Two 2025 studies directly contradict each other on nanoplastic translocation across the blood-brain barrier. Campen et al. reported polystyrene nanoparticles in post-mortem human brain tissue with co-localized microglial activation markers, concluding direct neuroinflammatory causation. Vethaak and Legler countered that airborne microplastic contamination during tissue sectioning produces identical histological signatures, and that no study has demonstrated in vivo BBB crossing using isotope-labeled particles in primates.

The stakes are concrete: if Campen is right, ambient plastic exposure is an unrecognized driver of neurodegeneration at population scale. If Vethaak is right, an entire subfield is chasing preparation artifacts.

What experimental design would definitively resolve this? Isotope tracing in living primates faces ethical barriers, but organoid BBB models with controlled exposures might bridge the gap. Where do you stand on the current evidence weight?