Soils in Switzerland are protected by the environmental protection law. The ultimate purpose of the ordinance relating to impacts on the soil (OIS), dating from July 1998, is the long-term preservation of soil fertility. Soil contamination by hazardous inorganic substances is assessed according to a three-tier system, defined by guide, test and remediation values. All trace elements listed in the OIS are components of natural bedrock, occurring in any soil. The guide values refer strongly to the soil fertility, as defined in the ordinance. However, in contrast to the soil fertility, which is related to the site and soil conditions, the guide values are valid for all sites and soil uses. This makes it difficult to justify the measures to be taken (i.e. preventive emission control) once the guide values have been exceeded. Such measures make sense only if we can distinguish between the natural and the anthropogenic origins of the contaminants. Alternatively, the soil protection could be based on the test or remediation values mentioned above. Presently, however, the database in the OIS is too limited for such a change. This implies further research in the fields of soil chemistry and effect-oriented biology.