Applying Cadmium Relative Bioavailability to Assess Dietary Intake from Rice to Predict Cadmium Urinary Excretion in Nonsmokers

Dietary Cd intake is often estimated without considering Cd bioavailability. Measured urinary Cd for a cohort of 119 nonsmokers with rice as a staple was compared to predicted values from rice-Cd intake with and without considering Cd relative bioavailability (RBA) in rice based on a steady state mouse kidney bioassay and toxicokinetic model. The geometric mean (GM) of urinary Cd and β2-microglobulin was 1.08 and 234 μg g–1 creatinine. Applying Cd–RBA in foods to aggregate Cd intake (41.5 ± 12.4, 48.0 ± 9.3, 48.8 ± 21.3% for rice, wheat, and vegetables), rice was the largest contributor (71%). For 63 participants providing paired urine and rice samples, the predicted GM of urinary Cd at 4.14 μg g–1 based on total Cd in rice was 3.5 times that of measured value at 1.20 μg g–1, while incorporating Cd–RBA to assess rice-Cd intake made the two closer with GM at 1.07 μg g–1. The cohort findings were extended to a national scale, with urinary Cd for nonsmokers from rice Cd intake was mapped at province/city levels after considering rice Cd–RBA. Therefore, incorporating Cd bioavailability to assess dietary Cd intake is a valuable tool to accurately estimate human Cd exposure and associated health risk.