Tattoo removal breaks apart ink particles

The body can remove tattoos after they are broken down by laser

Tattoos place blobs of ink below the surface layers of the skin in packets too large for white blood cells to clear out. By breaking the ink into smaller pieces, they can be processed by the immune system, which is responsible for removing foreign matter.

Removal of different color tattoo inks may require multiple lasers

Light needs to be absorbed by ink particles to break them down into small enough pieces for the immune system to eliminate. Color ink reflects, rather than absorbs, lasers of the same color, while black ink absorbs all colored lasers.

Tattoos remain visible thanks to immune cells called macrophages

Macrophages are a robust part of the human immune system. These large cells engulf invading particles, like viruses and bacteria, and use enzymes to break them apart. They perceive ink as a foreign body but can't digest them. Macrophages hold on to the ink, helping maintain the tattoo pattern.

Tattoos remain visible on your skin thanks to immune cells called macrophages

The immune system fights tattoos

Our skin is a fascinating organ that wants nothing more than to protect our bodies from the outside world. Tattoos penetrate that protective wall to inject ink directly into the sensitive, immunologically rich layer of skin known as the dermis.

Tattoos, explained

Tattoos last because immune cells trap ink beneath the skin—but there's more to the story. This overview looks at how ancient cultures used tattoos for status, spirituality and punishment; how technology like the electric tattoo machine transformed the art form, and where innovations like smart tattoos could take it next.

Tattoos are made by injecting pigments into the skin

Tattoo ink is injected under the skin, which can leave the body open to infections and allergic reactions. While many tattoo artists are licensed professionals who follow sanitary guidelines, that’s not always the case.

Laser procedures have made tattoo removal much more common

An increasing number of Americans, including high-profile celebrities, get tattoos removed because laser removal has become more advanced and cost-effective. The tattoo industry is adjusting to this mainstream trend.

'Magic ink' is redefining the tattoo

One University of Colorado professor has developed an ink that can be "turned on" with exposure to UV light, and "turned off" with sunlight. While the ink could help those who want to hide their body art from family members or coworkers, there are potential uses for medical procedures.

Laser skin treatments can promote the production of collagen

Skin resurfacing vaporizes the top layer of skin to reveal healthier, new skin, while collagen can give the skin structure and elasticity. Such procedures treat scars and burns, but may leave light spots on the skin.

Red blood, skin, hair, and nail cells destroy their DNA upon maturing

To maximize the amount of oxygen they carry and more easily alter their shape to fit into narrow blood capillaries, red blood cells destroy their own nuclei. Cornified cells found in hair, nails, and the outermost layer of skin destroy their nuclei and other cellular contents to make room for keratin, which provides durability and structural support.

We're breathing microplastics

White blood cells can't fight off microplastics and that sparks inflammation and bigger health risks. They're in our food, water, even the rain. What does that mean for us?

Photolithography etches circuit components into a semiconductor wafer

A high-energy laser is fired at molten tin droplets, turning them into plasma that releases the ultraviolet light needed to burn the wafer's photoresist layer. A mask controls what parts of the wafer are etched for subsequent chemical processing.

Watch how to safely remove water from your ears

Do not stick a Q-tip into the ear canal—it can cause microtears of the delicate skin there and elevate infection risks. Instead, try tapping on the side of your tilted head after swimming to break the surface tension so water will drip out, or pulling your earlobe in different directions while the ear is pointed downwards. Another suggested approach is to place a few droplets of isopropyl alcohol or over-the-counter eardrops inside the ear to speed evaporation. If those approaches don't work, consider contacting your physician.

How fighter jet ejections work

One of the most complex pieces of equipment in a fighter jet is the pilot's ejection apparatus, and the process of ejecting is far more challenging and violent than its depicted in film. This six-minute video breaks down the protocol step-by-step.

Firework or sparkler burns, even if they cover a relatively small area of skin, can significantly affect our range of motion.

How one autoimmune disease patient is questing for inflammation cures

This article's writer, who has Hashimoto's Disease and characteristic symptoms from her body attacking her thyroid—like exhaustion, hair loss, and brain fog—shares big take-aways from an anti-inflammatory retreat in Italy. The writer suggests that a holistic approach to eating, sleeping, and stress management, are the only sustainable ways to lower inflammation.

Ebola infects and disables immune cells, triggering a cascade of events that leads to small blood clots throughout the body, weakening blood vessels and interrupting blood flow to key organs.

See how the Ebola virus affects blood circulation in the human body

Ebola infects and disables immune cells, causing a cascade of events that result in small blood clots throughout the body, weakening blood vessels, and interrupting blood flow to key organs.

How trauma gets ‘under the skin’

A study examining the muscle function of older adults who have at least one adverse childhood experience (ACE) suggests that trauma digs itself into muscle cells. Participants who reported childhood trauma were found to have lower maximum levels of cellular energy than people who reported fewer or no ACEs. Such compromised mitochondrial function "doesn't bode well," as it relates to a variety of health and age-related outcomes.

Breaking down various tongue disorders, from infections to genetics

Taste is one of our fundamental senses, but can be impeded by a wide variety of conditions including glossitis, angioedema, and black hairy tongue. Most are characterized by their color, shape, and sometimes change in function. Causes range from vitamin or mineral deficiencies to fluid accumulation, fungal infection, or more.

Volcanic ash is composed of fragments of volcanic rock, minerals, and glass

These abrasive particles are hazardous to aircraft. They can melt within engines and re-solidify on turbine blades, preventing forward propulsion. If inhaled, chemicals within ash can be toxic, and the particles can embed themselves into the lungs' ducts, causing suffocation.

The artwork at Burning Man is impressive and transient

Huge sculptures, mutant vehicles, concert stages, the Man, and other spectacles created at Burning Man each year are often destroyed by the end of the event. If they aren't burned, they'll often be repurposed or trashed.

Tokenization breaks text into pieces that LLMs use to process language

Instead of understanding the meaning of words, large language models break up sentences into words and subwords, assigning each a set of numbers called tokens. Grammar rules are then "learned" by finding associations between these sets of numbers.

Which organs can you live without?

While there are some organs (such as the heart) that people simply can’t live without, there are other organs that can be removed without a huge impact. Patients who have their appendix removed, for example, experience no changes to their daily...

See images of medical cases of firework injuries shared on this 'Instagram for doctors'

Included photos include scans of missing or damaged digits, a chunk of missing flesh, a facial injury from a homemade firework in a glass bottle that exploded in the patient's hand before it was thrown, and an injury where a patient's finger bone flew into someone's leg.

3-parent IVF removes most—but not all—faulty mitochondria

The process scoops out about 99% of the mother's mitochondrial DNA—replacing it with that of a donor woman—but because that roughly 1% is still in the system there is still a small chance of disease for the resulting child or future generations. (Some users may encounter a paywall.)

Comparing bioremediation with other treatment techniques, at three levels of complexity

Physical manipulation, such as collecting and moving contaminated material to a landfill, or chemical applications, which use strong, expensive substances and produce harmful byproducts, can be costly. While bioremediation leverages naturally occurring degradation processes that can be augmented without disrupting impacted ecosystems, these processes may be less effective in environments that bioremediation organisms are not adapted to.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Bone marrow (soft tissue found inside certain bones) generates roughly 500 billion new blood cells each day

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

The original copy of the Declaration of Independence is not a pristine document, and even features a smudged anonymous handprint in the bottom left corner.

To reduce wrinkles in clothing, research recommends gentle wash cycles with more water and tumble drying with smaller loads and longer times.

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

Poison ivy's rash-causing compound is found in the plant's roots, stem, and leaves—so coming into contact with any part of the plant can lead to rashes for the 85% of people who are allergic to it.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Watch how deep-sea mining equipment collects and processes polymetallic nodules—metal-rich, potato-shaped rocks—from the ocean floor and creates environmentally damaging plumes of sediments.

Shooting stars, or meteors, are fragments of asteroids and comets that burn up as they enter Earth's atmosphere, creating streaks in the sky called meteor showers.

Doctors differentiate between a phobia and fear by asking patients whether their fear interferes with their day-to-day activities.

All rainbows are 'raincircles' caused by water droplets separating white sunlight into a spectrum of colors, but Earth's surface blocks the bottom half of the circle from our line of sight.

When you complete a CAPTCHA on a website to prove you are human, you may be unknowingly training algorithms for self-driving cars, whose systems require training data to help identify crosswalks, bicycles, and other outdoor objects.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

The tragic Pulitzer Prize-winning image 'The Vulture and the Little Girl' (1993) generated controversy, raised concerns about ethics in photography, and eventually led to the photographer's death.

Massive 3D printers have been used to build homes by stacking layers of 'concrete toothpaste,' a fire-resistant material that effectively insulates against outside noise.

Art theft is the third-largest source of criminal revenues worldwide, thanks in part to the subjective nature of valuing a work of art.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Roughly 43 million US borrowers owe roughly $1.7T in student debt, the second-largest source of consumer debt behind mortgages.

The Beatles' US label rejected the band's first two singles, 'Please Please Me' and 'From Me to You,' with one executive calling the band 'dead in the water.'