受高背景土壤重金属的影响，我国西南碳酸盐岩出露地区农产品镉超标现象非常普遍。同时，受益于土壤中丰富的钙质营养，农产品兼具了高钙的特征。钙和镉互为拮抗，能在一定程度上决定其生物有效性，降低镉在农产品中的健康风险。基于此，本项研究拟应用体外模拟试验，观测该区域主要农产品钙/镉在口腔、胃和肠道中的溶出率，用以评价这些农产品的最大健康风险；应用Caco-2细胞模拟人体吸收过程，以钙/镉的化学计量比和浓度为主线，观测单一农产品，以及依据人群进食习惯构成的不同食源组合和配比条件下，钙/镉化学计量关系对其人体生物有效性的指示程度；进一步通过调节农产品肠道溶出液钙/镉离子的比例，观测钙/镉离子吸附容量和转运速率的变化，构建碳酸盐岩出露地区农产品中钙/镉化学计量关系与其人体生物有效性的拟合模型。该项研究的实施可为科学评价碳酸盐岩出露区域农产品的人体健康风险提供依据，为制定区域性农产品安全质量标准提供支撑。

With high heavy metal background soils, the phenomenon of Cd exceeding the national standard of agricultural products is very common in carbonate rocks outcrop area of Southwest China. At the same time, agricultural products have the characteristics of high calcium conducing to rich calcium nutrition in the soil. Ca and Cd are mutually antagonistic, which can determine their bioavailability to a certain extent and reduce the health risks of Cd in agricultural products. Based on this, this study is going to use in vitro simulation tests to observe the dissolution rate of Ca/Cd of major agricultural products in the oral, gastric and intestinal tract and further to evaluate the maximum health risks of these agricultural products; Caco-2 cells will be employed to simulate the process of human absorption. To recognize the influence of Ca/Cd stoichiometry on bioavailability of Ca/Cd, the stoichiometric ratio and of Ca/Cd concentration will be observed in a single agricultural product or mixed different foods based on the eating habits of the population. The model on the relationship between Ca/Cd bioavailability and Ca/Cd stoichiometry will be established by adjusting the ratio of Ca/Cd ions in the intestinal tract of agricultural products. The implementation of this project can provide a basis for scientific evaluation of human health risks of agricultural products in carbonate rock outcrop areas, and get foundation for the development of regional agricultural safety quality standards.