Many of the substances we use in normal everyday life are found natural in the soil environment. However, some – and more and more – substances are artificially made and can be called ”injurious to the environment”. Spillage of natural as well as artificial substances can cause contamination.
But when are we actually talking about ”contamination”? Simplified you can say that a contamination is characterized by the fact that ”there is too much of a certain substance”. Risk assessment of a contamination must show when it is “too much”. All living organisms must for instance have a certain amount of salt to stay alive, however, if we get too much we cannot thrive or we may die.
Many substances limit values are given based on investigations of how much we can tolerate, whereas for other substances the limits have been determined by politicians.
A risk assessment of a contamination is the synthesis of thorough investigations of the factual distribution and concentration of the contamination, assessments of future distribution as well as the characteristics of the substances and impact on the environment. Risk assessment, therefore, builds on many factors – for instance geological, hydrogeological, building technical, chemical, biological and toxicological aspects – which all must be investigated and assessed.
In other words the total assessment is often complex and therefore calculation models are used, if possible. However, no models can describe reality completely. The technical assessment, based on years of experience is, therefore, a crucial factor when an adequate and reliable risk assessment must be made.