New research has unveiled a grim reality: even seemingly healthy seabird chicks are suffering from widespread organ damage due to plastic pollution. The study, published in Science Advances, focused on sable shearwater chicks on Lord Howe Island, a nesting ground between Australia and New Zealand. Scientists found that consuming even less than a gram of plastic led to severe physiological damage, including brain deterioration similar to conditions like Alzheimer’s and Parkinson’s in other animals.
Dr. Alex Bond, a bird expert from the UK’s Natural History Museum and co-author of the study, noted that while the chicks appeared outwardly fine, blood tests revealed extensive cellular damage. “These birds don’t appear to be ill from the outside, but samples of their blood contain a variety of indicators of cell damage and death,” Bond explained. Researchers discovered a sharp decline in brain-derived neurotrophic factor (BDNF), a crucial protein for neural health, leading to interruptions in cognitive development, particularly in the birds’ song control system.
The Hidden Toll of Plastic Consumption
Every year, over 20% of all plastic waste enters the environment unchecked, making its way into oceans where seabirds ingest it. Lord Howe Island’s seabirds are among the most plastic-contaminated birds on Earth, bringing back an estimated 688,000 pieces of plastic annually. These fragments accumulate in the chicks’ digestive systems, reducing space for actual food and leading to inflammation and scarring—a condition researchers have named “plasticosis.”
To gauge the extent of internal damage, scientists examined over 30 chicks that displayed no external symptoms of illness. By flushing their stomachs and analyzing their blood, they categorized them into low and high-impact groups based on the amount of plastic they had consumed. The results were alarming: a quarter of all protein expressions differed between the groups. Birds in the high-impact category exhibited significant damage to their stomachs, kidneys, and other organs. Low levels of the antioxidant GPX3, crucial for mitigating oxidative stress, were also recorded. This deficiency could impair the birds’ ability to endure the extreme exertion of long-distance migration.
Plastic’s Unseen Impact on the Brain
One of the most shocking revelations from the study was the neurological damage in the shearwater chicks. Plastic exposure led to reduced BDNF levels, disrupting brain function. PhD researcher Alix de Jersey from the University of Tasmania highlighted the potential consequences for the species: “Seabird colonies are an overwhelming symphony of calls, screeches, and chatter. To survive, sable shearwaters need to distinguish between fine-scale acoustic cues to locate their partners. Plastic interrupts this system, which could impact their ability to create and maintain pair bonds.”
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The presence of proteins linked to brain injury in the birds’ blood further shocked researchers. “We expected proteins normally found inside cells to have escaped into the blood based on our previous research,” Bond said, “but it was quite unexpected to find proteins associated with brain damage as well.” This suggests that plastic pollution is causing neurological harm comparable to degenerative diseases in humans.
A Canary in the Coal Mine for Human Health?
The research underscores the broader implications of plastic pollution, not just for seabirds but for all living organisms, including humans. Scientists have found micro- and nanoplastics throughout the human body, even in the brain, but the full health consequences remain uncertain. However, existing studies link plastic exposure to increased risks of heart disease, stroke, and organ damage—paralleling the findings in seabirds.
With seabirds among the most affected species, researchers are advocating for a comprehensive database of protein signatures to assess the long-term impacts of plastic pollution across wildlife. “Seabirds are among the animals most affected by plastic ingestion,” de Jersey emphasized, “and studies of their protein signatures are increasingly revealing plastic’s association with inflammation, oxidative stress, fibrosis, and altered metabolism.”
The findings present an urgent call for action. If plastic is wreaking such havoc on seabirds, it is likely having a similarly devastating effect on other species, including humans. The invisible toll of plastic pollution may be far worse than previously thought, and without intervention, its consequences could be irreversible.