Brain pollution by plastic.
“We expected to see the microplastics in the feces of the animal, that wasn’t altogether surprising,” Ross told Earther. “Then we found them deep inside liver cells, spleen, [and] kidneys. Not just the center of the digestive tract, but actually in the tissue of the digestive tract.”

Because the plastics were found in organs including the liver, spleen, and brain, it meant that the many bits of swallowed microplastics had entered the bloodstream. This is what allowed the microplastics to make their way into organs outside of the digestive tract."
https://gizmodo.com/microplastics-behavioral-changes-in-mice-alzheimers-stu-1850785217