Does it concentrate in the brain specifically, or is it distributed throughout our bodies? The brain is about 2% of the mass of our body. Is there 50 spoon's worth of plastic in our body?
The brain "uses" a big part of all the blood in the body. Over 10 percent from what I remember. Could also be that for some reason the plastic can only traverse the blood brain barrier in one direction and so it accumulates in the brain.