What effects plastics have on our oceans is of big concern to environmentalists. Worryingly, researchers have now discovered that tiny particles of plastic can build up in fish brains and change their behavior.

Shockingly, about 10 percent of all plastic made by humans ends up in the sea. Lots of studies have looked into how large plastics impact the marine world, yet the effects of nanosized plastic particles are still relatively unknown.

The new study, published in Scientific Reports, has shown that tiny particles, referred to as “nanoplastics”, can accumulate in fish brains.

"Our study is the first to show that nanosized plastic particles can accumulate in fish brains," said study author Tommy Cedervall, from Lund University in Sweden, in a statement.

The researchers found that tiny particles of plastic can spread through the marine food chain. They are eaten by plankton, which is then consumed by fish. The particles are small enough to cross the blood-brain barrier, meaning they can make their way to the fish's brains. 

This buildup of plastic in the brain was found to have a worrying knock-on effect – it went on to affect fish behavior. Fish that had nanoplastics in their brains were less likely to explore their surroundings and slower at eating than their healthier counterparts. These strange alterations in behavior are concerning as they could make the fish less likely to survive. The researchers believe that the changes are a direct result of brain damage caused by the nanoplastics.

The scientists also noted the importance of researching the effects of plastic particles of all sorts of different sizes. They found that the tiny nanoplastics managed to kill plankton, yet larger particles of the material did not.

"It is important to study how plastics affect ecosystems and that nanoplastic particles likely have a more dangerous impact on aquatic ecosystems than larger pieces of plastics," said Cedervall.

The fact that plastic can build up in fish brains points to a big question – can it accumulate in other types of tissue and therefore be transferred to human consumers?

However, not enough research has been done on the topic and Cedervall is reluctant to make any links.  

"No, we are not aware of any such studies and are therefore very cautious about commenting on it," he said.