Cylinders of a highly volatile poisonous liquid were disposed of safely in South Dublin today with the help of US environment experts.

The seven containers of hydrogen cyanide (HCN) were successfully chemically neutralised without the use of any explosives.

The chemical is commonly listed amongst chemical warfare agents that cause general poisoning and was most infamously employed by the Nazi regime under the brand name Zyklon B.

A tiny amount in the air – just 300mgs per cubic metre – would kill a person in minutes. The toxicity is caused by the cyanide ion, which prevents cellular respiration.

The cylinders had been stored at the pest control company Rentokil and were moved to the county council owned compound at Grange Castle, Co Dublin for the neutralisation.

US company Integrated Environmental Services (IES), specialists in on-site management of waste compressed gas cylinders, undertook the project. The firm said there was no risk to the public during the operation and the nearby golf course was closed during the neutralising process.

Four IES personnel travelled from Atlanta and used specialist equipment flown in from the US to carry out the safe disposal procedure.

Senior Executive Officer at South Dublin County Council John Quinlivan said: “We are delighted with the way IES conducted the process. We were satisfied from the start that |the content of the cylinders could be disposed of safely, without risk to the public and we can confirm this now.

“It had been intended to utilise the Army rifle range in Co Wicklow and to use explosives to dispose of the contents of the cylinders, but when IES x-rayed the cylinders they found they were “substantially more stable than was anticipated” and recommended the first option should be to chemically neutralise the contents.”

The Environmental Protection Agency (EPA) was alerted to the plan in advance of the operation.

South Dublin County Council organised the safe disposal of the waste after a request from Rentokil.

South Dublin County Council will publish details of the work done by IES as part of a case history and it will be available to other local authorities and other agencies.