Get rid of brightly colored plastics, say anti-waste researchers

Retailers are being urged to stop making everyday products such as drinks bottles, outdoor furniture and toys from brightly colored plastic after researchers found it breaks down into microplastics faster than brighter colours.

The red, blue and green plastic became “very brittle and fragmented”, while the black, white and silver samples were “largely intact” over the three-year period, according to the findings of the University of Leicester-led project.

The extent of environmental pollution caused by plastic waste means that microplastics, or tiny plastic particles, are everywhere. Indeed, they have recently been found in human testicles, with scientists suggesting a possible link to men’s declining sperm count.

In this case, researchers from Great Britain and the University of Cape Town in South Africa used complementary studies to show that plastics of the same composition degrade at different rates depending on the color.

British researchers placed different colored lids on the roof of a university building to expose it to the sun and weather for three years. A South African study used plastic objects found on a remote beach.

“It is amazing that samples left to weather on a roof in Leicester and samples taken on a windswept beach at the southern tip of the African continent show similar results,” said Dr. Sarah Key, who led the project.

“Experiments have shown that even in a relatively cool and cloudy environment for just three years, huge differences in the formation of microplastics can be observed.”

This field study, published in the journal Environmental Pollution, is the first such evidence of this effect. He suggests that retailers and manufacturers should be more considerate of the color of short-lived plastics.

“I’ve often wondered why microplastics in beach sand often look like all the colors of the rainbow,” said Professor Sarah Gabbott, also from the University of Leicester, who co-authored the study.

“I assumed that my eyes were deceiving me and that I was only seeing the more colorful microplastics because they were easier to see. It has been shown that there is likely to be more brightly colored microplastics in the environment because these plastic objects pigmented in red, green and blue are more prone to fragmentation into millions of tiny but colorful microplastic particles.

Adam Herriott, chief plastics specialist at anti-waste charity Wrap, said colored plastics had traditionally been used to make products stand out in shops, but the organization was already advising manufacturers to avoid pigments to make the plastics easier to recycle.

“If you mix the colors together, you get a weird gray or greenish color,” he said. Research was another reason to do it. “If we can avoid these bright colors in food packaging, especially high-waste items like fragile packages or bottle caps, that would be better.”

The findings show that black, white and silver pigments protect the plastic from harmful ultraviolet (UV) radiation, while other pigments do not. UV damage changes the polymer structure of the plastic, making it brittle and prone to fragmentation.

“Manufacturers should consider both the recyclability of the material and the likelihood of it being thrown away when designing plastic items and packaging,” said Key. “For items that are used outdoors or are exposed to a lot of sunlight, such as plastic outdoor furniture, consider avoiding colors like red, green and blue to make them last as long as possible.”