Any plastic packaging will eventually turn into microplastics if it’s left outside. But bright red, green, or blue plastic turns into pollution much faster than the colors white, black, and silver.
In a new study, researchers at the U.K.’s University of Leicester put samples of colored plastic on the roof of a university lab and studied what happened over three years as the plastic was exposed to sun and rain. The more plain-colored plastic didn’t change much. But the bright colors quickly became brittle and fragmented, even in the U.K.’s cloudy weather.
Collaborators at the University of Cape Town collected samples of plastic packaging from a beach in South Africa. The sand was full of colored microplastics. But the only old pieces of plastic that were still intact—some stamped with dates 30 years old—were white and black. (The researchers focused on colored plastic, and didn’t study the impact on clear versions of the material.)
How some colors act like “sunscreen for plastics”
Black plastic is made with carbon, and white and silver plastic are made with titanium oxide. The chemicals help protect the plastic from the sun. The other colors absorb much more sunlight. “That basically leads to them degrading more because plastic degradation is all about UV radiation,” says study coauthor Sarah Gabbott, a professor at the University of Leicester’s School of Geography, Geology, and the Environment. “Carbon and titanium oxide are like a kind of sunscreen for plastics.”
That doesn’t mean that black and white plastic won’t also break down. But because it lasts longer, it can be easier to clean up. By the time plastic fragments into microplastics or even tinier nanoplastics, it’s much more difficult to remove from the environment. “All this does is it gives you a bit more time to collect the pieces,” says Gabbott.
Microplastics are now ubiquitous, found in everything from salt and beer to Arctic snow and clouds. They’re in wildlife, including bees, otters, and whales. (Whales eat as much as 10 million pieces of microplastic a day.) They’re in human breast milk, and in human hearts, lungs, and other organs. Research is only beginning to uncover the significant health implications, including the fact that microplastics can expose you to toxic chemicals that get absorbed through the skin.
For manufacturers, it’s one more factor to consider in packaging design. Color choices have other implications, including how easy it is to recycle; black plastic typically can’t be sorted out at recycling centers because the sorting equipment can’t recognize it, and some other colors are also less likely to be recycled because they can’t easily be turned into new material. And because recycling rates are abysmally low, the best option is likely to ditch single-use plastic completely.
