The damage caused by plastic pollution goes far beyond the digestive system.

Beneath the skin of seemingly healthy seabirds, new research has revealed the widespread effect of plastics on crucial proteins made by the liver, kidneys and even the brain. Samples taken on Lord Howe Island, which lies between Australia and New Zealand, showed that young birds which appeared healthy were suffering from severe damage to multiple organs. Seabirds which had only eaten less than a gram of plastic were already suffering serious consequences. These impacts extended to the brain, where declines in a crucial protein known as brain-derived neurotrophic factor (BDNF) were similar to levels associated with conditions like Alzheimer’s disease, Parkinson’s disease and dementia in other animals…Sable shearwaters, a type of seabird, feed this plastic to their chicks, where it clogs their digestive system so there’s less space left for food. The team even named a specific disease, plasticosis, to describe the scarring that plastic causes inside the stomachs of these seabirds.

Beyond these more obvious impacts, plastic also sheds minute fragments that can travel even deeper into the body. These are known as microplastics if they’re less than five millimetres in size, or nanoplastics if they’re less than a micron….

These tiny plastics have been found in every environment, even inside our own bodies. Recent research suggests that our brains contain around a spoon’s worth of micro- and nanoplastics, but the health impacts of this are still not entirely understood.

Excerpt James Ashworth, Natural History Museum (UK) Plastic pollution causing dementia-like signs in seabird chicks, Mar. 12, 2025