DEVELOPERS who intend to build family homes on toxic land in Greenock have sensationally admitted 'assurances' given to the Scottish Government about the safety of the site were not true.

Link Group Ltd had previously refused to answer questions over claims that dangerous and cancer-causing poisons in the ground were 'not leachable or soluble and will not migrate horizontally'.

Now — following a Greenock Telegraph investigation — Link, set to receive £15m of public money for developing the former Ravenscraig Hospital land it bought for £1, has conceded that advice was incorrect.

The admission comes after we contacted contamination expert Professor Andrew Watterson, who debunked the safety claims — which had been repeated in official government correspondence.

Link insisted last night that the 83-acre site — which has planning permission for 198 social homes — poses a 'low risk' and that the existence of harmful toxins is not 'overly concerning'.

But respected academic Professor Watterson told the Telegraph: "As there is no safe level established for exposure of humans to any carcinogens, and some of these are also known to be linked to oestrogen disruption at very low levels, the preferred remediation policy should be to ensure no exposure.

"If this cannot be achieved and guaranteed in the long-term, then there are strong arguments for not developing such sites, however low the estimates of risks to human health are."

Local government, housing and planning minister Kevin Stewart repeated Link's safety claims about the contaminants in a letter which came to the Telegraph's attention last month.

Professor Watterson, of the University of Stirling, said: "My understanding is that under various conditions and exposure to various environmental factors, some of the heavy metals found on the site would be leachable.

"In some circumstances they would be soluble and in some circumstances capable of migration."

The government says that Link provided the 'assurances' which led to Mr Stewart repeating them in correspondence with Inverclyde MSP Stuart McMillan in February.

Among confirmed 'multiple exceedances' of pollutants found within the ground are cadmium, mercury, arsenic and lead.

Professor Watterson said that a plan to have capping layers of 'strong synthetic fabric' on the ground 'will have a finite life'.

He added: "There could be extreme conditions...that could damage or breach containment measures, as could site maintenance and alterations."

The professor says there must be 'effective site monitoring and not one-off site verification which applies to remediated sites at the moment', saying that this would 'document the effectiveness of the site remediation for years and decades to come'.

He said: "I think there are some Scottish-wide issues arising from both the Ravenscraig proposed development and Coatbridge schools linked to this that merit much further investigation."

Professor Watterson based his comments on the Telegraph's coverage of the Ravenscraig matter, correspondence between councillors and other politicians, as well Inverclyde Council documents.

He said: "There is no such thing as capping and containment that will last forever.

"Membranes and materials used to 'seal in' contaminants will invariably fail at some stage or be damaged and prove less effective.

"Recent research has begun, for example, to reveal that groundwater contamination due to failed membranes may not necessarily present a short-term problem in the first decade, or even the second, but the risk assessment of containment will change significantly for the worse over the middle and long term."

A Link spokesman said: "Yes, heavy metals, like the majority of other commonly found contaminants would be leachable in certain conditions and potentially capable of migration and that is the primary reason the undertaking of water environment risk assessments is a key part of the ground investigation, testing, monitoring and interpretative reporting process required to satisfy planning requirements for any form of new development.

"There are numerous site-specific factors to be taken into consideration including but not limited to the permeability of the underlying geology, the spatial distribution of any contaminants recorded within the soil, the depth to groundwater and the distance to surface water receptors.

"The post-demolition investigations have included a wide range of water environment related testing which are utilised to inform the site-specific risk assessment which to date is indicating there to be a low risk to the water environment.

"The existence of these potentially leachable contaminants is neither an unusual or overly concerning situation, since the majority, if not all residential housing sites that are developed in Scotland are similarly affected to a greater or lesser degree compared to the former Ravenscraig Hospital site."

The government says it is for the council to determine whether Link's remediation strategy — which does not involve removal of soil — 'is fit for purpose'.