What Is a Guideline Value

Guideline values have embedded in them policy decisions on acceptable levels of risk which may have been made taking costs and benefits into account.13 

Unlike a fish out of water, a table of guideline values separated from its explanatory text does not die. Instead it takes on a new, unintentional and often undesirable life of its own. The numbers therein take on a significance far in excess of that for which they were intended contexts are lost, boundaries are forgotten and interpretations of exceedance become irrelevant. In the attempt to speed up, simplify or reduce the cost of risk assessment the magic number reigns. 

For example in recent years in the UK exceedance of the ICRCL threshold levels for metals and arsenic have been wrongly interpreted as indicating the need for remediation. 

It cannot be overemphasised that the use of non-UK values should only be countenanced if on a site-specific basis the values can be shown to be appropriate and protective of the relevant receptor(s) of concern. 

Ferguson and J. Denner, Developing Guideline (Trigger) Values for Contaminants in Soil Underlying Risk Analysis and Risk Management Concepts, Land Contam. Reclam., 1994,2,117-123. 

---