Oct. 24 (UPI) -- Levels of microplastics in the Baltic Sea haven't risen for three decades, according to sampling and analysis by efforts by researchers in Germany and Denmark.
Scientists from the Technical University of Denmark, the University of Copenhagen and the Helmholtz Centre for Ocean Research Kiel, in Germany, have been measuring the amount of micro plastics in fish and water samples from the Baltic since 1987.
This week, researchers published a summary of their findings over the last 30 years in the journal Science of The Total Environment.
"The result is surprising. There is the same amount of plastic in both the water and the fish when you go back 30 years," Torkel Gissel Nielsen, a professor at the Technical University of Denmark, said in a news release.
The result is surprising because the production of plastics has increased, along with the planet's population, and because plastics take more than a century to break down. Elsewhere, studies have found increasing concentrations of microplastics.
"So where has the plastic gone? Does it sink to the bottom? Are there organisms that can break it down? Or is it carried away by currents?" Nielsen asked.
Researchers hope the results of their study don't give the false impression that the problem of microplastics pollution is going away. In addition to analyzing Baltic water samples, scientist have surveyed the insides of hundreds of herring and sprat specimens. The stomachs of one in five fish have revealed plastic particles and fragments -- most frequently synthetic fibers from clothing.
"It is important to focus on the fact that microplastics do not belong in the sea, and we still need to reduce their spreading so they do not end up in the aquatic environment and the food chain," Sabrina Beer, who was a masters student at the University of Copenhagen at the time of the research.
While the amounts of microplastics found in the Baltic isn't overwhelming -- the team found 0.3 microplastic fibers in every cubic meter of water -- scientists are still working to understand the ecological risks posed by plastic pollution.
One of their gravest risks likely lies in their ability to attract other contaminants. Toxic chemicals can attach to microplastics, making them more likely be absorbed by and accumulate in the tissue of marine organisms.
"There remains a need for a greater focus on microplastics in our seas," Breer said. "Our study paves the way for studying other aspects of the significance of microplastics, and levels of microplastics from the air to the seabed."