Ongoing research at Galway Mayo Institute of Technology has found that seabirds around the coast regularly ingest plastic that they mistake for food.
250 dead birds were examined, of which 20% had plastic in their stomachs.
A number of seabirds had swallowed so much plastic, they had no room for food and died of malnutrition.
The United Nations says marine plastic is now a major threat to the oceans.
Dr Heidi Acampora of the Marine and Freshwater Research Centre of GMIT said: "In total we had 20 species collected and 14 of these had plastics. If plastic is abundant at sea and is just floating there they mistake it for prey, for food."
In the case of one seabird species, the Fulmar, 93% of birds examined had swallowed plastic, including plastics beads, styrofoam and sharp pieces of sheet plastic.
"If they have all of that in their stomachs there is very little space for food so they end up dying from starvation. They don't get any nutrition from the plastic," said Dr Acampora.
Karin Dubsky, a marine ecologist and International Coordinator of Coastwatch, said: "We have to totally rethink our use of plastic, it’s a massive problem. There is literally no shore in the world where you don’t come across some."
There have been calls on the Government to introduce deposit-on-return schemes on plastic bottles, measures to discourage plastic packaging and marine litter proofing on all new products before they reach the market.
This weekend Coastwatch volunteers will begin to carry out their annual coastal environmental survey.
The survey, which is in its 30th year, will continue for a number of weeks and will provide a data source on the state of the shoreline.
Separately Cleans Coasts, which is part of An Taisce will also conduct beach cleans at 135 locations this weekend.
Information on exact locations can be found on www.cleancoasts.org