We see them everywhere in popular culture: actors, professional athletes, and rock stars adorned with tattoos on their arms and other assorted body parts, sometimes to the point where you cannot see any natural skin.

While style trends continually change over time, some have more lasting consequences than others — a fact that applies to tattoos. Not only can they mark the skin permanently (even painful removal is not complete) but now medical research has determined that getting tattoos can lead to disease.

In fact, a new study has determined that people with multiple tattoos that cover much of their skin run a higher risk for contracting blood-borne diseases, including hepatitis C. The reason for this is because tattooing involves a needle puncturing the skin upwards of 80 to 150 times per second to inject the tattoo ink. This results in exposure to blood and bodily fluids, whereby infectious agents can be transmitted from one person to the next if the instruments are not properly cleaned between uses.

Also, the dyes that are used are not always stored in sterile containers and may harbor infectious agents. They may contain such undesirable ingredients as house paint, printer ink, or industrial carbon. By entering the body through the skin, these chemicals might then travel through the blood to such vital organs as the kidneys, lungs, and lymph nodes. One growing trend is the use of glow-in-the-dark ink to make tattoos, the health consequences of which are unknown.

In the study in question, published in the International Journal of Infectious Diseases, researchers looked at data from 124 studies that covered 30 countries. What they found was a direct link between the number of tattoos a person has and the incidence of hepatitis C.

Other problems that may arise include possible HIV exposure, allergic reactions, and bacterial and fungal infections. Finally, tattoo removal also presented its own potential complications.

The news is particularly relevant in light of the fact tattoos that are very popular today, especially among younger people. It has been estimated that 36 percent of the U.S. population under the age of 30 has a tattoo, and the increasing social acceptance of them may have a profound influence over whether that number increases with time.

For now, the authors of the study indicate that the findings support the establishment of public health guidelines regarding tattoo artists and their machinery and supplies. This could be accomplished through regulatory inspections and proper record keeping. Greater education and awareness of the potential health hazards of tattoos to the general public, especially younger clientele, may be warranted as well.