Humans have marked their bodies with tattoos for millennia. These designs have always been personal and functioned as amulets, status symbols, declarations of love, signs of religious beliefs, and adornment. Often their uses extended beyond the decorative and were utilized as a form of therapy or even punishment.1
“Otzi the Iceman,” discovered on the Italian-Austrian border in 1991, became the earliest known example in terms of tattoos on the actual body; he was carbon-dated at around 5,200 years old. His body was found to harbor 57 tattooed dots and small crosses on his lower spine, right knee, and ankle joints, likely suggestive of his tattoos holding therapeutic significance.2 Ancient Egyptian women had tattoos on their bodies and limbs and were present on several female mummies dating back to c2000 bc. Numerous figurines depicting tattooing on their bodies have also been discovered from up to c4000 to 3500 bc, many with tattoos on their thighs.3 Crude needles and pigmented bowls used in early tattooing have also been found in Egypt, France, Spain, and Portugal.3,4
In the late 1800, the invention of the electric tattooing machine revolutionized the art of tattooing.1 This advance brought tattooing into the mainstream culture in many countries. In the United States, it is estimated that up to one-quarter of young to middle-aged adults have at least one tattoo.5,6 However, despite the popularity of tattooing in the United States, it is still poorly regulated.
Tattoos result from the exogenous deposition of micron-sized ink or other pigment-containing particles into the dermis, deliberately or as result of trauma. Instruction on how to administer a tattoo were published as early as 6th century, in a book entitled “Medicae Artis Principes,” written by the Greek Physician Aetius.7 Tattoos can be classified as decorative, cosmetic, medical, traumatic, and iatrogenic.
DECORATIVE TATTOOS: Decorative tattoos are most common and are further subdivided into professional and amateur. Professional tattoos are typically placed more deeply in the dermis by the vibrating needle of a tattoo machine, along with a greater density of pigment. Professional tattoo pigments are mostly dyes used in chemical industry, which incorporate different kinds of organic and inorganic pigments. Inorganic pigments may be composed of cadmium, chromium, mercury, iron, titanium, aluminum, silica, copper, bromine, sulfur, carbon, and magnesium.8 The number of organic materials used is even more impressive, with most classified as either azo or non-azo, or polycyclic compounds.9 One study10 has shown photodecomposition of two widely used azo-containing tattoo pigments into known carcinogenic and cytotoxic products.
Amateur tattoos are often homemade carbon-rich mixtures that are often mixed with chipped automobile paints or other industrial sources to boost the color. Both professional and amateur tattoo pigments are composed of non-homogeneous granules size as well of unknown purity and composition.