An investigation by Newstalk Breakfast has revealed cocaine residue was found in public toilets at the Natural History Museum and Heuston Station.

A team went out and tested bars and public buildings in Dublin city using a testing kit of cocaine-detecting wipes.

The wipe changes to a blue colour if cocaine traces are present.

The wipe turned blue when cocaine was detected | Image: YouTube/Newstalk

Overall, toilets in 15 bars - ranging from late bars to traditional pubs - and five public buildings in the capital were tested.

The cistern, toilet lid, toilet roll holder and any shelves in the toilet were tested.

Ten of the bars tested were found to have traces of cocaine - that is 67%.

The results varied in strength - some places showed up small blue dots on the sheets.

Image: YouTube/Newstalk

But others saw a handprint of blue present on the sheet.

A number of well-known public buildings were found to not have any cocaine present - including Trinity College Dublin and the GPO.

However as the GPO has no public toilets, the team took samples from a number of public desks.

A Government department building was also tested and no cocaine was detected.

Two out of the five public buildings were found to have cocaine residue.