A simplified model for simulating lifetime accumulation of persistent organic pollutants in humans with steady-state identification

Abstract

Persistent organic pollutants (POPs) have posed a significant threat to global public health for decades. The ongoing exposure in the pre-and postban periods has created significant knowledge gaps in assessing the long-term health effects of POPs. In this study, we developed a simplified human accumulation load (HAL) model to simulate POP accumulation across general, individual, and intergenerational levels through seven scenarios. The steady-state was rigorously quantified by knee point (the point of maximum curvature in accumulation curves), reached in 6.11 years, and a ΔHAL: I_AMT (intake amount) ratio < 1 %, reached in 6.64 years, for a POP with 1-year half-life at 10 ng daily intake. General-level simulations over 100 years showed that the timing of steady-state is determined solely by the half-life of POPs, while accumulation levels are shaped by intake amount, frequency and half-life. Individual-level simulations revealed that changes in intake or half-life result in accumulation curves converging to the same values. Intergenerational simulations for perfluorooctanoic acid (PFOA) revealed peak offspring serum concentrations of 4.48 ng mL⁻¹ (boys) and 4.36 ng mL⁻¹ (girls) after lactation. Over a decade was required to reach 0.2 ng mL⁻¹ , a safe biomonitoring equivalent. The model effectively elucidated the impact of background and ongoing exposure on biases in deriving POP half-life values in humans. The HAL model provides a robust tool for predicting stabilization post-emission reductions, aiding global strategies to manage these persistent contaminants effectively.