The objective of the present study was to derive a Ni bioaccessibility value for screening-level risk assessment of Ni substances in ingested materials including soils where multiple Ni substances are expected but not definitively identified. Broad ranges of Ni mass loading and dissolution time of a simple gastric assay were applied to pure Ni substances (removing the confounding factors of soil constituents on dissolution), thus broadening the applicability of the conclusions. The data were also used to support current knowledge of 'read across' for Ni substances. Release of Ni from pure manufactured Ni substances (Ni metal, NiO, NiSO4, Ni3S2, and NiS) was determined relative to Ni mass and substance surface area loading. Mass loadings ranged from 0.33 to 20.0 g Ni per L of 0.15 M HCl, and dissolution time ranged from 1 to 168 h. Proton exhaustion was indicated only at the highest loading (20 g/L) of NiO and Ni-M. Dissolution of substances other than NiSO4 was most likely limited by formation of intermediate products at the particle surface or particle agglomeration, impeding access to the principal Ni substance. The bioaccessibility of Ni for these substances was consistent with previously published data: substances other than NiSO4 were < 48% bioaccessible for a variety of gastric assays, which is much lower than all data for NiSO4, the usual reference substance. Thus, we suggest that Ni bioaccessibility data from gastric assays that are most relevant to human exposure can be relied upon to develop scientifically sound screening-level human health RA decisions for Ni contamination in soils and sediments in the absence of detailed Ni speciation.

中文翻译：

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推导 Ni 生物可及性值，用于对包括土壤在内的摄入材料中的 Ni 物质进行筛选级风险评估。

本研究的目的是推导出 Ni 生物可及性值，用于对摄入材料中的 Ni 物质进行筛查级风险评估，包括预计多种 Ni 物质但未明确鉴定的土壤。对纯 Ni 物质应用了广泛的 Ni 质量负载和溶解时间的简单胃测定（去除了土壤成分对溶解的混杂因素），从而拓宽了结论的适用性。这些数据还用于支持当前对 Ni 物质“阅读”的知识。相对于 Ni 质量和物质表面积负载量确定从纯制造的 Ni 物质（Ni 金属、NiO、NiSO4、Ni3S2 和 NiS）中释放的 Ni。每升 0.15 M HCl 的质量负载范围为 0.33 至 20.0 g Ni，溶解时间范围为 1 至 168 小时。仅在 NiO 和 Ni-M 的最高负载量 (20 g/L) 下表明质子耗尽。NiSO4 以外的物质的溶解很可能受到颗粒表面中间产物形成或颗粒团聚的限制，从而阻碍了对主要 Ni 物质的获取。Ni 对这些物质的生物可及性与之前公布的数据一致：对于各种胃检测，除 NiSO4 以外的物质的生物可及性 < 48%，这远低于常用参考物质 NiSO4 的所有数据。因此，我们建议在没有详细 Ni 形态的情况下，可以依赖与人类暴露最相关的胃检测中的 Ni 生物可及性数据来制定科学合理的筛查水平的人类健康 RA 决策，以检测土壤和沉积物中的 Ni 污染。