Seagull eggs have been found to be contaminated with chemical additives used in plastic production.
A study looked for evidence of phthalates – a group of chemicals added to plastics to keep them flexible – in newly laid herring gull eggs in Cornwall, UK.
All 13 eggs that were tested were found to contain phthalates, with up to six types of phthalate per egg.
These chemicals function as pro-oxidants – potentially causing oxidative stress that can damage cells.
“Herring gull mothers pass on vital nutrients to their offspring via their eggs,” said study author Jon Blount at the University of Exeter, UK.
“This includes lipids that nourish developing embryos, and vitamin E, which helps to protect chicks from oxidative stress that can occur during development and at hatching.
“Unfortunately, our findings suggest that mothers are inadvertently passing on phthalates and products of lipid damage – and eggs with higher phthalate contamination also contained greater amounts of lipid damage and less vitamin E.”
The researchers say the impact of their findings on developing chicks isn’t yet known, and further research is needed.
Phthalates – which are used in most plastic products and readily leach out – can build up in living organisms by becoming concentrated in fatty tissues.
While the study doesn’t show where the gulls acquired the phthalates, they have been previously found in species preyed on by herring gulls, and the birds are known to swallow plastic.
“Research on the impact of plastic on animals has largely focused on entanglement and ingestion of plastic fragments,” said Blount. “Far less is known about the impacts of plastic additives on the body.
“By testing eggs, our study gives us a snapshot of the mother’s health – and it appears phthalate contamination could be associated with increased oxidative stress, and mothers transfer this cost to their offspring via the egg,” he said.
“More research is now needed to discover how developing offspring are affected by being exposed to phthalates before they have even emerged as a hatchling.”
Journal reference: Marine Pollution Bulletin , DOI: 10.1016/j.marpolbul.2021.112564
This article was first published by The New Scientist on 16 June 2021. Lead Image: A herring gull chick and eggs by Prof Jon Blount.
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