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To test high cadmium (Cd) concentration may not be high in health risk when considering Cd bioavailability, we assessed variation of Cd relative bioavailability (RBA, relative to CdCl2) using a mouse assay for 14 vegetables of water spinach, amaranth, and pakchoi. Cadmium concentration varied from 0.13 ± 0.01–0.37 ± 0.00 μg g–1 fw. Cadmium-RBA also varied significantly from 22.9 ± 2.12–77.2 ± 4.46%, however, the variation was overall opposite to that of Cd concentration, as indicated by a strong negative correlation between Cd-RBA and Cd concentration (R2 = 0.43). Based on both Cd concentration and bioavailability, the identified high-Cd pakchoi variety resulted in significantly lower Cd intake than the high-Cd varieties of water spinach and amaranth (4.74 ± 0.05 vs. 10.1 ± 0.54 and 8.03 ± 0.04 μg kg–1 bw week–1) due to significantly lower Cd-RBA (22.9 ± 2.12 vs. 77.2 ± 4.46 and 51.3 ± 2.93%). The lower Cd-RBA in pakchoi was due to its significantly higher Ca and lower phytate concentrations, which facilitated the role of Ca in inhibiting intestinal Cd absorption. This was ascertained by observation of decreased Cd-RBA (90.5 ± 12.0% to 63.5 ± 5.53%) for a water spinach when elevating its Ca concentration by 30% with foliar Ca application. Our results suggest that to assess food Cd risk, both total Cd and Cd bioavailability should be considered. Refereed/Peer-reviewed

Soils are often co-contaminated with As, Pb, and Cd. To what extent ingested metal(loid)s interact with each other in the gastrointestinal tract and influence their RBA (relative bioavailability) is largely unknown. Three soils predominantly contaminated with As (MS, mining/smelting impacted), Pb (WR, wire rope production impacted), and Cd (EP, enamel pottery production impacted) were administered to mice individually or in binary and tertiary combinations with sodium arsenate, Cd chloride, and/or Pb acetate. In binary combinations, 10-fold higher Pb addition decreased As-RBA in MS (26.0 ± 6.28% to 17.1 ± 1.08%), while 10-fold higher As addition decreased Pb-RBA in WR (61.3 ± 2.41% to 28.8 ± 5.45%). This was possibly due to the formation of insoluble Pb arsenate in mouse intestinal tract, as indicated by the formation of precipitates when As and Pb co-occurred in water or simulated human gastrointestinal fluids. Due to competition for shared absorption transporters, 10- A nd 100-fold higher Pb addition decreased Cd-RBA in EP (95.8 ± 12.9% to 67.8 ± 12.8% and 62.8 ± 8.24%). Tertiary combinations showed that interactions between two metal(loid)s were affected by the presence of the third metal(loid). Our study suggests that As oxyanion could interact with Pb or Cd ions in the mouse gastrointestinal tract, and the interactions vary depending on concentration and solution characteristics Refereed/Peer-reviewed

To determine the effectiveness of mineral dietary supplements to modulate cadmium (Cd) exposure, an in vivo mouse bioassay was conducted to determine Cd relative bioavailability (Cd-RBA) in Cd-contaminated rice (0.80 mg Cd kg(-1)) with and without Zn, Fe, or Ca supplements as nitrate or chloride salts. Without mineral supplements, Cd-RBA was 43 +/- 5.3% based on average Cd accumulation in the liver plus kidneys as the end point. Among Ca(NO3)(2), Zn(NO3)(2), and Fe(NO3)(2) supplements, 150-5000 mg kg(-1) Ca was the most effective in reducing rice Cd-RBA by 31-80% to 8.5-29%, while 30-200 mg kg(-1) Zn supplements was ineffective, with Cd-RBA being 33-57%. Low Fe at