Food crop accumulation and bioavailability assessment for antimony (Sb) compared with arsenic (As) in contaminated soils

Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was < 10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75 +/- 0.52 mu g L-1) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was < 7 % for total As and < 3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.