Largest Particle Size
Cities measured
87
Detected in
87 / 87
Elevated / alert
22
Highest
420 μm — Karachi
Overview
The largest detected microplastic particle size provides context about contamination source — large particles (> 1000 μm) suggest recent fragmentation or direct release; smaller particles (< 10 μm) raise greater concern as they can cross biological barriers.
Health Relevance
Particles < 10 μm can be internalised by cells. Particles < 1 μm (nanoplastics) can cross the blood-brain barrier in animal models. Nanoplastics are the least studied and potentially most concerning fraction.
Regulatory Limits
Drinking Water Directive 2020/2184
No regulatory limit on particle size.
Controversy & Contested Science
Most microplastics research has focused on particles > 50 μm due to analytical limitations. The nanoplastic fraction is essentially invisible to conventional monitoring. A 2022 study reported nanoplastics in 8 of 10 human blood samples tested. The scale of nanoplastic generation from environmental microplastic weathering — potentially trillions of particles per microplastic item — represents a monitoring and regulatory challenge that current frameworks are not designed to address.