Retailers are being encouraged to stop using brightly coloured plastics for everyday products such as drinks bottles, outdoor furniture, and toys. This call to action comes after research showed that coloured plastics degrade into microplastics faster than their plainer counterparts.
Microplastics are everywhere, in fact the pollutants were recently discovered in human testicles, and were potentially linked to declining sperm counts.
Study on microplastics
A study led by the University of Leicester found that red, blue, and green plastics become “very brittle and fragmented” over time, while black, white, and silver plastics remain “largely unaffected.”
The joint project between scientists from the UK and the University of Cape Town in South Africa, spanning three years, found that plastics based on colour had varying degradation rates.
How did scientists conclude this?
In the study, UK researchers placed bottle lids of different colours on a university rooftop, exposing them to sun and weather for three years. Simultaneously, scientists in South Africa examined plastic items found on a remote beach.
Both studies yielded similar results, revealing significant differences in microplastic formation based on colour.
Dr Sarah Key, who led the project, remarked, “It’s amazing that samples left to weather on a rooftop in Leicester and those collected on a windswept beach at the southern tip of the African continent show similar results.”
“What the experiments showed is that even in a relatively cool and cloudy environment for only three years, huge differences can be seen in the formation of microplastics,” she added.
This field study is the first to provide such proof. It suggests that retailers and manufacturers should reconsider the use of brightly coloured plastics, especially for short-lived products.
The findings have been published in the journal Environmental Pollution.
Professor Sarah Gabbott, co-author of the study, revealed that she “often wondered why microplastics in beach sand often appear to be all the colours of the rainbow.”
“I assumed that my eyes were being deceived and that I was just seeing the more colourful microplastics because they were easier to spot.”
“Turns out there really are likely to be more brightly coloured microplastics in the environment because those plastic items pigmented red, green, and blue are more susceptible to being fragmented into millions of tiny yet colourful microplastic particles.”
Adam Herriott, a senior specialist for plastics at the anti-waste charity Wrap, explained that coloured plastics have traditionally been used to make products stand out. However, the organisation now advises manufacturers to avoid using pigments to facilitate recycling.
Why do coloured plastics break up faster?
The study found that unlike other pigments, black, white, and silver colourants protect plastics from damaging ultraviolet (UV) radiation. UV exposure alters the polymer structure of plastics, making them brittle and prone to fragmentation.
(With inputs from agencies)