Researchers at the University of New Mexico found that the human brain now contains a significant amount of plastic, with concentrations higher than in the liver or kidneys. This plastic is coming from microplastics that have crossed the blood-brain barrier, with ultra-processed foods identified as a key delivery system for these particles. This contamination occurs at various stages, from plastic irrigation systems in crops to plastic packaging materials that release particles when opened or heated.

The accumulation of plastic in the brain has been linked to rising rates of depression, dementia, and other mental health disorders. Brain tissue from individuals with dementia contained three to five times more plastic than those without, though the study design cannot prove causation. While dietary changes can help limit exposure to microplastics, broader efforts are needed to reduce plastic production and develop safer food contact materials to address this emerging health concern.