FIGURE 1
Conceptual Framework Illustrating Integration of Historical Reconstruction and Toxicokinetic Modeling
Note. Scientists use environmental modeling (e.g., groundwater, fate and transport, water distribution) to estimate past concentrations of chemicals of concern. They can then feed the concentrations into TK models to estimate internal dose and support public health decisions. ATSDR = Agency for Toxic Substances and Disease Registry.
els simulate how chemicals are absorbed, distributed, metabolized, and eliminated, allowing estimation of concentrations in blood and tissues (Boone et al., 2025). Per- and polyfluoroalkyl substances (PFAS) TK models further allow estimation of individual serum levels based on exposure and life-his- tory characteristics (Lynch et al., 2023). Applications in Communities The integration of HR and TK modeling has been instrumental in evaluating real-world exposure scenarios and supporting affected communities. One of the most well-known applications is the reconstruction of his- torical drinking water contamination at U.S. Marine Corps Base Camp Lejeune. ATSDR scientists estimated monthly contaminant
concentrations over several decades, enabling epidemiologic studies that identified associa- tions between exposure and adverse health outcomes, and supported clinical and health- related decisions for exposed populations (Maslia et al., 2013; Ruckart et al., 2013). Beyond Camp Lejeune, ATSDR has applied these approaches in a growing number of communities negatively impacted by emerg- ing contaminants such as PFAS. In these set- tings, HR methods are used to reconstruct past drinking water concentrations, while TK models estimate internal doses and serum levels. These combined approaches allow sci- entists to evaluate cumulative exposures over time, even when contamination has been mitigated or monitoring begins after peak exposure periods.
Multisite PFAS investigations further dem- onstrate how these tools can be applied at scale. By integrating reconstructed environ- mental concentrations with biomonitoring data and participant life history information, ATSDR and its partners can better character- ize exposure variability across populations and identify groups at higher risk (Lynch et al., 2023; Pavuk et al., 2025). Importantly, these studies also provide a framework for linking exposure data with clinical and epi- demiologic outcomes, strengthening the evi- dence base for public health action. Equally important, HR and TK modeling support community engagement. Residents often seek answers about past exposures that direct measurement alone cannot address. By reconstructing exposure histories and
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November 2026 • Journal of Environmental Health
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