From a bag to particles small enough to be eaten
Sunlight, wave action, and abrasion break plastic litter into smaller pieces. The plastic does not simply disappear: fragments can persist in the environment, including as microplastics and, at still smaller scales, nanoplastics. Their size and shape vary, so they are not all indistinguishable from the algae and other food that tiny marine animals eat.
Some zooplankton—small drifting animals that form a major link in ocean food webs—can ingest plastic particles. In laboratory and field research, particles have also been found moving from prey to predators. That is one route by which plastic can pass through a food web, though it does not mean every predator accumulates every particle it consumes.
Passing upward is not the same as multiplying
A fish may eat many pieces of prey, but the plastic inside that prey does not automatically build up in the fish in the same proportion. Some particles are expelled; others may remain in tissues for a time. The outcome depends on particle size, the animal, and how it feeds and digests. Plastic particles are not known to magnify up the food chain in the simple, inevitable way the caption suggests. Certain chemicals associated with plastics can behave differently, but their movement and accumulation depend on the chemical and exposure.
People can encounter plastic particles through food, water, and air. Seafood is one possible route, and researchers are investigating what happens after particles enter the body. Reports of particles in human tissues do not establish that they arrived through seafood, became permanently lodged in the brain, or caused a particular health effect.
The lasting concern is less a neat chain of steadily increasing contamination than a stubborn source of exposure: plastic fragments remain available to wildlife and people long after the original packaging is gone.
