Evaluation of Cadmium Transfer from Soil to the Human Body Through Maize Consumption in a Cadmium Anomaly Area of Southwestern China

Abstract

Evaluating the bioavailability, bioaccessibility, and transferability of cadmium (Cd) in soil-grain-human systems is essential in areas with a Cd anomaly in the karst region of southwestern China. In the present study, the main controlling factors and prediction models for Cd transfer in a soil-grain-human system were investigated in a typical area where natural processes and anthropogenic activities interact in the karst region of southwestern China. The environmental availability of Cd (diethylenetriaminepentaacetic acid-and CaCl 2 -extractable Cd [Cd CaCl2 ]) in the soil varies significantly because of the diversity of soil properties. However, Cd concentrations in the maize grain were significantly related only to the Cd CaCl2 concentrations in the soil (r = 0.595, p < 0.01), indicating that soil Cd CaCl2 is a good indicator for evaluating Cd uptake by maize grain. Of all the measured soil properties, the soil cation exchange capacity (CEC) and the soil calcium (Ca soil ) were the most important factors influencing Cd accumulation in the soil-maize grain system. A transfer model combining Cd CaCl2 , soil CEC, and Ca soil was sufficiently reliable for predicting Cd accumulation in the maize grain (R 2 = 0.505). Although there is room for improvement regarding the prediction performance of the chain model combining soil Cd CaCl2 with Ca soil to predict the bioaccessible Cd concentration in maize grain (R 2 = 0.344 for the gastric phase and R 2 = 0.356 for the gastrointestinal phase), our findings provide a useful reference to further explore a model that can be used for a relatively rapid and reliable estimation of dietary Cd exposure for specific regions prior to crop harvest.