New research shows that chemical additives used in plastic manufacture have been found in herring gull eggs.

Phthalates are a group of chemicals that are added to plastics to keep them flexible.

The study by the Universities of Exeter and Queensland looked for evidence of phthalates in newly laid herring gull eggs – and found up to six types of phthalate per egg.

Phthalates act as pro-oxidants – they potentially cause “oxidative stress” that can damage cells.

“Herring gull mothers pass on vital nutrients to their offspring through their eggs,” said Professor Jon Blount of the Center for Ecology and Conservation on the Penryn campus of the University of Exeter in Cornwall.

“These include lipids, which nourish developing embryos, and vitamin E, which protects chicks from oxidative stress that can occur during development and hatching.

“Unfortunately, our results suggest that mothers accidentally pass on phthalates and lipid-damaged products – and eggs with a higher phthalate load also contained larger amounts of lipid-damaged and less vitamin E.”

The effects on developing chicks are unknown and more research is needed.

The researchers collected 13 herring gull eggs from sites in Cornwall, UK, and all 13 contained phthalates.

Phthalates – which are used in most plastic products and easily suck out – can be found in almost every environment on earth today.

They can “bioaccumulate” (build up in living organisms) by accumulating in adipose tissue.

The study doesn’t show where the gulls acquired the phthalates, but phthalates were previously found in species that are hunted by herring gulls, and the birds have been known to ingest plastic.

“Research into the effects of plastic on animals has largely focused on the entanglement and ingestion of plastic fragments,” said Professor Blount.

“Far less is known about the effects of plastic additives on the car body.

“By testing eggs, our study gives us a snapshot of the mother’s health – and it appears that phthalate contamination could be linked to increased oxidative stress, and mothers pass these costs on to their offspring through the egg.

“More research is now needed to find out how developing offspring are affected by exposure to phthalates before they even hatch as young.”

He added: “We need to look more closely at the pervasive threats posed by plastics – not just the degradation of plastic items themselves, but the spread of the many chemicals they contain.

“Where do they end up and what impact do they have on wildlife and ecosystems?”


The study received an initiator grant from QUEX, a partnership between the Universities of Exeter and Queensland.

The paper published in the magazine Marine Pollution Bulletin, is entitled: “Phthalate diversity in eggs and associations with oxidative stress in the European herring gull (Larus Argentatus ). ”


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