Impact of soils amended with Zn and Pb smelter dust on Cd concentrations in potatoes

A major exposure route of cadmium (Cd) to humans is via consumption of polluted plants. In particular, Cd concentrations in potatoes need to be monitored because they comprise a major proportion of the daily diet of adults in several countries. In field experiments potatoes were grown on soils (medium sand, pH similar to 7, and soil organic matter (SOM) 0.8%), to which Zn-Pb smelter dust was added to produce Cd concentrations of 3 to 106 mg/kg. The yield of potato tubers did not decrease at 3 mg/kg Cd in soil, the accepted ''Maximum Cumulative Amount (MCA)''. All experimental plots with Cd concentrations above 3 mg/kg produced lower potato yields with increasing Cd levels. The Cd concentration in potato tubers was only below the acceptable threshold value (ATV < 0.15 mg/kg) in potatoes from the control plots. In all the other plots, potato tubers, both peeled and unpeeled, contained increased levels of Cd above the ATV value. This was also observed on soil with 3 mg/kg Cd (MCA) and a relatively high pH. The MCA value of 3 mg/kg Cd should be revised especially for light mineral soils, as has been proposed recently by the European Economic Community and in Poland.