A dump holding 200,000 tonnes of rubbish is being washed into the sea more than 20 years after the problem was identified, a report on the dangers of erosion has found.
The disused landfill north of Bray, which stopped taking in waste at least 25 years ago, is being eaten away after advancing waves from the Irish Sea washed out clay walls.
Environmental group Coastwatch revealed about 200m of the face of the tip has been exposed by the weather and a sbestos, rusted metal, heavy plastics, bricks and bags can be seen at the foot of eroded cliffs.
It was one of 511 spots across the Republic surveyed for erosion damage last year with more than a quarter classed as a serious risk.
The Coastwatch report said erosion is not only the most widespread threat to the 7000km of coast, but also at the highest on record for 26 years.
Karin Dubsky, Coastwatch Europe co-ordinator in Ireland, said a national policy rather than county by county approach to protecting the coastline is badly needed.
"Virtually every golf links in the country has rock armour around it," she said.
"Eighty years ago there was a national approach to erosion but now it is very hit and miss. Lacking a national policy is a big weakness, and having no public discussion about it is appalling in 2015."
The Coastwatch report said the increasing concern and visible impact from erosion in some parts of the country was undoubtedly due to the huge Atlantic storms in January and February last year, particularly the western seaboard.
Its survey found Wexford, Wicklow, Kerry, Clare, Galway and Mayo have been particularly badly hit.
Wexford has 40 sites under threat out of 55 surveyed and at Ardamine two houses and a number of access routes were lost in winter storms last year.
In Meath, where the coastline only strecthes to 11km, 16 out of 20 surveys identified erosion threats.
The Government set aside 70m euro last year to deal with repairs to eroded coasts.
The problems with Bray dump were identified by a student in 1993 and subsequently reported on by Coastwatch in 2005 and 2006 but no permanent solution to stop the decades old rubbish from being washed into the sea has been agreed. T he land is now privately owned.
Material from the dump, including suspected dangerous chemicals, have been removed for research by the Coastwatch team at Trinity College Dublin.
Coastwatch called for old dumps need to be marked on county development plans and for reports on them by councils to be made public.