The Science Behind Tattoos and Tattoo Removals

By: Nicole Soussana  |  March 22, 2020
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By Nicole Soussana, Staff Writer

As part of a Jewish institution, there is an obvious possibility for interesting and stimulating discussions involving the halachic ramifications of tattoos. However, a scientific discussion of tattoos can be equally as engaging. 

Our bodies have a built-in system designed to destroy foreign objects that find their way inside. This is the immune system which helps in tremendous ways, such as fighting against diseases and infections. Macrophages are the fighter cells of our immune system. If we consider tattoo ink to be a foreign object introduced into our bodies, why does it stay in place and why wouldn’t our immune system get rid of it? 

The process of receiving a tattoo includes piercing ink deep into the skin; specifically, ink is inserted into the dermis layer, below the epidermis. The ink doesn’t stay there on its own. According to a study published in the Journal of Experimental Medicine in 2018, macrophages attack the tattoo ink and maintain the ink in their cellular membranes, which become colored as a result. In their attempt to destroy the ink, our macrophages actually maintain their pigment.

As we know, cells die eventually. So what happens when these macrophages die? Does the ink disappear? We know that the ink doesn’t disappear because we see people every day with tattoos which last permanently. When the macrophage dies, it leaves behind ink which is absorbed by a new macrophage, creating an endless cycle of preservation. 

In an experiment involving mice, results displayed that macrophages indeed have the capacity to “swallow” dark pigments. Through additional experimentation, the scientists killed these macrophages to test whether the tattoo remained. It turns out that the tattoos remained, providing proof for this cycle of macrophage absorption. 

An earlier theory of how tattoo ink remains in our dermis seems to be nearly the opposite of the above discussion. These earlier articles claim that macrophages aren’t big enough to destroy all of the ink, and therefore the remaining ink stains the skin cells permanently. This means that only the ink which is not consumed by a macrophage results in permanent coloring of the skin, rather than the macrophages themselves lending to pigmentation. Our epidermis can shed 40,000 skin cells per hour, so stained skin cells in the dermis can remain that way almost permanently. During a tattoo removal, ink pigments are broken up with a laser, which allows for new macrophages to destroy the remaining ink.

According to a more recent article, tattoo removal destroys macrophages carrying the ink into smaller bits. Our lymphatic system, also part of the immune system, then drains the ink. Some tattoo removals require many sessions or may only result in fading, and this is explained by the constant attack from successive macrophages. If all macrophages in the area can be removed, the process could theoretically be easier. 

While the knowledge of how tattoos really function may not affect daily life in a practical way, it is interesting to know how an ancient practice plays out scientifically. Additionally, it’s surprising to note how rapidly science can change its view on a given topic. Who knows what future experimentation can explain.

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