Elements *Target value of soil (mg/kg) ***Permissible value of plant (mg/kg) Cd 0.8 0.02 Zn 50 0.60 Cu 36 10 Cr 100 1.30 Pb 85 2 Ni 35 10

*Target values are specified to indicate desirable maximum levels of elements in unpolluted soils Source: Denneman and Robberse 1990; Ministry of Housing, Netherlands 1994 ***Source: WHO (1996)

Table 11: WHO permissible limits for heavy metals in plant and soil.