In Vitro Gastrointestinal Method To Estimate Relative Bioavailable Cadmium in Contaminated Soil

The capacity of an in vitro gastrointestinal (IVG) method to predict relative bioavailable Cd from soil ingestion was evaluated. Bioaccessible Cd determined by the IVG method was compared with relative bioavailable Cd measured from dosing trials using juvenile swine for 10 soils contaminated with Cd from 23.8 to 465 mg kg-1. The effect of the food-dosing vehicle (i.e., dough) in the IVG method was evaluated. Bioaccessible Cd was measured in the gastric extraction and intestinal extraction steps of the IVG method. Means for bioaccessible Cd, in parentheses, fell in the following order: gastric extraction step without dough (63.0%) > intestinal extraction step without dough (39.1%) > gastric extraction step with dough (38.2%) > intestinal extraction step with dough (12.9%). It is possible that phytic acid associated with the addition of dough decreased bioaccessible Cd. In vivo relative bioavailable Cd ranged from 10.4 to 116% with a mean of 63.4%. Linear relationships between the IVG gastric extraction step without dough (r = 0.86), the IVG intestinal extraction step with dough (r = 0.80), and the in vivo relative bioavailable Cd were found. Inexpensive in vitro methods might be useful in estimating the relative biovailability of Cd in soils from contaminated sites.