Citation:

Kastury, F., S. Placitu, J. Boland, R. Karna, Kirk G. Scheckel, E. Smith, AND A. Juhasz. Relationship between Pb relative bioavailability and bioaccessibility in phosphate amended soil: Uncertainty associated with predicting Pb immobilization efficacy using in vitro assays. ENVIRONMENT INTERNATIONAL. Elsevier B.V., Amsterdam, Netherlands, 131:104967, (2019). https://doi.org/10.1016/j.envint.2019.104967

Impact/Purpose:

Lead (Pb) exposure from incidental soil ingestion is a significant global concern due to its negative impact on neurological and cognitive development in children. Pb immobilisation via phosphate treatment is an in-situ remediation strategy that has been documented to reduce Pb exposure in humans, swine, minipig, rats and mice. Phosphate amendments may promote the formation of Pb-phosphate species (e.g. pyromorphites and tertiary Pb phosphates), which exhibit low solubility in the acidic conditions of the stomach, thereby limiting absorption in the small intestines. It has also been suggested that if Pb-phosphates are not formed in-situ, they may form in-vivo following solubilisation of Pb and phosphate in the stomach and reaction in the small intestines. This study was conducted to explore an IVIVC between Pb RBA and IVBA. In order to achieve this aim, mining/smelting impacted soil from Broken Hill was treated with phosphate and the Pb RBA and IVBA was assessed. This data, in conjunction with data from Juhasz et al. (2016), was used in linear regression models to investigate if a predictive relationship exists between Pb RBA and IVBA for assessing the efficacy of phosphate amended soils.

Description:

In this study, an in vitro in vivo correlation (IVIVC) between Pb in vitro bioaccessibility (IVBA) and relative bioavailability (RBA) was explored to determine whether the efficacy of Pb immobilization in phosphate amended soils could be predicted using an in vitro approach. Mining/smelting impacted soil from Broken Hill, Australia (582–3536 mg/kg of Pb in the 1000 mg/kg Pb while treatment effect ratios of 0.89–0.99 (SBRC-G), 0.09–0.71 (SBRC-I) and 0.27–0.80 (RBA) were observed in PA amended soil (Pb:P = 1:5). Although significant (p < 0.05) correlation were obtained between Pb RBA and IVBA (%) determined using SBRC-G (r = 0.64) and SBRC-I (r = 0.67), the strengths of the relationships were weak (r2 = 0.41–0.45). This research highlights the complexities associated with the prediction of Pb RBA in phosphate amended soil.

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