Independent Consultant, Laguna Woods, CA, United States.
ICF, Inc., Durham, NC, United States.
Environ Int. 2023 Aug;178:107983. doi: 10.1016/j.envint.2023.107983. Epub 2023 May 30.
Historically, soil ingestion rate estimates were based on trace element-based mass balance (MB) study results. These were used in assessing exposures and health risks for children residing in Superfund or chemically contaminated communities. However, soil and dust can have considerable differences with respect to their sources, chemical, physical, and toxicological characteristics. Unfortunately, the MB approach is incapable of disentangling dust ingestion rates from soil ingestion rates. Alternative methods, such as activity pattern and biokinetic modeling techniques, have also been used to predict soil and dust ingestion rates. The results from these studies differed from those obtained from the MB studies. This research evaluated the MB methodology and formulated a physical model which characterized the environmental and behavioral determinants of soil and dust ingestion exposures by children. This new approach explicitly separates outdoor soil exposures from the indoor tracked-in soil portion of the dust and total dust exposures by utilizing information from five key MB studies along with new information derived from the SHEDS-Soil/Dust time-activity pattern-based modeling runs. Application of this new hybrid methodology showed that the predicted mean soil ingestion rates are 30%-70% less than the "total soil" ingestion rates obtained from the selected MB studies. In contrast, most of the predicted dust ingestion rate estimates were typically greater than the predicted soil ingestion rates. Moreover, the predicted total soil plus dust ingestion rates were found to be mostly higher (by ≤ 60%) than the MB-based "total soil" ingestion rates. Except for one study these results were higher than the results produced by the stand-alone SHEDS-Soil/Dust model runs. Across the MB studies analyzed, predicted outdoor soil ingestion rate contributions to "total soil" ingestion rates varied between 29% and 70% while the tracked-in soil portion of the indoor dust ingestion rates varied between 30% and 71%.
从历史上看，土壤摄入量的估计是基于微量元素的质量平衡 (MB) 研究结果。这些结果用于评估居住在超级基金或化学污染社区的儿童的暴露和健康风险。然而，土壤和灰尘在来源、化学、物理和毒理学特性方面可能有很大的差异。不幸的是，MB 方法无法将灰尘摄入量与土壤摄入量区分开来。替代方法，如活动模式和生物动力学建模技术，也被用于预测土壤和灰尘摄入量。这些研究的结果与 MB 研究的结果不同。本研究评估了 MB 方法，并制定了一个物理模型，该模型描述了儿童土壤和灰尘摄入暴露的环境和行为决定因素。这种新方法通过利用来自五项关键 MB 研究的信息以及来自 SHEDS-Soil/Dust 基于时间活动模式的建模运行的新信息，明确将室外土壤暴露与室内追踪土壤部分的灰尘和总灰尘暴露区分开来。这种新的混合方法的应用表明，预测的平均土壤摄入量比从选定的 MB 研究中获得的“总土壤”摄入量低 30%-70%。相比之下，大多数预测的灰尘摄入量估计值通常大于预测的土壤摄入量。此外，发现预测的总土壤加灰尘摄入量大多高于基于 MB 的“总土壤”摄入量（≤60%）。除了一项研究外，这些结果都高于独立的 SHEDS-Soil/Dust 模型运行产生的结果。在分析的 MB 研究中，预测的室外土壤摄入量对“总土壤”摄入量的贡献在 29%至 70%之间变化，而室内灰尘摄入量的追踪土壤部分在 30%至 71%之间变化。
