Study finds that bright-colored plastics degrade faster
A three-year collaborative research project between US scientists and the University of Cape Town in South Africa has revealed that the rate of plastic degradation is color-dependent. The study, spearheaded by the University of Leicester, discovered that red, blue, and green plastics become "very brittle and fragmented" over time. Conversely, black, white, and silver plastics were found to remain "largely unaffected."
Retailers are advised against using brightly colored plastics
In light of these findings, retailers are now being encouraged to avoid using brightly colored plastics for everyday items such as drinks bottles, outdoor furniture, and toys. This advice stems from the research conclusion that colored plastics break down into microplastics faster than their less vibrant counterparts. Microplastics have been found in various environments, including human testicles, where they have been potentially linked to declining sperm counts.
Research methodology and findings across continents
The study involved US researchers placing bottle lids of various colors on a university rooftop for three years to expose them to sun and weather. Simultaneously, scientists in South Africa examined plastic items found on a remote beach. Both studies revealed significant differences in microplastic formation based on the color of the plastic. Dr. Sarah Key, who led the project, found it amazing that samples from a Leicester rooftop and a windy beach in Africa showed similar results.
Brightly colored plastics: A concern for short-lived products
Key added that even in a relatively cool and cloudy environment for only three years, significant differences can be seen in microplastic formation. This pioneering field study suggests that retailers and manufacturers should reconsider using brightly colored plastics, particularly for short-lived products. The results have been published in the journal Environmental Pollution. Co-author of the study, Professor Sarah Gabbott, shared her curiosity about why microplastics in beach sand frequently exhibit a rainbow of colors.
Colored plastics: A barrier to recycling
Initially, Gabbott believed she was noticing more colorful microplastics due to their visibility, but she later discovered that brightly colored microplastics are genuinely more common. This is due to red, green, and blue pigmented plastic items being more susceptible to fragmentation into millions of tiny yet colorful microplastic particles. Adam Herriott from Wrap, an anti-waste charity organization explained that colored plastics have traditionally been used to make products stand out. However, Wrap now advises manufacturers to avoid using pigments.
Why do colored plastics degrade more quickly?
The study unveiled that black, white, and silver pigments provide protection to plastics against detrimental ultraviolet (UV) radiation. UV exposure induces structural alterations in plastics, resulting in brittleness and susceptibility to fragmentation. However, these particular pigments serve as effective shields, safeguarding the plastic polymers from UV-induced damage. Consequently, they maintain the structural integrity of plastics, mitigating the adverse effects of UV exposure on their composition and durability.
