Microplastics in decedents with and without dementia

Rising global concentrations of environmental micro- and nanoplastics
(MNPs) drive concerns for human exposure and health outcomes.
Complementary methods for the robust detection of tissue MNPs, including
pyrolysis gas chromatography-mass spectrometry, attenuated total
reflectance-Fourier transform infrared spectrometry, and electron
microscopy with energy-dispersive spectroscopy, confirm the presence of
MNPs in human kidney, liver, and brain. MNPs in these organs primarily
consist of polyethylene, with lesser but significant concentrations of
other polymers. Brain tissues harbor higher proportions of polyethylene
compared to the plastic composition in the liver or kidney, and electron
microscopy verified the nature of the isolated brain MNPs, which present
largely as nanoscale shard-like fragments. Plastic concentrations in these
decedent tissues were not influenced by age, sex, race/ethnicity, or cause
of death, the time of death (2016 versus 2024) was a significant factor,
with increasing MNP concentrations over time in both liver and brain
samples (P=0.01).  Finally, an even greater accumulation of MNPs
was observed in a cohort of decedent's brains with a documented
dementia diagnosis, with notable deposition in cerebrovascular walls and
in immune cells. These results highlight a critical need to better
understand the routes of exposure, uptake and clearance pathways, and
potential health consequences of plastics in human tissues, particularly
in the brain.