Tattoo Inks and Heavy Metals
The growing popularity that tattoos have gained in the world, makes us wonder what risks consumers are exposed to when putting a design on their skin.
What consumers of this type of art most often consider is the design to be created and who will be the artist that will make it. They rarely ask themselves how much it will hurt or what the possible risks of infection are if the tattoo is not applied in a safe environment and under the right hygiene conditions. But these are far from being the only health risks.
How is a tattoo applied?
When someone goes to a studio to get a tattoo, the selected artist uses a special machine with needles that inject small droplets of insoluble ink in the second layer of skin called dermis, using an up and down movement.
Once the ink is inserted into the dermis, not everything stays in the place of the tattoo, according to research. Some ink particles can migrate through the lymphatic system and bloodstream and are carried to the lymph nodes. Research in mice suggests that some ink particles may also end up in the liver. 
However, despite the growing popularity of the art, the toxicology of tattoos is still not well understood.
What risks are you exposed to when you get a tattoo?
Although tattoos are very common throughout the world, they pose certain risks to human health. Some of the risks associated with tattoos are very obvious.
The main and best-known risk is the exposure to bacterial or even viral infections due to poor hygiene conditions in the studio, bad management of material by the tattooist, or ink contamination.
Another known risk is the allergic reaction or sensitivity that some people may develop. Even if the person does not suffer any reaction with his first tattoo, it can happen with a later tattoo. This type of reaction, besides being annoying, is usually dangerous and you should go immediately to a specialist so that he can treat it.
Beyond the risk of injecting heavy metals into the skin through tattoo inks, getting a tattoo is a dangerous situation. If the sanitary conditions are not adequate and the instrument usedis not properly sterilized, you risk being exposed to hepatitis B or C, tuberculosis, syphilis, malaria, HIV or even leprosy.
Is ink the most dangerous factor to consider?
The manufacture of tattoo inks in the United States is supervised by the United States Food and Drug Administration (FDA), but as a cosmetic. As the FDA states, “due to other competing public health priorities and the lack of prior evidence of safety issues specifically associated with these pigments, the FDA has not traditionally exercised regulatory authority over color additives in pigments used in tattoo inks.” 
The ink used for tattoos is monitored by the FDA and other regulatory agencies such as the Environmental Protection Agency (EPA). In the year 2019, some batches of tattoo inks contaminated with bacteria harmful to human health were detected through FDA inspection of distributors and manufacturers of these products during fiscal year 2018-2019. 
Tattoo inks contaminated with microorganisms can cause infection and cause serious injury when injected into the skin during tattooing because the skin barrier is compromised. Symptoms commonly reported with infections associated with tattoo ink include the appearance of rashes or reddish-popular lesions where it has been applied.
In addition to bacterial contamination, there is another factor that is much more worrisome and very difficult to control. This is the presence of heavy metals in the components of the inks and the possible impact these may have on the human body.
What are heavy metals and how do they affect health?
Heavy metals are a group of chemical elements that have a high density. They are generally toxic to humans even in low concentrations.  Most heavy metals have a high atomic number, atomic weight and specific gravity above 5.0.
Some heavy metals are often used as dyes in tattoos. Examples include titanium and aluminum; and where non-metallic dyes are used, they may include traces of antimony, arsenic, beryllium, chromium, cobalt, lead, nickel, and selenium. 
Understanding exposure to lead and other metals once they are incorporated into a tattoo is not easy. A healed tattoo is a complicated set of ink particles trapped inside dermal fibroblasts, macrophages, and mast cells.
A 2005 study  on these inks explains that a wide range of elements are found in the tattooed human tissue, among them are sensitizers such as Nickel, Chromium, Manganese and Cobalt as part of the pigments that give them color. Besides Carbon Black, which is known to be a possible carcinogen for group 2B humans according to research by the IARC Monographs Working Group , the most common ingredient in tattoo inks is Titanium Dioxide (TiO2), a white pigment used to create certain shades when mixed with coloring elements. The toxicity of TiO2 depends on its crystal structure. Slow healing and itching is frequently associated with white tattoos, probably due to the presence of this compound.
Some studies have found that red tattoo ink often contains Azo dyes. Azo inks are organic compounds that are of great concern because of their potential toxicity and carcinogenic properties. Red ink appears to be related to chronic and allergic skin reactions caused by tattoos.
A study conducted in Iran, in 2014,looking at the heavy metal content of tattoo inks,  revealed that the type of pigment used in tattoo inks contributes to their heavy metal content. All tattoo ink samples used for this study contained detectable lead and cadmium contents. The cadmium content in all colors of the group in the Chinese and US branded samples was well above the limited maximum of 0.2 mg/kg set by the EPA and the highest was for the color white at 2.1473 mg/kg. The highest and lowest levels of lead were observed in black and white, respectively.
The white, yellow and orange samples showed the highest level of zinc content, while all samples had less zinc content compared to the maximum zinc concentrations of 50 mg/kg in the tattoo and permanent makeup substances given in the EPA guidelines in 2012.
Exposure of the body to these elements can have quite serious consequences. Sometimes they act as a pseudo element of the body, while at other times they can interfere with metabolic processes.
Lead, for example, causes toxicity in living cells by following ionic and oxidative stress mechanisms. Many researchers have shown that oxidative stress in living cells is caused by the imbalance between the production of free radicals and the generation of antioxidants to detoxify reactive intermediates or to repair the resulting damage. 
Mercury, on the other hand, is widely known to be a dangerous metal that can cause acute poisoning. The brain is the main organ that is affected by mercury exposure.However, other organs can also be damaged such as nerves, kidneys and muscles. Animals exposed to mercury show adverse neurological and behavioral changes. 
Another metal found in some tattoo inks is Cadmium. This element is very toxic and once it is absorbed by humans, it remains in the body for life. The mechanism of Cadmium toxicity is not clearly understood, but the effects on cells are quite remarkable. In the liver it can cause hepatotoxicity and it can also accumulate in the tissues of the kidneys causing nephrotoxicity, as well as it can cause iron deficiencies.
But this explanation of the effect of some heavy metals on the human body seems to take into consideration that the metals circulate freely in the body, and according to popular belief, the tattoo should remain unchanged over time, but is this really the case?
Does the ink stay in the area of the tattoo?
As published by the LiveScience portal, most tattoo pigments remain after a person gets a tattoo. Ink that is not removed by macrophages remains in the dermisor in skin cells called fibroblasts.
However, researchers are now looking more closely at tattoo ink that travels to other parts of the body, especially the lymph nodes.
Much remains to be learned about how pigments interact with the metabolism of the human body. For example, studies by the National Center for Toxicological Research  report that yellow ink is broken down by enzymes and metabolized by the body. This pigment is also broken down by sunlight and often becomes colorless. However, chemically altered traces of these pigments remain in the skin layer, and it is not yet known whether they are toxic or not, but it is known that small amounts of ink particles always pass into the lymphatic system and accumulate in the lymph nodes.
In addition, tattoos can make difficult to diagnose skin cancer or can cause false identifications of cancer in the lymph nodes. 
Toxicology of Tattoo Ink and Cancer
Tattoo-related complications began to be reported in the late 19th century. Specifically, the occurrence of skin cancers is of concern due to the possible introduction of carcinogenic, pro-carcinogenic, and toxic compounds into the skin.
In France, recent legislation requires manufacturers to provide the exact composition of inks, and in Germany, the use of Azo pigments that can be broken down into aromatic amines is illegal.
Control and regulation remains difficult because most inks are purchased abroad via the Internet or during tattooing conventions. Tattoo dyes include pigments, which can be inorganic metal salts or different types of organic molecules, and organic dyes. And the allergenic metals known as chromium, nickel and cobalt have been found to exceed safe allergen limits.
The tattoo inks analyzed in a study published in 2012 by the Lancet Oncology Journal were composed of several metallic salts, some found in high concentrations and others in low or trace concentrations. The traditional classification based on the rule that a color is equal to a metallic salt (i.e. red = mercury, blue = cobalt, green = chrome, purple = magnesium, etc.), which is still mentioned in some textbooks and reviews, is too restrictive and definitely outdated. European market studies have shown that most of the tattoo compounds currently available on the market are Azo pigments or polycyclic compounds, some of which are carcinogenic (anisidine, nitro-o-toluidine, chloro-o-o-toluidine and 3,3 -dichlorobenzidine).
So far, tattoo pigments have not been evaluated by the International Agency for Research on Cancer as tattoo dyes, although some components of tattoo inks have been classified. Mercury, cobalt sulfate, other soluble cobalt salts, and carbon black are classified as Group 2B (possibly carcinogenic to humans), while cadmium and cadmium compounds are in Group 1 (carcinogenic to humans). By-products, some of which are absent from the initial ink, may appear after ultraviolet or laser exposures.
Knowledge of the toxicology of tattoo inks has been improved by several groups who have studied the potential health risk of tattoo inks by analyzing the composition and by-products of tattoo inks in various in vitro circumstances.
So, it’s really a matter of smart choices. Getting one or many tattoos will always be a personal decision, and should not be taken lightly. It is necessary to be informed about the risks we are taking in order to evaluate the best options and thus lead the long and happy life we want with our families.
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