CADMIUM IN AUSTRALIAN POTATO-TUBERS AND SOILS

Cadmium (Cd) has been identified as a potential contaminant in Foods p osing health risks to humans and, in Australia, potatoes (Solanum tube rosum L.) have been identified as contributing a large proportion of t he average dietary Cd intake. To assess the concentrations of Cd in Au stralian potatoes and soil factors likely to lead to high Cd concentra tions, commercial crops and soils were sampled at 352 sites throughout potato production areas in Australia. Across all states, fresh weight (FW) tuber Cd concentrations ranged from 0.004 to 0.232 mg kg(-1) wit h an overall mean value of 0.041 and a median of 0.033 mg kg(-1) (FW). Approximately 92 samples out of 359 (25.6%) exceeded the current maxi mum permitted concentration (MPC) of 0.05 mg kg(-1) (FW) and 18 (5.0%) exceeded 0.1 mg kg(-1) (FW). Concentrations of Cd (EDTA-extractable) in topsoils ranged from 0.01 to 0.59 mg kg(-1) with mean and median va lues of 0.14 and 0.10 mg kg(-1), respectively. There was no relationsh ip between Cd concentrations in soil and tubers. Stepwise forward mult iple regression analysis of the data indicated that Cl and Zn concentr ations in the topsoil, soil pH, and potato cultivar accounted for 57% of the variation in tuber Cd concentrations, with Cl being the dominan t factor. Comparison of soil-plant transfer coefficients (TCs) for Cd with limited international data sets suggests that TCs for Australian soils used for potato production are relatively high.