Brain samples held 7 to 30 times the plastic of liver

Researchers at the University of New Mexico analyzed decedent brain, liver, and kidney tissue donated through a medical examiner's office, using several independent detection methods to confirm and quantify plastic particles rather than relying on a single test that could be fooled by contamination.

Brain tissue held 7 to 30 times the plastic concentration of liver or kidney, mostly polyethylene in tiny shard-like fragments. The median in brain samples rose from about 3,300 micrograms per gram in 2016 to about 4,900 in 2024, an increase of nearly 50 percent.

Brains from people with a documented dementia diagnosis showed notably higher plastic accumulation than others, concentrated in blood vessel walls and immune cells, though the study cannot say whether the plastic contributed to the disease or simply built up more in already-damaged tissue. The source of the plastic, how it crosses into brain tissue, and what, if anything, it does there once lodged remain open questions the researchers flagged directly.

Plastic, quietly accumulating in the skull.