Scientists from the University of Stirling have uncovered a hidden environmental impact of sunscreen. According to their research published in the Journal of Hazardous Materials, the substance Ethylhexyl Methoxycinnamate (EHMC), a common ingredient in many sunscreens, significantly slows down the breakdown of plastic in marine environments and alters the microbial communities on its surface.
Plastic submerged in seawater quickly becomes colonized by microbes that form a protective biofilm, known as the “plastisphere.” The study revealed that EHMC exacerbates this process. It causes beneficial bacteria that could help degrade the plastic to disappear, being replaced by more resilient, potentially harmful microorganisms, such as Pseudomonas. These bacteria not only strengthen the biofilms but can also cause infections in humans.
Furthermore, under the influence of EHMC, these microbes switch to an anaerobic (oxygen-deprived) mode of survival, making the plastic even more resistant to decomposition. This effect is particularly worrying in regions with warm climates, high tourism rates, and significant amounts of sunscreen being washed into the ocean.
The researchers are labeling the combination of plastic and sunscreen components as a form of “double pollution.” They are urging authorities to reconsider the regulation of such substances, highlighting the paradox where a product designed to protect human skin simultaneously contributes to increased marine pollution.
This finding adds to previous scientific work, including studies that demonstrated even advanced wastewater treatment plants are unable to effectively remove microplastics. Particles smaller than five millimeters continue to enter natural environments, carrying hazardous chemicals with them.
