when it comes to ink, it should be in a single-use cup and then disposed. It should never be taken directly from the main source bottle or returned to that bottle.

Remember, think before you ink, for your health’s sake.