Research Shows That Bright Plastics May Degrade Faster, Resulting In More Microplastics Being Produced

Researchers led by the University of Leicester have demonstrated that plastics with bright colors such as red, blue, and green degrade and form microplastics faster than plastics with purer colors. Their research findings indicate that the coloring agents used in plastic product formulations significantly affect their degradation and decomposition rates, potentially leading to faster introduction of harmful plastics into the environment. Two supplementary studies were conducted to compare degradation, published in the journal Environmental Pollution. This is the first time that this effect has been demonstrated in field research and may be important for retailers when designing plastics and packaging. Researchers from the University of Leicester in the UK and the University of Cape Town in South Africa used two complementary studies to show that plastics of the same composition degrade at different rates, depending on the color added. A study used bottle caps of various colors and placed them on the roofs of university buildings, exposed to sunlight and elements for three years. The second study used plastic items of different colors found on remote beaches in South Africa. It is important to analyze the sample only when the date stamp on the plastic product can indicate the manufacturing date of the plastic. Scientists measure the degree of chemical degradation of samples by observing the degree of reaction between the sample and oxygen in the air using Fourier transform infrared spectroscopy (FTIR). They also measured the structural integrity before and after, using fracture strength tests to measure their brittleness and fragility. The results of these two studies indicate that black, white, and silver plastics are largely unaffected, while blue, green, and red samples become very fragile and fragmented during the same period. In fact, the old samples from South Africa were all solid colors, and no brightly colored plastic products were found. But the sand itself is filled with many colored microplastics. Black, white, and silver colorants can protect plastics from damage, indicating that black, white, and silver colorants can protect plastics from ultraviolet (UV) radiation, while other pigments do not. UV damage can alter the polymer structure of plastics, making them brittle and prone to breakage. This study was led by Dr. Sarah Key, who conducted it while pursuing her PhD in Chemistry at the University of Leicester and was funded by the CENTA Central England NERC Training Alliance. She is now a senior research analyst at the climate action non-governmental organization WRAP (Waste and Resources Action Programme). Dr. Key said, "Surprisingly, samples left on rooftops in Leicester, UK, and collected on windblown beaches at the southern end of the African continent showed similar results. Experiments have shown that even in relatively cool and cloudy environments lasting only three years, significant differences in microplastic formation can be observed. Colored plastics, such as red and green, quickly degrade and form microplastics. When you look at purer colors, such as black and white, they are actually very stable and intact. The next time you clean up some plastic waste, take note of the color and think about how long it will decompose. Regardless of the color, be sure to check the packaging to learn more about how to recycle plastic packaging. It is suggested to consider more the color of short-lived plastics. Microplastics exhibit different characteristics from their original bulk materials, and little is known about their impact on the environment. We know that they can release toxic plastic additives into the environment, and they may be transferred to humans through the food chain and water supply, as well as toxic chemicals on their surfaces. This study is of great significance for material design and suggests that manufacturers should consider the color of short-lived plastics more. Dr. Key added, "Manufacturers should consider both the recyclability of materials and the possibility of littering when designing plastic products and packaging. For items that are used outdoors or widely exposed to sunlight, such as plastic outdoor furniture, consider avoiding colors like red, green, and blue to allow them to last as long as possible. If the plastic is designed to decompose, such as through the use of pro oxidant additives, consider the role of color in it." Co author Professor Sarah Gabbott from the School of Geography, Geology, and Environment at the University of Leicester said, "I often wonder why microplastics on the beach often look like all the colors of a rainbow. Before our research, I thought my eyes were deceived, I just saw it. More diverse and colorful microplastics because they are easier to detect. It has been proven that there may indeed be brightly colored microplastics in the environment, as those red, green, and blue plastic products are more easily broken down into millions of tiny but colorful microplastic particles.