Researchers from CSIRO and Imperial College London have assessed how widespread the threat of plastic is for the world's seabirds, including albatrosses, shearwaters and penguins, and found the majority of seabird species have plastic in their gut. The study, led by Dr Chris Wilcox with co-authors Dr Denise Hardesty and Dr Erik van Sebille and published today in the journal PNAS, found that nearly 60 per cent of all seabird species have plastic in their gut.

Based on analysis of published studies since the early 1960s, the researchers found that plastic is increasingly common in seabird's stomachs.

In 1960, plastic was found in the stomach of less than 5 per cent of individual seabirds, rising to 80 per cent by 2010.

The researchers predict that plastic ingestion will affect 99 per cent of the world's seabird species by 2050, based on current trends.

The scientists estimate that 90 per cent of all seabirds alive today have eaten plastic of some kind.

This includes bags, bottle caps, and plastic fibres from synthetic clothes, which have washed out into the ocean from urban rivers, sewers and waste deposits.

Birds mistake the brightly coloured items for food, or swallow them by accident, and this causes gut impaction, weight loss and sometimes even death.

"For the first time, we have a global prediction of how wide-reaching plastic impacts may be on marine species - and the results are striking," senior research scientist at CSIRO Oceans and Atmosphere Dr Wilcox said.

"We predict, using historical observations, that 90 per cent of individual seabirds have eaten plastic. This is a huge amount and really points to the ubiquity of plastic pollution."

Dr Denise Hardesty from CSIRO Oceans and Atmosphere said seabirds were excellent indicators of ecosystem health.

"Finding such widespread estimates of plastic in seabirds is borne out by some of the fieldwork we've carried out where I've found nearly 200 pieces of plastic in a single seabird," Dr Hardesty said.