Soil Guideline Values (SGVs) are figures which are used in non-statutory technical guidance for assessors carrying out risk assessments to determine whether land is considered "contaminated" under United Kingdom law, that is "land which appears to... be in such a condition, by reason of substances in, on or under the land, that (a) significant harm is being caused or there is a significant possibility of such harm being caused..."[1] This guidance stipulates three stages in such risk assessments: Soil Guideline Values are used in the second stage, GQRA, to determine whether harm caused by long-term exposure to a given soil concentration of chemicals may present an unacceptable risk to human health in some generic land-use scenario.
However, there are no currently valid SGVs for many important and common elements, such as copper, zinc, lead or chromium.
The only body mandated to produce these values is the Environment Agency, following extensive consultation with other government departments.
In lieu of such figures, equivalent values known as "Generic Assessment Criteria" (GAC) may be calculated by any individual or organisation, starting from toxicity and relevant data and using the CLEA model, just as the Environment Agency calculates SGVs.
For example, in the case of a playing field, it could be argued that the residential scenario is suitably conservative: