[Establishing maximum permissible values in soil for health protection with the Lur model]

Environmental pollution can be the origin of health problems and it is seen by populations as a hazard. Therefore, when environmental maximum levels of contaminants are set it is necessary to guarantee public health protection and to promote a healthy environment. In the Basque Autonomous Community (Spain) the establishment of maximum levels of contaminants in soil has followed the model named LUR, based on the risk assessment methodology. These values are levels of pollutant that are supposed not to represent an unacceptable risk for human beings.

Maximum levels of contaminants in soil arise from establishing a maximum tolerable risk and assessing toxicity information and human exposure in relation to land uses. The model has considered 5 land uses for exposure: children playground, residential with garden, residential, public park and industrial/commercial. The routes of exposure taken into account have been soil ingestion, consumption of home-grown vegetables, soil particle and vapour inhalation and dermal absorption. When inhalation and dermal absorption contribute largely to contaminant intake, standards are less robust because uncertainty in exposure assessment in these cases is high.

The results of applying this methodology to the case of two contaminants are presented: cadmium, as a non carcinogenic inorganic contaminant, and benzo(a)pyrene, as a carcinogenic organic contaminant. Limitations of the methodology are discussed.