A chemical commonly found in sun cream could be making plastics in oceans even harder to break down, according to new research by the University of Stirling.
Scientists at the learning institute found that the chemical Ethylhexyl Methoxycinnamate, commonly known as EHMC, could be slowing the degradation of discarded plastic in seas, and may be helping biofilm bacteria – which have a greater protection from harsh conditions – to thrive.
By forming slimy layers called the plastisphere, microbes can grow on plastic waste in the ocean. As well as forming the plastisphere, plastics also absorb other pollutants – including sunscreens washed off human skin that are insoluble in water, and these can then attach to marine plastic surfaces.
Sunscreens, like oil, are hydrophobic – meaning that they do not dissolve in water. This makes them a combined threat, as they can accumulate on plastics and remain in the environment, the university explained.
Led by Dr Sabine Matallana-Surget, an associate professor in the faculty of natural sciences, the team is now appealing to policymakers to take ‘urgent’ action to tackle what they call the ‘invisible threat of sunscreen’.
Dr Matallana-Surget said, “These changes matter. By suppressing the aerobic bacteria that help degrade plastic, and selecting those that stabilise or reinforce the biofilm, UV filters would prolong the life of plastics in the ocean – making them more resistant to breakdown by sunlight or microbes. Targeted research and policy interventions are therefore urgently needed to mitigate these compounded ecological threats.”
Dr Matallana-Surget led the research in collaboration with Dr Charlotte Lee – who undertook the core experimental work – and Dr Lauren Messer at the University of Stirling, alongside Professor Ruddy Wattiez at the University of Mons in Belgium.
The project, which stemmed from Dr Matallana-Surget’s initial concept of investigating the emerging double pollution issue, has built on 15 years of joint work between the teams in Stirling and Mons.
Research was funded by the UKRI Natural Environment Research Council (NERC) and the National Research Foundation Singapore. It was further supported by the European Regional Development Fund and the Walloon Region, Belgium.
