The Science Behind Tattoos: Why They Are Permanent and The Difficulties of Removal


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The skin is one of the largest organs of the body. It is a magnificent thing as not only does our skin self-renew throughout our life, it also protects us from invading pathogens and acts as our first line of defense. Some choose to decorate theirs with tattoos, a tradition that is predicted to date back thousands of years as Otzi the 5300-year-old ice man has been found to have 61 tattoos. Marking the body in a permanent way has been associated with the expression of spirituality among many different cultures and has also been affiliated with gang members. Nowadays it’s not uncommon to see someone sporting some ink and cosmetic tattoos are a routine procedure such as replacing eyebrows and are even offered to patients who have undergone a breast reconstruction in order to recreate the appearance of their nipple!

In the past people would often use any object they could find that could penetrate the skin and deposit the ink, whereas modern tattooing is based on Thomas Edison’s automatic engraving machine, which basically inserts tiny dye-filled needles into the skin at a frequency between 50-3000 times per minute. So there really is no wonder that having tattoo isn’t always the most pleasant of experiences.

We are always reminded by those that disapprove of our body art that ‘you’ll regret it when you’re older’ and whilst that may be true for some, it’s likely that due to the permanent nature of tattoos that we’re going to have some pretty badass-looking OAPs in the future.

So what is it about the tattooing process that makes them stand their ground?

The key to this is the layer in which the ink is inserted. The skin is composed of many layers and rather than injecting the ink into the outermost self-renewing epidermis that is often shed, it is instead injected into the deeper dermis. The dermis is comprised of a number of structures including cells of the immune system known as macrophages.

Tattooing literally involves the repeated breaking of the skin and the creation of multiple wounds, which trigger an inflammatory response, recruiting these macrophages to the site of damage where they essentially ‘eat’ some of the damaged material, some of which contains the ink. Some of the cells carry the ink to the lymph nodes where they are degraded, whereas the more greedy cells quite happily reside in the dermis, displaying their newfound pigment. As with many cells of the body these macrophages don’t live forever and are replaced by younger cells, which in turn ‘eat’ them up and now show off their new ink, hence why tattoos stick around for a very long time. The ink will fade with time as new batches of cells take over the positions of those previous and dilute the vibrancy of the colour and UV light can also contribute to this breakdown of pigment.

So now we have this amazing new ink. Fab. But what happens when we realize that Google Translate didn’t do such a great job on that Kanji symbol that was meant to say ‘creativity’ but actually spells ‘calamity’?

The most commonly used method of removal is done so by a laser, which penetrates the epidermis and breaks apart the ink into smaller particles, making them easier for macrophages to take up. The efficiency of removal depends on the wavelength of light used, with black being the easiest colour to remove. Every colour requires a different wavelength of light and complications may arise as there are around 100 different inks currently in use and the person removing your tattoo may not necessarily know the exact colour of the ink used.

The second is dermabrasion, which is used for a variety of skin conditions including the removal of scars and involves scraping the top two layers of skin off using a high-speed brush or a diamond wheel with rough edges. Whilst this process does work quite well, it comes with a recovery time of up to 12 weeks.

Surgically removing the skin containing the tattoo is another more gruesome method of tattoo removal and one that will likely lead to scarring.

Interestingly a Canadian PhD student has formulated a cream that removes tattoos whilst apparently avoiding damage to the skin. The cream targets the macrophages by stimulating new ones to arrive at the site of application to engulf those containing the ink so that the tattoo gradually gets eaten away. At present this isn’t available for human use and has only been tested on pigs’ ears, but it is a potential method of removal for those of us who regret our ink.

The bottom line is that a tattoo is for life and removing it is often more painful than getting it in the first place. Current methods of removal aren’t 100% efficient at getting rid of the tattoo completely, therefore if you’re going to go under the needle, make sure that you’re completely happy with your design. Considering that we shed anything up to a million skin cells each day, it’s amazing that such images can be carried within our skin for a lifetime. Respect your tattoo and respect your skin, because the relationship with your tattoo will probably last longer than your love affair with tribal.

#LaurenNuttall #Biology #Tattoos

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