Modern tattooing inks are carbon based pigments that have uses outside of commercial tattoo applications. Although the United States Food and Drug Administration technically requires premarket approval of pigments it has not actually approved the use of any ink or pigments for tattooing (because of a lack of resources for such relatively minor responsibilities).[citation needed] As of 2004 the FDA does perform studies to determine if the contents are possibly dangerous, and follow up with legal action if they find them to have disallowed contents, including traces of heavy metals (such as iron oxide) or other carcinogenic materials (see CA lawsuit). The first known study to characterize the composition of these pigments was started in 2005 at Northern Arizona University (Finley-Jones and Wagner). The FDA expects local authorities to legislate and test tattoo pigments and inks made for the use of permanent cosmetics. In California, the state prohibits certain ingredients and pursues companies who fail to notify the consumer of the contents of tattoo pigments. Recently, the state of California sued nine pigment and ink manufacturers, requiring them to more adequately label their products.
Acrylonitrile butadiene styrene (ABS plastic) ground down to an average diameter of slightly less than 1 micrometer is used as the colorant in the brighter tattoo pigments. The tattoo pigments that use ABS result in very vivid tattoos. Many popular brands of tattoo pigment contain ABS as a colorant. ABS colorants produce extremely vivid tattoos that are less likely to fade or blur than the traditional pigments, but ABS tattoo pigment is also harder to remove because it is so much less reactive to lasers.
There has been concern expressed about the interaction between magnetic resonance imaging (MRI) procedures and tattoo pigments, some of which contain trace metals. Allegedly, the magnetic fields produced by MRI machines could interact with these metal particles, potentially causing burns or distortions in the image. The television show MythBusters tested the hypothesis, and found no interaction between tattoo inks and MRI.
Professional tattoists rely primarily on the same pigment base found in cosmetics. Amateurs will often use drawing inks such as low grade India ink, but these inks often contain impurities and toxins which can lead to illness or infection. Although "greywork" is often done with a better quality pelikan #17 or Talens drawing ink mixed with a darker lining ink to optain a softer grey.