The secret dumping of radioactive waste in landfill sites in Belfast and Derry posed no risk to human health, a British Department of the Environment review has stated.
A conservative approach was taken by allowing the toxic material to decay for long periods before its disposal, the review added.
Previously confidential UK government files from 1983 disclosed the controlled burials, which included medical waste.
The report commissioned by Environment Minister Mark Durkan said: “In Northern Ireland Environment Agency’s view this practice presented no plausible risk to people or the environment.
“The Public Health Agency (PHA) has been consulted and shares this view in respect of human health.”
A government file released under the 30-year rule highlighted the historical disposal of radioactive substances at landfill sites at Culmore in Derry and Duncrue Street in Belfast.
It included a response to a parliamentary question on the subject in November 1983.
Whilst this information was in the public domain like all parliamentary questions, its presence in a file which had been withheld appears to have led to concerns that the use of controlled burial was secret, today’s report said.
NIEA staff used information from archived files, radioactive waste reports and information provided by councils in Derry and Belfast.
Five landfills were authorised for controlled burial of low level radioactive waste, although archive information said only two were used.
The report said the material disposed of at Culmore and Duncrue need not have been subjected to the additional precautions associated with controlled burial but the approach taken was conservative.
Low level radioactive material was sent from Altnagelvin hospital to Culmore. It included small components from equipment used to generate a substance injected into patients for routine diagnostic tests.
Hospitals, universities and a small number of industrial premises were authorised to dispose of low level solid radioactive waste via controlled burial to Duncrue.
It included contaminated gloves, tissues, glassware, general laboratory items and components.
Equipment affected by naturally occurring radioactive material from the decommissioning of a fertiliser manufacturing plant were also deposited.
The report concluded disposals were carried out in accordance with the law and appropriate conditions were set at the time.
“There is evidence that a conservative approach was taken by regulators and by holders of authorisations,” it said.
“For example, materials were often decay stored for long periods and some materials were disposed of by controlled burial where the guidance suggests disposal along with ordinary refuse would have been acceptable at the time.”