Soil-plant transfer of organic chemicals and derivation of trigger values

The Federal Soil Protection Act [Anonymus, 1998] was technically realized by the Federal Soil Protection and Contaminated Sites Ordinance (BBodSchV) of July 12th, 1999. Precautionary values and trigger values as laid down in the Law(1) are an important instrument to realise its requirements. Trigger values are related to various soil uses and objectives of protection, which are "human health", "quality of food and feed", and "leachate to ground-water". Any procedure to derive trigger values for the objective "quality of food and feed" has to consider the soil-plant transfer of chemicals for soils under agricultural use and household gardens. Thus, the production function of soil is taken into account. The exact procedure to obtain trigger values for "quality of food and feed" is explained. By this means, trigger values for "quality of food and feed" already were derived for some metal compounds, namely arsenic, lead, mercury and thallium. Beside metal compounds several organic substances are also of priority; for example, a trigger value for benzo(a)pyrene and an action value for PCBs has to be defined. The pathway soil-plant is a sensible exposure route due to potential accumulation in the food chain. A summary on the methodology and results of trigger value derivation for some selected organic chemicals previously used as pesticides and of different data sizes with respect to the soil-plant transfer process is given.