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Recycling used gum, and cycling through tattoo-munching cells

by Carmen Drahl
April 2, 2018 | A version of this story appeared in Volume 96, Issue 14


A collection of bright-pink products made from recycled chewing gum is shown, including a comb, a ruler, a frisbee, and a guitar pick.
Credit: Gumdrop
By gum: These bubble-gum-pink products all contain at least 20% used chewing gum.

Used gum, reincarnate

One fine afternoon, design student Anna Bullus decided to pick up every piece of litter she could find. She brought her newfound treasures home, and then—with gloves on, the Newscripts gang hopes—examined each one. Wedged inside a crinkled packet of chips, she found the inspiration she’d been looking for: a used piece of bubble gum.

Today, Bullus’s U.K.-based firm, Gumdrop, recycles those sticky wads into dog bowls, combs, and even rubber boots. Gumdrop’s signature product is a bright pink recycling bin, made in part from recycled gum, where passersby can deposit their masticated trash.

The rubbery, recyclable vehicle for chewing gum’s sugar and flavorings, called gum base, is a mix of resins, polymers, and plasticizers. The U.S. Food & Drug Administration permits more than40 chemicals under the classification of gum base, including natural resins such as chicle, as well as synthetic polymers such as polyisobutylene.

The company hasn’t disclosed its precise recycling process. According to a spokesperson, the gum and bin get recycled together. When the gum recycling bin is full, it first heads to a plant that removes wrappers, cigarette butts, and the like. The material goes through two more processes before eventually becoming polymer pellets that will work with standard plastic-molding equipment. The resulting products are 100% recycled material and contain a minimum of 20% recycled gum, along with other components.

Gumdrop currently distributes bins only in the U.K., but they’ve had considerable success. Heathrow Airport saved $8,500 in cleaning costs during an eight-week trial. Bullus thinks the bins can inspire gum chewers to stop littering. “I do believe that through right design,” she told the BBC, “we can actually change the way people behave.”


Tattoo ink’s circle of life

Credit: C&EN/ACS Productions
Find out from our friends at ACS Reactions how macrophages help make tattoos permanent.

Chew on this: While tattoos do stick around, they may be more dynamic than you think.

A man shows off a misspelled tattoo, “No Regerts,” on his forearm.
Credit: Shutterstock
Should’ve spell-checked: Insights into skin macrophages might improve tattoo removal.

When people get that anchor on their bicep, or have “Justin Bieber 4eva” emblazoned on their lower back, they probably don’t give much thought to tattoo biochemistry. The prevailing wisdom was that tattoos persist because the ink stains connective tissue cells in the skin’s dermis. More recent evidence suggests that different cells in the dermis, immune-system macrophages, are involved instead. Macrophages flock to sites of injury, and needle punches from tattooing definitely qualify. The macrophages engulf the invading ink much as they would a pathogen. They can’t degrade the ink, so they sit in place for good, their one-celled bellies distended with pigment.


Or so scientists thought. Immunologists in France have now demonstrated that these tat-munching macrophages don’t have extreme longevity; they die like other cells. Dying macrophages release their ink, but neighboring macrophages are there to recapture it, says Sandrine Henri of the Immunology Center of Marseille-Luminy, who co-led the study. In other words, there’s not one set of eternal macrophages hanging on to your body art but a constant cycle of death and birth, passing your ink down through the cellular generations (J. Exp. Med. 2018, DOI: 10.1084/jem.20171608).

This insight could make it easier to erase tattoos that folks may regret. Laser removal doesn’t always work, and macrophages may be a factor, Henri theorizes. “The aim of the laser is to break up the ink into small pieces,” small enough for macrophages to degrade, she explains. Temporarily suppressing macrophages before laser treatment would make all the tattoo ink accessible, she tells Newscripts. “And if the ink is all free at once, the laser will be more efficient.” No word on whether her lab will get matching tattoos to test this hypothesis.

Carmen Drahl wrote this week’s column. Please send comments and suggestions to


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